BIOLOGICAL AND MICROBIAL CONTROL Efficacy of Beauveria bassiana for Red Flour Beetle When Applied with Plant Essential Oils or in Mineral Oil and Organosilicone Carriers

The carriers mineral oil and Silwet L-77 and the botanical insecticides Neemix 4.5 and Hexacide were evaluated for their impacts on the efÞcacy of Beauveria bassiana (Balsamo) Vuillemin conidiaagainst redßourbeetle,Triboliumcastaneum(Herbst), larvae.Thedosagesof liquid treatments were quantiÞed by both conidia concentration in the spray volume and conidia deposition on the target surface. The latter approach allowed comparison with dry, unformulated conidia. The median lethal concentrations of B. bassiana in 0.05% Silwet L-77 solution or without a carrier were approximately double that for conidia in mineral oil. Carriers had highly signiÞcant effects on the efÞcacy ofB.bassiana. The lower efÞcacy of conidia in aqueous SilwetL-77mayhavebeen the result of conidia loss from the larval surface because of the siloxaneÕs spreading properties. Neemix 4.5 (4.5% azadirachtin) delayed pupation and did not reduce the germination rate of B. bassiana conidia, but it signiÞcantly reducedT. castaneummortality at twoof four tested fungusdoses.Hexacide(5%rosemary oil) caused signiÞcant mortality when applied without B. bassiana, but it did not affect pupation, the germination rate of conidia, or T. castaneum mortality when used in combination with the fungus.