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Title: Effects of Cry1F and Cry34Ab1/35Ab1 on storage pests

Author
item Oppert, Brenda
item ELLIS, R - Dow Agrosciences
item BABCOCK, JONATHAN - Dow Agrosciences

Submitted to: Journal of Stored Products Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2010
Publication Date: 8/3/2010
Citation: Oppert, B.S., Ellis, R.T., Babcock, J. 2010. Effects of Cry1F and Cry34Ab1/35Ab1 on storage pests. Journal of Stored Products Research. 46(3):143-148.

Interpretive Summary: New control methods are needed for storage pests. Two microbial toxins were evaluated for efficacy in a number of different storage pests. The data suggest that neither toxin had significant activity in the storage pests that were tested. Therefore, the utility for controlling stored product insects with these toxins is predicted to be low. However, the data also suggest that these toxins exhibit a high degree of selectivity and would pose minimal risks to nontarget species.

Technical Abstract: Two crystalline protoxins from Bacillus thuringiensis (Bt), Cry1Fa1 and Cry34Ab1/Cry35Ab1 (Cry1F, Cry34/35), were evaluated for efficacy against lepidopteran and coleopteran storage pests. Cry1F was tested against the lepidopterans Sitotroga cerealella (Angoumois grain moth) and colonies of the lepidopteran Plodia interpunctella (Indianmeal moth) that are susceptible or resistant to Bt Cry1Ab and Cry1Ac toxins, Bt subspecies entomocidus, and the commercial formulation Dipel®. Cry1F also was tested against coleopterans Cryptolestes pusillus (flat grain beetle) and Tribolium castaneum (red flour beetle). Cry34/35 was tested against S. cerealella, C. pusillus, and T. castaneum, and against additional coleopteran storage pests, including Tenebrio molitor (yellow mealworm), Trogoderma variabile (warehouse beetle), Oryzaephilus surinamenis (sawtoothed grain beetle), Rhyzopertha dominica (lesser grain borer), and Sitophilus oryzae (rice weevil). Our results indicate that strains of Bt-susceptible or -resistant P. interpunctella generally were more sensitive to Cry1Ac protoxin or Cry1Ab toxin than either Cry1F protoxin or Dipel. Despite difficulties with the bioassay of lepidopteran S. cerealella larvae, the data suggest that Cry 1F and Cry34/35 caused increased larval mortality, and a developmental delay was observed and no pupae emerged with 0.9% Cry1F. Neither Cry1F nor the corn rootworm-active toxin Cry34/35 significantly affected the biological parameters of the coleopteran species evaluated.