Evaluation of toxicity of biorational insecticides against larvae of the alfalfa weevil

Publication date: Available online 5 May 2016 Source:Toxicology Reports Author(s): Gadi V.P. Reddy, Frank B. Antwi, Govinda Shrestha, Takashi Kuriwada The alfalfa weevil, Hypera postica (Coleoptera: Curculionidae), is a major pest of alfalfa Medicago sativa L. (Fabaceae). While H. postica usually causes the most damage before the first cutting, in summer of 2015 damaging levels of the pest persisted in Montana well after the first harvest of alfalfa. Although conventional insecticides can control H. postica, these chemicals have adverse effects on non-target organisms including pollinators and natural enemy insects. In this context, use of biorational insecticides would be the best alternative options, as they are known to pose less risk to non-target organisms. We therefore examined the six commercially available biorational insecticides against H. postica under the laboratory condition: Mycotrol ® ESO (Beauveria bassiana GHA), Aza-Direct ® (Azadirachtin), Met52 ® EC (Metarhizium brunneum F52), Xpectro OD ® (Beauveria bassiana GHA+pyrethrins), Xpulse OD ® (Beauveria bassiana GHA+Azadirachtin) and Entrust WP ® (spinosad 80%). Concentrations of 0.1, 0.5, 1.0, and 2.0 times the lowest labelled rates were tested for all products. However, in the case of Entrust WP, additional concentrations of 0.001 and 0.01 times the lowest label rate were also assessed. Mortality rates were determined at 1 to 9days post treatment. Based on lethal concentrations and rela...
Source: Toxicology Reports - Category: Toxicology Source Type: research