Fitness costs ofWolbachiashift in locally‐adaptedAedes aegyptimosquitoes

Abstract

Aedes aegypti mosquito eggs can remain quiescent for many months before hatching, allowing populations to persist through unfavourable conditions. A. aegypti infected with the Wolbachia strain wMel have been released in tropical and subtropical regions for dengue control. wMel reduces the viability of quiescent eggs, but this physiological cost might be expected to evolve in natural mosquito populations that frequently experience stressful conditions. We found that the cost of wMel infection differed consistently between mosquitoes collected from different locations and became weaker across laboratory generations, suggesting environmentspecific adaptation of mosquitoes to the wMel infection. Reciprocal crossing experiments show that differences in the cost of wMel to quiescent egg viability were mainly due to mosquito genetic background and not Wolbachia origin. wMel-infected mosquitoes hatching from long-term quiescent eggs showed partial loss of cytoplasmic incompatibility and female infertility, highlighting additional costs of long-term quiescence. Our study provides the first evidence for a shift in Wolbachia phenotypic effects following deliberate field release and establishment and it highlights interactions between Wolbachia infections and mosquito genetic backgrounds. The unexpected changes in fitness costs observed here suggest potential tradeoffs with undescribed fitness benefits of the wMel infection.

Wolbachia Infection through Hybridization to Enhance an Incompatible Insect Technique-Based Suppression of Aedes albopictus in Eastern Spain

“…albopictus over 15 years of coevolution. This phenomenon has been highlighted before in other systems and can also be very fast due to selection [ 75 , 76 ].…”

“…In fact, establishing a new infection ex novo in a wild population of a vector species through Wolbachia transinfection requires specific infrastructures and specialized personnel together with a great deal of time. Indeed, high numbers of microinjection attempts are generally required to succeed (because of the generally low success rate), and the goal can be jeopardized by causes related to the suitability of the host, the stability of the infection, and the possible effects of the novel infection on host fitness [ 66 , 76 ].…”

Wolbachia strain wAlbB shows favourable characteristics for dengue control use in Aedes aegypti from Burkina Faso

“…Nevertheless, it is also known that w AlbB can induce diverse fitness costs in its new host Ae . aegypti , including reduced fertility after a long time of quiescence and reduced quiescent egg viability, most likely determined by the host background (Lau et al, 2021; Lau et al, 2022; Ross & Hoffmann, 2022). Wolbachia ‐induced reproductive fitness costs could be explained by a competition for nutritional resources provided by the host, to which Wolbachia is highly dependent (Allman et al, 2020).…”

“…The phenotypic stability—including viral blockage capacity—of Wolbachia strains, like variants of strain w Mel (native to Drosophila melanogaster ), was shown to be impaired by exposure to high tropical temperatures, in particular during larval stages (Mancini et al, 2021; Ross et al, 2017; Ross et al, 2019). In addition, long egg desiccation conditions can impose substantial fitness costs on w Mel and w AlbB‐carrying females (Ross et al, 2021a; Ross et al, 2023; Ross & Hoffmann, 2022). Therefore, the evaluation of the balance between Wolbachia‐conferred costs and benefits to the hosts, and the interactions with environmental factors, will be decisive for strain selection and will ensure the long‐term viability of the strategy.…”

Using models and maps to inform Target Product Profiles and Preferred Product Characteristics: the example of Wolbachia replacement

“…For instance, data from the releases in Yogyakarta shows that Wolbachia releases had minimal impact on the population size: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0010284 2.2.9. We assumed that Wolbachia exerts a fitness cost, following the reported evidence (e.g., Joubert et al, 2016;Ross & Hoffmann, 2022), and as a consequence of this, the total population size was reduced following replacement with Wolbachia-infected mosquitoes.…”