Repellency and Toxicity of Mint Oil to American and German Cockroaches (Dictyoptera: Blattidae and Blattellidae)

The repellency and toxicity of mint oil to American, Periplaneta americana (L.), and German, Blattella germanica (L.), cockroaches were evaluated in a series of laboratory experiments. In topical application experiments, mint oil was toxic to both species with toxicities (LD50s) of 2.57 (1.98– 4.20) in 10 l and 3.83 (2.35–7.34)% in 2 l for American and German cockroaches, respectively. In continuous exposure experiments, Mortality (LT50) values for American cockroaches ranged from 246.8 min with 3% mint oil to 64.2 min with 100% mint oil. LT50 values for German cockroaches ranged from 318 to 5.6 min for 3% and 30% mint oil, respectively. American and German cockroaches had knockdown (KT50) values of ≈7.4 and 9.2 h, respectively, when fumigated with 50 l of 100% mint oil; 100% of both species were killed after 24 h. Mint oil deposits were ≈100% repellent in Ebeling choice boxes to both species during each day of the 14-d experiment. Mint oil-based formulations could provide another integrated pest management tool for cockroach management, especially in situations in which conventional insecticides would be in-