New Distributional Records of Scelionidae (Hymenoptera) Egg Parasitoids of Eurygaster spp. in Cereal Fields

Abstract

Eurygaster spp. (Hemiptera: Scutelleridae), commonly known as sunn pests, represent one of the most economically devastating insect complexes affecting cereal crops, particularly wheat and barley, across temperate and semi-arid agricultural regions. Egg parasitoids belonging to the family Scelionidae (Hymenoptera) are recognized as critical natural enemies capable of significantly suppressing Eurygaster populations through parasitism of egg masses under field conditions. However, distributional knowledge of scelionid parasitoid assemblages associated with Eurygaster spp. remains incomplete, limiting the effective exploitation of these biological control agents in cereal-based agroecosystems. This study reports new distributional records of scelionid egg parasitoids recovered from Eurygaster egg masses systematically collected from cereal fields across previously undersampled geographic regions. Parasitoid specimens were identified to species level using integrative morphological examination of key taxonomic characters, including head morphology, wing venation, and metasomal sculpture. Parasitism rates were calculated for each recorded scelionid species, and host–parasitoid associations were documented in relation to Eurygaster species composition, crop phenology, and seasonal abundance. The recovered scelionid fauna includes species with range extensions beyond previously documented boundaries, substantially expanding the known geographic distributions of several taxa. Dominance patterns among parasitoid species and their relative contribution to overall egg mortality are discussed in an ecological and biocontrol context. These new distributional records provide foundational data for augmentative and conservation biological control programs targeting sunn pest populations and underscore the importance of systematic surveys in characterizing parasitoid diversity within cereal agroecosystems.