昆虫寄生性線虫のセンチニクバエ Boettcherisca peregrina とイエバエ Musca domestica 幼虫に対する殺虫効力

Abstract

Entomogenous nematodes, Steinernema feltiae (ALL and Mexican strains), S. bibionis, S. glaseri, and Heterorhabditis heriothidis were evaluated for their infectivity to larvae of a Japanese species of flesh fly, Boettcherisca peregrina by the contact method with nematode suspension. The 3rd instar larvae of B. peregrina were forced to contact with a suspension of infective larvae of nematodes for 48hr and the mortality of treated insects calculated from adult fly emergence was determined. Both strains (ALL and Mexican) of S. feltiae and S. bibionis were most infective to B. peregrina larvae, followed by H. heriothidis, whereas S. glaseri showed no significant infectivity to larvae of the fly. To investigate the effect of temperature on infectivity of nematodes, the 3rd instar larvae of B. peregrina were incubated with a suspension of nematodes at 5 different temperatures between 15 and 35℃ for 48hr. S. feltiae (ALL and Mexican strains) were most infective at 25 and 30℃, less infective at 30℃, and showed no remarkable activity at 15 and 35℃. Loss of S. feltiae infectivity at 35℃ was due to death or weakening of nematodes at higher temperature. Loss of infectivity at 15℃, on the contrary, was caused by immobility of nematodes at lower temperature. Housefly (SRS strain) larvae were reared in a medium containing S. feltiae (ALL strain) for evaluation of its infectivity. The 2nd instar housefly larvae were placed on standard barley bran media with infective larvae of the nematode and adult fly emergence was subsequently observed. S. feltiae almost completely inhibited house fly emergence at a concentration of (10)^5 per 100g larval medium.