Abstract

In Ethiopia, Apis mellifera L. are the most important honeybees to produce diverse bee products. In addition, bees also improve crop yields through their active and efficient pollination. However, they have been killed due to the misuse of various insecticides. For this reason this study was proposed to determine in the laboratory the level of toxicity of some insecticides used widely on honeybees foraging on onion flowers. Adult A. mellifera bandasii honeybees 21 to 24 days old were collected at the Adami Tullu Agricultural Research Center (ATARC) apiary. Easy to clean and well-ventilated 15 x 10 x 15 cm cages were used for feeding, contact and fumigation tests. Six insecticides: deltamethrin 2.5 EC, diazinon 60 EC, endosulfan 35 EC, lambda-cyhalothrin 5 EC, malathion 50 EC and profenofos 750 EC, were evaluated in the laboratory at the rates suggested for onion field spraying. Each treatment was replicated three times and arranged in a completely randomized design. All of the insecticides in the contact and feeding tests were toxic to honeybees and caused mortality within a few hours after exposure. In the fumigation test, profenofos did not cause honeybee mortality until the third hour, but the remaining insecticides caused varying mortality within 24 h.

Key words: Insecticides, toxicity, honeybee, bee products and crop yields.