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Pesticide Toxicology Laboratory

ISU Entomology / Pesticide Toxicology Laboratory / Bacillus thuringiensis toxin (Cry1Ab) has no direct effect on larvae of the green lacewing Chryoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Bacillus thuringiensis toxin (Cry1Ab) has no direct effect on larvae of the green lacewing Chryoperla carnea (Stephens) (Neuroptera: Chrysopidae)

Authors: Romeis, J.; Dutton, A.; Bigler, F.
Journal, Volume, Year: Journal of Insect Physiology, volume 50:175-183, 2004
Summary

Good follow up to previous work showing that the C. carnea larvae were negatively affected by feeding on Bt-fed prey sources. The earlier studies could not separate a negative effect of Bt directly from an effect of eating intoxicated larvae that made a potentially poor food source. In the current study, lyophilized Cry1Ab protein was fed directly to C. carnea larvae via a sucrose solution. The doses were up to 10,000 times greater than what occurred in the previous trophic studies. No toxic effects were observed. Additionally there was not an effect on subsequent utilization of prey.

Comments

Showed that effect previously observed was likely to be due to reduced fitness of prey and that Cry1Ab protein has very little toxicity to C. carnea. The larvae only lived about 10 days on the sugar solution, regardless of Bt inclusion, so the sugar solution is not an ideal food. For the purpose of an acute test, it was a good delivery medium, but would not be suitable for a chronic test.