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1 October 2010 Potential of Ripe Pawpaw Fruit Extract as an Insecticide and Feeding Deterrent for Striped Cucumber Beetle (Coleoptera: Chrysomelidae) on Squash
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Laboratory experiments were performed to study the effects of pawpaw, Asimina triloba (L.) Dunal, fruit extract on mortality and feeding deterrence of striped cucumber beetle, Acalymma vittatum (F.). Recently, fruit tissues of pawpaw were found to contain phenolic and antioxidant compounds, as well as annonaceous acetogenin compounds having insecticidal activity. Ripe pawpaw fruit pulp from a range of pawpaw varieties was extracted with 100% ethyl alcohol to obtain acetogenin compounds. Pulp extracts of 0, 10, 100, 1,000, 10,000 and 50,000 ppm were then used to assess feeding deterrence and mortality of beetles. Buttercup squash leaf disks 3.5 cm in diameter were treated individually with each concentration and placed on water moistened filter paper in plastic Petri dishes (9 cm diam). Five striped cucumber beetles were placed on each leaf disk. All Petri dishes were then placed in an environmental growth chamber at 27°C and a 16:8 h light:dark photoperiod. Feeding activity was recorded 1, 4 and 24 h after beetle introduction. After 24 h the beetles were removed. Beetles did not feed on treated squash leaves at either 1 or 4 h of exposure. However, significant feeding occurred between 4 and 24 h after beetle introduction. Feeding was lowest and feeding damage least on 50,000 ppm pawpaw-treated leaf disks compared with leaf disks treated with < 10,000 ppm dilutions. Pawpaw fruit extract reduced feeding by 89% and 97% in the 10,000 and 50,000 ppm treatments, respectively. The calculated LC50 value was 50,538 ppm whereas the LCF10 (concentration at which only 10% of the leaves were consumed) was 2,033 ppm. At 10,000 ppm 10% of the beetles were killed; however, only 3% of the leaf tissue was consumed. Thus, pawpaw fruit extract may be an effective insect feeding deterrent. The duration of treatment effectiveness and susceptibility of other pest and beneficial insect species to the extracts also needs to be examined.
John D. Sedlacek, Karen L. Friley, Jeremiah D. Lowe and Kirk W. Pomper "Potential of Ripe Pawpaw Fruit Extract as an Insecticide and Feeding Deterrent for Striped Cucumber Beetle (Coleoptera: Chrysomelidae) on Squash," Journal of Entomological Science 45(4), (1 October 2010).
Received: 25 March 2010; Accepted: 1 June 2010; Published: 1 October 2010

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