Females of the Northern house mosquito, Culex pipiens, enter an overwintering dormancy, or diapause, in response to short day lengths and low environmental temperatures. Diapausing female mosquitoes feed exclusively on sugar-rich products rather than human or animal blood, thereby reducing disease transmission. During diapause, Major Royal Jelly Protein 1 (MRJP1) is upregulated in females of Cx. pipiens. This protein is highly abundant in royal jelly, a substance produced by honey bees (Apis mellifera), that is fed to future queens throughout larval development and stimulates longevity and fecundity. However, the role of MRJP1 in Cx. pipiens is unknown. We investigated how supplementing the diets of both diapausing and nondiapausing females of Cx. pipiens with royal jelly affects gene expression, egg follicle length, fat content, protein content, longevity, and metabolic profile. We found that feeding royal jelly to long day-reared females significantly reduced the egg follicle lengths of females and switched their metabolic profiles to be similar to diapausing females. In contrast, feeding royal jelly to short day-reared females significantly reduced lifespan and switched their metabolic profile to be similar nondiapausing mosquitoes. Moreover, RNAi directed against MRJPI significantly increased egg follicle length of short day-reared females, suggesting that these females averted diapause, although RNAi against MRJP1 also extended the lifespan of short day-reared females. Taken together, our data show that consuming royal jelly reverses the seasonal responses of Cx. pipiens and that these responses are likely mediated in part by MRJP1.
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Light Pollution Disrupts Seasonal Differences in the Daily Activity and Metabolic Profiles of the Northern House Mosquito, Culex pipiens
The Northern house mosquito transmits West Nile virus and survives the winter by entering a state of dormancy called diapause. Light pollution has been shown to interfere with diapause initiation in this mosquito. The effects of light pollution on daily activity rhythms and metabolic products have not been thoroughly investigated in diapausing and non-diapausing Northern house mosquitoes. We found that light pollution affected mosquito activity levels and several metabolic products differently depending on photoperiod, indicating that light pollution may disrupt nutrient accumulation and possibly interfere with diapause initiation in this species.
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- Award ID(s):
- 1944324
- PAR ID:
- 10422853
- Date Published:
- Journal Name:
- Insects
- ISSN:
- 2075-4450
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Cities are generally hotter than surrounding rural areas due to the Urban Heat Island (UHI) effect. These increases in temperature advance plant and animal phenology, development, and reproduction in the spring. However, research determining how increased temperatures affect the seasonal physiology of animals in the fall has been limited. The Northern house mosquito, Culex pipiens, is abundant in cities and transmits several pathogens including West Nile virus. Females of this species enter a state of developmental arrest, or reproductive diapause, in response to short days and low temperatures during autumn. Diapausing females halt reproduction and blood-feeding, and instead accumulate fat and seek sheltered overwintering sites. We found that exposure to increased temperatures in the lab that mimic the UHI effect induced ovarian development and blood-feeding, and that females exposed to these temperatures were as fecund as non-diapausing mosquitoes. We also found that females exposed to higher temperatures had lower survival rates in winter-like conditions, despite having accumulated equivalent lipid reserves relative to their diapausing congeners. These data suggest that urban warming may inhibit diapause initiation in the autumn, thereby extending the active biting season of temperate mosquitoes.more » « less
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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. pipiensthroughout evolution. We then compared the levels of histone methylation in the ovaries and fat body tissues of diapausing and non‐diapausingCx. pipiensusing western blots. Our data indicate that histone methylation levels in the ovaries ofCx. pipiensdo 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.more » « less
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Consuming royal jelly alters several phenotypes associated with overwintering dormancy in mosquitoesIntroductionFemales of the Northern house mosquito,Culex pipiens, enter an overwintering dormancy, or diapause, in response to short day lengths and low environmental temperatures that is characterized by small egg follicles and high starvation resistance. During diapause,Culex pipiensMajor Royal Jelly Protein 1 ortholog (CpMRJP1) is upregulated in females ofCx. pipiens. This protein is highly abundant in royal jelly, a substance produced by honey bees (Apis mellifera), that is fed to future queens throughout larval development and induces the queen phenotype (e.g., high reproductive activity and longer lifespan). However, the role of CpMRJP1 inCx. pipiensis unknown. MethodsWe first conducted a phylogenetic analysis to determine how the sequence of CpMRJP1 compares with other species. We then investigated how supplementing the diets of both diapausing and nondiapausing females ofCx. pipienswith royal jelly affects egg follicle length, fat content, protein content, starvation resistance, and metabolic profile. ResultsWe found that feeding royal jelly to females reared in long-day, diapause-averting conditions significantly reduced the egg follicle lengths and switched their metabolic profiles to be similar to diapausing females. In contrast, feeding royal jelly to females reared in short-day, diapause-inducing conditions significantly reduced lifespan and switched their metabolic profile to be similar nondiapausing mosquitoes. Moreover, RNAi directed againstCpMRJPIsignificantly increased egg follicle length of short-day reared females, suggesting that these females averted diapause. DiscussionTaken together, our data show that consuming royal jelly reverses several key seasonal phenotypes ofCx. pipiensand that these responses are likely mediated in part by CpMRJP1.more » « less
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