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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Insect Behavior and Biocontrol Research » Research » Publications at this Location » Publication #326115

Research Project: Improved Biologically-Based Methods for Insect Pest Management of Crop Insect Pests

Location: Insect Behavior and Biocontrol Research

Title: Intraspecific difference in plant defense induction by fall armyworm strains

item Acevedo, F - Pennsylvania State University
item Peiffer, M - Pennsylvania State University
item Ray, S - Pennsylvania State University
item Meagher, Robert - Rob
item Luthe, D - Pennsylvania State University
item Felton, G - Pennsylvania State University

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2017
Publication Date: 1/14/2018
Citation: Acevedo, F.E., Peiffer, M., Ray, S., Meagher Jr, R.L., Luthe, D., Felton, G. 2018. Intraspecific difference in plant defense induction by fall armyworm strains. New Phytologist. 218:310-321.

Interpretive Summary: The caterpillar of the fall armyworm, Spodoptera frugiperda, is a pest of many row and vegetable crops and various turf grasses in the Americas. As a species, the fall armyworm is comprised of two strains (corn and rice) that preferentially feed on each of these different host plants. How these strains adapt to different host plants is mostly unknown. Researchers with The Pennsylvania State University and a researcher with the USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, tested the role of certain plant defensive chemicals as they influenced the host plant association with the fall armyworm strains. When fed on either corn or Bermuda grass, the different chemicals were found in the saliva of the fall armyworm caterpillars. The different salivary components resulted in different defensive responses in their host plant. These plant defenses negatively affected the growth of the caterpillars and may help explain how the two host strains behave under field conditions. The information can contribute to the development of effective control methods for these and other moth crop pests.

Technical Abstract: The association of insect strains to different host plants has been claimed to influence reproductive isolation. However, the underlying mechanisms by which these strains adapt to different host plants are mostly unknown. In this paper we investigated the role of induced plant defenses in the host plant association of insect strains. We used the fall armyworm (FAW) Spodoptera frugiperda strains and their host plants, maize and Bermuda grass as a model system. Our results show that the FAW strains induce different defense responses in their host plants due to differences in the composition of their caterpillar saliva. Specifically, these strains exhibit differences in the activity of the salivary enzyme phospholipase C (PLC), which triggers different defense responses in maize and Bermuda grass. The levels of plant defense responses were negatively correlated with caterpillar weight gain indicating a fitness effect, and thus, may influence host plant performance in field conditions.