Pollination Peril: The Impact of Neonicotinoids’ on Foraging Behaviour of Indian Honey Bee (Apis cerana Fab). (Hymenoptera; Apidae) in Sunflower Fields

Abstract

Honey bees are essential for sunflower pollination, which boosts crop yield and quality. The decline in bee populations, worsened by neonicotinoid insecticides, poses a significant threat to agriculture. This study examined the effects of neonicotinoids -specifically imidacloprid and thiamethoxam -on the foraging activity and health of Apis cerana Fabricius within sunflower crops. Sunflower seeds (RHA-92) were sown and managed according to standard agricultural practices, with the field divided into three sub-blocks (30 x 40 feet), each receiving one of three treatments: imidacloprid, thiamethoxam, or untreated control. Insecticides were applied at recommended doses when 50 per cent of the plants were in the flowering stage. The crops were covered with a nylon net before flowering to prevent external contamination. A colony of A. cerana, was introduced into each plot one day after insecticide application. Foraging activity, bee behavior, and colony health were monitored daily for seven days post-application, with bee visits to flower heads recorded hourly. Results showed a significant decrease in foraging activity in treated plots, with imidacloprid causing the most pronounced reduction - from 5.40 bees/head/5 min. on day one to 2.13 bees/head/5 min. by day three. Thiamethoxam also led to reduced activity but to a lesser extent. The untreated control maintained stable foraging levels throughout the study. These findings underscore that neonicotinoid insecticides, particularly imidacloprid, severely impair the foraging behavior of A. cerana, highlighting the need for careful use of these chemicals to mitigate their adverse effects on bee populations and ensure effective pollination in agriculture.