Delimiting strategic zones for the development of fall armyworm (Lepidoptera: Noctuidae) on corn in the State of Florida

Authors: GARCIA, ADRIANO - Universidade De Sao Paulo; GODOY, WESLEY - Universidade De Sao Paulo; Gruters-Thomas, Jean; Nagoshi, Rodney; Meagher, Robert - Rob

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/13/2017
Publication Date: 12/18/2017
Citation: Garcia, A.G., Godoy, W.A., Gruters Thomas, J.M., Nagoshi, R.N., Meagher Jr, R.L. 2017. Delimiting strategic zones for the development of fall armyworm (Lepidoptera: Noctuidae) on corn in the State of Florida. Journal of Economic Entomology. 111(1):120-126. https://doi.org/10.1093/jee/tox329.
DOI: https://doi.org/10.1093/jee/tox329

Interpretive Summary: The fall armyworm moth is a serious pest of row and vegetable crops in the U.S. This insect species is originally from the tropics and is not suited for temperate climates during winter. Therefore, it migrates from southern Florida and southern Texas each spring to infest crops as far north as southern Canada. Researchers with the University of São Paulo, Brazil, along with researchers from USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, conducted a laboratory experiment to define the temperature limits of this species. Larvae were collected in northern Florida and brought back to the laboratory, where a colony that fed on corn was initiated. The development of fall armyworm on corn leaves was determined at five constant temperatures. Based on the development time, the number of generations at various locations within Florida was estimated. Maps were constructed to provide a visual description of the data, using GIS (Geographic Information System). The highest number of generations was observed in the counties farther south, an area that plays a strategic role in maintaining fall armyworm populations. Additionally, it was concluded that in the absence of freeze periods, fall armyworm should be able to overwinter as far north as ~29°N, roughly 140 miles further north than what was estimated with earlier research. These findings provide a projection of areas where potential control measures should be employed to reduce the overwintering populations.

Technical Abstract: The fall armyworm, Spodoptera frugiperda (J. E. Smith), cannot survive prolonged periods of freezing temperatures, thereby limiting where it can overwinter in North America. Climate change is anticipated to reduce the frequency of freeze days in Florida over the decades, with the potential consequence of a significant expansion of the overwintering range, which in North America was assessed as south of ~27°N in the last century. To assess this possibility, the development of the fall armyworm on corn leaves, one of the main host plants in the United States, was determined at five constant temperatures ranging from 14°C to 30°C. Based on the development time, the thermal constant and the lower threshold temperature were used to estimate the number of generations of fall armyworm at 42 locations in the state of Florida, from 2006 to 2016. Maps were constructed to provide a visual description of the interpolated data, using GIS (Geographic Information System). The highest number of generations was observed in the counties farther south, an area that showed the highest 26 temperatures during the years and plays a strategic role in maintaining fall armyworm populations in corn fields. Additionally, we conclude that in the absence of freeze periods, fall armyworm should be able to overwinter as far north as ~29°N.