New Distributional Records of Parasitic Hymenoptera Attacking Cereal Stem Borers in Irrigated Agriculture

Abstract

New distributional records of parasitic Hymenoptera attacking cereal stem borers in irrigated agriculture were documented to update the diversity and geographical range of key parasitoid complexes associated with major cereal pests. Field surveys were conducted across irrigated cropping systems, and stem borer-infested plants were collected and reared under laboratory conditions to obtain emerging parasitoids. Adult parasitoids were identified using morphological diagnostic characters including wing venation, antennal segmentation, and metasomal structure, supported by available taxonomic keys. The study revealed several parasitoid species previously unrecorded from the surveyed irrigated regions, indicating an expanded distribution of economically important biological control agents. These hymenopteran parasitoids were associated with stem borers causing deadheart and whitehead symptoms in cereals, suggesting their significant role in natural pest suppression. Parasitism rates varied across locations and cropping seasons, influenced by irrigation intensity, crop stage, and habitat heterogeneity. Higher parasitoid abundance was observed in fields with reduced pesticide usage and greater crop diversity, highlighting the importance of agroecological conditions in sustaining natural enemy populations. The findings emphasize the contribution of parasitic Hymenoptera to the regulation of cereal stem borer populations in irrigated systems. These new distributional records enhance understanding of parasitoid biodiversity and support the development of conservation biological control strategies for sustainable cereal production.