Residual contact toxicity and repellence of Cupressus lusitanica Miller and Eucalyptus saligna Smith essential oils against major stored product insect pests

Abstract

In an effort to find eco-friendly alternatives to synthetic pesticides in grain storage, residual contact toxicity and repellence of Cupressus lusitanica and Eucalyptus saligna leaf essential oils were evaluated against adult Tribolium castaneum, Acanthoscelides obtectus and Sitophilus zeamais. In bioassays, oil was applied at 0.00, 0.05, 0.10, 0.15 and 0.20% v/w to wheat and bean grains and stored for 30–120days after which test insects were introduced into sub-samples of treated grains. Both oils at 0.20% v/w and 120days grain storage duration caused a mortality of 5.0–65.0% in test insects whereas in the repellence bioassay, at same doses and grain storage duration produced percent repellence values of 34–52.4% of test insects. Considering other pesticidal properties of C. lusitanica and E. saligna oils, current results point oils as potential residual contact toxicants and repellents for possible integration into insect pest management practices.