The objective of this study was to evaluate the comparative toxicity of the pyrethroid insecticide lambda-cyhalothrin to the velvetbean caterpillar, Anticarsia gemmatalis and to the nymphs of the southern green stink bug, Nezara virídula. The lethal dose (LD50) values were compared with the ones of the organophosphoms insecticide monocrotophos. The experiments were performed under laboratory conditions by topical application technique to 3rd instars of both caterpillars and nymphs. Mortality evaluations were made at 3, 6, 24, 48 and 72 hours after treatment. The LD50 parameters were determined by probit analyses through appropriate software. Lambda-cyhalothrin acted more rapidly than monocrotophos against the caterpillars, being approximately 140-190 times more toxic than the latter. Lambda-cyhalothrin was 20-40 times more active against the nymphs than monocrotophos. The pyrethroid insecticide was about 5-9 times more toxic to the velvetbean caterpillar than to the southern green stink bug.
comparative toxicity; lambda-cyhalothrin; monocrotophos; Anticarsia gemmatalis; Nezara viridula; topical application technique
