The insecticidal activities of 13 Lamiaceae plant oils and their components against adult German cockroaches, Blattella germanica L. (Blattodea: Blattellidae), were evaluated using fumigant and contact bioassay. Among the tested oils, basil, pennyroyal, and spearmint showed the strongest insecticidal activities against adult B. germanica. Insecticidal activity of pennyroyal was 100% against male B. germinica at 1.25 mg concentration in fumigant bioassay. Basil and spearmint revealed 100% and 100% insecticidal activity against male B. germinica at 5 mg concentration, but their activities reduced to 80% and 25% at 2.5 mg concentration, respectively. In contact toxicity bioassy, basil, pennyroyal, and spearmint oils exhibited 100%, 100%, and 98% mortality against female B. germanica at 1 mg/♀, respectively. Among the constituents identified in basil, pennyroyal and spearmint oils, insecticidal activity of pulegone was the strongest against male and female B. germanica.

Twelve Lamiaceae plant essential oils (EOs) and their components were evaluated for their fumigant and contact toxicities. Inhibition of AChE by the major components of active EOs was also assessed. Strong fumigant toxicity was observed from EOs of Mentha piperita and Perilla frutescens. Menthone and menthol, and perilla aldehyde were identified as major components of the above two EOs, respectively. The LC50 (mg/L) values of M. piperita, P. frutescens, menthone, menthol and perilla aldehyde were 3.87, 2.44, 5.76, 1.88, and 0.99 against male, and 4.10, 3.31, 5.13, 1.94, and 1.15 against female, respectively. Strong contact toxicity was observed from the EOs of Satureja montana and Thymus zygis. Thymol and carvacrol were major components of these two EOs. The LD50 (μg/fly) values for contact toxicity of S. montana, T. zygis, thymol and carvacrol were 2.95, 2.93, 1.63, and 1.30 for male, and 4.59, 5.09, 2.68, and 2.60 for female, respectively. Among the five major components, perilla aldehyde showed most active inhibition activity against AChE of both sexes of SWD.