Antennal Responses, Repellency, and Toxicity of Essential Oil Formulations on the German Cockroach (Blattodea: Ectobiidae)

Abstract

The toxicity, repellency, and the electroantennogram responses induced by six essential oil formulations and their components against the pyrethroid-susceptible (S) and resistant (D and E) strains of the German cockroach, Blattella germanica (L.) (Blattodea: Ectobiidae) were tested. This was achieved using the direct spray and continuous exposure assays, 2-choice olfactometer, flushing assays, and the electroantennogram technique, respectively. Essentria® All Purpose Insect Concentrate (Essentria®) generated the strongest antennal response (1-4 mV). Menthone generated the largest average antennal response (0.066 mV – 8.324 mV) of all the individual active components studied. Essentria® showed the highest average repellency (64.6%) across both assays. The cockroaches had the highest mortality after exposure to Excite R™ [median Lethal Time (LT50) = 3.772 hours], in the continuous exposure assay, and Essentria® (average LT50 = 1.343 minutes), in the direct spray assay. These results indicate that essential oil formulations and components and are toxic, repellent, and can be detected by the German cockroach.