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United States Department of Agriculture

Agricultural Research Service

Title: Field Evaluation of the Fungus Beauveria Bassiana in Attracticidal Refined and Unrefined Canola Oil Carriers, Vs. Refined Soybean Oil and Orchex Oil, to Control Rangeland Grasshoppers

Authors
item Foster, N. - USDA-APHIS-PPQ
item Reuter, C. - USDA-APHIS-PPQ
item Helbig, B - USDA-APHIS-PPQ
item Huddleston, C - USDA-APHIS-PPQ
item Radsick, B - USDA-APHIS-PPQ
item Black, L - USDA-APHIS-PPQ
item Black, L - USDA-APHIS-PPQ
item Kozel, L - USDA-APHIS-PPQ
item Bradley, J - USDA-APHIS-PPQ
item Jaronski, Stefan
item Fitzgerald, Bryan
item Viets, Christine
item Gaffri, Selene
item Grace, Julie

Submitted to: Advances in Applied Acridology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 1, 2005
Publication Date: March 1, 2005
Citation: Foster, N., Reuter, C., Helbig, B., Huddleston, C., Radsick, B., Black, L., Black, L., Kozel, L., Bradley, J., Jaronski, S., Fitzgerald, B.C., Viets, C.E., Gaffri, S., Grace, J.A. 2005. Field evaluation of the fungus beauveria bassiana in attracticidal refined and unrefined canola oil carriers, vs. refined soybean oil and orchex oil, to control rangeland grasshoppers. Advances in Applied Acridology.

Interpretive Summary: There has been recent interest in vegetable oils rich in linoleic, linolenic and oleic acids, (e.g., corn and canola oils) as grasshopper-attractive oil carriers for chemical and microbial insecticides. Greenhouse research by the USDA ARS coauthors and a University of Wyoming/USDA ARS field trial in 2002 indicated that there was potential for such oils in an attracticidal formulation to enhance the efficacy of Beauveria bassiana Strain GHA in a strip-treatment, Reduced Agent Area Treatment System (RAATS). In field trials in 2003 and 2004 we failed to discern statistically significant enhancement of Beauveria efficacy by raw or refined canola oil, vs. a paraffinic crop oil. Enhanced thermoregulatory behavior ('behavioral fever') among the target grasshoppers was observed to significantly interfere with field efficacy in both years. In 2004 considerable background prevalence (>60%) of Beauveria infections obscured differences among treatment-related infection rates in post-treatment grasshopper samples and, presumably, population effects. At this point in the development of Beauveria bassiana for grasshopper management, further studies to utilize the existing isolate and formulation within a 'stressor concept' (combining a sub-lethal dose of another agent and the fungus) as suggested by the senior author in 1995 seem warranted and a logical next step.

Technical Abstract: Greenhouse research by the USDA ARS coauthors and a University of Wyoming/USDA ARS field trial in 2002 indicated that there was potential for certain vegetable oils in an attracticidal formulation to enhance the efficacy of Beauveria bassiana Strain GHA in a strip-treatment. In 2003, results from replicated 16.2 ha plot studies in S.D., against populations of Ageneotettix deorum and Aulocara elliotti, indicated no statistically significant differences in population reductions among the Beauveria bassiana treatments with refined canola oil or Orchex 792 oil carriers, applied in a RAATS approach (50% coverage of a protected area) vs. untreated control populations, even though laboratory evaluations of post-treatment field collections showed there was sufficient grasshopper exposure to conidia to cause >80% infection and death. In 2004, results from replicated 16.2 ha plot studies conducted in S.D. against the same species, indicated there were no statistical differences in population reductions among the Beauveria bassiana treatments with raw canola oil, refined canola oil or soybean oil carriers, vs. untreated controls in a RAATS approach (50% coverage). Considerable background prevalence (>60%) of Beauveria infections obscured differences among treatment-related infection rates in post-treatment grasshopper samples. Both studies strongly suggest that simply replacing paraffinic oil with a vegetable oil may not produce enhanced mortality in unconfined field populations of grasshoppers in typical rangeland situations in S.D., whether it be in traditional broadcast or RAATs applications. Enhanced thermoregulatory behavior ('behavioral fever') among the target grasshoppers was observed to significantly interfere with field efficacy in both years. Field-collected grasshoppers unable to thermoregulate suffered >80% mortality and mycosis within 7 days, while commensurate field populations did not display similar reductions.

Last Modified: 11/22/2014