Biology subjects

Blagrove, M.

Publications and source records attributed to Blagrove, M..

3 recordsLinked to original sources

bioRxiv2026

Thermal fertility limits reveal underestimated climatic suitability for Aedes aegypti in temperate regions

Predicting species distributions under climate change typically relies on thermal limits for survival. However, recent evidence suggests that sublethal temperatures that reduce fertility can constrain distributions more strongly than temperatures causing mortality alone. Despite the importance of mosquitoes as vectors of human disease, thermal fertility limits remain largely uncharacterized in these insects. Here, we show that fertility in Aedes aegypti is highly sensitive to thermal stress and exhibits distinct sex-specific responses. Adult males were more vulnerable to both heat and cold exposure than females. At 38{degrees}C, survival remained high in both sexes despite significant reproductive impairment, indicating that sterility can occur independently of mortality. Similarly, exposure to 2{degrees}C induced male sterility whereas females maintained reproductive function. Morphological analyses of reproductive organs showed temperature-associated damage consistent with the observed fertility loss. Incorporating these fertility thresholds into ecological niche models generated different predictions of climatic suitability compared with models based solely on lethal temperature limits. Our findings demonstrate that sublethal effects on reproduction can substantially influence estimates of mosquito climatic suitability and highlight the importance of incorporating fertility based thermal limits into projections of vector distributions and disease risk under future climate change.

ecology↗

bioRxiv2025

Impact of temperature on vector competence of Culex pipiens molestus: implications for Usutu virus transmission in temperate regions

IntroductionUsutu virus (USUV) has been detected annually in the southeast of England since 2020. USUV RNA has been identified in wild birds and mosquito populations, and exposure of captive birds to USUV at Zoological Society of London (ZSL) has also been confirmed. Since its first detection in London, USUVs distribution has expanded across the South East, highlighting a need to understand the transmission dynamics of this virus in the UK. The primary vectors of USUV in the UK are likely Culex pipiens mosquitoes. Two biotypes have been identified, the bird-feeding Cx. pipiens pipiens and Cx. pipiens molestus which shows no restriction in host preference. The latter may play an important role in transmitting USUV from birds to humans. MethodsA laboratory colony of Cx. pipiens molestus mosquitoes were orally infected with the London strain of USUV and, incubated at 22 {degrees}C, 20 {degrees}C and 18{degrees} C for up to 28 days. Body samples and mosquito saliva samples were collected and analysed using a quantitative real-time reverse transcription PCR to determine infection and transmission potential, respectively. ResultsUSUV RNA was detected in all sample times at all temperatures assessed; with the highest temperature (22 {degrees}C) showing the greatest proportion of saliva and body positive samples. At this temperature, there was also an eight-fold increase in the relative viral copy number in the mosquito bodies, which was unobserved at other experimental temperatures. When a more sensitive PCR assay was used at the lowest experimental temperature used (18 {degrees}C) USUV RNA was present in the mosquito saliva and body samples for longer and showed a greater proportion of positive samples when compared to 20 {degrees}C. ConclusionThis study has demonstrated that Cx. pipiens molestus may be able to transmit USUV at 22 {degrees}C. Active replication of USUV was identified in the mosquito bodies at 22 {degrees}C but could not be demonstrated at lower temperatures, suggesting that 20 {degrees}C to 22 {degrees}C may be an important temperature threshold in USUV replication and transmission. Utilisation of a more sensitive assay for the lower experimental temperatures revealed that USUV was detectable at 18 {degrees}C. Therefore, when conducting infection studies on temperate mosquito-borne viruses, it is important to consider assay sensitivity.

molecular biology↗

bioRxiv2021

Immune priming can prevent WNV establishment in Culex quinquefasciatus mosquitoes: evidence for immune priming based reversal of WNV-mediated immune suppression.

Mosquito-borne infectious diseases cause wide-spread loss of life and livelihood often in low-income settings. However, control of mosquito-vectored viral diseases such as West Nile virus (WNV) and Japanese encephalitis virus (JEV) remains challenging. Here we use an existing feature of the insect immune system to effectively vaccinate Culex quinquefasciatus mosquitoes against WNV infection. We find that priming mosquitoes by exposure to inactivated WNV reduces their likelihood of developing transmissible infections of WNV after live infection. We used RNA sequencing to identify gene expression in response to WNV and JEV infection, and the role of prior priming exposure on constitutive and induced expression on infection. Infection with either Flavivirus causes broad suppression of gene expression. WNV and JEV infection resulted in suppression of different suites of genes with notable immune genes, such as antimicrobial peptides, being strongly suppressed on WNV infection. We hypothesise that the increased resistance to WNV infection seen in primed mosquitoes may be the result of priming nullifying the immune suppression found in non-primed WNV-fed mosquitoes, potentially through greater expression of mRNA regulatory genes such as cap-binding proteins in primed mosquitoes. Author summaryMosquitoes vector many devastating infectious diseases. Two such vectored viral diseases are West Nile virus (WNV) and Japanese encephalitis virus (JEV). Control of these diseases remains challenging, and no vaccine exists for WNV. Here, we tested whether we could instead vaccinate the mosquitoes against WNV. By injecting mosquitoes with dead WNV we found that we could reduce the number of infected mosquitoes by half. We then used whole-genome RNA sequencing to identify which genes are transcribed, which will help us understand genes that are important for this form of insect immune priming, and for responses to normal WNV and JEV infection. We found that WNV suppresses the expression of many immune genes but these genes are expressed normally in vaccinated mosquitoes. Our findings expand our understanding of mosquito infection with these viruses but also demonstrate how prior exposure to a disease can produce lasting protection.

genomics↗