Base-line susceptibility of the oriental latrine fly, Chrysomya megacephala (Diptera: Calliphoridae), to five insectides.

Susceptibility to five insecticides was assessed on seven colonies of the oriental latrine fly, Chrysomya megacephala (Fabricius), originating from Japan, Hong Kong, Philippines, Indonesia and Papua New Guinea, and on C. saffranèa (Bigot) from PNG. All the colonies were susceptible to fenitrothion, diazinon, dichlorvos, permethrin and gamma-HCH, although the Jakarta, Manila and Tokyo colonies of C.megacephala were least susceptible (most tolerant) to diazinon, dichlorvos and permethrin. Feral forms of both Chrysomya species were 4-5-fold more susceptible to permethrin at the LD50 level than were all six colonies of the synanthropic form of C.megacephala.