Scarifying Agents and Pathogens Screened Against Pecan Weevil Larvae in the Laboratory, 1986

Abstract

Abstract Pecan weevil larvae were exposed to various scarifying agents, pathogens, and combinations of these 2 groups in 1 pt styrofoam cups. Ten holes were punched in the bottom of the cups for drainage. Pecans infested with weevil larvae and soil were collected from an insecticide free orchard at Byron, Ga., in late Sep. Nuts were held in the laboratory and weevil larvae were collected as they emerged. The soil was sterilized and the soil moisture content was brought to field capacity (13%). Clay was packed in the bottom half of the cups. Topsoil was placed on the clay filling the next quarter of the cup. Treatments were then added to the top soil and 10 mature weevil larvae were placed in each of 8 cups/treatment. Cups were covered with parafilm. Treatments included tests 1 and 2—diatomaceous earth (MN36 and MP78), perlite, sand, vermiculite, and untreated; test 3—Beauveria bassiana ex pecan weevil (in solution and as dry spores on top of the soil), Metarhizium anisopliae ex pecan weevil (in solution), perlite, sand, soil containing dead pecan weevil larvae, vermiculite, and untreated; and test 4—Bacillus thuringiensis tenehrio, Bacillus thuringiensis tenehrio + diatomaceous earth (MN36), Beauveria bassiana + diatomaceous earth (MN36), Metarhizium anisopliae + diatomaceous earth (MN36), soil containing an unknown agent causing disease in the acorn weevil Conotrachelus posticatus Boheman, and untreated. Cups were scored for weevil mortality after 30 days in test 1 and 120 days in tests 2-4. Data were analyzed by analysis of variance and contrasts.