RELATIVE TOXICITY OF MUSTARD ESSENTIAL OIL TO INSECT-PESTS OF STORED PRODUCTS

Abstract

The relative toxicity of the mustard (Brassica rapa L.) essential oil (MEO) on young and old larvae, pupae, and adults of Sitophilus zeamais and Callosobruchus maculatus was determined using concen- tration-response bioassays. The respiration rate of adults was measured to determine its influence on its toxic- ity. Different developmental stages of both species differed significantly in their response to MEO, with the adults being much more susceptible than the immature stages. Although adult mortality did not differ between species, the adult respiration rate of C. maculatus was significantly higher than that of S. zeamais. Thus, the toxicity oil for adults was not influenced by natural respiration rate of species investigated.