Identification and Seasonal Activity of Aphidius spp. (Hymenoptera: Braconidae) Parasitizing Cereal Aphids

Abstract

Aphid populations are major constraints in cereal production systems, and their natural regulation by parasitoids plays a key role in integrated pest management. The present study investigated the identification and seasonal activity of Aphidius spp. (Hymenoptera: Braconidae) parasitizing cereal aphids under field conditions. Surveys were conducted in major cereal-growing areas to collect aphid mummies and live aphids across different crop growth stages and seasons. Parasitoid emergence was recorded, and adults were identified based on morphological characteristics including wing venation, antennal segments, and genital structures, supported by taxonomic keys. Seasonal monitoring revealed distinct fluctuations in Aphidius spp. activity corresponding to changes in aphid population density and environmental conditions. Higher parasitoid abundance and parasitism rates were observed during moderate temperature and relative humidity conditions that favored both host and parasitoid development. Peak parasitism generally coincided with maximum aphid population density, indicating a density-dependent relationship between host and parasitoid dynamics. Differences in species composition of Aphidius complexes were observed across cereal ecosystems, suggesting habitat-specific adaptation and temporal niche partitioning among parasitoid species. Environmental factors such as temperature, humidity, and crop phenology significantly influenced parasitoid emergence, survival, and field efficacy. The findings highlight the important role of Aphidius spp. in natural biological control of cereal aphids and emphasize the need for conserving parasitoid populations in agroecosystems. This study provides valuable insights into seasonal parasitoid dynamics and supports the development of ecologically based pest management strategies aimed at enhancing biological control efficiency in cereal production systems.