Parasitism Associated with Brachypterous Males in the Sugarcane Leafhopper, Perkinsiella vitiensis1

Abstract

Samples of Perkinsiella vitiensis Kirkaldy, the Fijian sugarcane leafhopper, were collected at weekly intervals from cane fields in the mill area near Lautoka on the island of Viti Levu, Fiji, during 1965. Between January and early June the percentage of parasitized adult leafhoppers varied according to sex and form (Table 1). For the remainder of the year, the period that the leafhopper population had a low density, there was a small number of parasites. The population fluctuations of P. vitiensis in this area during 1965 were described by Osborn et al. (1966). The parasite, a strepsipteran, identified by pupal dissection, was probably Elenchus tenuicornis Kirby. This species is the only strepsipteran parasite of P. vitiensis recorded by Box (1953). Macropterous females were the least affected group: only 0.8% were parasitized in comparison with 1.7% of the macropterous males. Brachypterous forms of both sexes were more heavily parasitized. The degree of parasitism for brachypterous insects is not significantly different from that of macropterous insects at the 5% level in a x2 test of the population of female polymorphs. In the same test applied to data on male polymorphs, significantly more brachypterous insects are found to be parasitized ( P <0.0001). There is no significant difference between the numbers of parasitized adults and nymphs.