Tag Archives: Wildlife

Phylogenetics of Dracunculus Nematodes in North America

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Madeline Giner, from the University of Texas at San Antonio, studied the phylogenetics of Dracunculus in the lab of Dr. Christopher Cleveland.

The Dracunculus genus contains parasitic nematodes that infect a variety of hosts, including reptiles and mammals. Dracunculus medinensis, the Guinea worm, has gained much attention due to its history of infecting humans. Less studied are other dracunculids, including Dracunculus insignis and D. lutrae which are native to North America. D. insignis can infect a variety of mammalian hosts, whereas D. lutrae specifically infects North American river otters (Lontra canadensis). The goal of this project was to investigate the genetic diversity of Dracunculus in wildlife species from the Eastern USA and investigate spatial and host patterns of infection. Phylogenetic relationships were examined using the cytochrome c oxidase I (COI) gene targets. We hypothesized otters would predominantly have D. lutrae, and D. insignis would be identified from other hosts. Our experimental methods included DNA extraction, gene-specific amplification (PCR), Sanger sequencing, and phylogenetic analysis using the software Geneious. Our results indicate that a majority of worms from otters (19/65), raccoons (Procyon lotor, 22/22), and Virginia opossums (Didelphis virginiana, 2/2) were D. insignis. However, a worm from an otter from Florida had 100% identity to a novel Dracunculus sp. previously detected in Georgia, and a Georgia otter worm is closely related to another novel dracunculid species from Florida. In conclusion, D. insignis was present in most locations and hosts, D. lutrae is absent, and an additional host is now known for two novel Dracunculus species. These data provide new information about Dracunculus diversity in US wildlife, but additional investigation is required.

GIner

What’s The Buzz Around Hydrogen Peroxide? An analysis of honey bee preference and mortality to differing hydrogen peroxide concentrations

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Carlos Martinez-Mejia from New York University worked with Dr. Lewis Bartlett.

Abstract Hydrogen peroxide has proven antimicrobial benefits and is created in honey when honeybees add glucose oxidase. This behavior makes honey bees another self-medicating animal and gives honey the longevity and antiseptic properties that we see. Hydrogen peroxide has been tested for toxicity in honeybees as well as parasites found in colonies. Honeybees have previously been seen to withstand higher concentrations of hydrogen peroxide than their insect counterparts. However, the exact toxicological limit of hydrogen peroxide that honeybees can withstand has not been officially established. Likewise, understanding if honeybees can identify these different concentrations and if this changes their preferences is still under investigation. Here we show that honeybees avoided hydrogen peroxide solutions in both sucrose and glucose when compared to the control sugar solution- differences in concentration and sugar were found to be significant in preference behavior. In addition, as hydrogen peroxide concentration increases- as does the proportional death of honey bees. At 4% H2O2 less than 40% of honey bees died. Knowing that hydrogen peroxide production for honey bees is a very metabolically taxing process- the hypothesis was that honey bees would rather have higher concentrations than go through the tiring process themselves. The results instead showed that on average honey bees avoided hydrogen peroxide when compared to the control sugar solution. Similarly, although honey bees have a higher tolerance toward hydrogen peroxide than other insects- 10% H2O2 was believed to be fully lethal but in some cases as many as 30% of honey bees survived at this dose. These results shed light on the relationship that honey bees have with hydrogen peroxide both regarding possible preference and toxicity threshold. We anticipate these trials to be a starting point for future pollinator health and pest control studies. Understanding the robustness of honey bees to such high concentrations of hydrogen peroxide opens the door for pesticide research that can effectively terminate pests while leaving the mass majority of honey bees unscathed.

Martinez_Mejia

Geographic variation of Wolbachia-induced cytoplasmic incompatibility in the fly Drosophila recens

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Sydney Keane, a Biology and Chemistry major from East Texas Baptist University, worked with Dr. Kelly Dyer examining the effects of infection on reproduction in Drosophila.

Abstract:  are bacterial parasites that commonly infect arthropods and nematodes. These parasites have damaging effects on the progeny of those they infect, including cytoplasmic incompatibility (CI). CI occurs when an infected male and an uninfected female mate, resulting in fewer eggs that successfully hatch into larvae than normal. In this study, infected virgin males from Drosophila recens were collected from multiple strains across three locations, and coupled with uninfected virgin females from the same species. After allowing the females to lay eggs for 72 hours, I recorded the numbers of eggs that hatched and that did not hatch. Males were tested for Wolbachia infection using PCR. After analyzing the data, I found that the overall hatch rate in each location was low, the amount of CI in each location did not vary significantly, the amount of CI in the experimental group compared to the control was significantly high, and that the number of total eggs produced varied significantly between the locations. The overall percentage of CI found within all of the locations examined was approximately 72%. These results show that the presence of Wolbachia is similarly effecting various populations of the fly throughout North America and that the level of CI occurring within this species may cause a drastic decrease in the population size over time.

 

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Modeling Chagas disease vector infection prevalence: incorporating life history characteristics and community composition

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Authors: Carolina Cabrera, Nicole L. Gottdenker

Abstract Multihost vector-borne pathogens play an important role in human and veterinary public health worldwide, and understanding factors that drive their transmission is critical to the development of vector-borne disease prevention and control. Two potentially important drivers of multihost vector-born pathogen transmission are 1) the community composition of reservoir host species that come in contact with the vector in a particular habitat, and 2) the life history characteristics of reservoir hosts. One of the most important multihost vector-borne pathogens in the Americas, infecting over 10 million people, is the protozoan parasite Trypanosoma cruzi, the cause of Chagas disease in humans. T. cruzi circulates between wild and domestic animal reservoirs and humans, and is transmitted by a triatomine vector. The objective of this study is to develop a mathematical model that attempts to incorporate biological realities of Trypanosoma cruzi transmission between reservoir hosts and a triatomine vector. Specifically, we evaluate the Chagas disease system in Panama, consisting of a wide range of mammalian reservoir hosts and the main vector Rhodnius pallescens. We link a deterministic SI model for pathogen transmission in the vector with an SI model that describes host community transmission, incorporating host community structure and host life history characteristics, as well as hosts that have been previously infected with T. cruzi, but have developed partial immunity and are less competent reservoirs. Using field and molecular blood meal data, and values from the literature, we calculate a reservoir potential index for the different habitats within this Chagas disease system and evaluate the degree to which changes in reservoir community structure and life history characteristics impact vector infection prevalence.

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