TRANSCRIPTOMIC DETERMINATION OF GENES INVOLVED IN THE NUTRITIONAL ECOLOGY OF FALL ARMYWORM PLANT HOST STRAINS

Fall armyworm, Spodoptera frugiperda, has been well documented for over 200 years as a significant pest in the USA and other regions of the western hemisphere. Due in part to occurrence of plant host strains, it can feed on over 60 species of plants including a wide variety of crops used for food, fiber and biofuels. Pest management depends on insecticides and an increasing reliance on transgenic crops. Yet resistance to both controls occurs in the field. Thus, efforts to discover and develop inborn plant resistant varieties are crucial to improvement and sustainability of integrated pest management of fall armyworm and other caterpillar pests. Proficient discovery and development of in born plant resistance requires understanding the functional genomics (gene sequences, functions and effects) underlying the nutritional ecology of insect crop pests. Fall armyworm is an excellent model system for investigating these genomic mechanisms. This project's scientists have found a link between larval nutritional ecology, development of resistant corn lines, dispersal and other life-history characteristics of fall armyworm. Existence of two genetically different plant host strains defined by their nutritional ecology as corn and rice strains could lead to deciphering genes determining how variation in nutritional adaptation leads to host plant preference. Such research cannot proceed because the necessary functional genomic knowledge is lacking for fall armyworm and other crop pests. Therefore, a primary benefit of this project will be a public, WEB-accessible transcriptome with sequences of expressed genes whose function is defined according to tissue, life stage, host strain and putative biochemical function. Another benefit will be a public catalogue of variation in sequence coding for use as genetic markers that will be highly valuable in deducing implications of population dynamics, gene flow, resistance and dispersal on pest management. Functionally important variation underlying the nutritional ecology of organisms' is governed by regulation of gene expression. Thus, this project will use the transcriptome to analyze changes in gene expression level as fall armyworm feed on the caterpillar resistant MP708 corn line. MP708 producing Mir-CP plant protease is one of the most promising in born (not genetically engineered) lines of corn resistant to moth caterpillar pests. Degradative action of Mir-CP on protein comprising the peritrophic membrane of caterpillar guts is unique and disrupts nutrient utilization. A third benefit from this project will be advancing development of MP708 corn by discovering gene expression profiles in specific caterpillar tissues and host strains that respond to the effects of eating resistant MP708 corn. Overall, this project will create public genomic toolsets available for enhanced understanding of prominent moth pest biology and discover host plant-dependent effects on the nutritional ecology of these pests leading to improved pest management through the use of inborn plant resistance.