effects of two temperature storage regimes on the efficacy of 3 commercial gel baits against the german cockroach, blattella germanica l. (dictyoptera: blattellidae)

background: to compare the effectiveness of 3 commercial gel bait formulations containing fipronil (goliath ã cockroach gel 0.05% ai), chlorpyrifos-a (clean bait ã gel, 2% ai), and chloropyrifos-b (serpa ã gel 2% ai) against german cock­roaches ( blattella germanica ) when stored at 23°c and 30° c after treatment. methods: laboratory bioassays consisted of placing groups of fifteen cockroaches (a random combination of adult, mixed sex and large nymphs-stage 6) into a 5 l cylindrical plastic container with one drop of product (avg 0.10 g ± 0.01 g) applied to a 76 mm x 26 mm glass microscope slide affixed to the bottom of each container (one product tested per container). cumula­tive mortality was assessed at 6 h, 1, 2, 3, 4, and 5 d after application. to determine the further effects of storage tempera­ture after treatment on residual activity of the gels, a drop of each product was applied to separate glass microscope slides and stored at either 23º c (warm) or 30º c (hot) under dark conditions for 0, 1, 7, 14, 30, 45, 60 and 90 d after applica­tion. results: freshly applied baits (day 0) containing fipronil provided complete cockroach mortality (100%) within 5 d whereas chloryrifos-a and chlorpyrifos-b provided »72% and 88% mortality, respectively. generally, cockroach mortality was greater when gels were stored at 30 ° c compared with 23º c. conclusion: the fipronil gel formulation proved to be as efficacious as the chlorpyrifos gels and in some instances sur­pased the latter formulations depending on storage time and temperature by providing »90% mortality at 90 d post treat­ment.