Submitted to: Journal of Nematology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/18/2006
Publication Date: 12/1/2006
Citation: Shapiro Ilan, D.I., Cottrell, T.E., Brown, I., Gardner, W.A., Hubbard, R.K., Wood, B.W. 2006. Effect of soil moisture and a surfactant on entomopathogenic nematode suppression of the pecan weevil, Curculio caryae. Journal of Nematology. 38:474-482. Interpretive Summary: Entomopathogenic nematodes are small round worms that can be used as natural insecticides. These nematodes kill insects but do not harm people or the environment. The nematodes are currently being used to control a number of commercially important insect pests. We studied the potential to use nematodes to control the pecan weevil. The pecan weevil is a major pest of pecans. We tested a variety of different kinds of nematodes (species and strains) in a variety of conditions. Some of the nematode strains were able to cause high levels of mortality in pecan weevil in laboratory and greenhouse experiments. Yet in under field conditions it appears higher levels of control are needed before nematodes can be used commercially. We are currently developing improved strains of nematodes for pecan weevil control.
Technical Abstract: Our overall goal was to investigate several aspects of Curculio caryae suppression using entomopathogenic nematodes. Our results indicated no effect of a surfactant (Kinetic) on C. caryae suppression with entomopathogenic nematodes. Nematode efficacy was tested in a loamy sand at negative 0.01, 0.06, .0.3, 1.0, and 15 bars. Curculio caryae larval survival tended to decrease as moisture levels increased. Nematodes were most effective at -0.06 bars. At -.01 bars, larval survival was ' 5% regardless of nematode presence. In a greenhouse test, C. caryae larval survival was lower in S. carpocapsae (Italian) and S. riobrave (7-12) treatments than in S. carpocapsae (Agriotos), S. carpocapsae (Mexican), and S. riobrave (355). In field experiments, S. carpocapsae (Italian) provided some suppression (ca. up to 60% mortality), but treatment effects were generally only detectable one day after treatment. Nematode strains possessing both high levels of virulence and a greater ability to withstand environmental conditions in the field need to be developed and tested.