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Re: [SANET-MG] honey bee motion for EU

Hi Stephan Gallagher,
You have asked me a very important question but it is one that really requires fuller experimental studies, preferably studies conducted by independent investigators. As you are probably aware , Dipel (Bt spores) is often used to treat the entrances to honey bee colonies to discourage mite parasites. However, the interaction between Dipel or pure Cry toxins and fungal parasites or bee viruses on honey bee larvae or adults has not been studied to my best knowledge. However, as the abstracts below show, Nosema infected corn borer larvae much more susceptible to both Dipel and pure cry toxin. The point is that fungal parasite infected bees may be sensitive to Dipel and Bt toxin and Bt may enhance parasite and virus infection to a similar but less pronounced impact than do the neonicotinoid pesticides which are very potent indeed. Recent reports suggest that the insect immune system is focused on a long standing battle between fungal parasites and the insects and things that impair the insect immune system such as the neonicotinoids and Bt need careful scrutiny before the bees are eliminated by tipping the contest in favor of the fungal parasites not just after. Finally, I have been impressed by the apparent unwillingness of regulators to considers the kinds of interaction mentioned above and the granting agencies seem unwilling to support such important research. Hope my reply answered your question? sincerely, joe cummins . Pierce CM, Solter LF and Weinzierl RA. Interactions between Nosema pyrausta (Microsporidia: Nosematidae) and Bacillus thuringiensis subsp. kurstaki in the European corn borer (Lepidoptera: Pyralidae). J Econ Entomol. 2001 Dec;94(6):1361-8. Larval susceptibility to Bacillus thuringiensis was determined for Nosema pyrausta-infected and uninfected European corn borers, Ostrinia nubilalis (Hübner), in bioassays using a commercial formulation of B. thuringiensis subsp. kurstaki, Dipel ES, incorporated into diet. LC50 values for N. pyrausta-infected larvae were significantly lower (P < 0.0001) than for uninfected larvae and declined with increasing levels of infection.

Reardon BJ, Hellmich RL, Sumerford DV and Lewis LC. Growth, development, and survival of Nosema pyrausta-infected European corn borers (Lepidoptera: Crambidae) reared on meridic diet and Cry1Ab. J Econ Entomol. 2004 Aug;97(4):1198-201. The LC50 of infected larvae was about half that of uninfected larvae, indicating that infected larvae are more vulnerable to toxin. This work has implications for resistance management of O. nubilalis and demonstrates that it is important to determine whether N. pyrausta is present when testing susceptibility of larvae to transgenic corn hybrids.

Stephen Gallagher wrote:
Prof. Cummins,

Is there any way to determine whether topical application of natural Bt as intermittant foliar spray could play a role on bees within an organic system, similar to that of GM Bt built into crops? Does the parasitic fungus exist widely in unmodified environments, thus making any use of Bt problematic, at best, or is its pressence itself a result of practices of "conventional" agriculture?

Stephen Gallagher
Nathan Creek Organic Farm CSA
----- Original Message ----- From: "jcummins" <jcummins@UWO.CA>
Sent: Saturday, June 23, 2007 8:09 AM
Subject: [SANET-MG] honey bee motion for EU

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