Seasonal incidence and management of Sac brood disease in Apis mellifera L. Colonies of Kangra Valley of Himachal Pradesh1

Abstract

Momordica charantia L. (Cucurbitaceae) supports a diverse arthropod community comprising seven insect orders and one arachnid order, broadly classified as floral or extrafloral visitors. Floral visitors, mainly pollinators, included Apis cerana indica, Nomia melanderi, Parnara guttata, Arawacus togarna, Episyrphus balteatus, and Bactrocera cucurbitae. While bees were primary pollinators, lepidopterans and tephritids also utilized the crop for oviposition, with larvae acting as herbivores or pests; hoverfly larvae were aphid predators. Extrafloral visitors included herbivores (Aphis gossypii, Aulacophora foveicollis, Monolepta signata), predators (mantids, spiders, coccinellids), and six omnivorous, mutualistic ant species visiting leaf EFNs. Species occurrence varied seasonally—several pollinators and herbivores were absent in one season, and spider species alternated between rainy and post-rainy periods. Diversity indices indicated consistently higher richness and diversity for extrafloral visitors (Margalef SR: 4.29 rainy, 3.94 post-rainy; Shannon-Wiener H: 2.52 rainy, 2.39 post-rainy) than floral visitors (SR: 2.48 rainy, 1.79 post-rainy; H: 1.56 rainy, 1.58 post-rainy). Floral visitors showed high evenness (0.87-0.99), whereas extrafloral visitors were highly uneven during the rainy season (0.04), reflecting dominance by a few species. The results highlight that EFNs harbor a richer and more functionally diverse arthropod assemblage than flowers, with seasonal dynamics influencing community composition. These findings provide insights into plant-arthropod interactions and can guide integrated pest and pollination management in bitter gourd cultivation.