scholarly journals Cross-Generational Effects of Heat Stress on Fitness and Wolbachia Density in Aedes aegypti Mosquitoes

2019 ◽  
Vol 4 (1) ◽  
pp. 13 ◽  
Author(s):  
Isabelle Jia-Hui Foo ◽  
Ary A. Hoffmann ◽  
Perran A. Ross
Keyword(s):  
Heat Stress ◽  
Aedes Aegypti ◽  
Disease Transmission ◽  
Wing Length ◽  
Wolbachia Infection ◽  
Female Offspring ◽  
Starvation Tolerance ◽  
Generational Effects ◽  
Infection Types ◽  
Wolbachia Density

Aedes aegypti mosquitoes infected with Wolbachia symbionts are now being released into the field to control the spread of pathogenic human arboviruses. Wolbachia can spread throughout vector populations by inducing cytoplasmic incompatibility and can reduce disease transmission by interfering with virus replication. The success of this strategy depends on the effects of Wolbachia on mosquito fitness and the stability of Wolbachia infections across generations. Wolbachia infections are vulnerable to heat stress, and sustained periods of hot weather in the field may influence their utility as disease control agents, particularly if temperature effects persist across generations. To investigate the cross-generational effects of heat stress on Wolbachia density and mosquito fitness, we subjected Ae. aegypti with two different Wolbachia infection types (wMel, wAlbB) and uninfected controls to cyclical heat stress during larval development over two generations. We then tested adult starvation tolerance and wing length as measures of fitness and measured the density of wMel in adults. Both heat stress and Wolbachia infection reduced adult starvation tolerance. wMel Wolbachia density in female offspring was lower when mothers experienced heat stress, but male Wolbachia density did not depend on the rearing temperature of the previous generation. We also found cross-generational effects of heat stress on female starvation tolerance, but there was no cross-generational effect on wing length. Fitness costs of Wolbachia infections and cross-generational effects of heat stress on Wolbachia density may reduce the ability of Wolbachia to invade populations and control arbovirus transmission under specific environmental conditions.

scholarly journals Insecticide Resistance and Fitness: The Case of Four Aedes aegypti Populations from Different Brazilian Regions

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Mariana Rocha David ◽  
Gabriela Azambuja Garcia ◽  
Denise Valle ◽  
Rafael Maciel-de-Freitas
Keyword(s):  
Aedes Aegypti ◽  
Insecticide Resistance ◽  
Wing Length ◽  
Natural Populations ◽  
Pathogen Transmission ◽  
Fitness Cost ◽  
Starvation Tolerance ◽  
Energy Trade ◽  
Female Survival ◽  
Free Environment

Background. Chemical control is still a major strategy to constrain vector density and mitigate pathogen transmission. However, insecticide overuse poses a high selective pressure, favouring the spread of resistance alleles in natural populations. In an insecticide-free environment, a fitness cost is expected in resistant insects when compared to susceptible counterparts. This study investigates whether insecticide resistance to an organophosphate (temephos) and a pyrethroid (deltamethrin) is associated with fitness traits in four Aedes aegypti wild populations sampled every three months over one year. Findings. We measured development time from larvae to adult, female survival, wing length, fecundity, and adult resistance to starvation in field insecticide resistant Ae. aegypti populations four times over a year. These results were confronted with resistance levels to temephos and deltamethrin and with potentially related mechanisms, including a kdr mutation in the pyrethroid target site. No differences in fitness cost were found after contrasting mosquitoes from the same population collected throughout a year, irrespective of differences in insecticide resistance levels. Additionally, significant differences were not observed among field populations. However, compared to the reference strain Rockefeller, field females survived significantly less. Moreover, larval development was equal or slower in three out of four field populations. In no case differences were evidenced in starvation tolerance, wing length, and fecundity. Conclusions. Overall, field resistant mosquitoes seemed to have a slight fitness disadvantage when compared with the Rockefeller susceptible strain which might represent a potential fitness cost of insecticide resistance. However, after comparing Ae. aegypti from the same population but sampled at different moments, or from different field populations, mosquito life-history traits varied independently of resistance ratios. The metabolic deviations necessary to overcome the adverse effects of insecticides may cause an energy trade-off that affects energy allocation and ultimately basic demands of insect biology. The extent of fitness cost due to insecticide resistance is critical information to delay the evolution of resistance in wild vector populations.

scholarly journals Sex, age, and parental harmonic convergence behavior affect the immune performance of Aedes aegypti offspring

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Christine M. Reitmayer ◽  
Ashutosh K. Pathak ◽  
Laura C. Harrington ◽  
Melinda A. Brindley ◽  
Lauren J. Cator ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Disease Transmission ◽  
Female Offspring ◽  
Physiological Status ◽  
Offspring Performance ◽  
Selective Pressures ◽  
Wide Range ◽  
Harmonic Convergence ◽  
And Control ◽  
Insight Into

AbstractHarmonic convergence is a potential cue, female mosquitoes use to choose male mates. However, very little is known about the benefits this choice confers to offspring performance. Using Aedes aegypti (an important vector of human disease), we investigated whether offspring of converging parental pairs showed differences in immune competence compared to offspring derived from non-converging parental pairs. Here we show that harmonic convergence, along with several other interacting factors (sex, age, reproductive, and physiological status), significantly shaped offspring immune responses (melanization and response to a bacterial challenge). Harmonic convergence had a stronger effect on the immune response of male offspring than on female offspring. Further, female offspring from converging parental pairs disseminated dengue virus more quickly than offspring derived from non-converging parental pairs. Our results provide insight into a wide range of selective pressures shaping mosquito immune function and could have important implications for disease transmission and control.

scholarly journals Continued Susceptibility of the wMel Wolbachia Infection in Aedes aegypti to Heat Stress Following Field Deployment and Selection

Insects ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. 78 ◽  
Author(s):  
Perran Ross ◽  
Ary Hoffmann
Keyword(s):  
Heat Stress ◽  
Aedes Aegypti ◽  
High Temperatures ◽  
Wolbachia Infection ◽  
Field Exposure ◽  
Breeding Sites ◽  
Laboratory Selection ◽  
Mosquito Breeding ◽  
Field Deployment ◽  
Cyclical Heat

Aedes aegypti mosquitoes infected with the wMel strain of Wolbachia are being deployed to control the spread of arboviruses around the world through blockage of viral transmission. Blockage by Wolbachia in some scenarios may be affected by the susceptibility of wMel to cyclical heat stress during mosquito larval development. We therefore evaluated the potential to generate a heat-resistant strain of wMel in Ae. aegypti through artificial laboratory selection and through exposure to field temperatures across multiple generations. To generate an artificially selected strain, wMel-infected females reared under cyclical heat stress were crossed to wMel-infected males reared at 26 °C. The low proportion of larvae that hatched founded the next generation, and this process was repeated for eight generations. The wMel heat-selected strain (wMel-HS) was similar to wMel (unselected) in its ability to induce cytoplasmic incompatibility and restore compatibility when larvae were reared under cyclical heat stress, but wMel-HS adults exhibited reduced Wolbachia densities at 26 °C. To investigate the effects of field exposure, we compared the response of wMel-infected Ae. aegypti collected from Cairns, Australia where the infection has been established for seven years, to a wMel-infected population maintained in the laboratory for approximately 60 generations. Field and laboratory strains of wMel did not differ in their response to cyclical heat stress or in their phenotypic effects at 26 °C. The capacity for the wMel infection in Ae. aegypti to adapt to high temperatures therefore appears limited, and alternative strains may need to be considered for deployment in environments where high temperatures are regularly experienced in mosquito breeding sites.

scholarly journals Impacts of Low Temperatures on Wolbachia (Rickettsiales: Rickettsiaceae)-Infected Aedes aegypti (Diptera: Culicidae)

2020 ◽  
Vol 57 (5) ◽  
pp. 1567-1574 ◽  
Author(s):  
Meng-Jia Lau ◽  
Perran A Ross ◽  
Nancy M Endersby-Harshman ◽  
Ary A Hoffmann
Keyword(s):  
Life History ◽  
Low Temperature ◽  
Aedes Aegypti ◽  
Disease Transmission ◽  
Low Temperatures ◽  
Temperature Effects ◽  
Life Stage ◽  
Temperature Cycles ◽  
The Impact ◽  
Wolbachia Density

Abstract In recent decades, the occurrence and distribution of arboviral diseases transmitted by Aedes aegypti mosquitoes has increased. In a new control strategy, populations of mosquitoes infected with Wolbachia are being released to replace existing populations and suppress arboviral disease transmission. The success of this strategy can be affected by high temperature exposure, but the impact of low temperatures on Wolbachia-infected Ae. aegypti is unclear, even though low temperatures restrict the abundance and distribution of this species. In this study, we considered low temperature cycles relevant to the spring season that are close to the distribution limits of Ae. aegypti, and tested the effects of these temperature cycles on Ae. aegypti, Wolbachia strains wMel and wAlbB, and Wolbachia phage WO. Low temperatures influenced Ae. aegypti life-history traits, including pupation, adult eclosion, and fertility. The Wolbachia-infected mosquitoes, especially wAlbB, performed better than uninfected mosquitoes. Temperature shift experiments revealed that low temperature effects on life history and Wolbachia density depended on the life stage of exposure. Wolbachia density was suppressed at low temperatures but densities recovered with adult age. In wMel Wolbachia there were no low temperature effects specific to Wolbachia phage WO. The findings suggest that Wolbachia-infected Ae. aegypti are not adversely affected by low temperatures, indicating that the Wolbachia replacement strategy is suitable for areas experiencing cool temperatures seasonally.

scholarly journals Ligusticum sinense Nanoemulsion Gel as Potential Repellent against Aedes aegypti, Anopheles minimus, and Culex quinquefasciatus (Diptera: Culicidae)

Insects ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 596
Author(s):  
Anuluck Junkum ◽  
Wanchai Maleewong ◽  
Atiporn Saeung ◽  
Danita Champakaew ◽  
Arpaporn Chansang ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Culex Quinquefasciatus ◽  
Disease Transmission ◽  
Skin Irritation ◽  
Mosquito Vectors ◽  
Plant Family ◽  
Anopheles Minimus ◽  
Human Volunteers ◽  
Nanoemulsion Gel ◽  
Fresh Preparation

Ligusticum sinense Oliv. cv. is a species of Umbelliferae (Apiaceae), a large plant family in the order Apiales. In this study, L. sinense hexane extract nanoemulsion gel (LHE-NEG) was investigated for mosquito repellency and compared to the standard chemical, N,N-diethyl-3-methylbenzamide (DEET), with the goal of developing a natural alternative to synthetic repellents in protecting against mosquito vectors. The results demonstrated that LHE-NEG afforded remarkable repellency against Aedes aegypti, Anopheles minimus, and Culex quinquefasciatus, with median protection times (MPTs) of 5.5 (4.5–6.0), 11.5 (8.5–12.5), and 11.25 (8.5–12.5) h, respectively, which was comparable to those of DEET-nanoemulsion gel (DEET-NEG: 8.5 (7.0–9.0), 12.0 (10.0–12.5), and 12.5 (10.0–13.5) h, respectively). Evaluation of skin irritation in 30 human volunteers revealed no potential irritant from LHE-NEG. The physical and biological stability of LHE-NEG were determined after being kept under heating/cooling cycle conditions. The stored samples of LHE-NEG exhibited some changes in appearance and differing degrees of repellency between those kept for 3 and 6 heating/cooling cycles, thus providing slightly shorter MPTs of 4.25 (4.0–4.5) and 3.25 (2.5–3.5) h, respectively, when compared to those of 5.0 (4.5–6.0) h in fresh preparation. These findings encourage commercially developed LHE-based products as an alternative to conventional synthetic repellents in preventing mosquito bites and helping to interrupt mosquito-borne disease transmission.

Investigating Male Aedes aegypti (Diptera: Culicidae) Attraction to Different Oviposition Containers Using Various Configurations of the Sound Gravid Aedes Trap

2019 ◽  
Vol 57 (3) ◽  
pp. 957-961
Author(s):  
Kyran M Staunton ◽  
Barukh B Rohde ◽  
Michael Townsend ◽  
Jianyi Liu ◽  
Mark Desnoyer ◽  
...  
Keyword(s):  
Aedes Aegypti ◽  
Zika Virus ◽  
Disease Transmission ◽  
Urban Landscape ◽  
Mosquito Control ◽  
Transmission Risk ◽  
Northern Australia ◽  
Control Programs ◽  
Male Dispersal ◽  
Olfactory Attractant

Abstract Aedes aegypti (Linnaeus), the primary vectors of the arboviruses dengue virus and Zika virus, continue to expand their global distributions. In efforts to better control such species, several mosquito control programs are investigating the efficacy of rearing and releasing millions of altered male Aedes throughout landscapes to reduce populations and disease transmission risk. Unfortunately, little is known about Ae. aegypti, especially male, dispersal behaviors within urban habitats. We deployed Sound-producing Gravid Aedes Traps (SGATs) in Cairns, northern Australia, to investigate male Ae. aegypti attraction to various oviposition container configurations. The traps were arranged to include: 1) water only, 2) organically infused water, 3) infused water and L3 larvae, 4) infused water and a human-scented lure, and lastly 5) no water or olfactory attractant (dry). Our data suggest that males were more attracted to SGATs representing active larval sites than potential larval sites, but were equally attracted to dry SGATs relative to those containing water and/or infusion. Additionally, we found that female Ae. aegypti were equally attracted to wet SGATs, with or without infusion, but not dry ones. These results suggest that male Ae. aegypti within northern Australia are more attracted to active larval sites and equally attracted to dry containers as wet or infused ones. Additionally, female Ae. aegypti are unlikely to enter dry containers. Such findings contribute to our understanding of potentially attractive features for local and released Ae. aegypti throughout the northern Australian urban landscape.

scholarly journals Effects of Alternative Blood Sources on Wolbachia Infected Aedes aegypti Females within and across Generations

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 140 ◽  
Author(s):  
Véronique Paris ◽  
Ellen Cottingham ◽  
Perran Ross ◽  
Jason Axford ◽  
Ary Hoffmann
Keyword(s):  
Aedes Aegypti ◽  
Human Blood ◽  
Mass Rearing ◽  
Egg Hatch ◽  
Mass Release ◽  
Deliberate Release ◽  
Blood Source ◽  
Wolbachia Density ◽  
Infected Line ◽  
Strong Adaptation

Wolbachia bacteria have been identified as a tool for reducing the transmission of arboviruses transmitted by Aedes aegypti. Research groups around the world are now mass rearing Wolbachia-infected Ae. aegypti for deliberate release. We investigated the fitness impact of a crucial element of mass rearing: the blood meal required by female Ae. aegypti to lay eggs. Although Ae. aegypti almost exclusively feed on human blood, it is often difficult to use human blood in disease-endemic settings. When females were fed on sheep or pig blood rather than human blood, egg hatch rates decreased in all three lines tested (uninfected, or infected by wMel, or wAlbB Wolbachia). This finding was particularly pronounced when fed on sheep blood, although fecundity was not affected. Some of these effects persisted after an additional generation on human blood. Attempts to keep populations on sheep and pig blood sources only partly succeeded, suggesting that strong adaptation is required to develop a stably infected line on an alternative blood source. There was a decrease in Wolbachia density when Ae. aegypti were fed on non-human blood sources. Density increased in lines kept for multiple generations on the alternate sources but was still reduced relative to lines kept on human blood. These findings suggest that sheep and pig blood will entail a cost when used for maintaining Wolbachia-infected Ae. aegypti. These costs should be taken into account when planning mass release programs.

Maternal influences on size and emergence time of the cinnabar moth

1980 ◽  
Vol 58 (8) ◽  
pp. 1452-1457 ◽  
Author(s):  
Laura J. Richards ◽  
Judith H. Myers
Keyword(s):  
Genetic Variance ◽  
Hatching Success ◽  
Wing Length ◽  
Female Parent ◽  
Female Offspring ◽  
Pupal Weight ◽  
Emergence Time ◽  
Egg Weight ◽  
Maternal Influences ◽  
Cinnabar Moth

Maternal effects on egg weight, wing length, and emergence time were studied in the cinnabar moth. Egg weight was related to hatching success, but neither egg weight nor order of laying were related to pupal weight of larvae reared under greenhouse conditions. Heritabilities of wing length and emergence time calculated from the regression of mean offspring values on female parent were 0.30 ± 0.12 and 0.39 ± 0.14 respectively for female offspring. Regressions for male offspring were not significant. Significant differences between families in an ANOVA however were indicative of genetic variance. Genetic variance for female emergence time is discussed as one mechanism which has enabled synchronization of moth emergence with the appropriate phase of food plant phenology for larval development.

Optimal control approach for establishing wMelPop Wolbachia infection among wild Aedes aegypti populations

2018 ◽  
Vol 76 (7) ◽  
pp. 1907-1950 ◽  
Author(s):  
Doris E. Campo-Duarte ◽  
Olga Vasilieva ◽  
Daiver Cardona-Salgado ◽  
Mikhail Svinin
Keyword(s):  
Optimal Control ◽  
Aedes Aegypti ◽  
Wolbachia Infection ◽  
Control Approach ◽  
Optimal Control Approach

scholarly journals High-Throughput PCR Assays To Monitor Wolbachia Infection in the Dengue Mosquito (Aedes aegypti) and Drosophila simulans

2012 ◽  
Vol 78 (13) ◽  
pp. 4740-4743 ◽  
Author(s):  
Siu F. Lee ◽  
Vanessa L. White ◽  
Andrew R. Weeks ◽  
Ary A. Hoffmann ◽  
Nancy M. Endersby
Keyword(s):  
Aedes Aegypti ◽  
High Throughput ◽  
Large Scale ◽  
Wolbachia Infection ◽  
Drosophila Simulans ◽  
Content Type ◽  
Pcr Assays ◽  
Cost Efficient

ABSTRACTWe have developed and validated two new fluorescence-based PCR assays to detect theWolbachia wMel strain inAedes aegyptiand thewRi andwAu strains inDrosophila simulans. The new assays are accurate, informative, and cost-efficient for large-scaleWolbachiascreening.

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