Essential oil toxicity and detoxicative mechanisms in Choristoneura rosaceana, Trichoplusia ni, Dysaphis plantaginea and Myzus persicae

The obliquebanded leafroller (Choristoneura rosaceana), the cabbage looper (Trichoplusia ni), the rosy apple aphid (Dysaphis plantaginea) and the green peach aphid (Myzus periscae) are serious pests in many North American apple orchards and vegetable greenhouses. In an effort to find alternative pest control options, a selection of essential oils was tested against each insect pest species. Of the essential oils tested, patchouli oil was among the most toxic to all insect pests. Through this work, it was noted that there appeared to be a role for detoxification enzymes in detoxifying these essential oils. Accordingly, the general detoxicative abilities of each insect and the potential role of patchouli oil in inducing these enzymes were assessed. Esterase and glutathione S-transferase activity was highest in M. persicae while results from cytochrome P450 activity were less conclusive. In addition, patchouli oil appears to have differential abilities to induce or inhibit the detoxicative enzymes depending on the specific insect species and the enzyme involved, although results were not significant. A summary of these results will be provided.