Diversity of hymenopteran assemblages prevailed during reproductive stage of cotton—implications for natural control

Hymenoptera is one of the most important insect orders contributes to pollination, biocontrol and natural control largely unexplored from Bangladesh. We, therefore, assess the diversity and relative abundance of hymenopteran insects in cotton fields from five locations of Bangladesh using five types of traps (Malaise, Yellow Pan, Fluorescent Yellow Pan, Pitfall, and Sweep Net). Analysis of samples revealed presence of diverse type of hymenopteran insects from the studied locations, with a total of 1642 insects collected, representing 28 morphospecies and 16 families of the Hymenoptera. Formicidae, Braconidae, Diapridae, Figitidae, Ichneumonidae, Scelionidae constitutes the major families comprises of 36.37, 25.09, 5.36, 5.24, 5.18 and 4.93% of the populations respectively. Among the locations, cotton fields of Rangpur showed the highest species richness, diversity indices (Simpson, and Shannon values), while cotton fields located at Jashore had the lowest. Yellow and fluorescent pan traps captured insects from nearly all families, indicating broad sampling effectiveness. Malaise traps also sampled a wide range of families except for low captures of Formicidae. Pitfall traps primarily targeted Formicidae, consistent with their ground-dwelling hymenopterans. Sweep nets captured fewer families, reflecting a more selective sampling role. Among functional guilds, parasitoids were the most abundant, followed by predators, pollinators, and herbivores of hymenopteran insects. Overall, the hymenopteran community in cotton agroecosystems from Bangladesh was dominated by parasitoid families, indicating strong potential for natural biological control. Leveraging this natural enemy dominance could significantly reduce dependence on chemical insecticides. These findings support the integration of parasitoid conservation strategies into national Integrated Pest Management (IPM) programs and landscape-level pest management policies.