PERFORMANCE OF ABAMECTIN BAIT FORMULATIONS AGAINST GERMAN COCKROACHES(DICTYOPTERA, BLATTELLIDAE)

Commercial and experimental formulations of abamectin-based baits were evaluated in laboratory and field studies against the German cockroac h, Blateella germanica (L.). In continuous exposure tests with adult m ales, toxicity and presumably bait consumption varied with the design of the bioassay. LT(50)s ranged from approximate to 0.9 to >41 d for a n aerosol gel formulation for males deprived of water for 72 h before the test and for undeprived males tested with alternative food and wat er, respectively. Dry formulations had lower LT(50)s than water contai ning formulations for nondeprived males. There was no difference in ba it toxicity between males deprived of food or water, but in arena test s, moist formulations were preferred by mixed-stage populations of coc kroaches. Powder formulations were more repellent (approximate to 14.9 %) than moist formulations (approximate to 6.4%) in Ebeling choice box es assays, but all abamectin formulations had positive performance ind ices. A powder formulation reduced cockroach trap catch in infested ap artments more rapidly when applied to 50, rather than 12 sites, even w hen the same amount of bait was applied per apartment. When applied at approximate to 50 sites as a series of thin smears, an aerosol formul ation provided nearly an 80% reduction in trap catch. Other abamectin formulations provided substantial, but smaller reductions in trap catc h. Other abamectin baits can reduce German cockroach populations when properly applied.