Immature Nutfall of Coconuts in the Solomon Islands III.—Notes on the Life-history and Biology of Amblypelta

Abstract

Observations on the population density of Amblypelta cocophaga China on coconut palms in the Solomon Islands are described. Although the figures are somewhat larger than those previously reported for the related Coreid, Pseudotheraptus wayi Brown, in Zanzibar, the densities are still very low.Observations were made on the oviposition habits of A. cocophaga. The principal oviposition site, contrary to previous observations, was found to be on the undersides of the fronds, in the basal recesses of the leaflets. The first-instar nymphs on hatching have to make their way to the spadices in the centre of the palm crown; this explains why first-instar nymphs are themselves only rarely found on the spadices, and also why a single treatment with insecticide is not completely effective, since the oviposition sites escape the treatment. Observations on the number of eggs on coconut palms are recorded.Anastatus axiagasti Ferrière was found to be a common egg-parasite of Amblypelta cocophaga in certain plantations of Guadalcanal. Rates of parasitisation on coconut palms ranged from 15·5 to 55 per cent, with an average of 33·3 per cent. The percentage of successful hatching of Amblypelta eggs ranged from 19 to 38 per cent., with an average of 31·3 per cent.Investigation of the area of Baunani plantation in Malaita, where the Tachinid parasite, Trichopoda pennipes (F.), had been released in 1949, indicated that it has not survived there, or, if it has, is exercising no control over A. cocophaga.Observations are recorded on two predators of interest with regard to immature nutfall.