Scholarly Works, Entomology

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The Species-Specific Inversion Polymorphism of the X Chromosome in Anopheles messeae and Anopheles daciae Is Based on the Common Ancestral Variant X1
Soboleva, Evgeniya S.; Sharakhova, Maria V.; Sharakhov, Igor V.; Artemov, Gleb N. (MDPI, 2025-12-19)
Background/Objectives: Chromosomal inversions play an important role in the evolution of insects by forming genetic barriers between closely related species and facilitating local adaptation. Polymorphic inversions in malaria mosquitoes of the Maculipennis subgroup have been studied for over 50 years, yet the evolutionary ancestry of the gene orders remains unknown. In this study, we mapped the genes flanking the breakpoints of two polymorphic X-chromosome inversions in the cryptic species Anopheles messeae and Anopheles daciae of the Maculipennis subgroup. Methods: We used an iterative mapping approach to define the breakpoint regions, selecting flanking markers based on the genome assembly of the reference species, Anopheles atroparvus. To identify the ancestral X chromosomal arrangement in An. messeae and An. daciae, we developed and implemented the genomic inversion calculator (GIC), which uses greedy heuristics to determine the shortest evolutionary scenario of rearrangements. Results: Our knowledge of the relative genomic positions of the inversion breakpoints in An. daciae and An. messeae enabled us to use the An. atroparvus genome as an outgroup and the GIC tool to show that the X0 and X2 arrangements emerged independently along the evolutionary lineages of An. daciae and An. messeae, respectively, based on the X1 arrangement. Conclusions: These results refine the structure and boundaries of the X chromosome rearrangements and reconstruct the sequence of evolutionary events in the cryptic complex An. messeae–An. daciae, demonstrating that the X1 arrangement is ancestral. This study lays the groundwork for analyzing the molecular organization of breakpoints, the mechanisms of inversion formation, and their role in speciation.
Evaluation of selected foliar insectcides against stink bugs in edamame, 2022
Bradley, Sierra E.; Sutton, Kemper L.; Doughty, Helene; Zhang, Bo; McIntyre, Kelly; Kuhar, Thomas P. (Oxford University Press, 2023-01-01)
Membrane-localized MET engages PVR to mediate extranuclear juvenile hormone signaling in Aedes aegypti
Zhao, Wenhao; Griffith, Katara; Liang, Jiangtao; Dorodnitsyna, Maria; Liu, Pengcheng; Saunders, Thomas R.; Zhu, Jinsong (Proceedings of the National Academy of Sciences, 2025-11-18)
Although Methoprene-tolerant (MET) is well established as the intracellular receptor mediating the genomic actions of juvenile hormone (JH) in insects, the identity of the receptor responsible for initiating extranuclear JH responses has remained elusive. In the yellow fever mosquito Aedes aegypti, we identify the platelet-derived growth factor- and vascular endothelial growth factor-receptor related (PVR) protein as a key mediator of membrane-initiated JH signaling. JH treatment induces robust PVR phosphorylation in the fat body of adult female mosquitoes. Disruption of PVR function suppresses JH-induced activation of the phospholipase C and phosphatidylinositol 3-kinase signaling pathways and impairs primary follicle growth during the previtellogenic stage. Strikingly, JH-induced PVR phosphorylation and downstream signaling require MET, specifically its ligand-binding activity, but not its DNA-binding domain. A subpopulation of MET localizes to the plasma membrane of fat body cells, where it physically interacts with PVR between 24 h postemergence and 24 h post–blood feeding, suggesting that membrane-localized MET functions as the extranuclear JH receptor. Transcriptomic analyses following RNA interference (RNAi)-mediated knockdown of Met or Pvr demonstrate that PVR broadly contributes to JH-regulated gene expression. Notably, PVR-dependent signaling modulates genes that are also regulated by nuclear MET and enables JH to regulate additional gene sets independently of MET-mediated transcriptional regulation. These findings uncover a previously unrecognized MET–PVR signaling axis and support an integrated model of JH action in which membrane and nuclear pathways cooperate to enhance the specificity and complexity of JH function during the previtellogenic phase in mosquitoes.
Contrasting La Crosse Virus Lineage III Vector Competency in Two Geographical Populations of Aedes triseriatus and Aedes albopictus Mosquitoes
Faw, Lindsey R.; Armstrong, Philip M.; Paulson, Sally L.; Eastwood, Gillian (MDPI, 2025-12-11)
La Crosse virus (LACV) is a mosquito-borne virus (family Peribunyaviridae) that can result in severe human infection in children under sixteen. Historically, LACV comprised two lineages, predominantly in the Midwest and Appalachian regions of the US. In 2005, a virus of a third lineage was detected in the Northeast; however, this and subsequently isolated strains of lineage III have not, to date, been implicated in human disease. One hypothesis for this discrepancy is that vector mosquitoes have a reduced vector competency for LACV lineage III, thus preventing horizontal transmission and clinical cases. Here, we utilized two mosquito species, Aedes triseriatus, the native vector, and Aedes albopictus, an invasive potential vector, each from both a historic LACV range (Virginia) and from the region of lineage III (Connecticut). Utilizing oral feeding and intrathoracic inoculation methods of viral exposure, rates of LACV infection, dissemination, and transmission (proxied via salivary secretion) and capability for vertical transmission (proxied via virus-positive ovaries) were determined by harvesting mosquito bodies, legs, saliva, and ovaries, respectively. Overall, we did not detect consistent differences in transmission between any lineage, species, or state of origin, at day 14 post-infection. However, we highlight the transmission potential of LACV lineage III in all mosquito populations tested here, representing the first evidence of lineage III competency in Aedes triseriatus and Aedes albopictus, indicating the potential for human disease. We thus suggest that the absence of human cases of LACV lineage III is not modulated by a lack of vector competency in mosquitoes.
No detectable effect of urbanization on genetic drift or gene flow in specialist herbivorous insects of milkweed
Miles, Lindsay S.; Carlen, Elizabeth J.; Nassrullah, Zain; Munshi-South, Jason; Johnson, Marc T. J. (Public Library of Science, 2025-02-14)
Urbanization is hypothesized to isolate populations and restrict dispersal, leading to reduced genetic diversity and increased genetic differentiation. We tested this hypothesis in specialist herbivorous insects of milkweed, positing that higher dispersal ability would mitigate the negative effects of urbanization on genetic drift and gene flow, and that these effects would vary with city size. In this study, we collected 383 milkweed insects from urban and rural sites in Toronto, Canada, and five surrounding cities. Using ddRADseq, we generated 145,000 SPNs for monarchs, 10,000 SNPs for beetles, 6,000 SNPs for weevils to quantify genetic diversity, demographic history and population genetic structure. Contrary to our hypotheses, our results indicated no effect of urbanization or dispersal ability on diversity or genetic differentiation. Genetic diversity, measured as π, varied between 0.0013 and 0.0044 across species, with no urban vs. rural component, but with monarchs having >2 X higher diversity compared to beetles and weevils. Similarly, genetic differentiation was generally low, FST varying between 0.01 and 0.28, but there are no consistent trends among urban vs. rural samples for any of the three species. However, demographic analyses revealed a consistent decline in effective population size for all three sampled species, beginning around the last glacial maximum and intensifying over the past 1,000 years. Our findings suggest that both urbanization and dispersal ability have not been a major factor in reducing gene flow or increasing genetic drift among milkweed’s herbivorous insect populations. Instead, historical events such as climatic change since the last glacial maximum, and large-scale anthropogenic disturbance in general, have had a more pronounced impact on demography. These results highlight the importance of considering the combined effects of natural and anthropogenic long-term historical processes when studying population genetics in the context of urbanization.
Habitat Mosaic Limits Gene Flow and Promotes Morphological Adaptation in a Generalist Mammal
Booth, Warren; Montgomery, W. Ian; Miles, Lindsay S.; Montgomery, Stephen H.; Harrod, Chris; Schunke, Anja; Prodöhl, Paulo A. (Wiley, 2025-12-01)
Many habitat generalist species exploit habitat patches of differing types and quality, yet the influence of such habitat mosaics on genetic structure remains poorly understood. Here, we tested whether fine-scale habitat heterogeneity affects the population structure of the European wood mouse (Apodemus sylvaticus) by sampling three matched forest parks in Northern Ireland across hedgerow, forest edge, and inner forest habitats. Microsatellite analysis revealed strong genetic differentiation among sites and consistent divergence between habitat types within sites. Stable isotope data showed that hedgerow mice fed at a higher trophic level than inner forest individuals, with forest edge mice intermediate. Mandible shape also differed by habitat and was correlated with δ¹⁵N, though differences were subtle and may reflect both drift and plasticity. Together, these results indicate that habitat mosaics can promote repeated, fine-scale population divergence even in the absence of physical barriers. This highlights the role of ecological heterogeneity in structuring genetic variation in widespread generalists and cautions against assuming panmixia in continuous landscapes.
Efficacy of In-Furrow Insecticides For Control of Seedcorn Maggot in Fava Bean in Virginia, 2024
Rivera, David; Del Pozo-Valdivia, Alejandro; Kuhar, Thomas P. (Oxford University Press, 2025-01-20)
Evaluation of insecticide efficacy against diamondback moth and other lepidopteran pests in collards in Virginia, 2025
Sydnor, Taylore; Del Pozo-Valdivia, Alejandro; Kuhar, Thomas P. (Oxford University Press, 2025-01-20)
Efficacy of insecticides for control of corn earworm in sweet corn, Virginia, 2024
Long, William; Currin, Brian; Kuhar, Thomas P. (Oxford University Press, 2025-01-20)
Evaluation of insecticides for the control of wireworms and white grubs in sweetpotato, 2024
Swarm, Hannah; Kuhar, Thomas P. (Oxford University Press, 2025-01-20)
Linking crop history to Melanotus communis (Coleoptera: Elateridae) abundance in North Carolina and Virginia agroecosystems
Schoeppner, Emma; Kuhar, Thomas P.; Doughty, Hélène; Williams, Livy III; Millar, Jocelyn G.; Huseth, Anders (Oxford University Press, 2025-12)
Melanotus communis Gyllenhal (Coleoptera: Elateridae) is a significant wireworm pest of potato and sweetpotato in the southeastern United States. However, the impact of habitat proximity to surrounding crop fields on M. communis abundance remains unclear in this system. More refined risk assessment models to forecast populations as they relate to land use will aid in determining where fields are most vulnerable to damage, enabling more precise management interventions. Between 2022 and 2024, traps baited with M. communis sex pheromone were used to monitor adult male activity for ∼10 wk across 41 locations in North Carolina and Virginia. We combined trap data with remotely sensed land use data to correlate M. communis adult activity to surrounding habitats. The dependent variable used in models was overall mean abundance per location. Abundance was positively associated with the average proportional area of corn over 5 yr. These results are consistent with prior field-scale studies that showed that corn is a preferred host. Model estimates were expanded to understand the frequency of corn surrounding 2,884 potato or sweetpotato fields in 2024. Results showed clear spatial structuring of potato or sweetpotato fields that include corn as an abundant land use type over the prior 5 yr. This study provides a methods framework for expanding traditional landscape studies to communicate infestation risk over broad regions.
Chromosomal inversions and their potential impact on the evolution of arboviral vector Aedes aegypti
Liang, Jiangtao; Rose, Noah; Brusentsov, Ilya; Lukyanchikova, Varvara; Karagodin, Dmitriy; Feng, Yifan; Yurchenko, Andrey; Sharakhov, Igor V.; McBride, Carolyn; Sharakhova, Maria V. (Oxford University Press, 2024-06-29)
Chromosomal inversions play a crucial role in evolution and have been found to regulate epidemiologically significant traits in malaria mosquitoes. However, they have not been characterized in Aedes aegypti, the primary vector of arboviruses, due to the poor structure of its polytene chromosomes. The Hi-C proximity ligation approach was used to identify chromosomal inversions in 25 strains of A. aegypti obtained from its worldwide distribution and in one strain of Aedes mascarensis. The study identified 21 multimegabase polymorphic inversions ranging in size from 5 to 55 Mbp. Inversions were more abundant in African than in non-African strains, 15 versus 3 inversions, with the highest number observed in West Africa. All inversions were grouped into two geographic clusters of African or non-African origin, suggesting their association with A. aegypti subspecies. Inversions were unevenly distributed along chromosomal arms, with the highest number found in the 1q and 3p arms homologous to the inversion-rich 2R chromosomal arm in the malaria vector Anopheles gambiae. Direct comparison of inversions between A. aegypti and An. gambiae revealed significant overlap in their genomic locations. This finding may explain the parallel evolution of the two species under similar environmental conditions. Some of the inversions colocalized with chemoreceptor genes and quantitative trait loci associated with pathogen infection, suggesting their potential role in host preference and disease transmission. Our study revealed the large pool of structural variations in the A. aegypti genome and provides the foundation for future studies of their impact on the biology of this important arboviral vector.
Mosquito midgut stem cell cellular defense response limits Plasmodium parasite infection
Barletta, Ana-Beatriz F.; Smith, Jamie C.; Burkart, Emily; Bondarenko, Simon; Sharakhov, Igor V.; Criscione, Frank; O'Brochta, David; Barillas-Mury, Carolina (Nature Portfolio, 2024-02-16)
A novel cellular response of midgut progenitors (stem cells and enteroblasts) to Plasmodium berghei infection was investigated in Anopheles stephensi. The presence of developing oocysts triggers proliferation of midgut progenitors that is modulated by the Jak/STAT pathway and is proportional to the number of oocysts on individual midguts. The percentage of parasites in direct contact with enteroblasts increases over time, as progenitors proliferate. Silencing components of key signaling pathways through RNA interference (RNAi) that enhance proliferation of progenitor cells significantly decreased oocyst numbers, while limiting proliferation of progenitors increased oocyst survival. Live imaging revealed that enteroblasts interact directly with oocysts and eliminate them. Midgut progenitors sense the presence of Plasmodium oocysts and mount a cellular defense response that involves extensive proliferation and tissue remodeling, followed by oocysts lysis and phagocytosis of parasite remnants by enteroblasts.
Chromosomal inversions and their impact on insect evolution
Sharakhov, Igor V.; Sharakhova, Maria V. (Elsevier, 2024-12)
Insects can adapt quickly and effectively to rapid environmental change and maintain long-term adaptations, but the genetic mechanisms underlying this response are not fully understood. In this review, we summarize studies on the potential impact of chromosomal inversion polymorphisms on insect evolution at different spatial and temporal scales, ranging from long-term evolutionary stability to rapid emergence in response to emerging biotic and abiotic factors. The study of inversions has recently been advanced by comparative, population, and 3D genomics methods. The impact of inversions on insect genome evolution can be profound, including increased gene order rearrangements on sex chromosomes, accumulation of transposable elements, and facilitation of genome divergence. Understanding these processes provides critical insights into the evolutionary mechanisms shaping insect diversity.
Chromatin landscape, transcriptomic and ChIP-seq profiling of Anopheles stephensi MSQ43 cell line
Lukyanchikova, Varvara; Nuriddinov, Miroslav; Khabarova, Anna; Gridina, Maria; Popov, Andrey; Belokopytova, Polina; Sharakhov, Igor V.; Fishman, Veniamin (Springer, 2025-12-01)
Anopheles mosquitoes are known as dominant vectors of malaria parasites and other viral and bacterial pathogens. Deciphering Anopheles genomes has opened a new era of research and allowed in-depth investigation of several molecular mechanisms involved in pathogen transmission. However, there is a lack of appropriate model systems to study specific vector-pathogen interactions at the molecular level. Even inbred mosquito colonies represent genetically heterogeneous population and require special care facilities. Insect cell cultures could serve as a useful alternative due to the ease of handling and maintenance, especially for genomic studies requiring millions of cells per experiment. Here, we provide chromatin contact maps and a dataset of epigenetic characteristics, including histone mark profiles and RNA-seq data, as well as transfection conditions and promoter specificity for the mosquito cell line MSQ43.
Protocol for Hi-C-based identification of chromosomal inversions in mosquitoes
Lukyanchikova, Varvara; Brusentsov, Ilya I.; Karagodin, Dmitry A.; Sharakhova, Maria V.; Sharakhov, Igor V. (Elsevier, 2025-12-19)
Chromosomal inversions play an important role in the genomic evolution and adaptation of mosquito species. Here, we present a protocol for detecting chromosomal inversions in mosquitoes using Hi-C technology and chromatin contact heatmaps. We describe the steps for Hi-C library preparation using the Hi-C Arima+ kit, along with the Arima Library Prep Module, and provide several adaptations for mosquito samples. We then outline procedures for Hi-C data analysis, Hi-C heatmap generation, and the identification of polymorphic and fixed inversions. For additional details on the use and execution of this protocol, please refer to Lukyanchikova et al.¹
Analysis of somatic piRNAs in the malaria mosquito Anopheles coluzzii reveals atypical classes of genic small RNAs
Funikov, Sergei; Rezvykh, Alexander; Akulenko, Natalia; Liang, Jiangtao; Sharakhov, Igor V.; Kalmykova, Alla (Taylor & Francis, 2025-12-31)
Piwi-interacting small RNAs (piRNA) play a key role in controlling the activity of transposable elements (TEs) in the animal germline. In diverse arthropod species, including the pathogen vectors mosquitoes, the piRNA pathway is also active in nongonadal somatic tissues, where its targets and functions are less clear. Here, we studied the features of small RNA production in head and thorax tissues of an uninfected laboratory strain of Anopheles coluzzii focusing on the 24–32-nt-long RNAs. Small RNAs derived from repetitive elements constitute a minor fraction while most small RNAs process from long noncoding RNAs (lncRNAs) and protein-coding gene mRNAs. The majority of small RNAs derived from repetitive elements and lncRNAs exhibited typical piRNAs features. By contrast, majority of protein-coding gene-derived 24–32 nt small RNAs lack the hallmarks of piRNAs and have signatures of nontemplated 3' end tailing. Most of the atypical small RNAs exhibit female-biased expression and originate from mitochondrial and nuclear genes involved in energy metabolism. We also identified atypical genic small RNAs in Anopheles gambiae somatic tissues, which further validates the noncanonical mechanism of their production. We discuss a novel mechanism of small RNA production in mosquito somatic tissues and the possible functional significance of genic small RNAs.
Molecular evidence of pathogens and endosymbionts in the black horse fly Osca lata (Diptera: Tabanidae) in Southern Chile
Gonzalez, Christian R.; Reyes, Carolina; Castillo, Andres; Valderrama, Lara; Llanos, Lorena; Fernandez, Jorge; Eastwood, Gillian; Cancino-Faure, Beatriz (PLOS, 2024-09)
Little is known about the role of horse flies in potential pathogen transmission in Chile. This study provides evidence of the molecular detection of microorganisms in southern Chile. In the present study, adult Osca lata horse flies were trapped from Punucapa (39˚45’06”S/73˚ 16’08”W, Región de Los Ríos) and Puyehue (40˚39’10”S/72˚10’57”W, Región de Los Lagos), Chile. Among the 95 samples analyzed by PCR using specific primers, microorganisms were detected in 23.2% (n = 22) of the samples. Rickettsia spp. DNA was detected in 15.8% (n = 15) of the samples, Trypanosomatidae DNA in 5.3% (n = 5) of the samples, and filarial DNA in 2.1% (n = 2) of the samples. This study found that horse flies in the region are capable of carrying a variety of both parasites and endosymbionts. Further research is needed to understand the specific impact of horse flies as mechanical or biological vectors and develop effective control measures to prevent the spread of any microorganisms associated with disease.
Multiple Introductions of the Asian Longhorned Tick (Haemaphysalis longicornis) to the United States Revealed Using Mitogenomics
Narvaez, Zoe E.; Egizi, Andrea M.; Yabsley, Michael J.; Thompson, Alec T.; Moustafa, Mohamed; Alt, Erika; Bickerton, Matthew; Bjorgo, Kim; Butler, Rebecca A.; Cumbie, Alexandra; Eastwood, Gillian; Falco, Richard C.; Fonseca, Dina M.; Hang, Jun; Harper, Vanessa L.; Lewis, Nicole; Lovy, Jan; Maestas, Lauren P.; Mather, Thomas N.; Nakao, Ryo; Occi, James L.; Rainey, Tadhgh; Sal, Melanie; Stoops, Craig A.; Trout-Fryxell, Rebecca T.; Watson, Wes; Wagner, Nicole E.; Zheng, Aihua; Saelao, Perot; Price, Dana C. (Wiley, 2025-04)
The Asian longhorned tick (ALT), Haemaphysalis longicornis, is a three-host hard tick native to East Asia. Its opportunistic feeding habits make it an acute agricultural and medical threat, capable of spreading various zoonotic pathogens. An affinity for livestock and companion animals has allowed parthenogenetic populations of ALT to travel to and establish in overseas locations including the United States. To better understand the population dynamics of this rapidly expanding species, we sequenced the complete mitogenome of specimens collected from native and invasive ranges and performed phylogeographic analyses. As well as illustrating the diversity of Australasian and US ALT haplotypes, these methods have allowed us to estimate the source and frequency of successful introductions to the US. We highlight four potential introductions of parthenogenetic ALT, with likely origin populations identified in the Republic of Korea and Japan. These findings provide insight into potential routes of entry for ALT and other invasive tick species.
Inter-epidemic seroprevalence of Rift Valley fever virus and associated risk factors in humans in Eastern Rwanda
Nsengimana, Isidore; Kelvin, David; Uwibambe, Evodie; Rwagasore, Edson; Muvunyi, Claude M.; Eastwood, Gillian; Chengula, Augustino A.; Kasanga, Christopher J. (Public Library of Science, 2025-08-01)
Background: Rift Valley fever (RVF) is a mosquito-borne zoonosis that causes periodic and explosive epizootics/epidemics in Africa and the Arabian Peninsula. In Rwanda, RVF virus (RVFV) circulation has resulted into two major outbreaks in 2018 and 2022, both of which involving humans. Information on the magnitude of human exposure to RVFV in the country is scarce. This cross-sectional study aimed to investigate the seroprevalence of RVFV and associated risk factors in humans in the Eastern province of Rwanda, 3 years after the end of the 2018 outbreak. Methodology: A total of 552 outpatients at health facilities in five districts of the Eastern province were randomly sampled and interviewed between December 2021 and February 2022. Exposure to RVFV was examined by detection of anti-RVFV IgG/IgM antibodies in serum samples using a competitive enzyme linked immunosorbent assay (c-ELISA). Bivariate and multivariate logistic regressions were used to assess the association between risk factors and RVFV seropositivity. Results: The findings revealed an overall seroprevalence of 9.6%. The highest seropositivity, but without significant difference, was observed in Bugesera district (12.9%), followed by Kayonza, (10.8%), Kirehe (8.6%), Rwamagana (7.0%) and Ngoma (6.8%). Odds of seropositivity were significantly higher in people with a history of slaughtering animals (OR 2.26, 95% CI 1.04-4.91, p=0.03), and milking (OR 2.60, 95% CI 1.23-5.49, p=0.012). Sex and age-related differences were not significant. Conclusion: This study is a first serological survey of RVFV spillover to humans in the country and shows that rural communities in Rwanda have been exposed to RVFV. These findings suggest the Eastern province of Rwanda as a potential hotspot for RVFV circulation, and emphasize the need for a countrywide One Health-based surveillance, prevention, and control strategy to minimize the effects of RVFV in the country.

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