Integrating Biological Control into Pecan Weevil Management: A Sustainable Approach

Integrating Biological Control into Pecan Weevil Management: A Sustainable Approach

Summary

The focus of this past year’s research has been repeating and expanding our field trials aimed at testing the potential for entomopathogenic fungi to control pecan weevils. We conducted two field trials. In an effort to enhance efficacy and persistence of the treatments, we tested several novel approaches to applying the fungi including a new UV-protecting formulation, fungus bands that are attached to the tree trunk, use of cover crops and cultivation, and new fungal strains. We observed significant levels of weevil control from all treatments. Treatments that caused approximately 80% control of pecan weevil during the testing period (10-15 days) included trunk applications of Beauveria bassiana and Metarhizium anisopliae, cultivation and incorporation of a cover crop for B bassiana control. Additionally in the laboratory we examined soil amendments for their ability to enhance fungal survival. The results appear highly promising for use of these beneficial fungi in weevil management. In this coming (and final) year of the grant we will finish off our research trials (cover cropping, soil amendments, M. anisopliae experiments), and take our most promising treatments thus far (trunk applications with B. bassiana with sun-screen and M. anisopliae trunk bands) to grower demonstration trials. We have currently lined up two growers in Georgia and two or three in Texas.

Objectives/Performance Targets

1. Enhance persistence of C. caryae control with B. bassiana by one or more of the following:
A. Selecting superior B. bassiana strains.
B. Addition of soil amendments to improve B. bassiana persistence.
C. Developing improved formulations.
2. Determine the optimum area of B. bassiana application
3. Conduct feasibility and economic analyses to determine the potential of incorporating B.
bassiana into an integrated pest management system.
4. Extend the project findings to grower clientele.

Accomplishments/Milestones

The focus of this past year’s research has been repeating and expanding our field trials aimed at testing the potential for entomopathogenic fungi to control pecan weevils. In one experiment we tested the following treatments using the fungus Beauveria bassiana (GHA strain): 1) regular ground application, 2) ground application with addition of a cover crop, 3) ground application with cultivation, 4) ground application of a new strain (BbMS1), 5) trunk application, 6) trunk application with UV-protecting formulation, and 7) an untreated control. In a second experiment we tested a strain of M. anisopliae that was not previously tested (F52) by applying it to the ground and attaching fungal bands around the trunk, trunk bands alone, and a control. All fungal treatments caused significant weevil mortality relative to the controls. The fungal treatments persisted 10-15 days. Up to 80% mortality was observed. The most promising treatments so far appear to be application of B. bassiana to the trunk with UV-screen, and application of M. anisopliae in trunk bands.

We have found that both B. bassiana and M. anisopliae, when applied in novel fashions, can cause high levels of pecan weevil control.

During this past year, two presentations were made and 1 manuscript (non-refereed proceedings) was published. We anticipate 2-3 refereed manuscripts to be submitted (and likely accepted) by this time next year.

Presentations:
1) Shapiro-Ilan, Cottrell, Gardner, Behle, & Wood. Using fungus for biological control of pecan pests. Georgia Pecan Growers Association Annual Meeting. May 4, 2006, Perry, GA.

2) Shapiro-Ilan, Cottrell, Gardner, Behle, Nyczepir, & Wood. Alternative Control Tactics in Pecan. Southeastern Pecan Growers Association Annual Meeting. 2006, Panama City, FL.

Manuscript:
Shapiro-Ilan, D.I., Cottrell, T.E., Gardner, W.A., Behle, R.W., Nycepir, A.P. and Wood, B.W. Alternative pest control tactics in pecan. Southeastern Pecan Growers Meeting Proceedings (In press). 2006. (Proceedings). Accepted 3/25/2006.