A comprehensive assessment of inbreeding and laboratory adaptation in<i>Aedes aegypti</i>mosquitoes

Ross, Perran A; Endersby‐Harshman, Nancy M.; Hoffmann, Ary A.

doi:10.1101/237776

Cited by 31 publications

(35 citation statements)

References 99 publications

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“…Compared to studies performed over ten years ago, some deleterious effects of wMelPop appear weaker, particularly blood feeding traits (Moreira et al 2009b;Turley et al 2009) and male longevity (McMeniman et al 2009;Yeap et al 2011). Although this may indicate nuclear background evolution, direct comparisons with previous studies are difficult due to methodological differences and potential confounding effects of inbreeding, drift and laboratory adaptation that can occur during colony maintenance (Ross et al 2019a).…”

Section: Discussionmentioning

confidence: 94%

Persistent deleterious effects of an unstable deleteriousWolbachiainfection

Ross

Axford

Callahan

et al. 2019

Preprint

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Wolbachia are being used to reduce dengue transmission by Aedes aegypti mosquitoes around the world. To date releases have mostly involved Wolbachia strains with limited fitness effects but strains with larger fitness costs could be used to suppress mosquito populations. However, such infections are expected to evolve towards decreased deleterious effects. Here we investigate potential evolutionary changes in the wMelPop infection transferred from Drosophila melanogaster to Aedes aegypti more than ten years (~120 generations) ago. We show that most deleterious effects of this infection have persisted despite strong selection to ameliorate them. The wMelPop infection is difficult to maintain in laboratory colonies, likely due to the persistent deleterious effects coupled with occasional maternal transmission leakage. Furthermore, female mosquitoes can be scored incorrectly as infected due to transmission of Wolbachia through mating. Infection loss in colonies was not associated with evolutionary changes in the nuclear background. These findings suggest that Wolbachia transinfections with deleterious effects may have stable phenotypes which could ensure their long-term effectiveness if released in natural populations to reduce population size.Author summaryMosquitoes infected with Wolbachia bacteria are being deployed into the field where they can suppress mosquito populations and reduce dengue transmission. These programs rely on the use of Wolbachia strains that have desirable phenotypes, which can include deleterious fitness effects, reproductive manipulation and virus blocking. However, theory predicts that Wolbachia will evolve to become less costly to their hosts, reducing the effectiveness of these programs. We investigate the potential for evolutionary changes by performing a comprehensive phenotypic analysis of a deleterious Wolbachia strain, wMelPop, that was introduced to Aedes aegypti mosquitoes from Drosophila over ten years ago. In contrast to theoretical expectations and research from Drosophila, our results suggest that Wolbachia strains with deleterious effects may have stable phenotypes, ensuring their long-term effectiveness if released into natural populations.

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Section: Discussionmentioning

confidence: 94%

Persistent deleterious effects of an unstable deleteriousWolbachiainfection

Ross

Axford

Callahan

et al. 2019

Preprint

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“…Therefore, our laboratory maintenance protocol 46 should not lead to compromised host-seeking ability in the field, though other factors that can coincide with laboratory maintenance such as inbreeding may reduce fitness. 71 Different rearing procedures, such as the use of membrane feeders, non-human blood or small cages may also affect host-seeking ability if adaptation occurs.…”

Section: Discussionmentioning

confidence: 99%

Measuring the host-seeking ability of Aedes aegypti destined for field release

Lau

Endersby‐Harshman

Axford

et al. 2019

Preprint

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Host-seeking is an essential process in mosquito reproduction. Field releases of modified mosquitoes for population transformation rely on successful host-seeking by female mosquitoes, but host-seeking ability is rarely tested in a realistic context. We tested the host-seeking ability of female Aedes aegypti mosquitoes using a semi-field system. Females with different Wolbachia infection types (wMel-, wAlbB-infected and uninfected) or from different origins (laboratory and field) were released at one end of a semi-field cage and recaptured as they landed on human experimenters fifteen meters away. Mosquitoes from each population were then identified with molecular tools or through marking with a consistent weight of fluorescent powder. Wolbachia-infected and uninfected populations had similar average durations to landing and overall recapture proportions, as did laboratory and field-sourced A. aegypti. These results suggest that the host-seeking ability of mosquitoes is not negatively affected by Wolbachia infection or long-term laboratory maintenance. This method provides an approach to study the host-seeking ability of mosquitoes across a long distance which will be useful when evaluating strains of mosquitoes that are planned for releases into the field to suppress arbovirus transmission. An adjustment of this method may also be useful in sterile insect release programs because male host-seeking and swarming around female feeding sites can also be investigated.

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“…Laboratory adaptation was studied in Ae. aegypti for 13 generations using a population size of 100 adults [43]; that study showed that small Ae. aegypti populations can suffer a fitness cost.…”

Section: Generation Influence On Cold Tolerancementioning

confidence: 97%

Does winter cold really limit the dengue vector Aedes aegypti in Europe?

et al. 2020

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Background: Aedes aegypti is a potential vector for several arboviruses including dengue and Zika viruses. The species seems to be restricted to subtropical/tropical habitats and has difficulties in establishing permanent populations in southern Europe, probably due to constraints during the winter season. The aim of this study was to systematically analyze the cold tolerance (CT) of Ae. aegypti in its most cold-resistant life stage, the eggs. Methods: The CT of Ae. aegypti eggs was compared with that of Ae. albopictus which is well established in large parts of Europe. By systematically studying the literature (meta-analysis), we recognized that CT has been rarely tested in Ae. aegypti eggs, but eggs can survive at zero and sub-zero temperatures for certain exposure periods. To overcome potential bias from experimental differences between studies, we then conducted species comparisons using a harmonized high-resolution CT measuring method. From subtropical populations of the same origin, the survival (hatching in %) and emergence of adults of both species were measured after zero and sub-zero temperature exposures for up to 9 days (3 °C, 0 °C and − 2 °C: ≤ 9 days; − 6 °C: ≤ 2 days). Results: Our data show that Ae. aegypti eggs can survive low and sub-zero temperatures for a short time period similar to or even better than those of Ae. albopictus. Moreover, after short sub-zero exposures of eggs of both species, individuals still developed into viable adults (Ae. aegypti: 3 adults emerged after 6 days at − 2 °C, Ae. albopictus: 1 adult emerged after 1 day at − 6 °C). Conclusions: Thus, both the literature and the present experimental data indicate that a cold winter may not be the preventing factor for the re-establishment of the dengue vector Ae. aegypti in southern Europe.

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A comprehensive assessment of inbreeding and laboratory adaptation inAedes aegyptimosquitoes

Cited by 31 publications

References 99 publications

Persistent deleterious effects of an unstable deleteriousWolbachiainfection

Persistent deleterious effects of an unstable deleteriousWolbachiainfection

Measuring the host-seeking ability of Aedes aegypti destined for field release

Does winter cold really limit the dengue vector Aedes aegypti in Europe?

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