LABORATORY AND FIELD EVALUATIONS OF AN IMIDACLOPRID BAIT AGAINST GERMAN COCKROACHES (DICTYOPTERA: BLATTELLIDAE)

Abstract:
An experimental 2.15% imidacloprid-based gel bait containing »44% water was evaluated in laboratory and field studies against the German cockroach, Blattella germanica (L.). In continuous exposure tests, toxicity and presumably bait consumption varied with cockroach stage, deprivation of competitive food, and temperature. LT50s for cockroaches provided no competitive food ranged from »1.7 h for adult females to »31 h for adult males. LT50s for cockroaches provided competitive food ranged from »0.9 h for adult females to 190 h for small nymphs. Bait toxicity increased exponentially with temperature between 10 and 30°C. Most (90%) gravid females exposed to bait were killed within 24 h, however there was no effect on eventual hatch of attached oothecae or number of first instar nymphs. Repellency and potential for effectiveness of the bait were evaluated in Ebeling choice boxes. Even though the bait was significantly more repellent (»38%) than the untreated control (»14%), the bait had positive potential for effectiveness, or performance index (PI) values of >90 (on a scale of -100 to 100) after 14 d.. In field trials in heavily infested single family dwellings, 30 g of bait applied throughout the kitchen reduced German cockroach trap catch an average of »50% within 1 week and »80% after 4 weeks. The bait significantly reduced German cockroach trap catch in infested homes during a 4 week period. This imidacloprid gel bait can significantly reduce German cockroach populations when properly applied.