Seasonal incidence and management of sac brood disease in Apis mellifera L. Colonies of Kangra valley of Himachal Pradesh

Abstract

The present study, conducted from July 2024 to June 2025, focused on the seasonal incidence and management of Sac brood virus (SBV) in Apis mellifera colonies in the Kangra valley of Himachal Pradesh (stationary) and migratory areas of Anupgarh, Rajasthan. Observations revealed that colony strength, brood area, pollen stores, and honey reserves fluctuated seasonally, with peak performance from April to August. SBV incidence ranged from 2.00% to 4.33% under stationary and 2.00% to 47.00% under migratory conditions. Disease occurrence showed a positive correlation with weather parameters (minimum temperature, rainfall, humidity) and internal hive humidity. Field trials were conducted to test eco-friendly management strategies against SBV. Among various treatments, Agaricus bisporus (3 ml/250 ml sugar solution) was the most effective, reducing SBV infestation by 72.46%. Other effective treatments included Agaricus bisporus (1.0 ml/250 ml) with 64.04% reduction, clove oil with 56.08%, and Ocimum basilicum with 36.55% reduction in disease. In contrast, Melia azedarach (12.65%) and Azadirachta indica (20.46%) showed minimal effectiveness in controlling SBV. The findings suggest that fungal extracts and certain plant-based treatments can significantly reduce sac brood virus infections in honeybee colonies, offering safer alternatives to chemical treatments.This study highlights the seasonal trends of sac brood and supports the use of biological methods for its control, especially in migratory beekeeping practices where disease pressure tends to be higher.