title: Antagonism between Beauveria bassiana and imidacloprid when combined for Bemisia argentifolii (Homoptera: Aleyrodidae) control.
abstract: Imidacloprid and the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuillemin are both used to control the whitefly Bemisia argentifolii Bellows & Perring. We tested whether the two control strategies acted additively, synergistically, or antagonistically when combined for whitefly control. We found antagonism in that B. bassiana inhibited the effectiveness of imidacloprid. When B. bassiana was combined with imidacloprid, insect response was either less than or similar to (depending on B. bassiana rates) that when imidacloprid was used alone. Adding imidacloprid to B. bassiana treatments always increased mortality, but the increase was less than additive. Beauveria bassiana spore germination and colony formation were not inhibited by imidacloprid in vitro, and B. bassiana did not adsorb or degrade imidacloprid in a tank mix. We hypothesize that B. bassiana caused a behavioral response that reduced insect feeding and uptake of imidacloprid.
authors.affiliation: Kika De La Garza Subtropical Agricultural Research Center, USDA-ARS, Weslaco, TX, USA.
authors.forename: R R
authors.initials: RR
authors.lastname: James
authors.forename: G W
authors.initials: GW
authors.lastname: Elzen
mesh_terms: D000818:Animals; D001203:Ascomycota; D006430:Hemiptera; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010572:Pest Control, Biological / Q000379:methods*; D012987:Soil
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D012987:Soil; C082359:imidacloprid