Fumigant toxicity of six essential oils to the immature stages and adults of Tribolium confusum

Abstract

Six essential oils derived from Lavandula hybrida, Laurus nobilis, Thuja orientalis, Citrus sinensis, Citrus limon, and Origanum vulgare were evaluated in a preliminary fumigation screening test on 10-, 25- and 31-days-old larvae, 2-days-old pupae and 10- and 60-days-old adults of Tribolium confusum. Beetles were exposed to essential oils' vapors at a series of concentrations ranging from 0.27 to 165 μl/l of air depending on the essential oil, insect developmental stage, age and sex. All but O. vulgare essential oils exhibited strong fumigant toxicity to all developmental stages of T. confusum. In general, 10 day-old larvae were the most susceptible and the 25 and 31 day-old larvae were the most tolerant. LC50 values ranging between 1.8 and 109 μl/l air depending on the essential oil and insect developmental stage, age and sex. Furthermore, pupae exposed to these essential oil vapours showed various degrees of inhibition of morphogenesis. © Benaki Phytopathological Institute.