Pteromalidae (Hymenoptera) Parasitoids of Fly Pests (Diptera) in Vegetable Agroecosystems

Abstract

Pteromalidae (Hymenoptera) parasitoids associated with dipteran fly pests in vegetable agroecosystems were investigated to assess species composition, host associations, and their potential role in natural biological control. Field surveys were conducted across diverse vegetable production systems, and fly-infested plant material and decomposing organic substrates were sampled for parasitoid emergence. Recovered pteromalid specimens were identified using detailed morphological characteristics, including antennal segmentation, wing venation patterns, and ovipositor structure, supported by COI-based DNA barcoding for species confirmation. Results revealed a diverse assemblage of pteromalid parasitoids associated with dipteran hosts, particularly those developing in soil, decaying matter, and vegetable crop residues. Parasitism rates varied across sites and were influenced by organic matter availability, crop management practices, and microclimatic conditions. Higher parasitoid diversity and abundance were observed in low-input and organically managed systems compared to intensive conventional fields, indicating the importance of habitat complexity in sustaining natural enemy populations. Seasonal trends showed peak parasitoid activity coinciding with high dipteran larval abundance during warm and humid conditions. Phylogenetic analysis grouped collected specimens within established Pteromalidae clades, revealing moderate genetic variation among populations and suggesting both widespread distribution and local adaptation. The study highlights the ecological importance of Pteromalidae as key regulators of dipteran pest populations in vegetable agroecosystems. These findings emphasize the potential of conserving and enhancing parasitoid diversity through improved crop residue management, reduced pesticide use, and habitat diversification as part of integrated pest management programs targeting fly pests in vegetable production systems.