The Institute of Science in Society, London, has released a report of research that suggests a combination of factors may be responsible for Colony Collapse Disorder.

According to Dr. Joe Cummins, author of the repost, there is evidence to suggest that sub-lethal amounts of certaian common systemic insecticides, such as Bt, could be making honeybees more susceptible to parasitic fungi such as Nosema. While the pesticides or fungi in themselves might not be enough to seriously harm a colony, the two factors may “interact synergistically” to play a role in killing honeybees.

I am not suggesting that biocontrol agents pose a threat to the honeybee, rather, the exposure to sub-lethal levels of systemic insecticides used in seed treatment of both conventional and GM crops and in widespread soil and foliar applications can affect beneficial insects by reducing their immunity to parasitic fungi. Furthermore, bees that otherwise are unaffected by exposure to Bt toxins in GM crops may succumb much more readily when they are infected with parasitic fungi…

In the ISIS press release, Parasitic Fungi and Pesticides Act Synergistically to Kill Honeybees?, Dr. Cummins calls for changes to the testing methods for pesticides, to look more closely at the effect of these products on honeybees in combination with parasitic fungi.

Regulators have allowed extensive deployment of systemic insecticides for seed treatment and they have allowed extensive use of foliar sprays of the systemic insecticides on a wide array of food and feed crops. The impact of such pesticides on honeybees has been evaluated using measurements of lethal dose of the pesticides alone, ignoring the clear evidence that sub-lethal doses of the insecticides act synergistically with fungal parasites of the insects. The honeybees may be falling victim to “friendly fire” directed to exterminating insect pests.