Interpretive Summary: Many native plants are natural sources of potentially useful drugs and pesticides. One such plant is the paw paw tree. Its bark and smaller twigs are laced with potent chemicals called acetogenins. Acetogenins are fatty compounds mainly produced by paw paw trees in the summer months as a poison to deter insect feeding. The inhibition of specific respiratory enzymes in living cells by acetogenins contributes to their antitumor and pesticidal properties. We tested the efficacy of paw paw tree extract containing acetogenins to kill two major agricultural pests: green peach aphids and blueberry gall midges. The acetogenin extracts were as effective as the microbial-based pesticide, spinosad and also compared favorably with malathion. Paw paw extract was much more toxic to aphids and gall midges than the broad-spectrum and neurotoxic insecticide, phosmet. Extracts from the paw paw tree have broad, effective and prolonged insecticidal activity, and unlike many currently used insecticides, they are safer to people and wildlife.

Technical Abstract: Annonaceous acetogenins extracted from the paw paw tree [Asimina triloba (L.) Dunal] are natural pesticides, and patents have been granted for their development as commercial pesticides. Their primary mode of action is the disruption of cellular respiration, which explains their broad-spectrum bioactivity against at least 15 species of arthropods and nematodes. Acetogenins (2000 ppm) dissolved in a 9.5% ethanol extract were highly bioactive against green peach aphids, Myzus persicae (Sulzer), rapidly killing 100% of nymphs and apterous adults, faster than the microbial-based insecticide, spinosad. The extract and spinosad were equally effective at inducing mortality for larval blueberry gall midges, Dasineura oxycoccana (Johnson). Toxicity of acetogenins compared favorably to malathion and topical applications were also more effective than phosmet for knocking down aphids and gall midges of varying ages. New classes of pesticides, like Annonaceous acetogenins, are needed to replace or supplement organophosphate and carbamate insecticides in IPM programs. The acetogenins are unusual among many natural insecticides in that they have broad pesticidal activity, induce rapid mortality, and have a complex mode of action that helps to thwart insecticidal resistance.