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INVESTIGATOR: Lopez-Martinez, G.

PERFORMING INSTITUTION:
NEW MEXICO STATE UNIVERSITY
1620 STANDLEY DR ACADEMIC RESH A RM 110
LAS CRUCES, NEW MEXICO 88003-1239

IMPROVING CACTUS MOTH CONTROL BY ENHANCING STERILE MALE PERFORMANCE

NON-TECHNICAL SUMMARY: The cactus moth Cactoblastis cactorum was introduced into the U.S. in 1989 and has expanded to South Carolina, Alabama, Louisiana, and Mississippi. Pest expansion into the western U.S. and Mexico could have devastating effects because collectively the Opuntia industry is worth about 76 Million US$/year including fruit, pads and dyes. The threat to biodiversity affects 79 species. Sterile Insect Technique (SIT) is a key component of the current area-wide control plan. SIT floods an area with sterile insects to mate with wild individuals, thereby producing inviable offspring. Ionizing radiation induces sterility by creating double-stranded DNA breaks that produce severe chromosomal damage. Additional radiation damage in other cellular structures results from production and accumulation of oxygen radicals and reaction products, essentially leading to insects with radiation sickness and decreased performance. Poor post-irradiation performance is a critical factor limiting the success of all SIT programs. A solution is suggested by my previous work on the fruit flies showing that low-oxygen pretreatments increase cellular antioxidant enzymes and post?irradiation fly performance, while maintaining sterility. In this grant I will use a biochemical perspective to design a series of low-oxygen pretreatments that will enhance post-irradiation cactus moth performance in lab and field assays, while maintaining sterility. Development of performance-enhancing pretreatments for cactus moths meet the broader challenge area in global food security and meets USDA program area priorities in improving food safety and keeping American agriculture competitive. I have three mentors, Daniel Hahn at University of Florida, and James Carpenter and Stephen Hight with USDA-ARS.

OBJECTIVES: Goals for this proposal: My main goal is to determine if exposure to low-oxygen pretreatments prior to irradiation will improve antioxidant capacity and enhance sterile insect performance in the field. Using a combination of antioxidant enhancing pretreatments, I will evaluate which treatments give the most benefit and are likely to improve the cactus moth SIT program. By fully integrating basic lab science with field applications I can truly test whether results achieved in the lab still work in the real world. My specific aims are:1) To determine whether moths exposed to low-oxygen environments prior to and during irradiation have enhanced antioxidant defenses. I will define low-oxygen pretreatments that fit into current rearing protocols that substantially enhance antioxidant capacity. The outcome of this aim will be to use these rapid biochemical assays to prioritize which treatments have the greatest increase in antioxidant capacity and thus should be tested further in laboratory bioassays of organismal performance (Aim 3). My preliminary data shows that 1h of low-oxygen substantially enhances antioxidant capacity (23%) while not affecting survival, and I expect that further improvements will be made with careful parameterization of treatments.2) To determine if low-oxygen pretreatments that lead to enhanced total antioxidant capacity are associated with increases in the activity of three major antioxidant enzymes (superoxide dismutase, catalase, and glutathione peroxidase). I will also determine whether animals exposed to pretreatments that boost antioxidant capacity suffer less post-irradiation cellular damage by assaying for the production of protein carbonyls and lipid peroxides. The outcome of this aim will be to parameterize the physiological responses associated with low-oxygen performance enhancement.3) To evaluate which of the antioxidant-enhancing treatments in Aim1, lead to better sterile insect performance in lab bioassays, including: emergence, longevity, flight ability, sterility, and mating success. I have already identified two treatments that substantially enhance antioxidant capacity (Fig. 2), and therefore Aim 3 is ready to progress even if I do not identify additional treatments with greater antioxidant improvement capacity in Aim 1. The output of Aim 3 will be to test whether treatments that improve antioxidant capacity also produce animals with the best performance in lab bioassays, determining whether antioxidant capacity can be used as a good predictor for whole organism performance.4) To determine if antioxidant-enhancing treatments that produce the best performance in biochemical and standard lab bio-assays, translate to greater longevity and dispersal in field releases. The output of Aim 4 will be to determine if my physiologically-guided approach of boosting antioxidant capacity will lead to real-world improvements in performance that can be directly applied to improving cactus moth control by SIT, and perhaps other SIT programs.