Laboratory Evaluation of the Toxicity of Proteus, Pymetrozine, Deltamethrin, and Pirimicarb on Lady Beetle Hippodamia Variegata (Goeze) (Col.: Coccinellidae)

Abstract

Abstract The implementation of an Integrated Pest Management (IPM) program requires selecting and using chemicals which are least harmful to natural enemies. In this study, the acute toxicity of the recommended field concentration of four conventional insecticides was evaluated in reference to the different life stages (L3, L4 and adult) of the variegated lady beetle Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae). The evaluated insecticides were Proteus, pymetrozine, deltamethrin, and pirimicarb. A completely randomized design (CRD) with four replications was used as the experimental design. The means were separated by the least significant difference (LSD). The mortalities of those predators treated with the field recommended concentrations of various insecticides, were significantly different. Proteus showed strong toxicity toward the different life stages of the predator. However, pymetrozine and pirimicarb caused less than a 50% mortality. Based on the lethal concentration (LC50) values at 24 h after treatment, the adult predator was the most susceptible to proteus, followed by deltamethrin, pymetrozine, and pirimicarb values of 35.977, 358.757, 915.667, and 2616.113. Based on sublethal concentrations (LC30), these values were 22.718, 261.957, 569.879, and 1521.424. Based on International Organization of Biological Control (IOBC) classification, the insecticides pirimicarb and pymetrozine were both categorized as having a Class 1 toxicity level (harmless), deltamethrin as having a Class 2 level (slightly harmful), and Proteus, a Class 4 toxicity level (harmful).