Toxicity of granular ant bait formulations against cockroaches (Dictyoptera: Blattellidae and Blattidae)

Abstract:
The toxicity of granular ant bait formulations containing abamectin B1, orthoboric acid, or propoxur was evaluated in a series of laboratory experiments against American, Periplaneta americana (L.), and German, Blattella germanica (L.), cockroaches. LT50 values for American cockroaches ranged from < 1 d for the 2% propoxur formulation (cockroaches were either fed or starved for 24 h before treatment) to > 22 d for the Advance® Carpenter Ant Bait formulation (cockroaches were starved for 24 h before treatment and presented alternative food together with the bait). For German cockroaches, LT50 values ranged from < 1 d for the 2% propoxur formulation to 5.33 d for the 5.0% orthoboric acid Niban® formulation. In these tests, cockroaches had access to food and water 24 h before treatment, but were not provided with alternative food during testing. American cockroaches starved prior to the experiment and provided no alternative food had significantly lower LT50 values in all treatments with the exception of the Advance Granular Ant bait formulation compared with cockroaches provided alternative food. In contrast, 24 h starvation reduced the LT50 values of 100% of the slow-acting bait formulations for German cockroaches deprived of alternative food. Our results demonstrated that design of a toxicity experiment may affect the LT50 values of a particular bait formulation. Granular ant baits are clearly toxic to American and German cockroaches and may provide control of these pests in multi-species infestations. These results also imply that ant baits may provide control of additional pests in integrated pest management (IPM) systems. The lower LT50 values for bait formulations tested against of 24 h starved cockroaches are consistent with the recommendation that sanitation should be an important component of both domestic and peridomestic cockroach IPM systems.