Jeremiah D. Lowe, Kirk W. Pomper, Sheri B. Crabtree, and Jessica Durham. Land Grant Program, Kentucky State University, Atwood Research Facility, Frankfort, KY 40601-2355

•The North American pawpaw [Asimina triloba (L.) Dunal] is a tree fruit in the initial stages of commercial production in the United States (Pomper and Layne, 2005; Fig. 1).

• Annonaceous acetogenins are fatty acid derivatives found in the Annonaceae family, which includes both the genera Annona and Asimina. (Alali, et al., 1999).

•Botanical insecticides are attractive alternatives to synthetic chemical insecticides for pest management of crops because they pose little threat to the environment or to human health; however, few botanicals are currently used in agriculture (Isman, 2006).

•Some acetogenin compounds are potent inhibitors of complex I in the mitochondrial respiratory chain and display anti-tumor and insecticidal properties (Alali et al., 1999).

•Previous studies have identified asimicin and bullatacin (Fig. 6 and 7) along with over 40 other bioactive acetogenins and other compounds in the crude extracts of twigs, unripe fruits, seeds, root, bark, and ripe fruit of pawpaw (Pomper et al., 2007) (Fig. 8). •Fruit biomass represents a potentially larger and a more cost effective source than twigs for extractable acetogenin compounds for use as a botanical pesticide.

•Acetogenin activity can vary with pawpaw cultivars (Pomper et al., 2007). Identification of pawpaw cultivars displaying a high acetogenin activity would be beneficial for growers wishing to grow pawpaw as a source of these compounds.

•Previously, only a few pawpaw cultivars had undergone assessment of their acetogenin activity.

•The objective of this study was to assess the acetogenin activity of ripe fruit from 16 different pawpaw genotypes.

•Pawpaw fruit were collected from 16 pawpaw genotypes in September 2005. Pulp from at least 5 ripe fruit were extracted from skin and seeds, placed in zip-lock bags, and stored in a -15circ C freezer.

OExtraction of Acetogenins and Brine Shrimp Testing (BST). Acetogenins were obtained by extracting 9 grams of freshly thawed pawpaw pulp with 95% ethanol. Following quantification a 2.5 mg/ml solution was made using 95% ethanol, and 1, 2, 10, 20, 200, and 2000 μl were added to 2 dram vials to correspond to 0, 0.5, 1, 5, 10, 100, and 1000 parts per million (ppm). After the ethanol was evaporated twenty brine shrimp larvae, taken 48 h after initiation of hatching in artificial sea water, were added to each vial, and the final volume of each vial was adjusted to 5 ml using the artificial sea water. After 24 h, survivors were counted. Each sample had at least three replications.

•Brine shrimp mortality varied with different pawpaw genotypes indicating varying acetogenin activity levels. •Brine shrimp mortality varied between 52% and 96% at 10 ppm. •Yields indicate ripe pulp can serve as a new large source of biomass for the extraction of acetogenin compounds. •Further studies will be needed to determine additional high and low acteogenin activity genotypes.

- Pawpaw genotypes contain varying levels of acetogenin activity, indicating that some genotypes would be more suited for commercial production of acetogenins than others.