The effects of some pesticides used in potato fields on the pre-adult stages of Chelonus oculator F. (Hymenoptera: Braconidae)

Abstract

Abstract One of the most important pests of potatoes is the Potato Tuber Moth Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae) worldwide and one of its new parasitoids is Chelonus oculator (F.) (Hymenoptera: Braconidae). All over the world, chemical control is commonly used in the control of P. operculella. However, the side effects of chemicals on nature and beneficial organisms have become very important nowadays. For this reason, the side effects of selected pesticides, against Potato Tuber Moth, on Chelonus oculator eggs and larvae were tested under laboratory conditions. Three insecticides (Spinetoram, Gamma cyhalothrin, Chlorantraniliprole), one fungicide (Phosphorus Acid), and a biological insecticide (Bacillus thuringiensis var. kurstaki) were applied to parasitized first and third-stage larvae and parasitized eggs. Application dose, half dose, and 1/20 dose of these products were used. All preparations used in the experiments had a highly toxic effect in the pre-adult period. Therefore, the sex ratio could not be determined due to the low number of emerged parasitoids. All doses of applied pesticides caused an increase in the development time of parasitoids developing from parasitized eggs and first larvae when compared to the control. It can be concluded that the development time of parasitoids decreased in 3rd instar larvae. We also evaluated the longevity of parasitoids and it was found that the adult life emerging from parasitized first and third instar potato moth larvae decreased. We also observed that the survival of adult parasitoids emerging from parasitized eggs was unstable. In this study, it was determined that pesticides applied to the parasitized host at different stages affected the adult weight of the parasitoid C. oculator. When the sex ratio of the parasitoid was examined, it was not possible to reach a definite conclusion due to the lack of sufficient individual emergence. The side effect results obtained can be evaluated in integrated control programs for the Potato tuber moth and its parasitoid Chelonus oculator.