- Award ID(s):
- 1754115
- PAR ID:
- 10232582
- Date Published:
- Journal Name:
- Parasites & Vectors
- Volume:
- 13
- Issue:
- 1
- ISSN:
- 1756-3305
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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ABSTRACT We examined how larvae of Culex restuans mosquito influences the bacterial abundance, composition and diversity in simulated container aquatic habitats. The microbiota of Cx. restuans larvae were also characterized and compared to those of their larval habitats. The presence of Cx. restuans larvae altered the bacterial community composition and reduced the bacterial abundance, diversity and richness. Azohydromonas sp., Delftia sp., Pseudomonas sp., Zooglea sp., unclassified Enterobacteriaceae and unclassified Bacteroidales were suppressed while Prosthecobacter sp., Hydrogenaphaga sp., Clostridium sp., unclassified Clostridiaceae and Chryseobacterium sp. were enhanced in the presence of Cx. restuans larvae. Cx. restuans larvae harbored distinct and less diverse bacterial community compared to their larval habitats. These findings demonstrate that Cx. restuans larvae play a key role in structuring the microbial communities in container aquatic habitats and may lower the nutritional quality and alter the decomposition process and food web dynamics in these aquatic systems. The findings also demonstrate that mosquito larvae are highly selective of the bacterial taxa from the larval environment that colonize their bodies. These findings provide new opportunities for more focused studies to identify the specific bacterial taxa that serve as food for mosquito larvae and those that could be harnessed for disease control.more » « less
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Abstract Background Culex mosquitoes are the primary vectors of West Nile virus (WNV) across the USA. Understanding when these vectors are active indicates times when WNV transmission can occur. This study determined the proportion of femaleCulex mosquitoes that were in diapause during the fall and winter and when they terminated diapause and began blood feeding in the spring.Methods Mosquitoes were collected from parks using various traps and/or aspirated from culverts in Franklin County, Ohio, from October to mid-May from 2019 to 2022.
Culex mosquitoes were morphologically identified to species, and the ovaries of females were dissected to determine their diapause and parity statuses.Results By early October 2021, roughly 95% of
Culex pipiens collected in culverts were in diapause and 98% ofCx. erraticus were in diapause. Furthermore, gravid and blood-fedCulex salinarius ,Cx. pipiens , andCx. restuans were collected in late November in 2019 and 2021 in standard mosquito traps. In the winter of 2021, the proportions of non-diapausingCulex decreased within culverts. The last non-diapausingCx. erraticus was collected in late December 2021 while the final non-diapausingCx. pipiens was collected in mid-January 2022, both in culverts. Roughly 50% ofCx. pipiens terminated diapause by mid-March 2022, further supported by our collections of gravid females in late March in all 3 years of mosquito collection. In fact, male mosquitoes ofCx. pipiens ,Cx. restuans , andCx. territans were collected by the 1st week of May in 2022, indicating that multiple species ofCulex produced a second generation that reached adulthood by this time.Conclusions We collected blood-fed and gravid
Culex females into late November in 2 of the 3 years of our collections, indicating that it might be possible for WNV transmission to occur in late fall in temperate climates like Ohio. The persistence of non-diapausingCx. pipiens andCx. erraticus throughout December has important implications for the winter survival of WNV vectors and our overall understanding of diapause. Finally, determining whenCulex terminate diapause in the spring may allow us to optimize mosquito management programs and reduce the spread of WNV before it is transmitted to humans.Graphical Abstract -
Abstract Background Mosquitoes in the genus
Culex are primary vectors in the US for West Nile virus (WNV) and other arboviruses. Climatic drivers such as temperature have differential effects on species-specific changes in mosquito range, distribution, and abundance, posing challenges for population modeling, disease forecasting, and subsequent public health decisions. Understanding these differences in underlying biological dynamics is crucial in the face of climate change.Methods We collected empirical data on thermal response for immature development rate, egg viability, oviposition, survival to adulthood, and adult lifespan for
Culex pipiens, Cx. quinquefasciatus, Cx. tarsalis , andCx. restuans from existing literature according to the PRISMA scoping review guidelines.Results We observed linear relationships with temperature for development rate and lifespan, and nonlinear relationships for survival and egg viability, with underlying variation between species. Optimal ranges and critical minima and maxima also appeared varied. To illustrate how model output can change with experimental input data from individual
Culex species, we applied a modified equation for temperature-dependent mosquito type reproduction number for endemic spread of WNV among mosquitoes and observed different effects.Conclusions Current models often input theoretical parameters estimated from a single vector species; we show the need to implement the real-world heterogeneity in thermal response between species and present a useful data resource for researchers working toward that goal.
Graphical Abstract -
Abstract Diapause is a hormonally driven response which is triggered by environmental cues that signal impending adverse conditions and prompts metabolic, developmental, and behavioral changes to allow survival until the return of favorable conditions. Microbial symbionts have been shown to influence the metabolism, development, and behavior of their host organisms, all of which are common diapause-associated characteristics. Surveys of bacterial components in relation to diapause have been examined in few systems, of which the species are usually inactive during dormancy, such as eggs or pupae. This is specifically intriguing as adult female diapause in Culex pipiens (Diptera: Culicidae) can last between 4 and 7 mo and females remain mobile within their hibernacula. Furthermore, it is unknown how microbiota changes associated with prolonged dormancy are different between the lab and field for insect systems. This study aims to characterize how the microbiota of C. pipiens changes throughout diapause under both field and lab settings when provided identical food and water resources. Based on these studies, C. pipiens microbiota shifts as diapause progresses and there are considerable differences between field and lab individuals even when provided the same carbohydrate and water sources. Specific bacterial communities have more association with different periods of diapause, field and lab rearing conditions, and nutritional reserve levels. These studies highlight that diapausing mosquito microbiota studies ideally should occur in field mesocosms and at multiple locations, to increase applicability to wild C. pipiens as prolonged exposure to artificial rearing conditions could impact metrics related to diapause-microbiome interactions. Additionally, these findings suggest that it would be worthwhile to establish if the microbiota shift during diapause impacts host physiology and whether this shift is critical to diapause success.
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Abstract Culex pipiens , the northern house mosquito, is a major vector of West Nile virus. To survive the severe winter, adult mosquitoes enter a diapause programme. Extended lifespan and an increase in lipid storage are key indicators of diapause. Post‐translational modifications to histone proteins impact the expression of genes and have been linked to the lifespan and energy utilisation of numerous insects. Here, we investigated the potential contribution of epigenetic alterations in initiating diapause in this mosquito species. Multiple sequence alignment of H3 sequences from other insect species demonstrates a high conservation of the H3 histone inCx. pipiens throughout evolution. We then compared the levels of histone methylation in the ovaries and fat body tissues of diapausing and non‐diapausingCx. pipiens using western blots. Our data indicate that histone methylation levels in the ovaries ofCx. pipiens do not change during diapause. In contrast, H3K27me2 levels decrease more than twofold in the fat body of diapausing mosquitoes relative to non‐diapausing counterparts. H3K27 methylation plays a crucial role in chromosome activation and inactivation during development in many insect species. This is predominantly governed by polycomb repressor complex 2. Intriguingly, a previous ChIP‐seq study demonstrated that the transcription factor FOXO (Forkhead box O) targets the genes that comprise this complex. In addition, H3K27me2 exhibits dynamic abundance throughout the diapause programme inCx. pipiens , suggesting its potential role in the initial activation of the diapause programme. This study expands our understanding of the relationship between alterations in epigenetic regulation and diapause.