1_Certain monoterpenes produced by aromatic plants are known to have lethal and sublethal effects on insects. As there is a need to replace conventional pesticides (organophosphates, carbamates, pyrethroids) with biorational pesticides, we evaluated the behavioural and toxicological responses of the German cockroach, Blattella germanica, exposed to the following monoterpenes, namely (+)-a-pinene, (–)-a-pinene, limonene, menthone, linalool, menthyl acetate and geraniol. Locomotor activity and repellency were quantified using a video tracking system. To study the effect on locomotor activity, larvae were exposed to filter papers treated with concentrations of monoterpenes ranging between 1.4 and 1,400 µg/cm2. Only menthyl acetate applied at a concentration of 14 µg/cm2 or higher increased the locomotor activity of the larvae. Repellency was evaluated by exposing larvae to circles of filter paper divided in two equal zones: one zone was treated with a solution of a monoterpene in acetone (14 or 140 µg/cm2) and the other with only acetone. Larvae were repelled by all the monoterpenes tested. The two concentrations of geraniol and the highest concentration of menthyl acetate and linalool were as repellent as DEET (positive control). The fumigant effect was evaluated by exposing larvae to vapour from 100 µl of pure monoterpene in a sealed container., 2_The values of the 50% Knock-down Times (KT50), expressed in minutes, were: (+)-a-pinene: 11.8, (–)-a-pinene: 14.6, limonene: 81.0, menthone: 141.0, and linalool: 238.6. (+)-a-Pinene was as good a fumigant as dichlorvos (positive control, KT50 = 9.7 min). The least effective compounds were menthyl acetate and geraniol (both affected less than 50% of larvae after 490 min of exposure). In conclusion, (+)-a-pinene (for its fumigant effect), menthyl acetate (for its hyperactivant effect) and menthone and geraniol (for their repellent properties) could potentially be used for controlling B. germanica., Raúl A. Alzogaray ... [et al.]., and Obsahuje seznam literatury
German cockroaches spend most of the day in aggregations within shelters, which they leave in nocturnal foraging trips; cockroaches are rarely seen outside shelters during daylight hours. However, when population density exceeds shelter availability, diurnal aggregations form in exposed, unsheltered locations. To determine if shelter availability affects fitness of B. germanica, we reared cohorts of nymphs in laboratory arenas with or without shelters, and measured reproduction and longevity of tagged adults. When shelters were available in arenas, nymphs developed faster, adults gained more body mass, and females produced more fertile oothecae than when arenas lacked shelters. Therefore, shelter alone has a significant positive effect on growth and reproduction of B. germanica, and reducing or eliminating shelters should affect population growth of B. germanica in residential and industrial settings. and César Gemeno, Gregory M. Williams, Coby Schal.