Lethal and sublethal effects of azadirachtin on the bumblebee <i>Bombus terrestris</i> (Hymenoptera: Apidae)

Autor/innen

  • Wagner F. Barbosa
  • Laurens De Meyer
  • Raul Narciso C. Guedes
  • Guy Smagghe

Abstract

Background: Lethal and sublethal effects of azadirachtin were studied on Bombus terrestris via oral exposure in the laboratory to bring out the potential risks of the compound to this important pollinator.
Results: Microcolonies chronically exposed to azadirachtin via treated sugar water during 11 weeks in the laboratory exhibited a high mortality ranging from 32 to 100 % with a range of concentrations between 3.2 and 320 mg litre-1. No reproduction was scored at concentrations higher than 3.2 mg litre-1. At 3.2 mg litre-1, azadirachtin significantly inhibited the egg laying and, consequently, the production of drones during 6 weeks. When azadirachtin was tested under an experimental setup in the laboratory where bumblebees need to forage for food, the sublethal effects were stronger as the numbers of drones were reduced already with a concentration of 0.64 mg litre-1. Besides, a negative correlation was found between the body mass of male offspring and azadirachtin concentration.
Conclusion: Azadirachtin can affect B. terrestris with a range of sublethal effects. This study confirms the need to test compounds on their safety, especially when they have to perform complex tasks such as foraging.

Keywords: chronic oral exposure, insect growth regulator (IGR), neem, repellence effect, reproduction

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Veröffentlicht

2015-10-12

Ausgabe

Nr. 450 (2015): "Hazards of pesticides to bees", 12th International Symposium of the ICP-PR Bee Protection Group

Rubrik

Section IV: Developments in laboratory, semifield and field testing for non-<i>Apis</i> bees

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