Chair of Forest Zoology and Entomology, Albert-Ludwigs-Universität Freiburg i.Br. Chair of Forest Zoology and Entomology
Albert-Ludwigs-Universität Freiburg i.Br.

Chair of Forest Zoology and Entomology
Freiburg i.Br.

List of Publications

Boppré M, Vane-Wright RI, Wickler W (2017) A hypothesis to explain accuracy of wasp resemblances. Ecol Evol 7:73-81 link

Mimicry is one of the oldest concepts in biology, but it still presents many puzzles and continues to be widely debated. Simulation of wasps with a yellow-black abdominal pattern by other insects (commonly called “wasp mimicry”) is traditionally considered a case of resemblance of unprofitable by profitable prey causing educated predators to avoid models and mimics to the advantage of both (Figure 1a). However, as wasps themselves are predators of insects, wasp mimicry can also be seen as a case of resemblance to one's own potential antagonist. We here propose an additional hypothesis to Batesian and Müllerian mimicry (both typically involving selection by learning vertebrate predators; cf. Table 1) that reflects another possible scenario for the evolution of multifold and in particular very accurate resemblances to wasps: an innate, visual inhibition of aggression among look-alike wasps, based on their social organization and high abundance. We argue that wasp species resembling each other need not only be Müllerian mutualists and that other insects resembling wasps need not only be Batesian mimics, but an innate ability of wasps to recognize each other during hunting is the driver in the evolution of a distinct kind of masquerade, in which model, mimic, and selecting agent belong to one or several species (Figure 1b). Wasp mimics resemble wasps not (only) to be mistaken by educated predators but rather, or in addition, to escape attack from their wasp models. Within a given ecosystem, there will be selection pressures leading to masquerade driven by wasps and/or to mimicry driven by other predators that have to learn to avoid them. Different pressures by guilds of these two types of selective agents could explain the widely differing fidelity with respect to the models in assemblages of yellow jackets and yellow jacket look-alikes.

Colegate SM, Gardner DR, Betz JM, Fischer OW, Liede-Schumann S, Boppré M (2016) Pro-toxic 1,2-dehydropyrrolizidine alkaloid esters, including unprecedented 10-membered macrocyclic diesters, in the medicinally-used Alafia cf. caudata and Amphineurion marginatum (Apocynaceae: Apocynoideae: Nerieae and Apocyneae). Phytochem Anal 17: 257-276 link

Introduction – Within the Apocynoideae (Apocynaceae) pro-toxic dehydropyrrolizidine alkaloids have been reported only in Echiteae. However, attraction of pyrrolizidine alkaloid-pharmacophagous insects suggested their presence in Alafia cf. caudata Stapf (Nerieae: Alafinae) and Amphineurion marginatum (Roxb.) D.J. Middleton (Apocyneae: Amphineuriinae), both used as medicinal plants.
Objective – To confirm the presence of dehydropyrrolizidine alkaloids in Alafia cf. caudata and Amphineurion marginatum and identify their structures.
Methods – Methanol extracts of air-dried roots, stems and leaves of non-flowering plantswere analysed using HPLC-ESI(+)MS and MS/MS or collision-induced dissociation MS in low and/or high resolution modes. Pyrrolizidine alkaloids were tentatively identified based on the mass spectrometry data. Solid phase extraction combinedwith semi-preparative HPLC were used to isolate major alkaloids. Structures were elucidated using NMR spectroscopy.
Results – Monoesters of retronecine with senecioic, hydroxysenecioic or syringic acids were identified in roots of Alafia cf. caudata. Two, unprecedented 10-membered macrocyclic dehydropyrrolizidine alkaloid diesters were isolated from roots of Amphineurion marginatum. Pyrrolizidine alkaloids were detected in root and leaf material of Alafia cf. caudata at 0.34 and 0.01% dry weight (DW), and 0.13, 0.02 and 0.09% DW in root, leaf and stem material of Amphineurion marginatum.
Conclusions – The presence of pro-toxic dehydropyrrolizidine alkaloids suggests that medical preparations of these plants pose potential health risks to consumers. Dehydropyrrolizidine alkaloids are evidently more widespread in Apocynoideae than previously assumed, and it would seem rewarding to study other members of this family for the presence of pyrrolizidines, dehydropyrrolizidines and dihydropyrrolizines.

Colegate SM, Boppré M, Monzón J, Betz JM (2015) Pro-toxic pyrrolizidine alkaloids in the traditional Andean herbal medicine "asmachilca". J Ethnopharmacol 172:179-194 link

Ethnopharmacological relevance: Asmachilca is a Peruvian medicinal herb preparation ostensibly derived from Aristeguietia gayana (Wedd.) R.M. King & H. Rob. (Asteraceae: Eupatorieae). Decoctions of the plant have a reported bronchodilation effect that is purported to be useful in the treatment of respiratory allergies, common cold and bronchial asthma. However, its attractiveness to pyrrolizidine alkaloid-pharmacophagous insects indicated a potential for toxicity for human consumers.
Aim of the study: To determine if commercial asmachilca samples, including fully processed herbal teas, contain potentially toxic 1,2-dehydropyrrolizidine alkaloids.
Materials and methods: Two brands of “Asmachilca” herbal tea bags and four other commercial samples of botanical materials for preparing asmachilca medicine were extracted and analyzed using HPLC-esi(+)MS and MS/MS for the characteristic retention times and mass spectra of known dehydropyrrolizidine alkaloids. Other suspected dehydropyrrolizidine alkaloids were tentatively identified based on MS/MS profiles and high resolution molecular weight determinations. Further structure elucidation of isolated alkaloids was based on 1D and 2D NMR spectroscopy.
Results: Asmachilca attracted many species of moths which are known to pharmacophagously gather dehydropyrrolizidine alkaloids. Analysis of 5 of the asmachilca samples revealed the major presence of the dehydropyrrolizidine alkaloid monoesters rinderine and supinine, and their N-oxides. The 6th sample was very similar but did not contain supinine or its N-oxide. Small quantities of other dehydropyrrolizidine alkaloid monoesters, including echinatine and intermedine, were also detected. In addition, two major metabolites, previously undescribed, were isolated and identified as dehydropyrrolizidine alkaloid monoesters with two “head-to-tail” linked viridifloric and/or trachelanthic acids. Estimates of total pyrrolizidine alkaloid and N-oxide content in the botanical components of asmachilca varied from 0.4 – 0.9% (w/dw, dry weight) based on equivalents of lycopsamine. The mean pyrrolizidine alkaloid content of a hot water infusion of a commercial asmachilca herbal tea bag was 2.2 ± 0.5 mg lycopsamine equivalents. Morphological and chemical evidence showed that asmachilca is prepared from different plant species.
Conclusions: All asmachilca samples and the herbal tea infusions contained toxicologicallyrelevant concentrations of pro-toxic 1,2-dehydropyrrolizidine alkaloid esters and, therefore, present a risk to the health of humans. This raises questions concerning the ongoing unrestricted availability of such products on the Peruvian and international market. In addition to medical surveys of consumers of asmachilca, in the context of chronic disease potentially associated with ingestion of the dehydropyrrolizidine alkaloids, the botanical origins of asmachilca preparations require detailed elucidation.

Boppré M (2015) Tropische Bärenspinner. Schön, überaus vielfältig und äußerst lehrreich. Pp 50–59 in Feest C, Kron C (Hrsg.) Regenwald. D-Darmstadt: Theiss. ISBN 978-3-8062-2799-4. PDF

Viele Bärenspinner gehören zu den schönen Nachtfaltern, farbenfroh, oft mit schillernden Flügel- und Körperpartien oder fast künstlich anmutenden Mustern. Auch für die Wissenschaft sind sie äußerst interessant: viele nutzen pflanzliche Gifte zum Schutz vor Feinden, ahmen andere Insekten nach, haben elaborierte Duftorgane, nutzen Duftstoffe als chemische Sprache oder produzieren Töne. Man weiß all das, obgleich bislang nur wenige der allein in der Neotropis weit mehr als 6000 Arten umfassenden Unterfamilie der Schmetterlinge (Lepidoptera) in einigen Details studiert worden sind – aber wohl die meisten Geheimnisse der Falter sind noch zu lüften. In diesem "Werkstattbericht" geht es um neue Befunde und um offene Fragen im Kontext grundsätzlicher Erkenntnisse, aber auch von Limitationen bei der praktischen Arbeit mit tropischen Nachtfaltern.

Tropical tiger moths. English translation; PDF available on request by mail.

Many tiger (wasp) moths (Arctiinae) belong to the nice moths: they are colourful, and often have iridescent parts on their wings and body, or almost artful-looking patterns. They are also highly interesting for science: many utilize plant toxins as protection against enemies, imitate well-fortified insects, possess greatly differentiated scent organs, use odours as chemical language or emit sound. Despite all of these findings, only a few species of this subfamily of the order Lepidoptera (butterflies and moths) – with more than 6,000 species only in the neotropics – have been studied in any detail – and most of their secrets are probably yet to be disclosed. This „workshop report“ addresses new findings and open questions in the context of general insights, and also the limitations and challenges of practical work with tropical insects.

Arctidos del tropico. Traducción Español de Patrick Dolle y Julio Monzón; PDF disponible a petición mediante un e-mail

Muchos árctidos forman parte de las bonitas y coloridas mariposas nocturnas de alas y cuerpos brillantes con estampados casi artísticos. También son muy interesantes para la ciencia: muchos árctidos usan tóxicos de plantas para protegerse de sus enemigos, tienen órganos muy polifacéticos para producir feromonas que usan como lenguaje químico, además de producir sonidos. Sabemos todo esto, a pesar de haber solo estudiado al detalle algunas de las 6.000 especies estimadas de ésta subfamilia de las mariposas (Lepidoptera), pero la mayoría de los secretos están todavía por descubrirse. Este reporte de nuestro „trabajo en obra” trata de nuevos descubrimientos y preguntas sin resolver en el contexto de un entendimiento general, así como de las limitaciones y obstáculos durante el trabajo práctico con insectos tropicales.

Boppré M, Colegate SM (2015) Recognition of pyrrolizidine alkaloid esters in the invasive aquatic plant Gymnocoronis spilanthoides (Asteraceae). Phytochem Anal 26:215–225 link

Introduction – The freshwater aquatic plant Gymnocoronis spilanthoides (Senegal tea plant, jazmín del bañado, Falscher Wasserfreund) is an invasive plant in many countries. Behavioural observations of pyrrolizidine alkaloid-pharmacophagous butterflies suggested the presence of pyrrolizidine alkaloids in the plant.
Objective – To determine whether the attraction of the butterflies to the plant is an accurate indicator of pyrrolizidine alkaloids in G. spilanthoides.
Methods – The alkaloid fraction of a methanolic extract of G. spilanthoides was analysed using HPLC with electrospray ionisation MS and MS/MS. Two HPLC approaches were used, that is, a C18 reversed-phase column with an acidic mobile phase, and a porous graphitic carbon column with a basic mobile phase.
Results – Pyrrolizidine alkaloids were confirmed, with the free base forms more prevalent than the N-oxides. The major alkaloids detected were lycopsamine and intermedine. The porous graphitic carbon HPLC column, with basic mobile phase conditions, resulted in better resolution of more pyrrolizidine alkaloids including rinderine, the heliotridine-based epimer of intermedine. Based on the MS/MS and high-resolution MS data, gymnocoronine was tentatively identified as an unusual C9 retronecine ester with 2,3-dihydroxy-2-propenylbutanoic acid. Among several minor-abundance monoester pyrrolizidines recognised, spilanthine was tentatively identified as an ester of isoretronecanol with the unusual 2-acetoxymethylbutanoic acid.
Conclusions – The butterflies proved to be reliable indicators for the presence of pro-toxic 1,2-de-hydropyrrolizidine alkaloids in G. spilanthoides, the first aquatic plant shown to produce these alkaloids. The presence of the anti-herbivory alkaloids may contribute to the plant’s invasive capabilities and would certainly be a consideration in any risk assessment of deliberate utilisation of the plant. The prolific growth of the plant and the structural diversity of its pyrrolizidine alkaloids may make it ideal for investigating biosynthetic pathways or for large-scale production of specific alkaloids.

Petschenka G, Fandrich S, Sander N, Wagschal V, Boppré M, Dobler S (2013) Stepwise evolution in the Na+/K+-ATPase of milkweed butterflies (Lepidoptera: Danaini). Evolution 67:2753–2761 link

Despite the monarch butterfly (Danaus plexippus) being famous for its adaptations to the defensive traits of its milkweed host plants, little is known about the macroevolution of these traits. Unlike most other animal species, monarchs are largely insensitive to cardenolides, since their target site, the sodium pump (Na+/K+-ATPase), has evolved amino acid substitutions which reduce cardenolide binding (so-called target site insensitivity, TSI). Since many, but not all, species of milkweed butterflies (Danaini) are associated with cardenolide-containing host plants, we analyzed 17 species, representing all phylogenetic lineages of milkweed butterflies, for the occurrence of TSI by sequence analyses of the Na+/K+-ATPase gene and by enzymatic assays with extracted Na+/K+-ATPase. Here we report that sensitivity to cardenolides was reduced in a stepwise manner during the macroevolution of milkweed butterflies. Strikingly, not all Danaini typically consuming cardenolides showed TSI, but rather TSI was more strongly associated with sequestration of toxic cardenolides. Thus, in line with current theory, tri-trophic interactions appear to exert a dramatic effect on the evolution of both plant and herbivore species.

Boppré M, Vane-Wright RI (2012) The butterfly house industry: conservation risks and educa­tion opportunities. Conservation and Society 10: 285–303 FREE PDF

This paper addresses the mass supply and use of butterflies for live exhibits, discusses the risks to biodiversity which this creates, and the educational opportunities it presents. Over the past 30 years a new type of insect zoo has become popular worldwide: the butterfly house. This has given rise to the global Butterfly House Industry (BHI) based on the mass production of butterfly pupae as a cash crop. Production is largely carried out by privately-owned butterfly farms in tropical countries, notably Central America and Southeast Asia. Most pupae are exported to North America and Europe, although the number of butterfly houses in tropical countries is growing. The BHI is described with respect to its stakeholders, their diverse interests, and its extent. It is estimated that the global turnover of the BHI is in the order of USD 100 million. From a conservation perspective, there is a tension between risks and benefits. The risks to biodiversity are primarily unsustainable production, potential bastardisation of local faunas and floras, and genetic mixing within and even between butterfly species. This paper discusses general ways of managing these risks. Ethical concerns range from fair trade issues to animal husbandry and the use of wildlife for entertainment. For the risks to biodiversity and unresolved ethical issues to be tolerable, the BHI needs to make a significant contribution to conservation, primarily through effective education about butterfly biology as a means to raise public awareness of basic ecological processes, and conservation and environmental issues. It should also engage with local conservation initiatives. Currently the BHI’s great potential for public good in these respects is rarely realised. The paper concludes by looking at the special nature of the BHI, and its need for effective self-regulation if it is to continue to escape from public scrutiny and the introduction of restrictive regulations. The BHI needs to engage in active cooperation between its various stakeholders regarding a raft of critical issues if it is to survive and fulfil a beneficial role in society. The BHI also needs to forge active partnerships with conservation NGOs, educationalists, and scientists—communities that also need to recognise their own responsibilities towards the industry. We also discuss the need for an effective umbrella organisation for the BHI, as well as a “Code for trading and exhibiting live butterflies”.

Mebs D, Wagner MG, Toennes SW, Wunder C, Boppré M (2012) Selective sequestration of cardenolide isomers by two species of Danaus butterflies (Lepidoptera, Nymphalidae: Danainae). Chemoecology:22:269-272 link

Several species of milkweed butterflies (Danaini) are known to sequester cardenolides from their milkweed host plants. In adults of Danaus plexippus and D. gilippus , jointly raised on Asclepias curassavica (Asclepiadaceae), two host-plant cardenolides (calotropin and calactin) were found in significantly different ratios: in D.plexippus and the plant, they occurred in roughly equal ratios, but in D. gilippus, calotropin had a 10–12 times lower concentration, suggesting a selective sequestration of calactin. The two Danaus species belong to different subgenera and the results may be relevant to a better understanding of the evolution of cardenolide sequestration in Danaini.

Edgar J, Colegate S, Boppré M, Molyneux R (2011) Pyrrolizidine alkaloids in food: a spectrum of potential health consequences. Food Addit Contam 28:308-324 link

Contamination of grain with 1,2-dehydropyrrolizidine ester alkaloids (dehydroPAs) and their N-oxides is responsible for acute and sub-acute food poisoning in Africa and in central and south Asia, with high morbidity and mortality. Herbal medicines and teas containing dehydroPAs have also caused fatal liver disease in both developed and developing countries. There is now increasing recognition that some staple and widely consumed foods are sometimes contaminated by dehydroPAs and their N-oxides at levels that, while insufficient to cause acute poisoning, greatly exceed maximum tolerable daily intakes and/or maximum levels determined by a number of independent risk assessment authorities. This suggests that there may have been cases of disease resulting from dietary exposure to dehydroPAs in the past but dehydroPAs were not recognised as the cause. A review of the literature shows that there are a number of reports of liver disease where either exposure to dehydroPAs was suspected but no source was identified or a dehydroPA-aetiology was not considered but the symptoms and pathology suggests their involvement. At low levels of exposure dehydroPAs cause progressive, chronic diseases such as cancer and pulmonary arterial hypertension, as well as cirrhosis, but proof of their involvement in human cases of these chronic diseases, including sources of exposure to dehydroPAs, has generally been lacking. Given current and growing recognition of hazardous level of dehydroPA contamination in a range of common foods, physicians and clinicians need to be alerted to this development and a reassessment of the aetiology of some cases of these diseases is warranted.

Boppré M (2011) The ecological context of pyrrolizidine alkaloids in food, feed and forage. Food Addit Contam 28:260-281 link

Plant-produced 1,2-dehydropyrrolizidine ester alkaloids and their N-oxides (PAs) not only cause acute poisoning of humans and livestock, the harmful cryptic effects of chronic exposure pose particular food safety risks that need to be addressed for consumer protection. In natural contexts, however, PAs cause few or no problems. Rather, these secondary plant metabolites are important elements of ecosystems and plant-animal relationships; the existence and persistence of PA-adapted organisms, in various ways, depends on the presence of PA-containing plants or even on PAs as such. PA-plants are widely distributed among unrelated families of the plant kingdom, there is great structural diversity of PAs, and the amounts of PAs produced are subject to great variation due to multiple causes. These realities, coupled with many deficiencies in our scientific understanding, make PAs in nature a subject with limited potential for valid generalizations and predictions, and complex and difficult to summarize. PAs, their producer plants and their users are integral parts of ecosystems worldwide, and we have to learn to live with these allelochemicals by accepting the presence of some harmful natural chemicals in our environment and by taking regulatory action to reduce health risks to humans. Regulations for consumer protection are long overdue. However, any such controls must be flexible enough to accommodate the findings of future research. Multidisciplinary efforts are required to fill gaps in knowledge and to come up with additional means to monitor the presence of PAs in food and feed.

Brower AVZ, Wahlberg N, Ogawa JR, Boppré M, Vane-Wright RI (2010) Phylogenetic relationships among genera of danaine butterflies (Lepidoptera: Nymphalidae) as implied by morphology and DNA sequences. System Biodiv 8(1): 75:89 link

Cladistic relationships among genera and subtribes of Danaini (the milkweed butterflies) were inferred by analysis of data combined from five sources: morphology of adults and immature stages, and DNA sequences from three gene regions. The results corroborate and greatly increase support for prior hypotheses based on morphology alone. A new index summarizing incongruence among data partitions, the Partition Congruence Proportion (PCP), is introduced. The significance of the inferred pattern of phylogenetic relationships for comparative chemical ecology of milkweed butterflies is briefly discussed.

Süß H, Rößler R, Boppré M, Fischer OW (2009) Drei neue fossile Hölzer der Morphogattung Primoginkgoxylon gen. nov. aus der Trias von Kenia. Feddes Repert 120:273-292 link

Drei permineralisierte Gymnospermenhölzer aus der Oberen Trias der Mazeras-Formation (Duruma-Gruppe, Mombasa-Becken) werden beschrieben und aufgrund ihrer ginkgoalen Holzstruktur der neu errichteten Morphogattung Primoginkgoxylon gen. nov. zugeordnet (P. crystallophorum, P. muthamii, P. shimbaense). Die Kieselhölzer sind dreidimensional anatomisch erhalten und stammen aus dem fluviatil-deltaischen Mazeras-Sandstein, aufgeschlossen im Tal des Manolo River im Mwaluganje Community Elephant Sanctuary/Shimba-Hills, im Südosten Kenias. Der Fundort wurde bisher nicht systematisch untersucht, erscheint jedoch sehr reich an Fossilien und verdient umfangreichere Untersuchungen wie in den Schlussbemerkungen erläutert wird.

Thoden TC, Boppré M (2010) Plants producing pyrrolizidine alkaloids: sustainable tools for nematode management? Nematology 12:1-24 link

1,2-dehydropyrrolizidine ester alkaloids (pyrrolizidine alkaloids; PAs) are a class of secondary plant metabolites found in hundreds of plant species. In vitro, PAs are known to affect plant-parasitic nematodes. Thus, PA-producing plants might be used in nematode management. So far, however, Crotalaria is the only PA-producing plant that has been used for nematode control. Consequently, we reviewed the literature on other PA plants and their effects on nematodes. This included the analysis of in vitro experiments with PA plant extracts, host tests with PA plants, as well as experiments in which PA-producing plants were used as different types of soil amendments (mulch, in situ mulching, extracts). Our results clearly show that, in addition to Crotalaria, certain other PAproducing plant species have the potential to be used in sustainable nematode management. This is especially true for management of sedentary endoparasitic nematode species. Promising applications include the use of PA plant extracts and mulches, as well as the use of PA plants for in situ mulching.

Thoden TC, Boppré M, Hallmann J (2009). Effects of pyrrolizidine alkaloids on plant-parasitic and free-living nematodes. Pest Manag Sci 65:823-830 link

Background: The management of plant-parasitic nematodes has been dominated for decades by the use of chemical nematicides such as methyl bromide. Their application is problematic because of negative environmental impacts. A possible alternative to synthetically derived nematicides is seen in the use of plants and/or their secondary metabolites. Those plants could either be used as nematicidal green manure, or as resource for nematicidal extracts. This study aimed to evaluate the effects of 1,2-dehydropyrrolizidine alkaloids (PAs), a group of secondary plant metabolites found in hundreds of plant species throughout the world, on the performance of plant-parasitic and free-living nematodes. Results: All tested PAs induced nematicidal, ovicidal and repellent effects on different plant-parasitic and free-living nematodes. No rating of toxicity was seen for the different structural types of PAs tested. However, the effects were often more pronounced for the tertiary than the oxidised form of PAs (free bases vs. N-oxides). Further, large differences were observed for the susceptibility of different nematode species to PAs. Conclusions: PAs do influence several performance parameters of nematodes. Therefore, PA-producing plant like Crotalaria spp. or Ageratum spp. might be promising candidates for nematode management strategies.

Thoden TC, Hallmann J , Boppré M (2009) Effects of plants containing pyrrolizidine alkaloids on the northern root-knot nematode Meloidogyne hapla. Europ J Plant Pathol 123:27-36 link

1,2-Dehydropyrrolizidine alkaloids (PAs), known to be nematotoxic in vitro, represent a class of secondary plant metabolites from hundreds of plant species worldwide. Pot experiments with the commercially available PA-containing plants Ageratum houstonianum, Borago officinalis, Senecio bicolor, and Symphytum officinalis demonstrate that Meloidogyne hapla is not per se repelled by these plants as all species were infested with nematodes. However, the development of M. hapla juveniles was completely suppressed on A. houstonianum and S. bicolor. Soil in which A. houstonianum and S. bicolor were cultivated and incorporated contained 200–400 times less nematodes than soil treated with Lycopersicon esculentum. Depending on their qualitative composition of PAs at least some of these plants thus appear to be valuable tools for integrated root-knot nematode management.

Thoden TC, Boppré M, Hallmann J (2008) Pyrrolizidin-Alkaloide produzierende Pflanzen: Natürliche Ressourcen zur Nematodenbekämpfung. Mitt Julius Kühn Institut 417:129link

Sowohl die Ausweitung des ökologischen Landbaus als auch das Verbot zahlreicher synthetischer Pflanzenschutzmittel hat dazu geführt, dass in vielen Bereichen des Pflanzenschutzes nach umweltfreundlichen Bekämpfungsverfahren gesucht wird. Dies gilt auch für die Bekämpfung pflanzenparasitärer Nematoden. Vielversprechend ist die Nutzung pflanzlicher Sekundärstoffe ("botanicals").In den Tropen und Subtropen konnten durch den Anbau verschiedener Crotalaria-Arten Erfolge bei der Nematodenbekämpfung erzielt werden. Der zugrundeliegende Wirkungsmechanismus blieb bislang unklar. Allerdings sind Pflanzen dieser Gattung dafür bekannt, dass sie Pyrrolizidin-Alkaloide (PA) enthalten. Unsere in-vitro Versuche mit verschiedenen reinen PA zeigen nun, dass diese konzentrationsabhängig nematotoxische, nematostatische und auch ovizide Effekte hervorrufen, und dies z.T. schon ab Konzentrationen von 100 ppm. Bei Topfversuchen im Gewächshaus führte der Anbau und die nachfolgende Einarbeitung von PA-Pflanzen wie Senecio bicolor oder Ageratum houstonianum zu einer deutlichen und anhaltenden Reduzierung von Meloidogyne hapla. Dabei drangen die Larven in die Wurzeln ein, konnten sich allerdings nicht weiterentwickeln. Auf diesen Ergebnissen basierend erachten wir PA-Pflanzen als vielversprechende natürliche Ressourcen zur Bekämpfung pflanzenparasitärer Nematoden.

Boppré M, Colegate SM, Edgar JA, Fischer OW (2008) Hepatotoxic pyrrolizidine alkaloids in pollen and drying-related implications for commercial processing of bee pollen. J Agric Food Chem 56: 5662-5672 link

Using HPLC-ESI-MS, several saturated and 1,2-dehydropyrrolizidine alkaloids were detected, mainly as their N-oxides, in fresh pollen collected from flowers of the pyrrolizidine alkaloid-producing plants Echium vulgare, E. plantagineum, Senecio jacobaea, S. ovatus and Eupatorium cannabinum, and/or pollen loads from bees (“bee pollen”) that foraged on those plants. The alkaloids were present at levels that ranged from ca 5 µg/g Echium plantagineum bee pollen and up to ca 800 µg/g Senecio jacobaea pollen collected directly from the plant. While most of the pyrrolizidine alkaloids were as expected from previous analyses of other tissues of these plants, the newly detected major alkaloidal metabolite in S. ovatus was tentatively identified, using its mass spectrometric data and biogenic considerations, as the previously unreported, saturated alkaloid, 2-hydroxysarracine. When subjected to heating at up to 60 ºC for up to 84 hours, the mainly saturated pyrrolizidine alkaloid content of Senecio ovatus pollen decreased by up to 75% and the profile changed in favour of the free bases. Similar heating had no effect on the pure 1,2-dehydropyrrolizidine alkaloids integerrimine or senecionine but did reduce the level of pure N-oxides of these alkaloids by 35% and 57% respectively. There was no significant effect of heating on the 1,2-dehydropyrrolizidine alkaloids (N-oxides and free bases) in a dried extract of Echium plantagineum other than a slight increase in the relative level of free bases. Heating the pollen loads of bees foraging on Echium plantagineum, at about 56 ºC for up to 100 hours, caused a decrease in echimidine-N-oxide of up to 50% and about a 100% increase in the free echimidine levels. Considered in conjunction with international concerns about the adverse effects of 1,2-dehydropyrrolizidine alkaloids, the results strongly indicate a need for monitoring pollen supplies intended for human consumption, at least until conditions for processing and/or selection are clearly defined such as to significantly reduce the hepatotoxic (and potentially carcinogenic and genotoxic) pyrrolizidine alkaloid content of the bee pollen.

Boppré M (2008) Adult Lepidoptera are not parasitised — or are they? Antenna 32(1):26-27 lesen / read

Schulz S, Estrada C, Yildizhan S, Boppré M, Gilbert LE (2008) An anti-aphrodisiac in Heliconius melpomene butterflies. J Chem Ecol 34: 82–93 link

Gilbert, Science 193:419–420 (1976) suggested that male-contributed odors of mated females of Heliconius erato could enforce monogamy. We investigated the pheromone system of a relative, Heliconius melpomene, using chemical analysis, behavioral experiments, and feeding experiments with labeled biosynthetic pheromone precursors. The abdominal scent glands of males contained a complex odor bouquet, consisting of the volatile compound (E)-ß-ocimene together with some trace components and a less volatile matrix made up predominately of esters of common C16- and C18-fatty acids with the alcohols ethanol, 2-propanol, 1-butanol, isobutanol, 1-hexanol, and (Z)-3-hexenol. This bouquet is formed during the first days after eclosion, and transferred during copulation to the females. Virgin female scent glands do not contain these compounds. The transfer of ocimene and the esters was shown by analysis of butterflies of both sexes before and after copulation. Additional proof was obtained by males fed with labeled D-13C6-glucose. They produced 13C-labeled ocimene and transferred it to females during copulation. Behavioral tests with ocimene applied to unmated females showed its repellency to males. The esters did not show such activity, but they moderated the evaporation rate of ocimene. Our investigation showed that ß-ocimene is an antiaphrodisiac pheromone of H. melpomene.

Edgar JA, Boppré M, Kaufmann E (2007) Insect-synthesised retronecine ester alkaloids: precursors of the common arctiine (Lepidoptera) pheromone hydroxydanaidal. J Chem Ecol 33:2266-2280 link

Many pyrrolizidine alkaloid (PA)-adapted insects convert PAs sequestered from their larval host plants, into "insect-PAs" in which the acid components of the alkaloids are replaced by small, branched aliphatic 2-hydroxy acids of insect origin. It has been proposed that insect-PAs are precursors of the pheromone hydroxydanaidal in male Estigmene acrea moths but it is not clear why they are specifically required or what are the structural features or chemical properties that make insect-PAs more suitable for conversion into hydroxydanaidal than superficially similar alkaloids of plant origin. Evidence is presented here that insect-PAs are also precursors of hydroxydanaidal in the polyphageous arctiine Creatonotos transiens and a new biosynthetic pathway to hydroxydanaidal is proposed that has a mandatory requirement for insect-PAs as intermediates.

Boppré M (2007) Lockstoff-Fallen für das Borkenkäfer-Management. Jean-Pierre Vités (*1923) Beitrag zum Biotechnischen Waldschutz. Pp 269-273 in Rüchardt C et al. (Hrsg.) 550 Jahre Albert-Ludwigs-Universität Freiburg 1457-2007. Band 4. Wegweisende naturwissenschaftliche und medizinische Forschung. Freiburg i.Br.: Verlag Karl Alber. lesen / read

Thoden TC, Boppré M, Hallmann J (2007) Pyrrolizidine alkaloids of Chromolaena odorata act as nematicidal agents and reduce infection of lettuce roots by Meloidogyne incognita. Nematology 9: 343-349. link

1,2-dehydropyrrolizidine alkaloids (PAs) represent a class of secondary plant compounds that are active in defence against herbivory. They are present in Chromolaena odorata, one of the most invasive weeds of Asia and Africa. In-vitro studies demonstrate that pure PAs from C. odorata roots have nematicidal effects to the root-knot nematode Meloidogyne incognita, even at concentrations of 70–350 ppm. In-vivo experiments show that mulch or aqueous crude extracts from C. odorata roots reduce the infection of lettuce by M. incognita. Thus, the use of PA containing plants appears as a valuable element for integrated nematode management.

Brower LP, Oberhauser KS, Boppré M, Brower AVZ, Vane-Wright RI (2007) Monarch sex: ancient rites, or recent wrongs? Antenna 31(1): 12-18. lesen / read

Boppré M, Colegate SM, Edgar JA (2005) Pyrrolizidine alkaloids of Echium vulgare honey found in pure pollen. J Agric Food Chem 53: 594-600. link

The pyrrolizidine alkaloids previously identified in floral honey attributed to Echium vulgare (Boraginaceae) have been detected (8000-14000 ppm) in pure pollen collected from the anthers of Echium vulgare. Pyrrolizidine alkaloids and/or their N-oxides were isolated from the aqueous acid extracts of pollen using strong cation exchange, solid phase extraction and identified using LCMS analysis. The pyrrolizidine alkaloids in the pollen are present mainly as the N-oxides. In addition to seven previously described pyrrolizidine alkaloids and/or their N-oxides (echimidine, acetylechimidine, uplandicine, 9-O-angelylretronecine, echiuplatine, leptanthine and echimiplatine), one unidentified (echivulgarine), but previously found in honey, and two previously undescribed (vulgarine and 7-O-acetylvulgarine) pyrrolizidine alkaloids and/or their N-oxides were identified in the pollen. Tentative structures for these unidentified pyrrolizidine alkaloids are proposed based on the mass spectrometric data and biogenetic considerations. The implications of these results for identifying the source and subsequent concentrations of pyrrolizidine alkaloids in honeys and commercial beepollen are briefly discussed.

Vane-Wright RI, Boppré M (2004) Adult morphology and the higher classification of Bia Hübner (Lepidoptera: Nymphalidae). Bonner zool Beitr 53: 235-254. link

The South American nymphalid Bia Hübner, 1819, treated for over 150 years by most lepidopterists as a member of the Satyrinae, has been shown by recent work on early stages and DNA to share characters with the Morphinae: Brassolini. Examination of the wing patterns and androconial organs of Bia, described in detail for the first time, reveals unusual features otherwise only known from brassolines. In particular, the tufted posterior androconial organ of the hindwing forming palisades is a synapomorphy for Bia and several genera of Brassolini, including Caligo. The genus Bia is formally transferred from the Satyrinae to the Morphinae: Brassolini as the sole member of the subtribe Biina Herrich-Schäffer, 1864, stat. nov., co-ordinate with Brassolina Boisduval, 1836, and Naropina Stichel, 1925.

CoenoSys®-Datenbank Lebensraum Wald. In: Südwestrundfunk (Hrsg.) DVD Lebensräume entdecken. Der Wald, 2004.

Schulz S, Beccaloni G, Brown KS, Boppré M, Freitas AVL, Ockenfels P, Trigo JR (2004) Semiochemicals derived from pyrrolizidine alkaloids in male ithomiine butterflies (Lepidoptera: Nymphalidae). Biochem System Ecol 32: 699-713. link

Analysis of male hairpencil components of 28 genera and 46 species of Ithomiinae butterflies showed the presence of 13 volatile compounds formed by hydrolysis, oxidation, lactonization and/or methylation of both necic acid and pyrrolizidine base portions of lycopsamine, an alkaloid widespread in nature and known to be specifically sought, ingested and stored by these insects. Six of these compoundshave not been reported before from insects. Comparison of occurrence patterns with proposed phylogenies of the 50 or more genera in the subfamily did not give clear patterns, though simpler derivatives well known in other Lepidoptera occurred throughout the subfamily, while more specific structures, including a lactone resulting from specific oxidation of an unactivated methyl group, were more typical of apomorphic genera.

Stritzke K, Schulz S, Boppré M (2003) Niaviolides, new macrocyclic sesquiterpenes secreted by males of the African butterfly Amauris niavius. Eur J Org Chem 2003: 1337-1342. link

The abdominal androconial organs (‘‘hairpencils’’) of the African butterfly Amauris niavius (Danainae) emit a complex scent bouquet consisting of previously described aromatic compounds, terpenoids, fatty acids, and hydrocarbons. This work reports the identification of two major sesquiterpenes, each possessing a unique 13-membered macrolide ring, originating from an α,ω-oxidation pattern of the sesquiterpene backbone. To the best of our knowledge, sesquiterpene macrolides have not been found before in nature. The structure elucidation of the two compounds, which we propose to call niaviolide (3) and epoxyniaviolide (4), by NMR and GC/MS experiments is presented, together with their subsequent synthesis. Finally, the absolute configuration of natural 4 was determined to be (S,S) by stereoselective synthesis and chiral gas chromatography.

Vane-Wright RI, Boppré M, Ackery PR (2002) Miriamica, a new genus of milkweed butterflies with unique alar androconial organs (Lepidoptera: Nymphalidae). Zool Anz 242: 255-267. lesen / read

Results of microscopical (SEM) investigations of the androconial organs of Parantica sita and P. weiskei are presented. Such is the structural novelty of the patch scales in P. weiskei that, in combination with other morphological characters, it is proposed that a new genus Miriamica is established to accommodate this species, together with a second species, M. thalassina, until now regarded as a subspecies of weiskei, separate from Parantica and other members of the subtribe Amaurina.

[(2002) Die "Hasenapotheke" – nur Jägerlatein? Deutsche Jagd Zeitung 22: 34-36.

Das Forstzoologische Institut an der Albert-Ludwigs-Universität in Freiburg will wissen, was dran ist an der sogenannten "Hasenapotheke". Die DJZ sprach mit dem Direktor des Instituts, Professor Dr. Michael Boppré.]

Boppré M, Fischer OW (1999) Harlekinschrecken (Orthoptera: Zonocerus) – Schadinsekten der besonderen Art. Gesunde Pflanzen 51: 141-149. link

Heuschrecken der Gattung Zonocerus sequestrieren Pyrrolizidin-Alkaloide (PA) nicht nur von bestimmten Futterpflanzen, sondern auch unabhängig vom Nahrungserwerb. Sie speichern diese sekundären Pflanzeninhaltsstoffe zum Schutz vor Antagonisten. Mit Blüten des eingeschleppten Unkrauts Chromolaena odorata (Asteraceae) haben Trockenzeit-Populationen eine neue und nahezu unerschöpfliche Quelle für PA und erreichen damit eine höhere Fitness, was sie zu Schädlingen in Land- und Forstwirtschaft macht. Das chemoökologische Verständnis um die "pharmakophage" Beziehung von Zonocerus zu PA ermöglicht das selektive Ködern einer schädlichen Heuschreckenart und liefert den Schlüssel für ein flexibel gestaltbares, umweltgerechtes und ökonomisch vertretbares Management der Harlekinschrecken. Das Beispiel erläutert ferner verschiedene grundsätzlich relevante Aspekte zur Biologie und zum Management von Insekten.

Boppré M (1999) 'Drug-addicted' insects in Africa. Metamorphosis 10: 3-15. lesen / read

Pharmacophagy and its diverse functional aspects is introduced using examples from studies on relationships between insects and pyrrolizidine alkaloids (PAs) in Africa. Remaining open questions are outlined, emphasizing the over-riding need for natural history information from the field on 'PA-insects' and 'PA-plants'.

Häuser CL, Boppré M (1997) Pyrrolizidine alkaloid-related pharmacophagy in neotropical moths. Pp 291-296 in Ulrich H (ed.) Tropical Biodiversity and Systematics. Proc Intern Symp Biodiversity and Systematics in Tropical Ecosystems. D-Bonn: ZFMK. lesen / read

Baiting tests with pure pyrrolizidine alkaloids (PAs) in Costa Rica, French Guiana, and Peru attracted more than 1,000 ctenuchid and arctiid moths representing 98 species. In combination with literature data on the attractivity of dry PA-containing plants, more than 200 moths species pharmacophagous for those substances can be assumed to exist in the neotropics, which is higher than the numbers hitherto recorded from the Old World tropics. The need for more comprehensive surveys in the neotropics for an evolutionary understanding of PA-related pharmacophagy is emphasized.  

Boppré M (1997) Pharmacophagy in adult Lepidoptera: the diversity of a syndrome. Pp 285-289 in Ulrich H (ed.) Tropical Biodiversity and Systematics. Proc Intern Symp Biodiversity and Systematics in Tropical Ecosystems. D-Bonn: ZFMK. lesen / read

The multiplicity of facets involved in non-nutritional relationships between adult Lepidoptera and plants containing pyrrolizidine alkaloids are briefly discussed, emphasizing aspects of specificity and (specific, individual and temporal) variation and their consequences, e.g., for understanding mechanisms of chemical defence and sexual communication in an evolutionary context.

Lindigkeit R, Biller A, Buch M, Schiebel H-M, Boppré M, Hartmann T (1997) The two faces of pyrrolizidine alkaloids: a tertiary amine and its N-oxide and their role in chemical defense of insects with acquired plant alkaloids. Europ J Biochemistry 245: 626-636. link

Larvae of Creatonotos transiens (Lepidoptera, Arctiidae) und Zonocerus variegatus (Orthoptera, Pyrgomorphidae) ingest 14C-Iabeled senecionine und its N-oxide with the same efficiency but sequester the two tracers exclusively as N-oxide. Larvae of the non-sequestering Spodoptera littoralis eliminate efficiently the ingested alkaloids. During feeding on the two alkaloidal forms transient levels of senecionine (but not of the N-oxide) are built up in the haemolymph of S. littoralis larvae. Based on these results, senecionine [18O]N-oxide was fed to C. transiens larvae und Z. variegatus adults. The senecionine N-oxide recovered from the haemolymph of the two insects shows an almost complete loss of 18O label, indicating reduction of the orally fed N-oxide in the guts, uptake of the tertiary alkaloid und its re-N-oxidation in the haemolymph. The enzyme responsible for N-oxidation is a soluble mixed function monooxygenase. It was isolated from the haemolymph of the sequestering arctiid Tyria jacobaeae and purified to electrophoretic homogeneity. The enzyme is a flavoprotein with a native Mr of 200000 und a subunit Mr of 51000. lt shows a pH optimum at 7.0, has its maximal activity at a temperature of 40-45°C und an isoelectric point at pH 4.9. The reaction is strictly NADPH-dependent (Km 1.3 µM). From 20 pyrrolizidine alkaloids so far tested as substrates, the enyzme N-oxidizes only alkaloids with structural elements which are essential for hepatotoxic und genotoxic pyrrolizidine alkaloids (i.e. 1,2-double bond, esterification of the allylic hydroxyl group, presence of a second free or esterified hydroxyl group at carbon 7). A great variety of related alkaloids und xenobiotics were tested as substrate, none was accepted. The Km values of senecionine, monocrotaline und heliotrine, representing the three main types of pyrrolizidine alkaloids, are 1.3 µM, 12.5 µM und 290 µM, respectively. The novel enzyme was named senecionine N-oxygenase (SNO). The enzyme was partially purified from two other arctiids. The three SNOs show the same general substrate specificity but differ in their affinities towards the main structural types of pyrrolizidine alkaloids. The enzymes from the two generalists (Creatonotos transiens and Arctia caja) display a broader substrate affinity than the enzyme from the specialist (Tyria jacobaeae). The two molecular forms of pyrrolizidine alkaloids, the lipophilic protoxic tertiary amine und its hydrophilic nontoxic N-oxide are discussed in respect to their bioactivation und detoxification in mammals und their rote as defensive chemicals in specialized insects. Pyrrolizidine-alkaloid-sequestering insects store the alkaloids as nontoxic N-oxides which are reduced in the guts of any potential insectivore. The lipophilic tertiary alkaloid is absorbed passively und then bioactivated by cytochrome P-450 oxidase.

Fischer OW, Boppré M (1997) Chemoecological studies reveal causes for increased population densities of Zonocerus (Orth.: Pyrgomorphidae) and offer new means for management. Pp 265-279 in Krall S, Peveling R, Ba Diallo D (eds) New Strategies in Locust Control. CH-Basel: Birkhäuser Verlag. lesen / read

Grasshoppers of the genus Zonocerus sequester pyrrolizidine alkaloids (PAs) not only from certain nutritional host plants but also independent of dietary requirements. Storage of PAs serves protection of the insects from antagonists, and thus aquisition of these secondary plant chemicals modulates the grasshopper's population dynamics. Flowers of the introduced weed Chromolaena odorata (Asteraceae) represent a novel and inexhaustable resource of PAs – but only for populations in the dry-season. Evidence is provided that better performance related to the presence of Chromolaena is a reason that dry-season populations became a serious pest in coincidence with the spread of the weed.
The chemoecological knowledge on the Zonocerus-PA relationship permits the development of selective baits, and with environmentally sound and cost-efficient application of insecticides the species can be lured to its doom. Multiple means for employing PA-baits within IMP concepts are possible, i.e. strategies of population management can be tailored according to actual demands and conditions. Apart from fighting the grasshopper in individual farms, a general reduction of Zonocerus populations is suggested to lower mean levels of abundance in areas with frequent upsurges; this could be done by combining PA-baits with mycoinsecticide technology.

Scherer G, Boppré M (1997) Attraction of Gabonia and Nzerekorena to pyrrolizidine alkaloids – with descriptions of 13 new species and notes on male structural peculiarities (Insecta, Coleoptera, Chrysomelidae, Alticinae). Spixiana 20: 7-38. lesen / read

Baits containing pyrrolizidine alkaloids (PAs) attracted 17 species of Gabonia and 1 of Nzerekorena in Kenya, East Africa. In Gabonia attraction is strongly male-biased (>>2600 ¢¢ vs 27 ™™). Attempts to discover the beetles' hostplants were unsuccessful, but hosts of several other Coleoptera were recorded, including that of 1 Gabonia species not attracted to PAs. In addition to field-observations, the paper provides descriptions of 13 new species (12 Gabonia and 1 Nzerekorena), keys to the species, and a morphological characterization of peculiar structures in males.

Häuser CL, Boppré M (1997) A revision of the Afrotropical taxa of the genus Amerila Walker (Lepidoptera: Arctiidae). System Entomol 22: 1-44. lesen / read

This paper comprises a complete revision of the Afrotropical species of the genus Amerila (Rhodogastria auct.), based on adult morphology. Examination of type material for most described taxa has resulted in numerous taxonomic changes. From a total of 47 previously described African taxa, 35 species including 5 newly described species and 2 new subspecies are recognized. For 10 taxa, lectotypes have been selected, and for 1 species a neotype had to be designated. For each species, in addition to synonymy, a brief diagnosis based on external characters and genitalia is given, and the known distribution summarized. All species are illustrated by photographs and illustrations of male genitalia (except A. rufifemur, the male of which is unknown), and a key for determination of males by external characters is provided.

Boppré M, Fischer OW (1996) Pharmacophagy in Zonocerus grasshoppers: Implications for plant protection and uncertainties with introduced plants. P 318 in Laux W (ed.) Mitteilungen aus der Biologischen Bundesanstalt für Land- und Forstwirtschaft Berlin-Dahlem, Heft 321; 50th German Meeting on Plant Protection, D-Münster, September 23-26, 1996. D: Berlin-Dahlem: Biologische Bundesanstalt für Land- und Forstwirtschaft.

Boppré M (1995) Pharmakophagie: Drogen, Sex, und Schmetterlinge. Biologie in unserer Zeit 25: 8-17. lesen / read

Der stürmischen Entwicklung analytisch-technischer Möglichkeiten in den letzten drei Jahrzehnten ist es zu verdanken. daß Substanzen selbst in Mikromengen chemisch charakterisierbar sind. Tausende neuer Naturstoffe konnten so identifiziert werden. Über ihre biologischen Funktionen beginnen wir, mehr and mehr zu lernen, und entdecken ungeahnt komplexe Beziehungen auf allen Ebenen, von der des Individuums bis zur Population und den vielfältig vernetzten Ökosystemen. Chemische Kommunikation spielt eine zentrale Rolle in der belebten Welt. Das Verständnis ihrer Grundlagen ist für uns Menschen zwangsläufig von immenser Bedeutung, nicht zuletzt für Bemühungen um umweltverträgliche Programme zum Management von Schadpopulationen.
Ziele und Aufgaben der jungen und multidisziplinären Chemischen Ökologie sind es, all diejenigen Interaktionen zwischen Organismen zu untersuchen, die durch Naturstoffe vermittelt werden. Zu ihren bislang herausragenden Themengebieten gehören beispielsweise Beziehungen zwischen Insekten und Pflanzen, aber auch Pheromone, das sind Sekrete, die der innerartlichen Kommunikation von Organismen dienen.
Hier wird über Insekten berichtet, die Wehrstoffe (Gifte) von Pflanzen unabhängig vom Nahrungserwerb aufnehmen können und diese Substanzen sowohl zum eigenen chemischen Schutz vor Gegenspielern als auch zur sexuellen Verständigung nutzen. Die chemische Ökologie solcher pharmakophager Insekten liefert grundlegende Kenntnisse über Insekten-Pflanzen-Beziehungen. Sie verknüpft dabei klassische biologische Forschungsgebiete wie (Balz-) Verhalten, (Sinnes- und Stoffwechsel-) Physiologie, (Funktions-)Morphologie und Taxonomie in einem ökologischen und evolutionsbiologischen Kontext untereinander wie auch mit der Naturstoffchemie.

Biller A, Boppré M, Witte L, Hartmann T (1994) Pyrrolizidine alkaloids in Chromolaena odorata. Chemical and chemoecological aspects. Phytochemistry 35: 615-619.

The tropical weed Chromolaena odorata contains the N-oxides of five pyrrolizidine alkaloids (PAs): 7- and 9-angeloylretronecine, intermedine, rinderine and 3'-acetylrinderine. Highest concentrations occur in roots and mature flower heads, while leaves and stems are almost devoid of alkaloids, and no PAs are present in nectar. The polyphagous grasshopper Zonocerus variegatus sequesters intermedine and rinderine from Chromolaena flowers and transforms up to 20% of these PAs into lycopsamine and echinatine, respectively, by inversion of configuration at C-3'. Pure rinderine injected into the haemolymph of Zonocerus is partly converted into intermedine, indicating inversion of configuration at C-7.

Boppré M (1994) Sex, drugs, and butterflies. Natural History 113: 26-33. lesen / read

Boppré M, Fischer OW (1994) Zonocerus and Chromolaena in West Africa. A chemoecological approach towards pest management. Pp 107-126 in Krall S, Wilps H (eds) New Trends in Locust Control. D-Eschborn: GTZ. lesen / read

Boppré M, Fischer OW (1993) Zonocerus et Chromolaena en Afrique de l´Quest. Une approche chimio-écologique de lutte biologie. Sahel PV Info (Bamako, Mali) # 56: 7-21.

Schulz S, Boppré M, Vane-Wright RI (1993) Specific mixtures of secretions from male scent organs of African milkweed butterflies (Danainae). Phil Trans R Soc Lond B 342: 161-181. link

The abdominal androconial organs (hairpencils: male scent glands) of samples of ten African milkweed butterfly species (Lepidoptera: Danainae) belonging to Danaus, Tirumala and Amauris, including all nine species commonly encountered in Kenya, have been analysed by gas chromatography and mass spectrometry. A total of 214 compounds have been identified, belonging to 14 chemical classes: hydrocarbons, alcohols, aldehydes, ketones, esters, lactones, carboxylic acids, oxidized carboxylic acids, aromatics, derivatives of pyrrolizidine alkaloids (PAs), monoterpenes, sesquiterpenes, other terpenoids and tetrahydrofurans. Various compounds only rarely or never found in insects before, including some previously unknown in nature, are present in the hairpencils. Excluding the numerous tetrahydrofurans, which were not investigated systematically, the number of compounds ranges from 12-59 per species. All ten species have distinct mixtures of volatiles, including, in all cases, species-specific compounds (autapomorphies). In addition, the co-occurrence of compounds between species (synapomorphies) exhibits a strongly hierarchical chemo-taxonomic pattern which has been demonstrated to be largely consistent with a previous cladistic analysis based on adult morphology. The potential significance of these findings in relation to chemical communication and speciation in these mimetic butterflies is discussed.

Boppré M, Malcolm SB (1993) Chemoecology metamorphosed. Chemoecology 4: 1-2. lesen / read

Boppré M (1993) Forstzoologie – quo vadis in Freiburg? Forstw Cbl 112: 295-303. lesen / read

Der anläßlich der Freiburger Forstlichen Hochschulwoche 1992 gehaltene Vortrag diskutiert Gedanken zu Lehr- und Forschungsaufgaben des Forstzoologischen Instituts. Nach Überlegungen zur Rolle der Forstzoologie als Disziplin werden einige Grundsätze zu Inhalten und zur Organisation der Lehre erörtert. Das Gebiet der "Chemischen Ökologie" wird vorgestellt und als Schwerpunkt der Forschung der Forstzoologie in Freiburg bewertet. Aktuelle Forschungsvorhaben der Arbeitsgruppe des Autors werden referiert.

Schulz S, Francke W, Boppré M, Eisner T, Meinwald J (1993) Insect pheromone biosynthesis: stereochemical pathway of hydroxydanaidal production from alkaloidal precursors in Creatonotos transiens (Lepidoptera, Arctiidae). Proc Natl Acad Sci USA 90: 6834-6838. lesen / read

The mechanism by which the moth Creatonotos transiens produces its male pheromone, (7R)-hydroxydanaidal, from heliotrine, an alkaloidal precursor of opposite (7S) stereochemistry, was investigated. Specifically deuteriated samples of heliotrine and epiheliotrine were prepared and fed to C. transiens larvae, and the steps in the biosynthetic process were monitored by gas chromatography/mass spectrometry. These analyses indicate that heliotrine is initially epimerized to (7S)-epiheliotrine by oxidation to the corresponding ketone followed by stereospecific reduction. The order of the subsequent steps is (i) aromatization of the dihydropyrrole ring, (ii) ester hydrolysis, and (iii) oxidation of the resulting primary alcohol to the final aldehyde. The ecological implications of this insect's ability (and the inability of another moth, Utetheisa ornatrix) to use representatives of two stereochemical families of alkaloids as pheromone precursors are discussed.

Vane-Wright RI, Boppré M (1993) Visual and chemical signalling in butterflies: functional and phylogenetic perspectives. Phil Trans R Soc B 340: 197-205. lesen / read

The two major signal functions for adult butterflies are protection against predators and intra-specific communication. Protective use of colour patterns (e.g. aposematism, crypsis) is mainly directed against visually-hunting vertebrate predators. Mate-location in butterflies is effected through behavioural adaptations of both sexes, and long-range visual searching by males. Recognition and selection of mates at close-range is largely controlled by species-specific male pheromone components, although other signals (e.g. colour, movement) play the initial role. Increased elaboration of pheromones for specific signalling has been hypothesised where the design of visual signals is constrained by defensive functions involving pattern convergence (co-mimicry). Male pheromones are also important for trait signalling, often being decisive in female mate choice.
The general context of visual and olfactory signals in butterfly communication is discussed using specific examples, including Amauris. Their low divergence in colour patterns contrasts with great differentiation in the chemistry of their scent-organ volatiles. Models for the evolution of chemical signalling systems in these mimetic butterflies are compared and assessed.
A more complete understanding of the evolution and function of butterfly signalling systems will require renewed effort in a number of areas. These include integrated studies on the use and significance of colours and scents, the measurement of colour, chemical analyses of pheromone bouquets, genetics, and receptor physiology. All of this work will need to be put in a better comparative framework through cladistic analysis of a wider variety of biologically contrasted butterfly groups, including previously studied cases lacking a rigorous phylogenetic perspective.

Boppré M (1993) The American monarch: courtship and chemical communication of a peculiar danaine butterfly. Pp 29-41 in Malcolm SB, Zalucki MP (eds) Biology and Conservation of the Monarch Butterfly. Los Angeles/CA: Natural History Museum of Los Angeles County. lesen / read

The androconial organs, courtship behavior, and the roles of chemical signals and allelochemicals in Danaus (Danaus) plexippus plexippus, the American monarch, are discussed in comparison with other danaine butterflies. In the monarch, and in other members of Danaus senus stricto, a change in mating strategy has evolved so that chemical communication plays a minor role in comparison with butterflies in other danaine genera. To date, there is no plausible explanation for this curious evolutionary change because many basic questions on the behavioral and chemical ecology of the monarch remain unanswered.

Boppré M, Biller A, Fischer OW, Hartmann T (1992) The non-nutritional relationship of Zonocerus (Orthoptera) to Chromolaena (Asteraceae). Pp 89-90 in Menken SBJ, Visser RJH, Harrewijn P (eds) Proc 8th Intern Symp Insect-Plant Relationships. NL-Dordrecht: Kluwer Acad Publ.

Vane-Wright RI, Schulz S, Boppré M (1992) The cladistics of Amauris butterflies: congruence, consensus and total evidence. Cladistics 8: 125-138.

Two data sets for 10 species of African milkweed butterflies (Nymphalidae, Danainae: one Danaus [D. chrysippus], two Tirumala [T. petiverana, T. formosa], seven Amauris) have been analyzed cladistically, separately and in combination. One data set comprised 32 morphological characters, the other comprised 68 chemical compounds from male scent organs. Analyzed separately, the two data sets produced six similar but non-identical minimum-length solutions. Analyzed together, the combined data set of 100 characters produced a single minimum-length tree, identical to one of the three solutions for the morphological data set. The combined data produced a more informative result than congruence comparisons based on strict or combinable component consensus analysis. These results, together with re-analysis of a morphological data set for all 15 species of Amauris [niavius, tartarea, ellioti, phoedon, comorana, echeria, vashti, crawshayi, hecate, albimaculata, damocles, ochlea, nossima, dannfelti, inferna] (which produced 12 minimum-length solutions), permit increased resolution of the existing classification of this Afrotropical genus, including the formal recognition of two subgenera, Amauris (Amauris) Hubner, and Amauris (Amaura) Geyer (stat. rev.). The fit of uniquely derived, unreversed chemical characters to the tree raises the possibility that stepwise additive evolution of semiochemicals may have occurred during cladogenesis of these mimetic butterflies. The implications for chemoecology and speciation are briefly discussed.

Boppré M (1991) Pheromonbiologie – chemoökologischer Kontext der Sexualpheromone von Lepidopteren. Verh Dtsch Zool Ges 84: 201-211. lesen / read

Geleitet von der Hoffnung auf umweltverträglichen Pflanzenschutz konzentriert(e) sich die Forschung an Lepidopteren-Pheromonen vorrangig auf die Identifizierung und Synthese von weiblichen Lockstoffen sowie auf Techniken ihrer Anwendung in Land- und Forstwirtschaft. Der praktische Einsatz von Pheromonen bleibt jedoch noch weit hinter den hohen Erwartungen und dem gewünschten Umfang zurück, weil die Kenntnisse zur Biologie der Schädlinge und zu biotischen wie abiotischen Rahmenbedingungen noch immer ungenügend sind. Große Wissenslücken bestehen insbesondere zur Pheromonbiologie an sich, d.h. wenn man das vollständige Sexualverhalten (und nicht nur die Partnerfindung) in einem verhaltensökologisch und evolutionsbiologisch ausgerichteten Kontext betrachtet.
Die Syntax weiblicher und männlicher Pheromonsysteme bei Schmetterlingen wird kurz dargestellt und aus chemoökologischer Sicht diskutiert, wobei insbesondere verhaltensökologische Fragen aufgeworfen werden. Beispiele zur Pheromonbiologie mit männlichen Signalstoffen demonstrieren, welch komplexe Verschränkungen verschiedenster Aspekte sich auftun, wenn sexuelle Selektion berücksichtigt wird. Vertieftes Wissen über chemische Kommunikationsmechanismen und -strategien, insbesondere in bezug auf ökologische Bedingungen, sowie zum Anpassungswert der vielfältigen Pheromonsysteme, läßt sich vermutlich nur wenig generalisieren, dient jedoch nicht nur dem von der Grundlagenforschung gesuchten Gesamtverständnis, sondern wird auch im Rahmen von Pest-Management hilfreich sein.

Boppré M (1991) A non-nutritional relationship of Zonocerus (Orthoptera) to Chromolaena (Asteraceae) and general implications for weed managment. Pp 153-157 in Muniappan R, Ferrar P (eds) Ecology and Management of Chromolaena odorata. Proc 2nd Intern Workshop on Biol Control of Chromolaena odorata. (BIOTROP Special Publ No 44.) Bogor, Indonesia: ORSTOM and SEAMEO BIOTROP.

The likely phamacophagous relationship between the grasshopper Zonocerus variegatus and the weed Chromolaena odorata (Eupatorium odoratum) in west Africa is discussed. The role of secondary plant substances in the ecology of exotic plants and their biological control is briefly considered with particular reference to the use of the moth Pareuchaetes pseudoinsulata for controlling E. odoratum.

Hartmann T, Biller A, Witte L, Ernst L, Boppré M (1990) Transformation of plant pyrrolizidine alkaloids into novel insect alkaloids by arctiid moths (Lepidoptera). Biochem Syst Ecol 18: 549-554. lesen / read

Two new pyrrolizidine alkaloids (PAs) were isolated from adults of Creatonotos transiens, the larvae of which had ingested retronecine or ester alkaloids. The structures were elucidated by GC-MS and 1H and 13C NMR spectroscopy as O9-(2-hydroxy-3-methylpentanoyl)retronecine (creatonotine) and its isomer O7-(2-hydroxy-3-methylpentanoyl)retronecine (isocreatonotine). The 2-hydroxy-3-methylpentanoic acid obtained by hydrolysis of the creatonotines is the 2S,3S-stereoisomer. The creatonotines as well as accompanying trace amounts of callimorphine were shown to be synthesized by both sexes from dietary retronecine by esterification. If Creatonotos larvae had been fed with Gynura scandens as PA source, the insect PAs accounted for about 75% of total PAs isolated from adults, indicating that Creatonotos degraded plant PAs and subsequently re-esterified the resulting retronecine. This work provides definitive proof that an arctiid moth is able to hydrolyse plant ester alkaloids and re-esterify the resulting necine base with acids which are intermediates of insect metabolism. PAs isolated from Creatonotos were exclusively present in the form of their N-oxides.

Eckrich M, Boppré M (1990) Chemical vs acoustic cues in the defence of arctiid moths (Lepidoptera) against small mammals. Verh Dtsch Zool Ges 83: 632. lesen / read

Vane-Wright RI, Boppré M (1990) The unknown male of Tiradelphe schneideri (Lepidoptera, Danainae) – missing piece in a butterfly puzzle. Tyô to Ga 41: 193-199.

Chemical communication in milkweed butterflies (Danainae) involves some remarkable specialisations, including pheromone components derived from specially gathered secondary plant compounds, and complex androconial systems. Within the Danaini, the androconia of most of the species produce pheromone-transfer-particles (PTPs), used as "love dust" during courtship. PTPs are generated in quite different ways in the different genera, notably Danaus and Tirumala, strongly suggestive of parallel evolution. At present we can offer no explanation for this – or the alternative possibility, that such specialized systems have undergone evolutionary transformation, one into another.
Tiradelphe schneideri, first described in 1984 as a new genus and species within the Danaini, is still only known from two female specimens from Mount Popomanaseu, Guadalcanal, in the Solomon Islands. Cladistic analysis has placed Tiradelphe in an unresolved group with Danaus and Tirumala. Discovery of the unknown male of Tiradelphe is therefore expected to shed new light on the evolution of these butterflies, including their chemical communication. Lepidopterists who may be able to visit the Solomon Islands in search of this rare insect are encouraged to contact the authors to discuss how best to gather the missing information needed to solve this butterfly puzzle.

Boppré M, Malcolm SB (1990) Chemoecology – a new journal. Chemoecology 1: 1-2. lesen / read

Boppré M (1990) Lepidoptera and pyrrolizidine alkaloids: exemplification of complexity in chemical ecology. J Chem Ecol 16: 165-185. link

Pyrrolizidine alkaloids (PAs) are defensive secondary metabolites found in numerous plant groups. Various insects belonging to different orders have special requirements for these compounds and sequester them from such plants for their own defence and often as pheromone precursors. The fitness of these insects depends on PAs and, in some cases, PAs even act as regulators of androconial organ development.
This paper discusses selected behavioural, chemical, physiological, and phylogenetic aspects of insect-PA relationships, and raises questions about the complex interactions of the variety of PA-related adaptations as they occur amongst a diverse array of species. Although many superficial similarities are recognized, few generalizations can yet be drawn. However, insect﷓PA relationships not only exemplify basic features of chemical ecology but illustrate a multiplicity of aspects and adaptations which we should expect to find in any thorough study of insect-plant relationship.

Boppré M (1989) Wie Insekten pflanzliche Sekundärstoffe nutzen – oder: Sex und Drogen bei Schmetterlingen. D-Freiburg: Gödecke.

Boppré M, Vane-Wright RI (1989) Androconial system in Danainae (Lepidoptera): functional morphology of Amauris, Danaus, Tirumala and Euploea. Zool J Linn Soc 97: 101-133. lesen / read

The morphology of abdominal and alar androconial organs of four species representing four genera of danaine butterflies is described in detail, based mainly on scanning electron microscopy. The findings are discussed with respect to functional significance and phyletic development of the organs.

Boppré M, Schneider D (1989) The biology of Creatonotos (Lepidoptera: Arctiidae) with special reference to the androconial system. Zool J Linn Soc 96: 339-356.

The reproductive biology of the arctiid moths Creatonotos transiens and C. gangis exhibits a novel ontogenetic phenomenon, the morphogenesis of male coremata size being directly controlled by the quantity of hostplant-derived pyrrolizidine alkaloids ingested by the larvae. In addition, the same alkaloids directly control the quantity of male pheromones synthesized and available for deployment by these scent organs. Reproduction in these insects thus shows striking linkages between ecological, behavioural, chemical and morphological features. This paper presents an account of the general biology of the moths, and reviews the literature on Creatomotos as a basis for reports on experimental work.

Bogner F, Boppré M (1989) Single cell recordings reveal hydroxydanaidal as the volatile compound attracting insects to pyrrolizidine alkaloids. Entomol exp appl 50: 171-184. lesen / read

Employment of electrophysiology in combination with simple chemical techniques elucidated the volatile which permit the localization of sources of pyrrolizidine alkaloids (PAs) by insects exploiting these secondary plant metabolites. Single cell recordings in Rhodogastria moths (Arctiidae) revealed a physiologically clearly separable type of antennal sensilla basiconia ('SB II') which responds to headspace air of certain PAs (e.g. monocrotaline), but not to a great variety of 'odorants'. However, stimulus sources of 1µg were required to elicit responses and the maximum frequency (obtained with stimulus sources of 5 mg) was only 50 imps/s. This suggested the occurrence of small amounts of airborne PA degradation products. Extraction and hydrolysis experiments in combination with thin-layer chromatography and using the sensory responses of antennal receptor cells as biological detectors eventually demonstrated that the dihydropyrrolizine 'hydroxydanaidal' emanates in small amounts from sources of those PAs which contain retronecine and heliotridine, respectively, as necine moiety. This substance was also implicated as the volatile mediating attractions of the insects to PA-containing plants, as well as to artificial PA-baits. With respects to the high sensitivity and specificity of SB II-receptor cells to hydroxydanaidal, in particular to its R(-)-enantiomer, they are analogous to the well studied receptor for sex-attractant phermones in Lepidoptera. Similar results were obtained with Danaus (Dananinae) and Euchromia (Ctenuchiidae). Initial behavioural tests have proven the attractive power of hydroxydanaidal for PA-insects and thus corroborate our interpretation of the electrophysiological findings.

Schulz S, Francke W, Boppré M (1988) Carboxylic acids from hairpencils of male Amauris butterflies (Lep.: Danainae). Biol Chem Hoppe Seyler 369: 633-638.

63 Carboxylic acids were identified from the male hairpencils of four species of the genus Amauris (Lep.: Danainae), namely A. echeria (Stoll), A. hecate (Butler), A. ochlea (Boisduval) and A. albimaculata Butler. Straight chain saturated as well as unsaturated carboxylic acids, some of which containing an additional oxygen function, contribute to the species-specificity of the odour bouquets. Oxygenated fatty acids form a new class of insect volatiles, 5 of the 10 ketoacids found represent new natural products. (E)-7-Oxo-11-tetradecenoic acid is the main volatile component of the hairpencils of A. echeria, the species with the highest amount of oxygenated fatty acids (70% of the extractable volatiles). 9-Hydroxyoctadecanoic acid is a major compound in both A. ochlea and A. albimaculata while in A. hecate oxygenated carboxylic acids are present in minute amounts only.

Boppré M, Pitkin BP (1988) Attraction of chloropid flies to pyrrolizidine alkaloids (Diptera: Chloropidae). Entomol Gener 13: 81-85. lesen / read

Both sexes of several species of Chloropidae in 4 genera (Melanochaeta, Chlorops, Eutropha, Oscinella) and 2 subfamilies (Chloropinae, Oscinellinae) have been found visiting pyrrolizidine alkaloid (PA) baits and ingesting these secondary plant chemicals. Some of the same species have also been observed visiting decaying plants and flowers containing PAs.

Boppré M (1987) Pharmacophage Insekten. Jhb Göttinger Akademie der Wiss 1986: 29-34.

Bergomaz R, Boppré M (1986) A simple instant diet for rearing Arctiidae and other moths. J Lep Soc 40: 131-137 download

A bean-based semiartificial diet was developed empirically for rearing species of Rhodogastria and Creatonotos (Arctiidae), foodplants for which were unavailable or unknown. It was also used successfully for Heterocera in 27 genera of five families, and is likely suitable for rearing additional species of moths. Preparation of the diet is simple even in the field, and its components are inexpensive.

Bogner F, Boppré M, Ernst K-D, Boeckh J (1986) CO2 sensitive receptors on labial palps of Rhodogastria moths (Lepidoptera: Arctiidae): physiology, fine structure and central projection. J Comp Physiol 158: 741-749. lesen / read

The tips of the labial palps of Rhodogastria possess a pit housing uniform sensilla (Fig. 1), histologically characterized by wall-pores and receptor cells with lamellated outer dendrites. The receptor cell axons project to glomeruli in the deutocerebrum which are not innervated by antennal receptors. From their histology as well as from their central projection these sense organs are identical with palpal pit organs of other Lepidoptera (Lee et al. 1958; Kent et al. 1986; Lee & Altner 1986). Physiologically, the palp-pit receptors respond uniformly; they are most excitable by stimulation with carbon dioxide while they exhibit relatively moderate responses to various odorants. The responses of CO2 show a steep dose-response characteristic. In ambient atmosphere (i.e., ca. 0.03% CO2) the cells are in an excited condition already; the seeming 'spontaneous activity' exhibited in air is decreased if the preparation is kept under N2 or O2 or CO2-free air. There is hardly any adaptation of the responses to continuous or repeated stimulation. Perhaps CO2 sensitivity is correlated with sensilla characterized by both wall-pores and lamellated dendrites. Pilot tests indicate that CO2 perception might be widespread in the Lepidoptera, but the biological significance remains obscure.

Boppré M (1986) Insects pharmacophagously utilizing defensive plant chemicals (pyrrolizidine alkaloids). Naturwissenschaften 73: 17-26. lesen / read

Insects of several orders (mainly Lepidoptera) gather pyrrolizidine alkaloids independent of feeding behaviour. By storing these secondary plant metabolites the insects gain protection from predators, and in various species the plant chemicals are used as precursors for the biosythesis of male pheromones; in Creatonotos they even regulate specifically the development of the androconial organs. The variety of aspects involved in this link between chemical defence and sexual communication as well as its consequences are discussed.
Insekten verschiedener Ordnungen (bes. Lepidopteren) nehmen unabhängig vom Nahrungserwerb Pyrrolizidin-Alkaloide auf. Diese sekundären Pflanzenmetabolite schützen sie vor Freßfeinden und dienen bei einigen Arten zudem als Vorstufen für die Biosynthese von männlichen Pheromonen; bei Creatonotos regulieren sie spezifisch das Wachstum der androconialen Organe. Die Vielfalt der an dieser Verflechtung von chemischem Schutz und sexueller Kommunikation beteiligten Aspekte und ihre Konsequenzen werden diskutiert.

Boppré M, Schneider D (1985) Pyrrolizidine alkaloids quantitatively regulate both scent organ morphogenesis and pheromone biosynthesis in male Creatonotos moths (Lep.: Arctiidae). J Comp Physiol 157: 569-577. lesen / read

Males of Creatonotos gangis and C. transiens possess coremata ('scent organs') of drastically varying sizes (Figs. 2, 3), which release R(-)-hydroxydanaidal (Fig. 1A) in varying amounts. Both the size of the organs and their pheromone content depend on the ingestion of pyrrolizidine alkaloids (PAs; Fig. 1 B, C) by the larvae. There is a direct correlation between amounts of PAs ingested and and the size of the organs (Fig. 4). It is the absolute amount of PAs ingested which determines the expression of corematal size, structurally different PAs have identical effects (Table 2); PAs are no essential dietary factors for the general development of the moths (Table 1), and the morphogenetic effect is restricted to the coremata. The findings are discussed in terms of developmental, ecological and functional aspects.

Bogner F, Boppré M (1985) A special olfactory receptor for alkaloid perception in adult Lepidoptera. Verh Dtsch Zool Ges 78: 281.

Bell TW, Boppré M, Schneider D, Meinwald J (1984) Stereochemical course of pheromone biosynthesis in the arctiid moth, Creatonotos transiens. Experientia 40: 713-714. lesen / read

The biosynthetic conversion of a pyrrolizidine alkaloid (heliotrine, IV) to a male moth pheromone (hydroxydanaidal, III) is found to proceed with inversion of configuration at the remaining asymmetric center (C-7).

Boppré M, Seibt U, Wickler W (1984) Pharmacophagy in grasshoppers? Zonocerus being attracted to and ingesting pure pyrrolizidine alkaloids. Entomol exp appl 35: 115-117. lesen / read

Z. elegans is attracted to pure pyrrolizidine alkaloids and to ingest them. This finding makes the species likely to be pharmacophagous; also, it might provide means of controlling Zonocerus, and it indicates the importance of olfaction for localizing and recognizing host-plants in grasshoppers.

Boppré M (1984) Redefining "pharmacophagy". J Chem Ecol 10: 1151-1154. lesen / read

Boppré M (1984) Chemically mediated interactions between butterflies. Symp R ent Soc 11: 259-275. ( = Vane-Wright RI, Ackery PR (eds) The Biology of Butterflies. GB-London: Academic Press) Reprinted edition 1989 by Princeton University Press.

Boppré M (1983) Leaf-scratching – a specialized behaviour of danaine butterflies for gathering secondary plant substances. Oecologia (Berl) 59: 414-416. lesen / read

Hansen K, Schneider D, Boppré M (1983) Chiral pheromone and reproductive isolation between the gypsy- and nun moth. Naturwissenschaften 70: 466-467. lesen / read

A laboratory study was carried out in the German Federal Republic in which recordings were made from single olfactory cells in antennal hairs of males of Lymantria dispar (L.) and L. monacha (L.) during stimulation with gland extracts and synthetic enantiomers of disparlure. The hexane extracts of the L. dispar glands stimulated almost exclusively the receptor cells specialised for (+)-disparlure, while both cells were stimulated simultaneously by the gland extracts of females of L. monacha. From the stimulus-response characteristics of the cells it was estimated that L. monacha produced about 90% (-)- and 10% (+)-disparlure, while L. dispar produced almost 100% (+)-disparlure. However, it must still be presumed that the reproductive isolation of the 2 species is only partly due to pheromone production and recognition.

Boppré M, Schneider D (1982) Insects and pyrrolizidine alkaloids. Proc 5th int Symp Insect-Plant Relationships, Wageningen, 1982, 374-375. NL-Wageningen: Poduc.

Schneider D, Boppré M, Zweig J, Horsley SB, Bell TW, Meinwald J, Hansen K, Diehl EW (1982) Scent organ development in Creatonotos moths: regulation by pyrrolizidine alkaloids. Science 215: 1264-1265.

7-Hydroxy-6,7-dihydro-5H-pyrrolizine-I-carboxaldehyde is the major volatile component of the scent organs in males of two species of Creatonotos (Lepidoptera, Arctiidae). The biosynthesis of this presumed pheromone depends on the presence of pyrrolizidine alkaloids in plants that are ingested by the larvae. In addition, these secondary plant substances control the morphogenesis of the scent organs. This morphogenetic effect of an alkaloid has not been observed previously.

Boppré M (1981) A synonomy in the genus Rhodogastria (Lep., Arctiidae) resulting from sexual dimorphism. Mitt Münch Ent Ges 71: 163-165.

Evidence is presented that Rhodogastria phaedra (Weymer) und R. leucoptera HAMPSON die Geschlechter einer Art darstellen. Dies ist der erste Nachweis von Sexual-Dimorphismus bei dieser Gattung.

Boppré M (1981) Adult Lepidoptera "feeding" at withered Heliotropium plants (Boraginaceae) in East Africa. Ecol Entomol 6: 449-452.

Schneider D, Boppré M (1981) Pyrrolizidin-Alkaloide als Vorstufen für die Duftstoff-Biosynthese und als Regulatoren der Duftorgan-Morphogenese bei Creatonotos (Lepidoptera: Arctiidae). Verh Dtsch Zool Ges 1981: 269.

Boppré M, Scherer G (1981) A new species of flea beetle (Alticinae) showing male-biased feeding at withered Heliotropium plants. Syst Entomol 6: 347-354.

A new species of chrysomelid beetle from Kenya is described and named G. gabriela Scherer. Microscopic peculiarities of the male antennae are characterized by means of scanning electron microscopy. The males of G. gabriela are attracted to and feed at withered plants of the genus Heliotropium (Boraginaceae) at dusk. No females were found. It is assumed that feeding at Heliotropium provides pyrrolizidine alkaloids (PAs), but the adaptive significance of the behavior is unclear. The findings are discussed in the context of utilization of PAs by Lepidoptera.

Edgar JA, Boppré M, Schneider D (1979) Pyrrolizidine alkaloid storage in African and Australian danaid butterflies. Experientia 35: 1447-1448. lesen / read

8 species of African and Australian danaid butterflies, captured in the field, were analyzed and found to contain pyrrolizidine alkaloids. It is suggested that these alkaloids, which are gathered by the adults from plants, contribute significantly to the chemical defences of the danaids.

Boppré M (1979) Untersuchungen zur Pheromonbiologie bei Monarchfaltern (Danaidae). Dissertation der Fakultät für Biologie der Ludwig-Maximilians-Universität, München.

Boppré M (1979) Lepidoptera and withered plants. Antenna (Bull R ent Soc Lond) 3: 7-9. lesen / read

Boppré M (1978) Chemical communication, plant relationships, and mimicry in the evolution of danaid butterflies. Entomol exp appl 24: 264-277. lesen / read

The knowledge on pheromone biology in danaid butterflies, on relations between adult danaids and pyrrolizidine alkaloid-containing plants, and on relations between danaid larvae and cardiac glycoside-containing foodplants is briefly reviewed and hypotheses on the phylogenetic origin and development of these penomena are discussed.

Boppré M, Petty RL, Schneider D, Meinwald J (1978) Behaviorally mediated contacts between scent organs: another prerequisite for pheromone production in Danaus chrysippus males (Lepidoptera). J Comp Physiol 126: 97-103. lesen / read

Males of Danaus butterflies possess 2 binate glandular organs: abdominal hairpencils, which release aphrodisiac pheromones during courtship behavior, and pockets on the hindwings. Between these 2 types of organs contacts are established behaviorally: the hairpencils are dipped into the alar pockets. GLC analyses of hairpencil and wing pocket extracts from D. chrysippus show that this contact behavior is a prerequisite for the synthesis of the ketonic pheromone component (for which the term danaidone is suggested) in physiologically normal amounts. Danaidone occurs on the hairpencils only after the males have ingested pyrrolizidine alkaloids as precursors, and after hairpencils have been dipped into the wing pockets. The appearance of danaidone in the wing pockets depends on the ingestion of alkaloidal precursor, but is not affected by the contact behavior mentioned. Mechanisms by which contact behavior might control pheromone biosynthesis are discussed.

Boppré M (1978) Das Experiment: Sexuallockstoff beim Seidenspinner. Biologie in unserer Zeit 8(4): 120-124. Reprinted in Falk H, Sitte P (Hrsg.) Experimente aus der Biologie. D-Weinheim: Verlag Chemie, Physik Verlag, 1980. Reprinted in Kremer BP, Keil M (Hrsg.) Experimente aus der Biologie. D-Weinheim: Verlag Chemie, Physik Verlag, 1993. lesen / read

Boppré M (1977) Pheromonbiologie am Beispiel der Monarchfalter (Danaidae). Biologie in unserer Zeit 7(6): 161-169.
Reprinted in Sitte P (Hrsg.) Horizonte der Biologie. D-Weinheim: Verlag Chemie, Physik Verlag, 1993. lesen / read

Petty RL, Boppré M, Schneider D, Meinwald J (1977) Identification and localization of volatile hairpencil components in male Amauris ochlea butterflies (Danaidae). Experientia 33: 1324-1326. lesen / read

By gas-chromatography and mass-spectroscopy 7 volatile substances have been found on the abdominal hairpencils of Amauris ochlea males, 6 substances have been identified. The spatial distribution of compounds is correlated to the 5 types of hairs comprising the scent organ.

Boppré M, Fecher K (1977) Structural complexity of scent organs of male danaid butterflies. Scanning electron microscopy, Vol. II, 639-644, Chicago/IL: IIT Research Institute.

The morphology of male scent organs of danaid butterflies can be investigated with a scanning electron microscope using air-dried specimens, even old ones from museum collections. Organisation and fine structure of abdominal hairpencils as well as of alar patches, pockets, and pouches show characteristics which supplement chemical, physiological, and behavioral results. Outstanding structures are pheromone-transfer-particles, which are produced in different ways and disseminated onto the female during courtship flight. SEM studies covering functional aspects led to a comparative study applicable for reconstructing the phylogentical development of danaids.

Boppré M (1976) Pheromon-Transfer-Partikel auf einem Duftpinselhaar eines Monarchfalters (Danaus formosa). Naturwiss Rdsch 29(9): cover photograph.

Schneider D, Boppré M, Schneider H, Thompson WR, Boriack CJ, Petty RL, Meinwald J (1975) A pheromone precursor and its uptake in male Danaus butterflies. J Comp Physiol 97: 245-256. lesen / read

1. Male Danaus chrysippus butterflies the larvae of which have been raised indoors on their natural foodplants (Asclepias) lack the pyrrolizidinone pheromone (Fig.1, I) which is known from the hairpencils of field-caught butterflies.
2. Male D. chrysippus have been observed actively approaching withered parts of a Heliotropium plant in Kenya. These observations could be repeated in the laboratory. On the plants, the males suck extensively.
3. A pyrrolizidine alkaloid (Fig. 1, II) has been isolated and characterized as Iycopsamine from this Heliotropium species.
4. Significant and up to "normal" amounts of I are found in the hairpencils after the indoors-raised males were allowed to: a) suck on withered and remoistened Heliotropium, or b) feed on a methanol extract of Heliotropium, or c) feed on a solution of alkaloid (II) isolated from Heliotropium (see Table 1, Fig. 2)). It therfore appears that substance II is a dietary precursor of I.
5. Electroantennogram recordings revealed the presence of antennal olfactory receptors for both substances I and II, as well as for the odor of the withered and remoistened Heliotropium (Fig. 3).
6. Experiments in which radiolabelled compounds were administered to D. gilippus berenice males also suggest that the pyrrolizidine pheromone (I) is biosynthesized from an exogenous alkaloid precursor.

Meinwald J, Boriack CJ, Schneider D, Boppré M, Wood WF, Eisner T (1974) Volatile ketones in the hairpencil secretion of danaid butterflies (Amauris and Danaus). Experientia 30: 721-722. lesen / read

Extrakte von Duftpinseln männlicher afrikanischer Schmetterlinge der Gattungen Amauris und Danaus wurden chemisch analysiert. Zwei Substanzen wurden isoliert: ein neues aromatisches Keton (3,4-dimethoxyacetophenon) und ein schon von anderen Danaiden bekanntes heterozyklisches Keton.