Genetic structure and phenotypic variation of Anopheles darlingi in northwest Colombia

Blood Source and Anesthetics Effects on the Maintenance of Anopheles darlingi in the Lab-Rearing Condition

Anopheles darlingi mosquitoes are the main malaria vectors in the Amazon region and play a significant role in the high transmission cycle of Plasmodium vivax, particularly in areas undergoing degradation of the Amazon. Establishing an An. darlingi colony under laboratory conditions allows for critical studies on this vector, including insecticide resistance, vector competence, and the development of new tools for controlling vivax malaria. However, the establishment of mass-rearing mosquito colonies has proven challenging, with success being heavily dependent on supporting their reproduction. A key factor in this process is finding the most efficient blood source for feeding. Here, we evaluated the reproductive potential of An. darlingi using different blood feeding methods and sources. First, we assessed the effect of anesthesia on reproductive potential by comparing anesthetized mosquitoes with those that were physically restrained. Next, we assessed the best blood source using both direct and indirect blood feeding methods, the latter involving an artificial feeding system. The blood sources tested included from rabbits, chickens, mice, bovines, and humans. In the anesthesia tests, no significant differences in the evaluated biological parameters were observed between anesthetized or non-anesthetized groups. Similarly, no significant differences were detected in the biological parameters assessed for each blood source, regardless of whether the feeding was direct or indirect. Because all blood sources proved effective, the practicality of obtaining and maintaining blood becomes a crucial factor. In this regard, bovine blood emerged as an effective and practical alternative for maintaining an An. darlingi colony under laboratory conditions.

Integrating wing morphometrics and mitochondrial DNA analysis to assess the filaria vector Mansonia uniformis (Diptera: Culicidae) populations in Thailand

Mansonia uniformis (Diptera: Culicidae) is recognized as a vector of Brugia malayi and has been reported to transmit Wuchereria bancrofti, both causing lymphatic filariasis in humans. This study employed geometric morphometrics (GM) to investigate wing shape variation and analyzed genetic diversity through cytochrome c oxidase subunit 1 (COI) gene analyses in Ma. uniformis populations across Thailand. Wing GM analyses indicated significant differences in wing shape based on Mahalanobis distances among nearly all population pairs (p < 0.05), with no significant correlation between wing shape and geographic distance (r = 0.210, p > 0.05). Genetic analyses identified 63 haplotypes and 49 polymorphic sites, with the overall population exhibiting a nucleotide diversity of 0.006 (± 0.001) and a haplotype diversity of 0.912 (± 0.017). Deviations from neutrality, as indicated by Tajima's D and Fu's FS tests for the overall Ma. uniformis populations in Thailand, were statistically significant and negative, suggesting population expansion (both p < 0.05). Analysis of molecular variance revealed no significant genetic structure when all populations were categorized based on collection sites and geographic regions. However, significant differences in FST values were observed between some populations. These findings enhance our understanding of the geographical and genetic factors influencing Ma. uniformis populations, which are crucial for developing effective control strategies in Thailand.

Susceptibility of Field-Collected Nyssorhynchus darlingi to Plasmodium spp. in Western Amazonian Brazil

Mosquito susceptibility to Plasmodium&nbsp;spp. infection is of paramount importance for malaria occurrence and sustainable transmission. Therefore, understanding the genetic features underlying the mechanisms of susceptibility traits is pivotal to assessing malaria transmission dynamics in endemic areas. The aim of this study was to investigate the susceptibility of Nyssorhynchus darlingi-the dominant malaria vector in Brazil-to Plasmodium spp. using a reduced representation genome-sequencing protocol. The investigation was performed using a genome-wide association study (GWAS) to identify mosquito genes that are predicted to modulate the susceptibility of natural populations of the mosquito to Plasmodium infection. After applying the sequence alignment protocol, we generated the variant panel and filtered variants; leading to the detection of 202,837 SNPs in all specimens analyzed. The resulting panel was used to perform GWAS by comparing the pool of SNP variants present in Ny.&nbsp;darlingi infected with Plasmodium spp. with the pool obtained in field-collected mosquitoes with no evidence of infection by the parasite (all mosquitoes were tested separately using RT-PCR). The GWAS results for infection status showed two statistically significant variants adjacent to important genes that can be associated with susceptibility to Plasmodium infection: Cytochrome P450 (cyp450) and chitinase. This study provides relevant knowledge on malaria transmission dynamics by using a genomic approach to identify mosquito genes associated with susceptibility to Plasmodium infection in Ny. darlingi in western Amazonian Brazil.

Wing geometry and genetic analyses reveal contrasting spatial structures between male and female Aedes aegypti (L.) (Diptera: Culicidae) populations in metropolitan Manila, Philippines

The population genetic structure of Aedes aegypti (Linnaeus, 1762) has been studied in order to understand its role as an efficient vector. Several studies utilized an integrative approach; to combine genetic and phenotypic data to determine its population structure but these studies have only focused on female populations. To address this particular gap, our study compared the population variability and structuring between its male and female populations using phenotypic and genetic data from a highly-urbanized and dengue-endemic region of the Philippines, Metropolitan Manila. Five mosquito populations comprised of female (n = 137) and male (n = 49) adult mosquitoes were used in this study. All mosquito individuals underwent geometric morphometric (26 landmarks), and genetic (11 microsatellite loci) analyses. Results revealed that F_ST estimates (genetic) were 0.055 and 0.009 while Q_ST estimates (phenotypic) were 0.318 and 0.309 in in male and female populations, respectively. Wing shape variation plots showed that male populations were distinctly separated from each other while female populations overlapped. Similarly, discriminant analysis of principal components using genetic data revealed that male populations were also distinctly separated from each other while female populations showed near-overlapping populations. Genetic and phenetic dendrograms showed the formation of two groups in male populations but no groups in female populations. Further analysis indicated a significant correlation (r = 0.68, p = 0.02) between the genetic and phenetic distances of male populations. Bayesian analysis using genetic data also detected multiple clusters in male (K = 3) and female (K = 2) populations, while no clusters were detected using the phenotypic data from both sexes. Our results revealed contrasting phenotypic and genetic patterns between male and female Ae. aegypti, indicating that male populations were more spatially structured than female populations.

The use of wing shape for characterising macroevolution in mosquitoes (Diptera: Culicidae)

The wing form of culicid mosquitoes shows considerable variation among groups: this phenomenon has been addressed by several studies through space-time analyses in mosquito populations, species, and genera. The observed variation results from a combination of two distinct factors: heredity and phenotypic plasticity. The first is usually related to wing shape, a complex character that may serve as a taxonomic marker in specific cases. We hypothesized that wing shape might be phylogenetically meaningful in Culicidae. In this study, we applied a geometric morphometrical approach based on 18 landmarks in 81 species of mosquitoes, representing 19 different genera, to investigate whether wing shape can help retrieve macroevolutionary patterns or identify any phylogenetic signals. We observed that wing shape differed considerably among groups, especially between Anophelinae and Culicinae subfamilies; thus, some wing shape elements may be synapomorphic. Comparisons among wing consensus after Procrustes superimposition revealed that landmark #1, located between the veins RS and R1, was the most variable. Sabethini tribe was distinguished from other taxa owing to a strong phylogenetic signal of its wings, whereas other culicids presented weaker signals and were not that distinguishable. Evolutionary forces such as natural selection, evolutionary limitation/constraint, or canalization mechanisms might drive the evolution of wing phenotype. These findings suggest that the wing undergoes evolution over long periods, but is not neutral enough to reconstruct the phylogenetic history of these insects. Gene-based studies should be performed to understand the driving forces in wing evolution.