Taxonomic Revision and Morphological Redescription of Trichogramma Species (Hymenoptera: Trichogrammatidae) in Cereal Agroecosystems

Abstract

Trichogrammatid wasps are among the most widely used egg parasitoids in biological control programs, particularly in cereal agroecosystems where lepidopteran pests cause significant yield losses. Despite their importance, taxonomic ambiguity and morphological similarity among species of Trichogramma often hinder accurate identification and effective utilization. The present study undertakes a taxonomic revision and morphological redescription of Trichogramma species associated with cereal crops. Field collections were carried out in wheat, maize, and sorghum ecosystems, and parasitized lepidopteran eggs were incubated under laboratory conditions to obtain adult parasitoids. Specimens were examined using stereomicroscopy and compound microscopy, focusing on diagnostic morphological characters such as antennal structure, male genital capsule, wing venation, and body sculpture. Morphometric measurements were recorded to differentiate closely related species complexes. The study resulted in the redescription of key Trichogramma species and clarification of diagnostic traits that are often variable or overlapping in earlier descriptions. Several species were confirmed to exhibit host specificity toward major cereal pests, while others showed broader host ranges. Variations in morphological traits were observed among populations, suggesting possible intraspecific diversity influenced by ecological conditions. The revision also highlights previously overlooked diagnostic features that improve species separation within the genus. These findings contribute to resolving long-standing taxonomic uncertainties and provide updated identification keys for accurate species determination. The study emphasizes the importance of precise taxonomy for effective implementation of Trichogramma-based biological control programs. Overall, the results enhance understanding of species diversity, morphology, and ecological distribution of Trichogramma in cereal agroecosystems, supporting their improved utilization in integrated pest management strategies.