Analysis of food resources, host availability and insecticidal impacts on the fecundity, longevity and parasitism efficiency of Diaertiella rapae (M’intosh)

Abstract

The use of pesticides may pose a serious threat to soil and water quality, human health, food safety, aquatic species and beneficial insects. Biological control is an effective component of integrated pest management comprising importation, augmentation and conservation. Conservation of natural enemies could enhance or limit the efficiency of herbivorous insect pests. The present study was designed to evaluate the efficiency of Diaeretiella rapae (McIntosh) and other food resources impacts on parasitoid’s fecundity, survival and efficiency. The effect of different insecticides [Carbosulfan, Imidacloprid, Diafenthiuron and Lufenuron] was also evaluated in a laboratory controlled experiment. The results revealed that females fed on aphid honeydew proved to be of poor quality as compared to other sugar sources, including honey and sugar solution and has a positive impact of mating on monogenesis. The negative impact was observed on oviposition activity by female reared in the laboratory having less number of mature eggs than females collected in the field. All insecticides demonstrated dose-dependent mortality of D. rapae. In conclusion, food and host availability and insecticides affect the efficiency of D. rapae. These results could lead to the hypothesis that D. rapae females have a high mortality rate in the field due to lower aphid hosts.