Orthopteran Pests

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A small number of grasshoppers, crickets and mole crickets are reported to interfere with tree crops in Papua New Guinea. Typically, Orthoptera have chewing mouthparts and feed mainly on the foliage and the soft bark of young seedlings and thus only cause problems in the nursery and during a short period after the seedlings are transplanted into the field. The soil-borne mole cricket Gryllotalpa (Gryllotalpidae) was recorded feeding on the roots and foliage of Tectona grandis seedlings. The huge grasshopper Valanga irregularis (Acrididae) was encountered at Wasab, feeding on the foliage of Eucalyptus deglupta. Other hoppers of this family are often abundant in newly planted areas adjacent to grassland. The problem of ring-barking or debarking often occurs in Bulolo’s Hoop pine plantations. It can be overcome by keeping the seedlings longer in the nursery, so that the bark becomes thicker and a less attractive source of food for the grasshoppers. The newspaper article below suggests wrapping the base of the seedlings’ stems with aluminium foil. According to experienced foresters, this is a method that seems to be less feasible. Regular weeding in and cutting the grass around nurseries and newly planted areas helps to protect the seedlings and minimises grasshopper-related problems.

Post Courier, 07/03/97

Grasshoppers devastate Bulolo Forest

By HAIVETA CHRIS

LOCUSTS are threatening the success of the Bulolo Forest Plantation program, a Japanese, forest expert seconded to the project said yesterday.

Japan International Co-operation Agency expert Hitofumi Abe told the forestry research seminar in Lae that the grasshoppers were killing up to 90 per cent of the hoop pine (Araucaria) seedlings within three months of planting, and he urged the Forest Research Institute to second some ecology experts to the project.

He said he had tried wrapping the stems of the seedlings in aluminium foil to ward off the insects and had achieved some success. Just over half of the protected seedlings were still surviving after six months, while more than 75 per cent of the plants left unprotected as a "control" had been killed by grasshopper attack.

Mr Abe said the few unprotected plants which survived might have done so because they had some characteristics which the grasshoppers did not like, and he suggested that that possibility required more research.

He said the grasshoppers were not native to the area and might have been brought in with the legumes used in the plantation to give nitrogen to the soil.


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Michael F. Schneider, 1999