The adaptive significance and prevalence of courtship feeding in Hawaiian swordtail crickets

Males of many insect species feed their partner during courtship and mating. Studies of male nutrient donation in various systems have established that nuptial feeding has evolved mostly through sexual selection. Although there is extensive diversity in form, the function of nuptial gifts is typically limited to either facilitating copulation or increasing ejaculate transfer, depending on the time at which the gift is consumed by females. Unlike other insects, the Hawaiian swordtail cricket Laupala (Gryllidae: Trigonidiinae) exhibits serial transfer of nuptial gifts. Males transfer multiple spermless 'micro' spermatophores over several hours before mating at the end of the day (i.e. before the transfer of a single sperm-containing 'macro' spermatophore). By experimental manipulation of male microspermatophore donation, I tested several hypotheses pertaining to the adaptive significance of nuptial gifts in this system. I found that microspermatophore transfer improves insemination, by causing the female reproductive tract to take in more sperm. This result reveals a previously undocumented function for premating nuptial gift donation among insects. Enhanced sperm transfer due to microspermatophore donation may represent male manipulation or an internal mechanism of post-copulatory choice by females. I also performed experimental manipulation of male photoperiod to investigate how time and gender influence nuptial gift production and mating behavior. I found that the timing of mating is limited in males but not females and that the time of pair formation has consequences for the degree of nuptial gift donation, which suggests that both mating timing and microspermatophore number is important for male reproductive success. Finally, I observed the mating behavior of several trigonidiine taxa for a comparative analysis of sexual behavior and found that other genera also utilize spermless microspermatophores, which suggests that microspermatophore donation may be a common nuptial gift strategy among swordtail crickets. The elaborate nuptial feeding behavior of Hawaiian swordtail crickets prior to mating represents a newly discovered strategy to increase male insemination success rather than mating success. Based on this unexpected result, it is worth exploring whether courtship behaviors in other cricket or insect mating systems have also evolved to increase sperm uptake.

Herbal Dietary Supplements: Safety, Efficacy, and Use by Breast Cancer Survivors

Gemstone Team IMAC (Integrative Medicine and Cancer)

Cognitive training: the effects of working memory training

Gemstone Team Cognitive Training

An analysis of the efficacy of low-scale concentrated photovoltaics

Gemstone Team LEAF (Light Energy Acquisition of the Future)

Effects of Web-Based Self-Reporting: College Students’ Self-Efficacy Regarding Fruit and Vegetable Intake

This study evaluated the effect of an online diet-tracking tool on college students’ self-efficacy regarding fruit and vegetable intake. A convenience sample of students completed online self-efficacy surveys before and after a six-week intervention in which they tracked dietary intake with an online tool. Group one (n=22 fall, n=43 spring) accessed a tracking tool without nutrition tips; group two (n=20 fall, n=33 spring) accessed the tool and weekly nutrition tips. The control group (n=36 fall, n=60 spring) had access to neither. Each semester there were significant changes in self-efficacy from pre- to post-test for men and for women when experimental groups were combined (p<0.05 for all); however, these changes were inconsistent. Qualitative data showed that participants responded well to the simplicity of the tool, the immediacy of feedback, and the customized database containing foods available on campus. Future models should improve user engagement by increasing convenience, potentially by automation.

Federal Nutrition Assistance at Farmers’ Markets: Evaluating Self-Efficacy and the Home Nutrition Environment

SNAP and WIC help alleviate food insecurity among low-income families; however, some still struggle with fruit and vegetable accessibility. Farmers' markets present the opportunity to purchase fresher foods than other food retailers; therefore, we chose this environment to conduct our research. A survey of 70 WIC/SNAP shoppers at three D.C. metropolitan area farmers' markets assessed the correlation between parental self-efficacy and the home nutrition environment (composed of family health behavior, perceived barriers, and fruit and vegetable offerings in the home) and found a significant relationship. Interviews were used to evaluate market accessibility, SNAP/WIC benefit redemption, and the feasibility of accepting these benefits. Both market participants and coordinators mentioned the greater variety and superior quality of farmers' market produce but also suggested several improvements. Findings suggest that SNAP incentive programs may increase fruit and vegetable purchases. Programs targeting consumer self efficacy may also produce positive outcomes.

An Investigation into the Efficacy of a pH-Sensitive Material for Milk Spoilage Detection

Ambiguous expiration dates on milk cartons can mislead consumers into prematurely disposing unspoiled milk and potentially drinking spoiled milk. These misconceptions can lead to wastage that harms the environment, or potential discomfort and illness. The incorporation of pH-sensitive indicators into plastic milk cartons has the potential to replace stamped expiration dates as the traditional method of milk spoilage indication. We studied the correlation between bacteria count and milk pH to establish pH measurement as an effective indicator of milk quality. We then developed a method for incorporating bromothymol blue, a pH-sensitive color-changing dye, into a hydrogel made of polyacrylamide. This hydrogel can be added to existing packaging for milk or other products with detectable pH changes. Additionally, we conducted a consumer survey and analyzed current food packaging trends in the market. Our research indicates that a spoilage-indicating milk carton could have strong market potential as food industries increasingly adopt intelligent packaging designs.