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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #268617
Title: Improved control of Curculio caryae (Coleoptera: Curculionidae) through multi-stage pre-emergence applications of Steinernema carpocapsae

Author
item Shapiro Ilan, David
item GARDNER, WAYNE - University Of Georgia

Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2011
Publication Date: 1/1/2012
Citation: Shapiro Ilan, D.I., Gardner, W. 2012. Improved control of Curculio caryae (Coleoptera: Curculionidae) through multi-stage pre-emergence applications of Steinernema carpocapsae. Journal of Entomological Science. 47:27-34.

Interpretive Summary: The pecan weevil is a key pest of pecan in North America. Entomopathogenic nematodes, also called beneficial nematodes, are small round worms that are environmentally friendly bio-pesticides. Beneficial nematodes do not harm humans, plants or the environment. These nematodes only attack insects. Entomopathogenic nematodes have potential as alternative control agents for the pecan weevil. In prior studies, when single applications of entomopathogenic nematodes were applied during adult weevil emergence, only moderate efficacy was observed. The objective of this study was to determine the compounded impact of multi-stage nematode applications on pecan weevil mortality over a two-year period. Experiments were conducted in a pecan orchard in Byron, GA. The nematode, called Steinernema carpocapsae, was applied 3 times in spring through fall of 2008 and 3 times during the spring and summer of 2009. The percentage of surviving pecan weevils was determined approximately 1 and 2 years after weevil larvae emerged. After 2 years, the nematode treatments provided 81% control relative to the untreated check. Overall, less than 1% of the weevils survived in the nematode treated pots. These results indicate promise for reducing the weevil below economic levels through repeated multi-stage applications of the S. carpocapsae nematode. In future research, the approach will be tested on an orchard scale, and nematode application rates and timing will be optimized.

Technical Abstract: The pecan weevil, Curculio caryae (Horn), is a key pest of pecan in North America. Entomopathogenic nematodes have potential as alternative control agents for C. caryae. In prior studies, when single applications of entomopathogenic nematodes were applied during adult weevil emergence, only moderate efficacy was observed. The objective of this study was to determine the compounded impact of multi-stage nematode applications on C. caryae mortality over a two-year period. Experiments were conducted in a pecan orchard in Byron, GA. In the fall of 2007, freshly emerged C. caryae larvae were placed in pots under the tree canopy. The nematode, Steinernema carpocapsae (Weiser), was applied 3 times in spring through fall of 2008 (targeting C. caryae larvae) and 3 times during the spring and summer of 2009 (primarily targeting adults). The percentage of surviving C. caryae was determined in the fall of 2008 and 2009, approximately 1 and 2 years after larvae emerged. In 2008 (1 year post-emergence), the number of surviving C. caryae was significantly less in treated pots (3.75%) compared with untreated pots (7.38%). In 2009 (2 years post-emergence), the number of surviving C. caryae was reduced further and was significantly less in treated pots (0.5%) compared with untreated pots (2.63%). When corrected for natural mortality, after 2 years the nematode treatments provided 81% control. These results indicate promise for reducing the weevil below economic levels through repeated multi-stage applications of S. carpocapsae. In future research, the approach will be tested on an orchard scale, and nematode application rates and timing will be optimized.