By Joe Cummins, Professor Emeritus of Genetics
The neonicotinoid insecticides should have been banned years ago to prevent irreversible loss of honey and bumble bees. USDA scientists find evidence that the insecticides interact with fungal parasites to cause CCD. Why are EPA and USDA dithering on the removal of neonicotinoid insecticides from the market?
In The Strange Disappearance of The Bees, made by the American film-maker Mark Daniels, Pettis (from USDA) and van Engelsdorp reveal that they exposed two groups of bees to the well-known bee disease nosema. One of the groups was also fed tiny doses of imidacloprid. There was a higher uptake of infection in the bees fed the insecticide, even though it could not subsequently be detected, which raises the possibility that such a phenomenon occurring in the wild might be simply undetectable.
A French study is described below.
Environ. Microbiol. 2010 Mar;12(3):774-82. Epub 2009 Dec 27.
Interactions between Nosema microspores and a neonicotinoid weaken honeybees (Apis mellifera).
Alaux C, Brunet JL, Dussaubat C, Mondet F, Tchamitchan S, Cousin M, Brillard J, Baldy A, Belzunces LP, Le Conte Y.
INRA, UMR 406 Abeilles et Environnement, Laboratoire Biologie et Protection de l'abeille, Site Agroparc, 84914 Avignon, France. email@example.com
Global pollinators, like honeybees, are declining in abundance and diversity, which can adversely affect natural ecosystems and agriculture. Therefore, we tested the current hypotheses describing honeybee losses as a multifactorial syndrome, by investigating integrative effects of an infectious organism and an insecticide on honeybee health.
We demonstrated that the interaction between the microsporidia Nosema and a neonicotinoid (imidacloprid) significantly weakened honeybees. In the short term, the combination of both agents caused the highest individual mortality rates and energetic stress.
By quantifying the strength of immunity at both the individual and social levels, we showed that neither the haemocyte number nor the phenoloxidase activity of individuals was affected by the different treatments. However, the activity of glucose oxidase, enabling bees to sterilize colony and brood food, was significantly decreased only by the combination of both factors compared with control, Nosema or imidacloprid groups, suggesting a synergistic interaction and in the long term a higher susceptibility of the colony to pathogens. This provides the first evidences that interaction between an infectious organism and a chemical can also threaten pollinators, interactions that are widely used to eliminate insect pests in integrative pest management.