Entomology

Permanent URI for this communityhttp://hdl.handle.net/1903/11813

Browse

Search Results

Now showing 1 - 10 of 22

EXAMINING INTERACTIONS AMONG FUNGAL INFECTION, SLEEP, AND HOST DEFENSE IN POPULATIONS OF WORLDWIDE, SLEEP INBRED PANEL, AND MUTANT DROSOPHILA MELANOGASTER
(2024) Nan, Mintong; St. Leger, Raymond; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Previous studies with mutant Drosophila melanogaster lines and the Drosophila Genetic Reference Panel (DGRP) reveal substantial variation in susceptibility to infection with Metarhizium anisopliae strain Ma549. These differences likely arise from variations in immunity, physiology, and behavior, yet the role of selection pressures in maintaining these disparities remains understudied. Using global Drosophila populations, the Sleep Inbred Panel (SIP), and sleep-deprived mutants, we investigated the interactions among fungal infection, sleep, and host defense. Testing 14,957 male and 15,287 female flies from 43 lines across 28 locations, we found that resistance to Ma549 correlates with latitudinal gradients in sleep duration, temperature, and humidity. Tropical populations may exhibit stronger defenses due to fungal diversity; however, the most disease-resistant males were also more susceptible to desiccation, indicating trade-offs between abiotic stress and disease resistance. Longer-sleeping males and virgin flies survived infections longer, and increased daytime sleep post-infection was particularly protective in resistant flies. These findings suggest that sleep and disease resistance are interrelated traits possibly shaped by clinal evolution. Using 10,917 males and 11,166 females selected for extreme long or short nighttime sleep duration, we found that short-sleepers, despite having fragmented sleep when healthy, outlived long-sleepers after Ma549 infection. Resistance differences were sex-specific: males were more resistant among short-sleepers, while females showed higher resistance among long-sleepers. Daytime sleep bout numbers correlated with dimorphic disease resistance. Additionally, Ma549 infection increased daytime sleep in both short- and long-sleepers, with short-sleeping males nearly matching long-sleepers in sleep duration post-infection. Virgins, regardless of sleep status, slept more and survived infection longer, indicating that sleep traits, sex, and mating status are closely linked to disease resistance. The study highlights that circadian rhythms influence sleep and immunity, with the sleep-deprived Shmns mutant failing to undergo sickness sleep and succumbing quickly to infection. Mutants with disrupted circadian rhythms (PER and CLK) also showed impaired sickness sleep; however, only the per gene offered protection against disease, while the Clk mutant had increased survival. Independent of mutant status, males slept more than females, and virgins slept more than mated flies, emphasizing the significance of circadian rhythms in sleep and disease resistance.
MECHANISMS REGULATING GREENHOUSE GAS EMISSIONS AND SOIL CARBON STORAGE IN MID-ATLANTIC COASTAL PLAIN WETLANDS
(2024) Stewart, Graham; Palmer, Margaret; Williams, Michael; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Wetlands are key components of the global carbon (C) cycle, storing significant amounts of C while emitting methane (CH4), a greenhouse gas. As wetland restoration emerges as a potential climate mitigation strategy, understanding the factors that influence wetland greenhouse gas exchange across land uses is essential for aligning management with ecology and biogeochemistry. This dissertation investigates variability in soil organic carbon (SOC) storage and CH4 flux in mid-Atlantic Coastal Plain wetlands, focusing on the roles of hydrology, vegetation, and land-use history in shaping underlying ecosystem processes.In Chapter 1, I surveyed SOC stocks across neighboring least-disturbed wetlands with similar vegetation and hydrogeomorphology and found substantial variation. Hydrologic regimes and relative topography partially explained variability, highlighting the importance of landscape heterogeneity in determining wetland C storage capacity. In Chapter 2, I measured CH4 fluxes across five dominant vegetation patch types in a freshwater wetland using a multi-scale approach. I found that vegetation patches had distinct CH4 signals throughout the growing season, likely driven by differences in the mechanisms that regulate fluxes. The magnitude of the CH4 source was linked to patch identity, suggesting that CH4 fluxes were properties of patch types, and that a patch-explicit representation may be needed for modeling and estimating wetland greenhouse gas exchange. In Chapter 3, I explored the temporal dynamics of CH4 flux across wetlands with different land-use histories, identifying key biophysical drivers at multiple time scales. I found that after two decades, CH4 dynamics in a restored wetland appeared to have converged with those at a natural wetland and diverged with those at a cultivated former wetland. Together, these findings demonstrate the importance of acknowledging and accounting for the inherent variability and context-specificity in wetland C dynamics and suggest that wetland management and restoration for climate mitigation requires a detailed understanding of wetland ecosystem processes.
ODONATA SPECIES COMPOSITION IN AGROECOSYSTEMS: PRELIMINARY SURVEYS WITH AN EMPHASIS ON POTENTIAL FOR BIOLOGICAL CONTROL ON FARMS
(2024) Hartman, Margaret Elizabeth; Lamp, William O; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Adult dragonflies and damselflies are efficient aerial predators that provide ecosystem service as consumers of pest arthropods. However, their role as predators of agricultural pests in agroecosystems has been understudied. The prey of odonates has been historically difficult to quantify but new molecular methods can make diet analysis easier. I conducted visual encounter surveys across four farms in 2020 and 2021. I found odonates were present on all farms surveyed but there were significant differences in abundance and richness. Fecal pellets were collected from 94 odonates in 2021 for prey DNA analysis using next generation sequencing. Nine odonate samples produced exceptional libraries, resulting in a large quantity of identifiable prey sequences. This preliminary study can help future researchers develop best practices for maintaining healthy farm water bodies and optimizing fecal DNA analysis methodology to better understand odonates’ potential for agricultural pest suppression.
A GOOD NEIGHBORHOOD TO RAISE A BROOD: TREE SPECIES DIVERSITY DECREASES PERIODICAL CICADA OVIPOSITION AND TREE RESPONSE
(2023) Jayd, Kristin; Burghardt, Karin; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Natural systems contain diverse assemblages of plants, providing a matrix of potential hosts that herbivores must navigate. Insect-plant host choice patterns are crucial to understanding both herbivore outbreaks and the consequences of outbreaks for plant hosts. Here, I follow the 2021 Brood X periodical cicada mass emergence event in the BiodiversiTREE forest diversity experiment at the Smithsonian Environmental Research Center (SERC) in Edgewater, MD, to uncover whether tree diversity influences cicada oviposition preferences or tree responses to oviposition (flagging), for 15 tree species grown in plots of single species or 12-species mixtures. While cicadas demonstrate clear tree species preferences, the diversity of the surrounding tree neighborhood plays at least as important a role in determining oviposition preference and tree flagging responses. Cicadas were threefold more likely to oviposit in trees grown in single species vs. mixed species plots. While overall, I find a concomitant decrease in tree flagging in diverse plots. I also document that species flag at different rates in response to the same oviposition scar density. Even when accounting for differential oviposition rates, surrounding tree diversity remains an essential additional predictor of tree flagging responses with trees in diverse plots less likely to flag at the same density of scars, suggesting a differential capacity of trees to tolerate damage when growing in single species plots. This study creates a richer understanding of the importance of tree context, specifically surrounding tree diversity, in shaping the ecological ramifications of a mass insect emergence event.
Urbanization and Landscape Heterogeneity Influence Culex Species Ecology and Genetics in Eastern North America
(2023) Arsenault-Benoit, Arielle L.; Fritz, Megan L.; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Vector-borne disease is an important facet of public health, as they account for nearly 20% of global disease burden. Multiple species, including at least one vector, at least one host, and a pathogen, must interact in vector-borne disease transmission cycles, and thus understanding human risk of vector-borne disease and public health outcomes requires a community ecology framework. Members of the Culex genus, including Cx. pipiens, Cx. quinquefasciatus, and Cx. restuans are sympatric in eastern North America and are vectors of West Nile virus. This dissertation explores the roles of habitat use, community ecology, phenology, and landscape heterogeneity on Culex spatiotemporal dynamics and genetics along urban to rural gradients in eastern North America. Through surveillance of belowground structures in Washington, D.C. over two years, I found that mosquito species of public health importance, including Aedes aegypti, Aedes albopictus, and members of the Culex pipiens assemblage, use these structures for breeding and development. Belowground structures may serve as refugia against extreme climatic conditions and facilitate overwintering survival for non-diapausing taxa and/or taxa with thermal tolerance limitations, potentially expanding their suitable ranges. On an urban to rural gradient in greater Washington, D.C. and Maryland, a complex of cryptic Culex WNv vectors co-occur on the landscape. Using molecular techniques and constrained ordination, I found that these cryptic Culex species were differently distributed at fine spatial scales, likely due to the impacts of urbanization on vector habitat and subsequent niche segregation. Culex pipiens were cosmopolitan and dominant across sites in greater Washington D.C. and Maryland. However, individuals with Cx. quinquefasciatus ancestry were limited to urban and peri-urban sites closest to the city center, and Cx. restuans were most abundant in rural and suburban sites furthest from the city center with dense and heterogeneous canopy cover. Previous work suggested that phenology has a considerable impact on Culex species dynamics; Cx. restuans was thought to be an early season species that cedes to Cx. pipiens over the course of the season. Initially, I did not detect an effect of season on Culex spatiotemporal dynamics when collections were undertaken from June through October, but when I expanded the collection season to include the months of April and May, the influence of season was evident. Therefore, the hallmark “crossing-over” point that is common in the Culex literature happens prior to the local mosquito abatement season in Washington and D.C. and Maryland. During the active surveillance and management period, season has little impact on Culex species abundance as compared to environmental factors measured along our urban to rural gradient. A replicated comparison of the abundance and relative frequency of Cx. pipiens and Cx. restuans along urbanization gradients in Washington D.C., greater Philadelphia, PA and greater Chicago, IL, using gradient forests demonstrated that phenology was consistently the most important predictor of the shift between a Cx. restuans-dominant community and a Cx. pipiens-dominant community. This crossing-over point trended later in the season with increasing latitude. Turnover in species abundance tended to occur at intermediate points along environmental gradients associated with urbanization, like percent impervious surface, percent tree cover, distance to city center, and vegetation index. Results of two analytical approaches (ordination and regression trees) and from three metropolitan areas support Cx. restuans as an early season species that is otherwise associated with sites with cooler temperatures, less impervious surface, more tree cover, a shallower water table, and increased distance from city center. Conversely, Cx. pipiens is more abundant than Cx. restuans in sites that are more characteristic of urbanization. Culex pipiens is globally ubiquitous and was common across site classes in the three localities in this study. This species comprises two bioforms, pipiens and molestus, which are characterized by divergent ecological, physiological, and behavioral traits. These bioforms can interbreed in the field and the lab. However, at all sites analyzed across three northeastern metropolitan areas, analysis of genotypes at a single neutral locus violated assumptions of Hardy Weinberg Equilibrium, suggesting that there is not unrestricted geneflow between bioforms across the landscape. The proportion of molestus alleles increased with increasing percent impervious surface and decreased vegetation, two environmental correlates of urbanization. Molestus alleles may confer an advantage in urban environments because they can leverage human infrastructure to overcome thermal limitations and persist in isolated belowground populations via autogeny and use of mammalian hosts. Overall, Culex WNv vectors are differentially distributed across urban to rural gradients in the northeastern United States. These aspects are influenced by a heterogeneous land use and landscape-level changes associated with urbanization. A clear understanding of vector life history, genetics, interspecies interactions, and distribution across the landscape can improve practitioners’ power and precision in predicting and managing vector borne disease transmission. While some patterns in species distribution and composition were universal across metropolitan areas, there was variation between localities that could significantly contribute to WNv transmission and human disease risk. Therefore, I conclude that modeling, as well as development of surveillance and management strategies for WNv vectors should be implemented locally to have the greatest impact on public health outcomes.
DEVELOPING A PERRENIAL LIVING MULCH SYSTEM FOR MANAGING PESTS AND AUGMENTING NATURAL BIOCONTROL IN MARYLAND CANTALOUPE SYSTEMS
(2022) Nunez, Demian Antonio; Hooks, Cerruti RR; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
This study investigated how alsike clover (Trifolium hybridum) and Virginia wildrye (Elymus virginicus), when interplanted as a living mulch with cantaloupe, (Cucumis melo var. cantalupensis) would impact herbivorous and beneficial arthropod numbers. An additional objective was to determine how these living mulches would impact fruit yield and quality. It was hypothesized that there would be a reduction of cantaloupe pest herbivores and increase in natural enemy abundances in the interplanting compared to monoculture cantaloupe system. Some arthropods conformed to these expectations. However, most had a neutral or inconsistent response to the living mulches. Striped cucumber beetles (Acalymma vitattum), a major pest, were unaffected by the living mulches on most sampling dates. During several periods in both study years, leaf piercing herbivores including aphids were found in greater numbers on cantaloupe interplanted with clover than wildrye and/or monoculture. Spiders were found in greater abundance in cantaloupe interplanted with clover than wildrye or monoculture plantings during several sampling periods. Other natural enemy guilds such as parasitic wasps and piercing predators were inconsistently influenced by living mulch types. Yield was highest in the monoculture plots and living mulch was correlated with changes in fruit texture and color.
A Survey of Bees in the University of Maryland Campus Area
(2021) Striegel, Theodore; Hawthorne, David; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
I sampled the wild bee community in the University of Maryland campus area in College Park, Maryland for one season and combined those data with that from previous years. The protocol was modified to significantly expand the geographic scope of the survey, covering a much wider spatial range of the campus. This combined data was used to assess population trends, best practices, and determine whether or not the expanded protocol offers advantages in capturing local wild bee diversity and/or analytical benefits over the previous survey. New data allowed for characterization of the local wild bee community and discerned a landscape driver of spatial variance in local diversity. Appropriateness of different geographic parameters was found to depend on survey goals.
Plant-insect interactions in a shifting coastal ecosystem: Avicennia germinans and its associated arthropods
(2020) Nathan, Mayda; Gruner, Daniel S; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
The climate’s role in determining where species occur is increasingly well understood, but our ability to predict how biotic interactions both influence and respond to species’ range shifts remains poor. This is particularly important when considering climate-change-driven range shifts in habitat-forming species like mangroves, given their impact on ecosystem structure and function. In this dissertation, I consider the arthropods associated with the black mangrove, Avicennia germinans, to explore whether patterns of arthropod diversity affect the rate of a plant’s range expansion, and, in turn, how a range-expanding plant alters arthropod communities in habitats where it is invading. Among arthropods with the potential to influence plants’ range dynamics, pollinators can directly affect plant reproduction and ability to spread into new territory. Breeding system experiments reveal that A. germinans relies on pollinators for full fruit set, and surveys along the Florida coast show a substantial northward decline in the overall frequency of pollinator visits to A. germinans flowers. However, the decline in abundance of some common pollinator taxa is partly offset by an increase in the frequency of other highly effective taxa. Furthermore, range-edge A. germinans produce more flowers than southern individuals, contributing to high range-edge fecundity and enabling range expansion. As a woody plant with nectar-producing flowers, A. germinans is a novel resource for arthropods in the salt marshes where it is encroaching. To understand arthropod community assembly on these frontier mangroves, and how mangrove presence affects marsh arthropod community composition, I compare arthropod communities in these adjacent vegetation types. Arthropods form distinct communities on mangroves and marsh vegetation, with at least one A. germinans specialist already present in this range-edge population. However, neither mangrove proximity nor the abundance of mangrove flowers appears to influence salt marsh arthropod community structure, indicating that mangrove encroachment may lead to a net increase in arthropod diversity in coastal regions by increasing habitat heterogeneity. In sum, plants that rely on pollinators can avoid range-edge reproductive failure by attracting a diverse group of pollinating taxa, and range-expanding plants can rapidly alter invaded communities by shaping diversity at very local scales.
LEAF-ASSOCIATED PERIPHYTON IN HETEROTROPHIC STREAMS: EFFECT ON MACROINVERTEBRATE ASSEMBLAGES AND GROWTH
(2020) Eckert, Rebecca A; Lamp, William O; Entomology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
Temperate headwater streams are often shaded, limiting autochthonous production, and therefore energetically supported by allochthonous material, e.g., leaves, via fungal and bacterial decomposition. Macroinvertebrate shredders feed on this leaf matrix, providing food for other organisms. Recent work indicates that periphyton (e.g., diatoms, green algae, cyanobacteria; hereafter, algae) interacts with microbial decomposers and provides higher quality food. Little work has, however, examined these interactions in natural settings. I investigated leaf-associated algae’s impact on macroinvertebrate leaf colonization in the field, followed by measuring growth and food preferences in the lab based on field results. First, I manipulated leaf light availability in high- and low-nutrient streams in winter and spring. Leaf-associated algal and fungal biomass were positively correlated in winter. Leaf C:N negatively correlated to algae in winter and fungi in spring, while N:P and C:P negatively correlated to fungi in winter and algae in spring. These factors predicted functional feeding guild biomass and abundance, e.g., predator biomass by algal and fungal biomass and spring shredder biomass by leaf stoichiometry. Algal biomass elicited differential taxon responses; e.g., Ephemerella (Ephemeroptera:Ephemerellidae) and Stenonema (Ephemeroptera:Heptageniidae) responded positively while Tipula (Diptera:Tipulidae) responded negatively. Second, I fed light- and dark-conditioned leaves to Ephemerella invaria and Caecidotea communis (Isopoda:Asellidae), which both consumed leaves and algae. C. communis experienced greater growth on light-conditioned leaves, indicating a high-quality resource, while E. invaria had no growth differences between treatments. Third, light- and dark-conditioned leaves were offered to five taxa, Amphinemura (Plecoptera:Nemouridae), Tipula, Stenonema, Lepidostoma (Trichoptera:Lepidostomatidae), and Caecidotea communis. Tipula alone demonstrated a preference which was for dark-conditioned leaves. These results indicate that leaf-associated algae are a food resource and attractant for some macroinvertebrates and a deterrent to others. Natural headwater streams are heterogeneous with leaves exposed to varying light levels, altering leaf-associated algae and providing differential food resources. Anthropogenic impacts often homogenize these streams. Although restoration seeks to restore heterogeneity, headwater stream algae are largely ignored. This work demonstrates the important role algae play in macroinvertebrate interactions with senescent leaves, highlighting the need to incorporate allochthonous and autochthonous resources into stream restoration and management efforts to support biodiversity.
Home sick: impacts of migratory beekeeping on honey bee (Apis mellifera) pests, pathogens, and colony size
(PeerJ, 2018-11-02) Alger, Samantha A.; Burnham, P. Alexander; Lamas, Zachary S.; Brody, Alison K.; Richardson, Leif L.
Honey bees are important pollinators of agricultural crops and the dramatic losses of honey bee colonies have risen to a level of international concern. Potential contributors to such losses include pesticide exposure, lack of floral resources and parasites and pathogens. The damaging effects of all of these may be exacerbated by apicultural practices. To meet the pollination demand of US crops, bees are transported to areas of high pollination demand throughout the year. Compared to stationary colonies, risk of parasitism and infectious disease may be greater for migratory bees than those that remain in a single location, although this has not been experimentally established. Here, we conducted a manipulative experiment to test whether viral pathogen and parasite loads increase as a result of colonies being transported for pollination of a major US crop, California almonds. We also tested if they subsequently transmit those diseases to stationary colonies upon return to their home apiaries. Colonies started with equivalent numbers of bees, however migratory colonies returned with fewer bees compared to stationary colonies and this difference remained one month later. Migratory colonies returned with higher black queen cell virus loads than stationary colonies, but loads were similar between groups one month later. Colonies exposed to migratory bees experienced a greater increase of deformed wing virus prevalence and load compared to the isolated group. The three groups had similar infestations of Varroa mites upon return of the migratory colonies. However, one month later, mite loads in migratory colonies were significantly lower compared to the other groups, possibly because of lower number of host bees. Our study demonstrates that migratory pollination practices has varying health effects for honey bee colonies. Further research is necessary to clarify how migratory pollination practices influence the disease dynamics of honey bee diseases we describe here.

Entomology

Browse

Filters

Settings

Sort By

Results per page

Search Results