Lack of host‐associated differentiation in <i>Ixodes scapularis</i> using population genetics

Entomologia Experimentalis et Applicata · 2024-12-10

Abstract The blacklegged tick, Ixodes scapularis (Say) (Acari: Ixodidae), is a vector of pathogens that cause diseases including anaplasmosis, babesiosis, and Lyme disease. It is a generalist vector feeding on a wide variety of vertebrate hosts. The transmission cycles of these pathogens are affected by the tick's host selection because host species differ in their ability to clear, maintain, or amplify these pathogens. Several generalist parasites exhibit host‐associated differentiation (HAD), a process that results in genetically distinct populations associated with different host species. Knowing whether I. scapularis exhibits HAD is important to better understand the ecology of these diseases. To test for HAD in I. scapularis , whole‐genome resequencing was performed on ticks collected directly from six hosts in the southern United States (i.e., cotton mice [Cricetidae: Peromyscus gossypinus Le Conte], opossum [Didelphidae: Didelphis virginiana Kerr], raccoon [Procyonidae: Procyon lotor L.], gray fox [Canidae: Urocyon cinereoargenteus Schreber], wild boar or feral hog [Suidae: Sus scrofa L.], and white‐tailed deer [Cervidae: Odocoileus virginianus Zimmermann]). For the hosts tested, HAD was not found. However, it could not be ruled out if HAD is occurring for ticks associated with lizards in this study. The results of this study contrast with findings from another host generalist, Dermacentor variabilis (Say), that does exhibit HAD. Our results suggest that these two tick species differ in their propensity for HAD. One explanation could be that I. scapularis can mate off‐host, maintaining panmixia, whereas D. variabilis mate only on the host. The lack of HAD in I. scapularis should be confirmed by sampling ticks from lizard and rodent hosts. These results will inform control efforts and the use of area‐wide tick control strategies.

Insect–microbe interactions and their influence on organisms and ecosystems

Ecology and Evolution · 2024-07-01 · 25 citations

Microorganisms are important associates of insect and arthropod species. Insect-associated microbes, including bacteria, fungi, and viruses, can drastically impact host physiology, ecology, and fitness, while many microbes still have no known role. Over the past decade, we have increased our knowledge of the taxonomic composition and functional roles of insect-associated microbiomes and viromes. There has been a more recent shift toward examining the complexity of microbial communities, including how they vary in response to different factors (e.g., host genome, microbial strain, environment, and time), and the consequences of this variation for the host and the wider ecological community. We provide an overview of insect-microbe interactions, the variety of associated microbial functions, and the evolutionary ecology of these relationships. We explore the influence of the environment and the interactive effects of insects and their microbiomes across trophic levels. Additionally, we discuss the potential for subsequent synergistic and reciprocal impacts on the associated microbiomes, ecological interactions, and communities. Lastly, we discuss some potential avenues for the future of insect-microbe interactions that include the modification of existing microbial symbionts as well as the construction of synthetic microbial communities.

How Homogenous is a Supercolony? High-Resolution Sequencing Revels Population Genetic Structure in the Introduced Range of Tawny Crazy Ant (Nylanderia fulva (Mayr): Hymenoptera: Formicidae)

Research Square · 2024-04-23

<title>Abstract</title> Background The tawny crazy ant (<italic>Nylanderia fulva</italic> (Mayr)) is native to South America and was first reported in the continental United States (US) in 1938. It was not until the 1990s in Florida and 2000s in Texas that this ant was considered a serious pest in the US. Tawny crazy ant (TCA) is currently considered an invasive pest in six US states. A limited number of low-density molecular markers have previously shown little genetic differentiation among <italic>Nylanderia fulva</italic> across their geographic distribution in the US. Results Using high-throughput sequencing we obtained high-density molecular markers, a total of 4,557 single nucleotide polymorphisms (SNPs), that provided increased resolution for detecting population genetic differences. There was genetic variation among tawny crazy ants in the US and Argentina. Additionally, there was substructure among some geographic locations in the US (i.e., Texas, Louisiana, Alabama, Mississippi, Georgia, and Florida). Samples from Colombia and Perú were genetically very distant from <italic>N. fulva</italic> in Argentina and US, and thus they are likely potential cryptic species or belong to another cryptic species complex. Conclusion There is genetic differentiation observed between and within tawny crazy ants in Argentina and the US as well as among tawny crazy ants in the US. Locations associated with port cities in the US are most closely related to ants from Buenos Aires, Argentina. The higher levels of differentiation among other locations and Buenos Aires may be the result of the introduction of an unidentified genotype, admixture, a sample size artifact, or a combination of these factors. Although these tawny crazy ants may act as a supercolony across wide geographic scales, our results support that <italic>N. fulva</italic> is structured into genetically differentiated populations.

Arthropod-microbe interactions and their influence on organisms and ecosystems

2024-07-30

Microorganisms are essential associates for virtually all arthropod species. Insect-associated microbes can improve the fitness of their host, be pathogens, or have no known role. During the past decade, we have increased our collective knowledge of the composition of insect-associated microbes along with the range of roles that these symbionts perform. Increases in knowledge are partly due to the continued advancements in genomic sequencing technologies. This understanding of individual microbe contributions and advancements in sequencing have allowed for a shift towards examining the complexity of microbial communities, as well as how these communities vary with different factors (e.g., microbe and/or host genetics, environment). We provide an overview of arthropod-symbiont interactions, the variety of symbiont functionalities, and the evolutionary ecology of these relationships. Additionally, we explored the influence of the environment on the modulation of insect-microbe interactions, the projected impacts of climate change, and the subsequent consequences on these ecological interactions. Lastly, we discuss some potential avenues for the future of arthropod-microbe interactions that include the modification of existing microbial symbionts as well as the construction of synthetic microbial communities. Our aim was to condense the current knowledge on insect-associated microbes and microbial communities while discussing research gaps and challenges for possible future directions.

Transcriptomic analysis of the honey bee (Apis mellifera) queen brain reveals that gene expression is affected by pesticide exposure during development

PLoS ONE · 2023-04-27 · 6 citations

Honey bees (Apis mellifera) play a pivotal role in agricultural production worldwide, primarily through the provision of pollination services. But despite their importance, honey bee health continues to be threatened by many factors, including parasitization by the mite Varroa destructor, poor queen quality, and pesticide exposure. Accumulation of pesticides in the hive's comb matrix over time inevitably leads to the exposure of developing brood, including queens, to wax contaminated with multiple compounds. Here, we characterized the brain transcriptome of queens that were reared in wax contaminated with pesticides commonly found in commercial beekeeping operations including either (a) a combination of 204,000 ppb of tau-fluvalinate and 91,900 ppb of coumaphos ("FC" group), (b) a combination of 9,800 ppb of chlorpyrifos and 53,700 ppb of chlorothalonil ("CC" group), or (c) 43,000 ppb of amitraz ("A" group). Control queens were reared in pesticide-free wax. Adult queens were allowed to mate naturally before being dissected. RNA isolated from brain tissue from three individuals per treatment group was sequenced using three technical replicates per queen. Using a cutoff log2 fold-change value of 1.5, we identified 247 differentially expressed genes (DEGs) in the FC group, 244 in the CC treatment group, and 668 in the A group, when comparing each group to the control. This is the first study to examine the sublethal effects of pesticides commonly found in wax (particularly amitraz) on the queen's brain transcriptome. Future studies should further explore the relationship between our molecular findings and the queen's behavior and physiology.

High-Resolution Population Genetic Structure of Tawny Crazy Ant (Nylanderia fulva Mayr: Hymenoptera: Formicidae) from the Origin in South America and Introduced Regions of the United States

Research Square · 2023-01-04 · 1 citations

<title>Abstract</title> Background The tawny crazy ant (<italic>Nylanderia fulva</italic> Mayr) is native to South America and was first reported in the continental United States (US) in 1938. It was not until the 1990s in Florida and 2000s in Texas that this ant was considered a serious pest in the US. Tawny crazy ant (TCA) is currently considered an invasive pest in six US states and this ant’s invasion success is attributed in part to a unicolonial nature, multiple queens per nest, natural enemies release in the invasive range, and ability to detoxify venom from other competitor ant species. A limited number of low-density molecular markers have previously shown little genetic differentiation among TCA populations across their geographic distribution in the US. Results Using High Throughput Sequencing (HTS) we obtained high-density molecular markers (i.e., SNPs) for TCA samples. With 26,657 SNPs we identified genetic variation among TCA populations in different states across the US (i.e., Texas, Louisiana, Alabama, Mississippi, Georgia, and Florida) and in South America (i.e., Argentina, Colombia, and Peru). Conclusion Our results underscore that for recently introduced invasive species, increasing the number of molecular markers used in population genetic studies can provide greater resolution. High-resolution information on regional genetic differences can help inform pest management strategies.

Oats

Elsevier eBooks · 2023-09-22 · 1 citations

Engineered and natural gene drives: mechanistically the same, yet not same in kind

Nature Communications · 2023-09-26

We propose the use of the terms natural gene drive (NGD) and engineered gene drive (EGD) arguing against James et al.1, who think both should be included within the term “gene drive”, based on their mechanistic similarities.

General science‐technology orientation, specific benefit–risk assessment frame, and public acceptance of gene drive biotechnology

Risk Analysis · 2023-10-26 · 4 citations

With limited understanding of most new biotechnologies, how do citizens form their opinion and what factors influence their attitudes about these innovations? In this study, we use gene drive biotechnology in agricultural pest management as an example and theoretically propose that given low levels of knowledge and awareness, citizens' acceptance of, or opposition to, gene drive is significantly shaped by two predisposition factors: individuals' general orientation toward science and technology, and their specific benefit-risk assessment frame. Empirically, we employ data collected from a recent US nationally representative public opinion survey (N = 1220) and conduct statistical analyses to test the hypotheses derived from our theoretical expectations. Our statistical analyses, based on various model specifications and controlling for individual-level covariates and state-fixed effects, show that citizens with a more favorable general orientation toward science and technology are more likely to accept gene drive. Our data analyses also demonstrate that citizens' specific gene drive assessment frame-consisting of a potential benefit dimension and a potential risk dimension, significantly shapes their attitudes as well-specifically, people emphasizing more on the benefit dimension are more likely to accept gene drive, whereas those who place more importance on the risk dimension tend to oppose it. We discuss contributions of our study and make suggestions for future research in the conclusion.