Post‐alighting responses of Mexican fruit flies (Dipt., Tephritidae) to different insecticides in paint on attractive spheres

Two new, comparatively safe insecticides (spinosad and imidacloprid) were compared with dimethoate (each at 1.5% active ingredient) for behavioural and mortality effects on Mexican fruit flies, Anastrepha ludens. Insecticide was mixed with sugar (as a feeding stimulant) and yellow latex paint (as an extending agent) applied to the surface of fruit‐mimicking biodegradable 7 cm spheres made of sugar, flour and glycerin. Flies feeding on spinosad‐treated spheres did not differ from flies feeding on untreated spheres in post‐feeding intra‐tree flight capability, amount of oviposition or mortality. Flies that fed on imidacloprid‐ or dimethoate‐treated spheres for as little as 30 s experienced both high reduction in oviposition and high mortality compared with flies that fed on untreated spheres, and the flies from imidacloprid‐treated spheres also showed a much reduced intra‐tree flight capability. If baited with attractive odour, biodegradable yellow spheres treated with a surface coating of imidacloprid in latex paint and sugar could have potential for suppressing Mexican fruit flies on host trees.