Toxicity and Antifeedant Activity of Selected Plant Extracts Against Lar- val Obliquebanded Leafroller, Choristoneura rosaceana (Harris)

Several plant extracts were evaluated against obliquebanded leafroller larvae to determine potential toxicity and antifeedant effects. Two of the plant extracts exhibited contact toxicity; the LC50 value of Humulus lupulus extract against 3 rd instar larvae was 24.5 μg / insect. In a no choice context, larval survivorship was reduced 23 57 % after feeding on a meridic pinto bean diet treated with the extracts. Furthermore, average female and male pupal weight was reduced for leafrollers that fed on diet treated with each of the individually-tested extracts at a 4 % concentration (w/w). Incorporation of Bifora radians and H. lupulus into diet deterred larval feeding at a 1 % concentration by weight. H. lupulus and Arctium lappa extracts were deleterious to larvae in each of the bioassay methods conducted, exhibiting toxic, developmental, and antifeedant effects. These two extracts may be promising candidates for further development as botanical insecticides that could potentially substitute broad-spectrum synthetic neurotoxins for leafroller control.