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United States Department of Agriculture

Agricultural Research Service

Title: A Survey for Insect-Killing Nematodes and Fungi Endemic to Pecan Orchards of the Southeastern U.S. and Their Virulence to the Pecan Weevil

item Shapiro Ilan, David
item Gardner, Wayne - UNIVERSITY OF GEORGIA
item Fuxa, James - LSU, BATON ROUGE, LA
item Wood, Bruce
item Nguyen, Khuong - UNIVERSITY OF FLORIDA
item Humber, Richard
item Hall, Michael - LSU, SHREVEPORT, LA

Submitted to: Pecan Grower
Publication Type: Trade Journal
Publication Acceptance Date: February 12, 2002
Publication Date: May 1, 2002
Citation: Shapiro Ilan, D.I., Gardner, W.A., Fuxa, J.R., Wood, B.W., Nguyen, K.B., Adams, B.J., Humber, R.A., Hall, M.J. 2002. A survey for insect-killing nematodes and fungi endemic to pecan orchards of the southeastern u.s. and their virulence to the pecan weevil. Pecan Grower. v.13(3). p.6-8.

Interpretive Summary: The pecan weevil is a devastating pest of pecans in the U.S. Currently, control of this pest relies solely on chemical insecticide treatments. Due to environmental and regulatory concerns, alternative control strategies must be developed. Certain insect-killing nematodes (tiny round worms) and insect-killing fungi may offer an ecological and economically sound solution. These fungi and nematodes kill many important insect pests, but do not harm humans, other animals, or the environment. The objective of this study was to discover new strains of insect-killing nematodes and fungi to combat the pecan weevil. Over 30 new strains of these fungi and nematodes were found in Arkansas, Georgia, Louisiana, and Mississippi pecan orchards. Although the new nematodes did not show great promise in killing the pecan weevil, some of the fungal isolates were found to be highly virulent.

Technical Abstract: The pecan weevil, Curculio caryae, is a major pest of pecans in the southeastern U.S. Entomopathogenic nematodes and fungi are potential alternatives to chemical insecticides for C. caryae control. Our objective was to survey pecan orchards in the southeastern U.S. for entomopathogenic nematodes and fungi and determine the new isolates' virulence to C. caryae larvae. Soil was collected from 105 sites in 21 orchards in Arkansas, Georgia, Louisiana, and Mississippi. We isolated entomopathogenic fungi and nematodes from 17 and 6 of the 21 orchards surveyed, respectively. The entomopathogenic fungi included Beauveria bassiana and Metarhizium anisopliae, and nematodes included Heterorhabditis bacteriophora Poinar, Steinernema carpocapsae (Weiser), S. glaseri (Steiner), and S. rarum (Doucet). This is the first report of S. rarum in the U.S. Results indicated poor susceptibility of the C. caryae larvae to entomopathogenic nematodes. Several fungal isolates caused significantly higher mortality in C. caryae larvae than other strains.

Last Modified: 4/19/2015