New Distributional Records of Aphidiidae (Hymenoptera) Parasitoids of Cotton Aphids in Irrigated Cropping Systems

Abstract

Extensive faunistic surveys were conducted in irrigated cotton cropping systems to document the diversity and distribution of aphidiid parasitoids associated with cotton aphids. Sampling was carried out across multiple cotton-growing regions during different crop growth stages through collection of aphid-infested plant material and subsequent laboratory rearing of parasitoids. Adult parasitoids emerging from mummified aphids were examined using detailed morphological characterization focusing on diagnostic features such as antennal segmentation, wing venation, metasomal structure, and coloration patterns. Several species belonging to the family Aphidiidae were identified, including multiple new distributional records associated with irrigated cotton ecosystems in the surveyed regions. Molecular characterization using mitochondrial cytochrome oxidase I (COI) gene sequencing supported species identification and clarified phylogenetic relationships among recovered taxa. The parasitoids were primarily associated with Aphis gossypii populations infesting cotton plants, where they play a key role in natural regulation of aphid outbreaks. Seasonal abundance patterns indicated higher parasitoid activity during periods of moderate temperature and adequate humidity that favored both aphid population growth and parasitoid development. Variation in species composition and parasitism rates was influenced by irrigation practices, crop phenology, and pesticide application intensity. Cotton fields with reduced insecticide input supported greater parasitoid diversity and higher levels of natural biological control compared with intensively managed fields. The discovery of new distributional records expands current knowledge of aphidiid biodiversity in cotton agroecosystems and highlights the ecological importance of native parasitoids in sustainable pest management. Conservation of these beneficial insects through reduced chemical input and habitat-friendly practices may enhance aphid suppression and improve ecological stability in cotton production system.