ESA Annual Meetings Online Program

Larval survival and plant injury of Cry1F-susceptible, -resistant, and -heterozygous genotypes of the fall armyworm on transgenic corn containing single or pyramided Bt genes

Monday, November 12, 2012: 9:03 AM
300 C, Floor Three (Knoxville Convention Center)
Ying Niu , Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA
Fei Yang , Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA
Liping Zhang , Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA
S. David Wangila , Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA
Robert L. Meagher , Behavioral and Biological Control Unit, USDA, Agricultural Research Service, Center for Medical, Agricultural & Veterinary Entomology (CMAVE), Gainesville, FL
B. Rogers Leonard , Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA
Fangneng Huang , Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA
Transgenic corn (Zea mays L.) products expressing multiple Bt proteins targeting a same pest have become commercially available in the U.S. In this study, larval survival and plant injury of Cry1F-susceptible (Cry1F-SS), -resistant (Cry1F-RR), and –heterozygous (Cry1F-RS) genotypes of the fall armyworm, Spodoptera frugiperda (J.E. Smith), on seven commercial corn hybrids were evaluated on leaf tissue in the laboratory and whole plants in the greenhouse during 2011-2012. The seven hybrids are two non-Bt and five Bt corn products representing five transgenic traits, which included four recently commercialized pyramided Bt corn traits: Genuity® VT Double ProTM, VT Triple ProTM, SmartStaxTM, and Agrisure® VipteraTM 3111, and a single gene Bt corn: Herculex® I. On whole plant tests in the greenhouse, larvae of the three insect genotypes on the two non-Bt corn hybrids caused an average leaf injury rating (Davis’ 1 to 9 scales) of 5.6 to 6.5 after 7 days and 8.8-9.0 after 15 days. Leaf injury rating of Cry1F-SS and –RS on Herculex® I plants was low, ranging from 1 (no damage) to 2.4, but it was high for Cry1F-RR larvae, with 5.8 after 7 days and 8.4 after 15 days. Leaf injury rating of the three insect genotypes was low on the two observation dates, < 2.5, against the four pyramided Bt corn hybrids. After 15 days, live larvae were observed in 37.5-75.0% of non-Bt plants. For the Herculex® I plants infested with Cry1F-RR larvae, this number was 43.8%. In contrast, no live larvae were observed on all four pyramided Bt corn hybrids regardless of the insect genotype. Data observed in the leaf tissue tests in the laboratory were consistent with the whole plant tests in the greenhouse. The results showed that the Cry1F-RR S. frugiperda was highly resistant to Cry1F corn, but susceptible to all four pyramided Bt corn hybrids, suggesting that these pyramided Bt corn traits should offer a means for Cry1F resistance management in S. frugiperda.

KEY WORDS: Transgenic corn, Cry1F, resistance management, Bacillus thuringiensis, gene-pyramiding, Spodoptera frugiperda

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