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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 Bulolos 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
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