de Montigny, Simone (Beloit College), Mentors: Chloé Lahondère (Virginia Tech) and David McLeod (Mary Baldwin University).
Investigating phytophagy, pollination, and toxin interactions between mosquito Aedes japonicus and fly poison (Amianthium muscitoxicum)
Abstract: Phytophagy plays a significant role in mosquito biology, influencing survival and reproductive success. This study investigates the interactions between the invasive mosquito species Aedes japonicus and the toxic plant Amianthium muscitoxicum (fly poison), with a focus on mosquito feeding behavior, pollination potential, and the effects of nectar on mosquito survival and behavior. Aedes japonicus is a disease vector mosquito which has recently invaded Eastern North America, and has been observed interacting with fly poison plants at Mountain Lake Biological Station in Pembroke, VA. Visitation assays were performed with A. muscitoxicum plants to assess sugar feeding and potential pollination. 40.3% of Ae. japonicus in visitations tested positive for fructose, indicating feeding on fly poison. Pollen screening revealed that 5.2% of mosquitoes carried pollen, suggesting potential for pollination. Force-feeding assays demonstrated that mosquitoes consuming fly poison nectar had significantly reduced survival compared to those fed a sucrose solution, with a median survival time of 2 days versus 11 days. These findings suggest that Ae. japonicus utilizes A. muscitoxicum as a source of carbohydrates, while the toxic properties of the nectar negatively impact their survival. Because of this, fly-poison toxins have a potential use in control methods for this invasive disease vector mosquito species. Future research should explore the viability of fruits produced by visited plants and further investigate the behavioral effects of toxic nectar. Insights gained through this research could contribute to developing control strategies for Ae. japonicus populations.
Erwin, Connor (University of Virginia), Mentor: Sarah McPeek (University of Virginia).
How variation in nectar traits of Amianthium muscitoxicum (Fly Poison) affects the foraging behavior of Strangalepta abbrieviata
Abstract: Spatial and temporal factors can cause swings in ecological resource availability. Animal foragers can accommodate shifts in resource quantity and quality by changing their behavior. Pollinators are a prime example of a forager guild that often depends on an environmentally malleable resource: floral nectar. Nectar traits such as volume and sugar concentration vary greatly in response to environmental factors such as precipitation. To understand how pollinators may respond to variable nectar environments, it is crucial to first understand which nectar trait components drive pollinator attraction. In this study, we looked at the attraction of the longhorn beetle Strangalepta abbrieviata towards different nectar traits of its primary food plant, Amianthium muscitoxicum.. We performed experiments to give S. abbrieviata a choice between different sugar concentrations and volumes of sugar water. The beetle pollinators were videotaped and we recorded the total time they spent on each sugar water treatment. Our results showed that both sugar concentration and volume were important components of nectar in attracting Strangalepta abbreviata. Of the two components, volume was the stronger attractant, but it did not completely mask the effect of sugar concentration on pollinator attraction. This data informs previously observed patterns of pollinator visitation and dynamics of selection of nectar traits in the wild Amianthium population.
Garcia, Sarah (Cornell University), Mentors: Chloé Lahondère (Virginia Tech) and David McLeod (Mary Baldwin University).
Investigating visual and olfactory sensory ecology of Culex territans and antiparasitic behavior of their hosts Rana clamitans and Rana catesbeiana
Abstract: Culex territans is a mosquito species that feeds exclusively on herpetofauna with preferences in North American populations for green frogs (Rana clamitans) and bullfrogs (Rana catesbeiana). It is known to be a vector of anuran pathogens such as frog chytrid fungus, anuran trypanosomes, and ranaviruses, all of which can be a burden to amphibian populations that are in decline worldwide. Little is known about the sensory ecology and host-seeking cues of this mosquito species, which limits our ability to control this disease vector. This study had three main objectives: 1) determine if patterns of UV-absorption and UV-reflection observed in R. clamitans and R. catesbeiana eyes and skin are attractive to Cx. territans, 2) discover what combinations of CO2 and frog odor are attractive to Cx. territans, and 3) determine whether or not green frogs and bullfrogs display antiparasitic behavior in the presence of mosquitoes. To answer these questions, visual assays under different light treatments, olfactometer assays with various CO2 concentrations and frog odor treatments, and feeding assays recorded for later observation, description, and quantification of antiparasitic behavior were conducted. It was found that Cx. territans 1) feeds comparably under UV, red, and full light conditions, 2) is not significantly attracted to any of the olfactory treatments tested, and 3) frogs display varying levels of antiparasitic behaviors at the species and individual level in a laboratory setting. This project provides insight into mosquito-host interactions, the evolution of blood-feeding in mosquitoes, and has implications for amphibian conservation.
Jiron, Griffin (University of Virginia), Mentor: Charlotte Greene (University of Virginia).
Male mate choice across age in a long-lived beetle (Bolitotherus cornutus)
Abstract: While the dominant view on sexual selection is one of choosy females and indiscriminate males, growing evidence supports a reciprocal model of sexual selection, where males maximize their reproduction through a preference for more fecund females. It’s known that populations where males frequently encounter females, where male investment in mating is high, and where female quality is variable are expected to evolve male mate choice. One driver of male mate choice evolution that has been less well-described is male age, especially in long-lived systems. Life history theory as well as past empirical work suggests that as males age, their choosiness should decrease, since their future reproductive potential diminishes over time. However, this trend has not explicitly been investigated in a system that lives for multiple breeding seasons. To explore whether male mate preference changes with age in a long-lived system, we measured mating behavior across female size in the long-lived beetle, B. cornutus. We found that young males significantly increase their mating investment for larger females, while old males showed no preference across female body size. Our findings support life history predictions, and further uncover how age may be influencing male mate preference independently from end-of-breeding-season effects.
Lepsch, Evelyn (University of Virginia), Mentor: Clara Stahlmann Roeder (University of Virginia).
Predicting social effects of climate change: increased temperature does not impact aggressive behavior in the forked fungus beetle (Bolitotherus cornutus)
Abstract: Temperature increase as a result of human activity is influencing population dynamics across the globe. It is of note that ectothermic species may also experience severe behavioral changes due to these increased temperatures, as their metabolic rates are strongly tied to the external environment. While most studies in this area investigate how temperature change affects extinction rates and population dynamics, examining behavioral changes is perhaps equally as important as such changes could alter species habitat, phenotype, selection pressures, or extinction rates. In this experiment, I investigated the effect of temperature change on aggression in Bolitotherus cornutus. As this species is ectothermic and males may fight for access to resources, I predicted that increased temperature increases aggressive behavior. I conducted three treatments at 19℃, 22℃, and 25℃ with 20 pairs of male beetles per treatment. I paired males together based on age and size and acclimated them to each temperature for 20 hours before conducting 2-hour behavioral assays followed by 2.5-hour fight trials. I observed 4 types of behaviors: contact aggression, evade behavior, latency to move, and proximity. I found no significant relationships between each of these four behaviors and temperature. This indicates that as temperatures rise, the aggressive behavior of the forked fungus beetle will remain the same. This also suggests that fights may occur at a constant rate in the coming decades, indicating that selection pressures for larger horn size and horn length will also remain the same. It is likely that some behaviors in B. cornutus will be affected by climate change in the near future; therefore, it is important to rule out which behaviors will change. Furthermore, the results of this study help illustrate what our warmer future will look like and what impacts climate change will have on ectotherm behavior.
Rand, Taylor (University of South Florida), Mentor: Erin Scott (University of Virginia).
Saproxylic arthropod diversity across log types and log communities
Abstract: Deadwood-dependent (saproxylic) arthropod communities play a crucial role in forest ecosystems, facilitating decomposition of wood and nutrient cycling in forests. High heterogeneity found within deadwood habitats is understood to support large and diverse saproxylic arthropod communities, but our understanding of how these communities differ across different factors impacting rotting log ecosystems is limited. Here, we investigate the impacts of two factors on saproxylic arthropod diversity: log wood type and abundance of Cryptocercus punctulatus. We sampled arthropod communities from 24 rotting logs in the western Appalachian Mountains and analyzed order-level diversity data. Our empirical data on community composition of rotting logs at intermediate to late stages of decay revealed that, on average, softwood logs have higher arthropod diversity than hardwood logs; logs with higher abundance of C. punctulatus were also found to have a correlation with higher arthropod abundance. In identifying and analyzing these factors that correlate with higher saproxylic arthropod diversity within logs, it is possible to adjust forest management policies to conserve saproxylic arthropod populations and facilitate healthy forest ecosystems.
Worthington, Quianday (Randolph College), Mentor: Clara Stahlmann Roeder (University of Virginia).
The impact of aggressive interactions on subsequent social and aggressive behaviors (Bolitotherus cornutus)
Abstract: Forked fungus beetles have shown that they change their aggressive behaviors in response to winning or losing a contest. The question still stands: How does the intensity of losing a fight affect future aggressive behaviors and how long does that effect last? In this study, I studied the intensity of the first fight. In the second fight, I saw if there are any behavioral changes in a beetle and when the beetle effect of losing a fight takes place. I hypothesized that if the first fight is more intense, the duration of the loser effect increases, initiated aggression behavior decreases, and evading behavior increases. I found that the days since the last loss significantly predict the amount of contact aggression observed in the subsequent fight (p=0.0028). This allows me to see how social behavior affects future behavior and how studying aggression is essential when examining how a fight’s intensity and duration affect a beetle’s behavior.
Zink, Shelby (University of Arkansas at Fort Smith), Mentor: David McLeod (Mary Baldwin University).
Effects of disturbance on the herpetofaunal community in a powerline right of way
Abstract: The effects of powerline right of ways (ROWs) on the herpetofaunal communities they disrupt are poorly understood Three sites on Salt Pond Mountain in Giles County, VA, were used to study the effects of disturbance caused by powerline ROWs on these highly sensitive indicators of environmental change.. Two 16m wide ROWs and one 46m wide ROW were used to compare disturbances of differing sizes. Nighttime and daytime surveys were conducted in ROWs and in the immediate forest. Across all sites, 442 total individuals and 11 species were observed. Of this total, 426 were salamanders. We found that salamander abundance is significantly lower in wide ROWs. We found that ROWs create an environmental edge effect, however this varies by site and variable. Salamander abundance increases with distance from the disturbance edge. Increasing the width of a ROW negatively impacts abundance. Environmental measurements were recorded using the methods of Brannon et al. to determine if the sites produced an effect of edge. Variables differed between sites. Sunlight intensity and soil moisture consistently differed in between a ROW and surrounding forest.