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Chikungunya and Zika are arboviruses transmitted by the mosquito Aedes aegypti . Mosquito fecundity and egg viability are important parameters of vectorial capacity. Here we aim to understand, comparatively, the effects of Chikungunya virus (CHIKV) and Zika virus (ZIKV) infections on the fecundity and fertility of young and old Aedes aegypti females. Using artificial infection blood feeding experiments we observed that both CHIKV and ZIKV do not alter the number of eggs laid when compared to uninfected females, although the egg fertility significantly decreases in both young and old CHIKV-infected females. There is an upward trend of null females (infertile females) from 2.1% in young to 6.8% in old ZIKV-infected females. Together, our data revealed that CHIKV and ZIKV affects differently Ae. aegypti physiology, that may be related to different viral spread in nature.

New tools and methods are currently under evaluation by the World Health Organization for preventing arbovirus transmission, such as dengue, Zika, and chikungunya. One promising approach involves deploying Aedes aegypti with the endosymbiotic bacterium Wolbachia pipientis to disrupt arbovirus transmission within endemic urban environments. The release program of mosquitoes with the Wolbachia ’s w Mel strain started in August 2017 in 6.88% of the city area of Rio de Janeiro, where 13.1% of the city’s population live (~890,000 inhabitants). The deployment of Wolbachia w Mel strain in Rio finished in December 2019 with a suboptimal 32% introgression of w Mel strain, which coincided with a 38% and 10% reduction of dengue and chikungunya, respectively. We conducted an independent evaluation during 20 consecutive months to evaluate whether the w Mel distribution and frequency would expand or retract. More than 50,000 mosquitoes were sampled in 12 neighborhoods with estimated 500,000 inhabitants, of which 39.2% were Ae. aegypti . In total, 7,613 of 19,427 collected Ae. aegypti were screened individually for w Mel. Climate, environmental and insecticide application data was used to model the spatiotemporal introgression of w Mel. The routine insecticide rotation adopted by the Brazilian Ministry of Health caused the crash of both w Mel-infected and -uninfected populations shortly after an increase in coverage with spinosad. However, the w Mel-uninfected mosquitoes recovered soon to levels even higher than before, whereas the w Mel-infected failed to recover after the population crash. The well documented fitness cost of w Mel in egg hatching leads to the absence of an egg bank necessary to recover after adult population was disrupted. Finally, we observed the mtDNA haplotype associated with released Wolbachia at a frequency of ~25% in field-caught uninfected mosquitoes. The reason underlying the poor introgression of Wolbachia w Mel strain is multifold. The adoption of an effective larvicide that crashed both w Mel-infected and -uninfected populations, the absence of an egg bank due to high fitness cost of egg hatching in the w Mel-infected mosquitoes, a suboptimal Wolbachia invasion before the intervention, and Wolbachia loss synergically contributed to the lower invasion and, by corollary, modest epidemiological outcome in Rio de Janeiro. Our results highlight the need to plan and implement technical guidance on Integrated Vector Management in Brazil prior and during the nationwide release of Wolbachia -infected mosquitoes to optimize dengue mitigation efforts while ensuring the judicious use of resources.

Circadian oscillators ( i . e ., circadian clocks) are essential to producing the circadian rhythms observed in virtually all multicellular organisms. In arthropods, many rhythmic behaviors are generated by oscillations of the central pacemaker, specific groups of neurons of the protocerebrum in which the circadian oscillator molecular machinery is expressed and works; however, oscillators located in other tissues ( i . e ., peripheral clocks) could also contribute to certain rhythms, but are not well known in non-model organisms. Here, we investigated whether eight clock genes that likely constitute the Aedes aegypti clock are expressed in a circadian manner in the previtellogenic ovaries of this mosquito. Also, we asked if insemination by conspecific males would alter the expression profiles of these clock genes. We observed that the clock genes do not have a rhythmic expression profile in the ovaries of virgin (VF) or inseminated (IF) females, except for period , which showed a rhythmic expression profile in ovaries of IF kept in light and dark (LD) cycles, but not in constant darkness (DD). The mean expression of seven clock genes was affected by the insemination status (VF or IF) or the light condition (LD 12:12 or DD), among which five were affected solely by the light condition, one solely by the insemination status, and one by both factors. Our results suggest that a functional circadian clock is absent in the ovaries of A . aegypti . Still, their differential mean expression promoted by light conditions or insemination suggests roles other than circadian rhythms in this mosquito’s ovaries.

New tools and methods are currently under evaluation by the World Health Organization for preventing arbovirus transmission, such as dengue, Zika, and chikungunya. One promising approach involves deploying Aedes aegypti with the endosymbiotic bacterium Wolbachia pipientis to disrupt arbovirus transmission within endemic urban environments. The release program of mosquitoes with the Wolbachia’s wMel strain started in August 2017 in 6.88% of the city area of Rio de Janeiro, where 13.1% of the city’s population live (~890,000 inhabitants). The deployment of Wolbachia wMel strain in Rio finished in December 2019 with a suboptimal 32% introgression of wMel strain, which coincided with a 38% and 10% reduction of dengue and chikungunya, respectively. We conducted an independent evaluation during 20 consecutive months to evaluate whether the wMel distribution and frequency would expand or retract. More than 50,000 mosquitoes were sampled in 12 neighborhoods with estimated 500,000 inhabitants, of which 39.2% were Ae. aegypti. In total, 7,613 of 19,427 collected Ae. aegypti were screened individually for wMel. Climate, environmental and insecticide application data was used to model the spatiotemporal introgression of wMel. The routine insecticide rotation adopted by the Brazilian Ministry of Health caused the crash of both wMel-infected and -uninfected populations shortly after an increase in coverage with spinosad. However, the wMel-uninfected mosquitoes recovered soon to levels even higher than before, whereas the wMel-infected failed to recover after the population crash. The well documented fitness cost of wMel in egg hatching leads to the absence of an egg bank necessary to recover after adult population was disrupted. Finally, we observed the mtDNA haplotype associated with released Wolbachia at a frequency of ~25% in field-caught uninfected mosquitoes. The reason underlying the poor introgression of Wolbachia wMel strain is multifold. The adoption of an effective larvicide that crashed both wMel-infected and -uninfected populations, the absence of an egg bank due to high fitness cost of egg hatching in the wMel-infected mosquitoes, a suboptimal Wolbachia invasion before the intervention, and Wolbachia loss synergically contributed to the lower invasion and, by corollary, modest epidemiological outcome in Rio de Janeiro. Our results highlight the need to plan and implement technical guidance on Integrated Vector Management in Brazil prior and during the nationwide release of Wolbachia-infected mosquitoes to optimize dengue mitigation efforts while ensuring the judicious use of resources.

The deployment of the Wolbachia wMel strain is currently underway in multiple dengue-endemic municipalities across Brazil. The efficacy of this strategy in Rio de Janeiro remains uncertain, primarily due to the difficulty in sustaining high wMel prevalence in regions previously subjected to large-scale releases. A key contributing factor was the routine rotation of insecticides within the framework of Integrated Vector Management (IVM), which led to the use of the larvicide Spinosad for Aedes control in urban areas. This compound was associated with a precipitous decline in Aedes aegypti mosquitoes, regardless the wMel infection status. While wMel-uninfected population recovered within weeks, wMel-infected population remained at low levels likely due to the fitness costs imposed by wMel on egg viability. To assess the long-term persistence of wMel following this demographic collapse, we conducted mosquito sampling across 12 neighborhoods in Rio de Janeiro, 30 months after mosquito populations crashed. Our findings reveal that wMel introgression remains suboptimal, with a mean frequency of 9.87% across the sampled areas. Only two neighborhoods exhibited wMel frequencies exceeding 15%, likely reflecting ongoing localized releases. The reduced prevalence underscores the challenges of achieving self-sustaining wMel establishment in complex urban environments and highlight critical considerations for the implementation of Wolbachia-based dengue control programs in endemic regions. This study was supported by grants from the CNPq – Conselho Nacional de Desenvolvimento Científico e Tecnológico (312282/2022-2, 307209/2023-7) and by FAPERJ – Fundação Carlos Chagas Filho de Amparo a Pesquisa no Estado do Rio de Janeiro (E-26/211.159/2019, E-26/204.108/2024, E26/2001.844/2017, E-26/210.335/2022, E-26/210.537/2024).

Fermented soybean grain (FSBG) is considered improper to use as a protein source in animal nutrition, since it is assumed that defects cause changes on its chemical composition and favor mycotoxins production, but chemical composition data does not support this theory and in vivo studies are missing. Thus, this study aimed to evaluate the effects of FSBG in feedlot lamb diets. For that, two types of FSBG (partially fermented and completely fermented, PFSBG and CFSBG) and one standard soybean grain (SSBG) were obtained and evaluated alone or as a component of experimental diets by in vitro and in vivo studies, where FSBG totally replaced SSBG in feedlot lamb diets, which was included in the experimental diets in 17.4% on dry matter basis as protein source. Before the studies, both soybeans were sent to a specialized laboratory where no mycotoxins were detected. As a result, lower DM and carbohydrate contents but higher crude protein, fiber, and indigestible NDF contents were measured in CFSBG than in SSBG. Furthermore, both types of FSBG showed lower digestibility in vitro dry matter (IVDMD) than SSBG when evaluated separately; however, when evaluated in experimental diets, the substitution of SSBG for FSBG did not affect IVDMD. It was also observed that FSBG also had less rumen-degradable protein than SSBG (mean 47.9 vs 86.4%). In the in vivo study, FSBG did not affect nutrient intake, apparent digestibility, or animal performance (i.e., average daily gain and carcass gain). Thus, mycotoxins-free FSBG may be an alternative to totally replace SSBG in feedlot lamb diets.