|Adamczyk Jr, John - INSECT MANGT.,MISSISSIPPI|
|Braman, Kristine - DEP.OF ENT.,U OF GEORGIA|
|Brandenburg, Rick - DEP.OF ENT.,NORTH CAROLIN|
|Nuessly, Gregg - EVERGLADES RES.,FLORIDA|
Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2005
Publication Date: June 20, 2006
Citation: Nagoshi, R.N., Meagher Jr, R.L., Adamczyk Jr, J.J., Braman, K., Brandenburg, R.L., Nuessly, G. 2006. New restriction fragment length polymorphisms in the Cytochrome Oxidase I gene facilitate host strain identification of fall armyworm (Lepidoptera: Noctuidae) populations in the Southeastern United States. Journal of Economic Entomology. 99(3):671-677. Interpretive Summary: Fall armyworm (FAW), is a significant pest of maize, sorghum, forage grasses for livestock, turf grasses, rice, cotton and peanuts whose range extends from southern Canada to most of South America. It is a migratory pest that cannot survive freezing winters, hence the infestation of most of North America stems from populations overwintering in south Florida and parts of Texas. Controlling FAW in these relatively localized overwintering areas prior to migration could significantly reduce FAW damage in more northern states. However, there are two physically identical strains that display significant differences in resistance to certain pesticides, susceptibility to different plant cultivars, and host plant preference. Because of difficulties in identifying strains, little is known about their behavior in the field and their distribution in different habitats. In this study USDA, ARS, scientists at the Center for Medical, Agricultural, and Veterinary Entomology, Gainesville, FL, used molecular biology techniques combined with pheromone trapping to examine strain-specific behaviors. Substantial variations in the seasonal distribution of the two strains were found suggesting previously unknown differences in migration behavior and response to environmental factors. This information is essential for the development of area-wide control strategies that could interfere with or delay the northward migration of FAW and therefore mitigate the damage from this pest in most of the continental United States and Canada.
Technical Abstract: Several restriction sites in the Cytochrome Oxidase I gene of fall armyworm, Spodoptera frugiperda (J. E. Smith), were identified by sequence analysis as potentially being specific to one of the two host strains. Strain-specificity was demonstrated for populations in Florida, Texas, Mississippi, Georgia, and North Carolina, with an AciI and SacI site specific to the rice-strain and a BsmI and HinfI site joining an already characterized MspI site as diagnostic of the corn-strain. All four of these sites can be detected by digestion of a single 568 bp PCR amplified fragment, but the use of two enzymes in separate digests was found to provide accurate and rapid determination of strain identity. The effectiveness of this method was demonstrated by the analysis of almost two hundred adult and larval specimens from the Mississippi delta region. The results indicated that the corn-strain is likely to be the primary strain infesting cotton and that an unexpected outbreak of fall armyworm on the ornamental tree Paulownia tomentosa was due almost entirely to the rice-strain.