Toxicity of Basil (Ocimum basilicum L.) and Rosemary (Rosmarinus officinali L.) extracts on Tribolum confusum (DuVal) (Coleoptera:Teneberionidae)

Abstract

This study was conducted to monitor the effect of two-plant extracts viz. leaves of Ocimum basilicum L. and Rosmarinus officinalis L. on the last larval and adult stages of Tribolum confusum (DuVal). Bioassay was made using the ethanol as a solvent for both plants to find out the median lethal concentration (LC₅₀). Results showed that the last larval instar was more highly susceptible to both plant extracts than the adult stages. The LC₅₀ of R. officinali were 113.15 and 135.18, whereas the LC₅₀ of O. basilicum extract were 148.38 and 218.78 ppm for the last larval and adult stages after 24 hours exposure respectively. The highest mortality percentages were 78% and 72% for R. officinali and 74%, 66% for O. basilicum against T. confusum last larval instar and adult stages, respectively, after 24 hours exposure at 250 ppm. The application of these botanicals extracts might be promising in protecting the stored grains against coleopteran pests.