Lepidopteran maize pests and the egg parasitoids of corn borers, Sesamia spp. (Lepidoptera: Noctuidae) in Southeastern Anatolia and lethal and sublethal effects of some insecticides on Telenomus busseolae (Hymenoptera: Scelionidae), an egg parasitoid of the corn borers

Maize (Zea mays L.) ranks among the most important crops due to its different evaluation methods and its production area and quantity have significantly expanded in Southeastern Anatolia, recently. The Lepidopteran maize pests are the leading yield reducing factor in maize cultivation. The first part of this study aimed to investigate the distribution and density of maize stalk borers, Sesamia nonagrioides, S. cretica (Lepidoptera: Noctuidae) and Ostrinia nubilalis (Lepidoptera: Crambidae) in Southeastern Anatolia region maize lands in 2018-2020. Sesamia spp. were found most abundant in Diyarbakır province when compared with other surveyed provinces. Survey results also demonstrated that the abundance of Sesamia spp. were higher in Bismil when compared to other counties. This study, also, aimed to determine the region-wide presence and the natural parasitism rates (discovery efficiency, discovery efficiency and parasitism efficiency) of the egg parasitoids, the most important natural enemies in biological control of Sesamia spp. The incubation of field collected Sesamia spp. eggs under laboratory conditions yielded two important egg parasitoids, Telenomus busseolae (Hymenoptera: Scelionidae) and Trichogramma evanescens (Hymenoptera: Trichogrammatidae). The former was found more widespread in Southeastern Turkey while the later were discovered more restricted spatially. In addition, T. busseolae was collected in all survey years, but T. evanescens was collected only in 2019 surveys. In laboratory studies, the effects of different doses (field recommended dose, T, T/2, T/4, T/8 and control) of chlorantraniliprole, imidacloprid, indoxacarb, lambda-cyhalothrin, lufenuron, malathion and thiamethoxam + lambda-cyhalothrin insecticides having different modes of action on preimaginal stages (early larvae, mature larvae and pupae) of T. busseolae are studied. The decreases in adult emergence rates of parasitoids exposed to insecticide treatments were classified according to International Organization for Biological and Integrated Control (IOBC) standards. In addition, the fecundity of the female parasitoids that managed to hatch after insecticide treatments and the emergence rate and sex (female) ratio of their offspring generation were examined. The emergence rate and the fecundity of the female parasitoids exposed to insecticides at preimaginal stages and the emergence rate and sex ratio of their offspring differed depending on the insecticide, the dose and the preimaginal stages. The following laboratory experiments investigated the oviposition and behavioral parameters during the patch residence time (patch exploitation duration) for the female parasitoids exposed to insecticide treatments at preimaginal stages. The frequencies of antennal rejection, ovipozitoral rejection, oviposition and temporary exits from the host patch and the oviposition index were significantly affected depending on the insecticide, the dose and the preimaginal stages. The biological and behavioral parameters of the parasitoid which constitute the basis of its natural parasitism efficiency, may be adversely affected by the insecticides employed in this study and these parameters should be considered in the selection of insecticides to be used in integrated pest management strategies.