Impact of Fipronil and Lambda-Cyhalothrin on Foraging Behaviour of <i>Apis dorsata</i> in Onion

This study investigated the impact of fipronil and lambda-cyhalothrin on the foraging behaviour of Apis dorsata in onion. Prior to treatment, foraging activity was 16.11 and 16.88 bees/ m²/ 10 min which dropped to 0.88 and 1.11 bees/ m²/ 10 min after the first day application of fipronil and lambda-cyhalothrin, respectively. Similarly, fipronil and lambda-cyhalothrin reduced foraging rates to 8.83 and 9.24/ m²/ 10 min. Foraging speed decreased significantly on the first day for both treatments but gradually recovered; fipronil-treated bees averaged 4.33 sec/flower initially and returned to 10.16 sec/ flower by day 6, while lambda-cyhalothrin-treated bees showed a decrease from 16.66 sec/ flower to 2.66 sec/ flower, stabilizing at 8.83 sec/ flower by day 5. Foraging rates varied with fipronil-treated plants showing a peak on day 1 (9.66 flowers/ min) before normalizing, while lambda-cyhalothrin-treated plants initially increased to 8.33 flowers/ min, then declined to 6.50 flowers/ min by day 14.