Improved biological control of pecan weevil through pre-emergence applications

Authors: Shapiro Ilan, David

Submitted to: Pecan Grower
Publication Type: Trade Journal
Publication Acceptance Date: 12/29/2009
Publication Date: 2/1/2010
Citation: Shapiro Ilan, D.I. 2010. Improved biological control of pecan weevil through pre-emergence applications. Pecan Grower. 21(3):18-20.

Interpretive Summary: Alternative approaches for suppression of the pecan weevil are desired. Microbial control agents such as insect-killing nematodes are potential alternatives. Nematodes are small round worms. These insect-killing nematodes, also known as beneficial nematodes, are natural bio-insecticides that are safe to humans and the environment. In prior studies, these nematodes were applied during weevil emergence with only moderate efficacy. In this study, a novel approach was tested, i.e., multiple applications to control pecan weevil before emergence. The idea is to kill the weevil before it has a chance to emerge and attack the crop. The experiment used the nematode Steinernema carpocapsae and was conducted in pots buried under the orchard canopy. The overall survival of pecan weevil in nematode treated pots was < 1%. Compared with non-treated pots the level of survival corresponded to 81.1% control. The experiment warrants repeating and expansion to an orchard scale. These initial results show promise for reducing the weevil below economic levels.

Technical Abstract: Alternative approaches for suppression of the pecan weevil, Curculio caryae, are desired. Microbial control agents such as entomopathogenic (insect-killing) nematodes are potential alternatives. In prior studies, these nematodes were applied during weevil emergence with only moderate efficacy. In this study, a novel approach was tested, i.e., multiple applications to control pecan weevil before emergence. The idea is to kill the weevil before it has a chance to emerge and attack the crop. The experiment used the nematode Steinernema carpocapsae and was conducted in pots buried under the orchard canopy. The overall survival of pecan weevil in nematode treated pots was < 1%. Compared with non-treated pots the level of survival corresponded to 81.1% control. The experiment warrants repeating and expansion to an orchard scale. These initial results show promise for reducing the weevil below economic levels.