Progress 11/01/13 to 08/31/14
Outputs Target Audience: The target audience for this work consists of fellow scientists involved in basic and applied research, and hopefully government officials in charge of invasive pest control strategies. Additionally, the general consumer (of all economic and social backgrounds) seeking a pesticide-free product make up a big proportion of my target audience. This works provides economically-relevant insight into the effect of low-oxygen hormesis as a low-cost improvement to current environmentally-friendly pesticide-free pest control strategies, like the sterile insect technique. Not only is the efficacy of SIT improved by this method, but the number of insects required for control is less and thus the overall the implementation of this technique should lead to a decrease in pest control costs for commodities that are attacked by invasive species. Essentially the target audience is anyone interested in the improvement of environmentally-friendly non-pesticidal control strategies. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? The project allowed me to manage my own grant, train my own students, and carry out experiments that otherwise I would have not been able to carry out working under someone else’s project. I was given the generous opportunity to move the funding from my post-doctoral position to my new assistant professor position. This allowed me to finish the ongoing research, while training two undergraduate students. I have become proficient in the design of field release studies, a skill I did not previously have. I have also become proficient in circular statistics required to analysis the type of data I collect during the field trials. The research I carried out as part of this project allowed to attain a highly competitive NIH fellowship for a training course in experiment aging at the Aging Institute of the University of Washington. This was both a great training opportunity, but also professional development. I attended at least 9 conferences during the duration of the project and in the last year gave three invited seminar on the work resulting from this project. How have the results been disseminated to communities of interest? The results of this project yielded five publications. Two of which came out in early 2014, two are in review, and the last one will be submitted later this year. The results were also presented at least nice conferences, several of which were international. Four invited seminars have resulted from this work as well. The two published papers gathered a fair amount of news coverage at the local (Gainesville, Florida TV station), state (several Florida TV/radio/news outlets), and national (NPR) levels. The research was feature in at least 10 websites including Science Daily and the Entomological Society of America’s News. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts What was accomplished under these goals?
1) All objectives proposed in Aim 1 were completed as proposed. Methods Aim 1: I tested exposures to either anoxia or hypoxia including 1, 1.5, and 2 hours. I applied these treatments at 3 different time points in the cactus moth lifecycle (1d before emergence, and 1d and 2d after emergence). The duration of increased antioxidant capacity was followed periodically for two days after treatment to estimate how long the effects of low-oxygen treatment lasted. I had proposed to try sequential low-oxygen exposures, but that was not necessary as single exposure produced the desired outcome. For the anoxia pretreatment, pupae or adult moths were placed in polyethylene bags and flushed with nitrogen for 2 minutes then heat-sealed. For the hypoxia pretreatment the pupae or moths will be heat-sealed in bags allowing the insects to continue consuming oxygen and thereby making the bag hypoxic. I estimated hypoxia levels in each treatment by using a gas-tight syringe to sample 5 ml of gas from each bagged sample at the end of the treatment period. Moths were exposed to hypoxia (low-oxygen) or anoxia (no oxygen) for different periods of time and mortality was assessed. It was determined that one hour of anoxia was the optimal treatment for the rest of the objectives in the project due to the consistent and strong elevation of antioxidant defense. Antioxidant defenses were determined biochemically using the total antioxidant capacity assay, as well as assay for superoxide dismutase, catalase, and glutathione peroxidase. The data was analyzed and we concluded that anoxia led to a 20 to 25% in total antioxidant capacity. This elevation in total antioxidant capacity was an expected change in knowledge which led to a publication and a change in action in Aim 4. 2) All objectives proposed in Aim 2 were completed as proposed. Methods Aim 2: I selected the anoxia treatment, which produced the greatest increase in total antioxidant capacity, for further biochemical dissection. I quantified the activity of individual antioxidant enzymes using modified commercially available kits from Cayman Chemical (SOD Assay kit and Glutathione Peroxidase Assay kit). I adapted an assay for catalase from the literature and used it to quantify levels of this antioxidant enzyme. Oxidative damage to membranes was quantified using the lipid peroxidation assay (TBARS). Protein carbonylation, a measure of oxidative damage to proteins, was quantified using an assay I had previously adapted from the literature (Levine et al. 1994). I carried multiple biochemical assays to determine that in fact superoxide dismutase (SOD) and glutathione peroxidase (GPx) are involved in the elevation of total antioxidant capacity recorded in Aim 1. Catalase was not elevated in response to anoxia. My data clearly shows a pattern in the reduction of oxidative damage to protein and lipids as early as two days after treatment. There is an additional reduction in oxidative damage evident four days after treatment. This aim allowed us to verify some of the mayor gene players behind anoxia hormesis and delivered a change in knowledge on how quickly and prolonged the hormetic effect can be in preventing oxidative damage to proteins and lipids. 3) All objectives proposed in Aim 3 were completed as proposed. Methods Aim 3: I designed and carried out several quality control/performance metrics for sterile lepidopteran performance. Based on input from my mentors who have vast knowledge in this area (James Carpenter and Stephen Hight), I adapted some assays currently in use for flies in order to investigate the effects of anoxia hormesis on cactus moth. I recorded flight ability, mating success, and longevity. Using the information from Aims 1 and 2, a quick a chance in action occurred when I had to redesign flight ability assays. Given that moths that received anoxia were so much active than those irradiated without hormesis, I redesigned the commonly used flight ability test and used one that not only provided flight ability, but also distance and time. This new assay (Lopez-Martinez et al 2014) was reliably repeated and the results were consistent. I found that anoxia prior to irradiation led to an increase in flight propensity, distance flown, and time spent flying. The results also show that anoxia moths are better at mating, and those males live longer. This aim also led to a change in action in the design of the field trial in Aim 4. 4) All objectives proposed in Aim 1 were completed. Methods Aim 4: I performed several release and recapture experiments in the field involving several releases over a period of several weeks following standard protocols designed and implemented by Carpenter, Hight, and other members of the cactus moth control program (Hight et al. 2005). I chose anoxia as the treatment to use in the field studies, given that it has the more robust hormetic response, reduction in post-irradiation oxidative damage, and great improvement in all performance metrics measured. I used Pherocon 1-C wing traps baited with newly developed cactus moth pheromone baits, to assess male dispersal across a circular grid from a central release point. Each trap was mounted to a hollow metal stake and placed in a cactus patch at a height of 0.75m. The original setup was seven transects consisting of nine traps each. Moths were marked with different color fluorescent powder (Day-Glo) and released in mid-afternoon (3:30pm) four times a week for four consecutive weeks. After the unexpected improvement of performance recorded in year 1, we tried again several times in year 2 and 3 with a different trapping design. We extended the trapping area 27-fold and used a circular grid pattern consisting of the levels. Traps were set at 15, 55, and 95 meters from the release point. Sterile male moths were released twice a week for four weeks, but traps were checked every day. Early on in Aim 4, a change in knowledge came when moths release in the field performed just like in the lab. Normally field trials do not mimic lab trials closely. But these sterile male moths flew further and lived longer in the field. This led to a change in action and I redesigned the field trial. Subsequent field trials used a trapping area that was 27 times larger than the original trial. With this new design we were able to collect more anoxia irradiated moths farther away from the release point and days after we no longer collected those moths irradiated without anoxia. This suggests that the effects of hormesis are not an artifact of lab experiments and in fact translate into real world application in a field infested with the pest in question. It is my hope that these results will lead to a chance in condition on how SIT programs incorporate protective treatments and possibly may lead to a more efficient and cost-effective approach to SIT.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
L�pez-Mart�nez G, Carpenter JE, Hight SD, Hahn, DA. Low-oxygen atmospheric treatment improves the performance of irradiation-sterilized male cactus moths used in SIT. Journal of Economic Entomology, 107: 185-197.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
L�pez-Mart�nez G, Hahn DA. Early life hormetic treatments decrease irradiation-induced oxidative damage, increase longevity, and enhance sexual performance during old age in the Caribbean fruit fly. PLOS One, 9: e88128.
- Type:
Journal Articles
Status:
Under Review
Year Published:
2014
Citation:
L�pez-Mart�nez G, Carpenter JE, Hight SD, Hahn DA. Anoxia-conditioning hormesis alters the relationship between irradiation doses for survival and sterility in the cactus moth, Cactoblastis cactorum (Lepidoptera: Pyralidae). Florida Entomologist.
- Type:
Journal Articles
Status:
Submitted
Year Published:
2015
Citation:
L�pez-Mart�nez G, Meagher RL, Bailey WD, Hahn DA. Low Oxygen atmosphere enhances post-irradiation survival and fertility in the cabbage looper, Trichoplusia ni.
- Type:
Journal Articles
Status:
Other
Year Published:
2015
Citation:
L�pez-Mart�nez G., Carpenter, J.E., Hight, S.D., and Hahn, D.A. Improving cactus moth SIT: the blending of lab-based hormetic approaches with real world pest control.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2013
Citation:
L�pez-Mart�nez G., Visser B, Williams CM, and Hahn DA. Repeated exposures to low-oxygen stress lead to hormetic effects during development and adulthood. Entomological Society of America. Austin, TX.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
L�pez-Mart�nez G., Visser B, Williams CM, and Hahn DA. Repeated anoxia exposures during development have hormetic effects that extend into adulthood. Society for Integrative and Comparative Biology. Austin, TX.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
L�pez-Mart�nez G. Physiological conditioning hormesis improves post-irradiation performance in young and aging flies. The 13th annual international conference on dose-response. Amherst, MA.
- Type:
Conference Papers and Presentations
Status:
Accepted
Year Published:
2014
Citation:
L�pez-Mart�nez G. Effect of free radical damage and hormesis on lifespan and immunity. NIH National Institute of Aging (NIA) Summer training course in experimental aging. University of Washington, Seattle, WA.
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