Molt disruption and mortality of Locusta migratoria var. manilensis (Meyen) (Orthoptera: Acrididae) caused by insect growth regulators

Abstract

The acute toxicity effects of topical applications of five insect growth regulators (IGRs) on the oriental migratory locust Locusta migratoria var. manilensis were assessed. Under laboratory conditions, at the highest tested dose rate of 300 ppm, the percent mortality and molt inhibition after two weeks for the five tested compounds were: flufenoxuron (97 and 83%), swallowwort alkaloids (48 and 85%), azadirachtin (100 and 93%), compound RH-5849 (45 and 22%), and pyriproxyfen (48 and 37%) respectively but low doses caused higher molt inhibition for compound RH-5849. These IGRs affected the timing of the subsequent molt, the average timing of the molt (of survivors) was delayed 0-2 days after treatments with flufenoxuron at dose rates between 18.75-300ppm, RH-5849 at dose rates between 150-300 ppm, but occurred 0-2 days early following treatment with azadirachtin, swallowwort alkaloids or pyriproxyfen at dose rates between 18.75-300ppm, and RH-5849 at dose rates between 37.5-75 ppm. Initial studies of the insecticidal effects of these insect growth regulators on L. migratoria manilensis show them to be very potent locust control agents.

Key words: Insect growth regulators, Locusta migratoria var. manilensis (Meyen), biological control, sustainability.