38th Annual Meeting of the Society for Invertebrate Pathology

August 7-11, 2005  Anchorage, Alaska, U.S.A
   

Impact of Bacillus thuringiensis Cry toxins on the predator Chrysoperla carnea (Neuroptera: Chrysopidae): in vivo binding, histopathological and prey-mediated effects

Ana Rodrigo-Simón1, Carlos Avilla2, José E. González-Zamora2 and Juan Ferré1
1Departamento de Genética, Universidad de Valencia. Dr. Moliner 50, 46100 Burjassot (Valencia). SPAIN.
2Departamento de Ciencias Agroforestales, E.U.I.T.A., Universidad de Sevilla. Ctra. Utrera, Km. 1. 41013 Sevilla. SPAIN.

Chrysoperla carnea is an important natural enemy of a wide range of crop pests, that is commonly chosen as a control to determine pesticidal side-effects and the ecological impact of Bacillus thuringiensis (Bt) crops. Specific binding of ingested Cry1Ac and cell damage was found in epithelial midgut cells of a susceptible insect, Helicoverpa armigera. However neither any histopathological effect of Cry1Ac nor inmunodetection of this protein in C. carnea was found. The prey-mediated effects of Cry1Ac, Cry1Ab and Cry2Ab on C. carnea were studied by feeding them with treated H. armigera and Ephestia kuehniella eggs. Pupation percentage, proportion of emerged adults and hatching percentage of eggs was no significantly different between treatments.

Our results suggest that H. armigera fed on Bt crops have not a detrimental effect on C. carnea in the field, were the diet is supplemented with other prays like Lepidoptera larvae and eggs, aphids and two spotted mites. We have shown that in the hypothetical case of that Cry1Ac toxin were ingested by C. carnea, no binding of this toxin to the midgut of the predator should occur.

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