Lethal and sub-lethal effects of the insecticide spirotetramat on the life table parameters of the wheat aphid, Schizaphis graminum (Rondani) and its predator Hippodamia variegata Goeze

Wheat (Triticum aestivum L.) is cultivated as a monocotyledonous plant in a large part of the world. The Wheat aphid, Schizaphis graminum Rondani (Hemiptera: Aphididae), is among the most important pests of wheat. One of the most important predators of this pest is Hippodamia variegata Goeze. Considering the use of insecticide spirotetramat in cereal fields, in this study, the lethal and sub-lethal effects of this insecticide were investigated on the biological characteristics and parameters of the life table of S. graminum and predator H. variegata. The experiments were performed at a temperature of 27 +/- 1(degrees)C, relative humidity of 65 +/- 10%, and a photoperiod of 16:8 (light:dark). For this purpose, biometric and life table experiments were performed by immersing wheat leaves in insecticide and placing adult aphids on them, and feeding adonis ladybird larvae from the treated aphids. Insecticide side effects were estimated using the International Organization for Biological Control (IOBC) method and a two-sex life table. The LC50 level of spirotetramat insecticide for aphids and predators was 210.93 and 725.86 mg/l, respectively. The results of this study indicate that there is a significant difference between treatments in terms of the intrinsic rate of increase (r), finite rate of increase (lambda), mean generation times (T), net reproduction rate (R-0), and gross reproduction rate (GRR) parameters in aphids and adonis ladybird. The highest and lowest rates of the reproduction and population growth of the studied insects were related to the control and LC30 spirotetramat treatments, respectively. According to the IOBC classification, the concentration of LC10 in spirotetramat was harmless to the adonis ladybird H. variegata, while the LC30 concentration of this insecticide was slightly harmful to this species. Experiments showed that the sub-lethal concentrations of the insecticide spirotetramat had a significant negative effect on the life table parameters of the Wheat aphid.