Rhipicephalus sanguineus Complex in the Americas: Systematic, Genetic Diversity, and Geographic Insights

The Rhipicephalus sanguineus group encompasses at least 12 validated species of Palearctic and Afrotropical hard ticks, which are relevant in veterinary medicine and public health. The taxonomy of R. sanguineus s.s., has been particularly intensely debated, due to its wide geographic distribution, morphological variants, parasite-host associations, and its capacity and vectorial competence for the transmission of several pathogens. By sequencing mitochondrial markers, it was possible to identify the existence of multiple lineages, among which the Tropical and the Temperate lineages stand out, particularly in America. However, the northern limit between these lineages is not clear due to the lack of extensive sampling across Mexico. For this reason, the aim of the present study was to determine the genetic diversity and structure of the R. sanguineus group in Mexico and to compare it with the populations reported in the Americas, in order to propose the northern limit of the R. sanguineus Tropical lineage and the potential regions of sympatry with R. sanguineus s.s. The findings of this study now confirm the presence of R. sanguineus s.s. in Mexico, showing a subtle genetic structure and high genetic diversity throughout its distribution in the Americas. In contrast, the Tropical lineage seems to be genetically less diverse in its overall distribution in the Americas. The genetic diversity of these two independent lineages could have important epidemiological implications in the transmission of tick pathogens.

Vectorial Competence Potential of Culex Quinquefasciatus (Say, 1923) from the Amazon Region to Transmit West Nile Virus Isolated in Brazil

The West Nile virus is characterized as a neurotropic pathogen that causes the West Nile fever. It is transmitted by mosquitoes, mainly of the Culex genus. In 2018, the Evandro Chagas Institute carried out the first isolation of WNV strain from a horse brain sample and in 2021 the same institute also isolated the WNV in a pool of mosquitoes of the Culex spp. from the Carajás region (Pará). Thus, this study aimed to determine the vectorial competence of Culex quinquefasciatus from the Amazon region of Brazil for transmission the WNV Brazilian strain. Oral infection of Cx. quinquefasciatus females belonging to F1 generation was performed with infected blood with WNV. Subsequently, analysis of infection, dissemination and transmission rates was performed, as well as verification of viral titers in the samples. The study demonstrated that Cx. quinquefasciatus can act as a potential vector of WNV in Brazil, since it was found that the Brazilian strain was able to overcome the host's anatomical barriers and spread to various regions, among them in saliva, in which, despite the low viral titers identified, it had a transmission rate of 100% on the 21st day after infection.

Sodalis Glossinidius and Wolbachia Infections in Wild Population of Glossina Morsitans Submorsitans Caught in the Area of Lake Iro in the South of Chad

Background: To improve vector control of tsetse transmitted trypanosomiases through a better understanging of the vectorial competence of tsetse flies, investigations have been undertaken on the bacterial fauna of different tsetse species. It is in this light that Wolbachia and Sodalis glossinidius were detected in wild populations of Glossina morsistans submorsistans caught in the area of lake Iro in the south of Chad with the aim of generating data that may help to understand the influence of these symbiotic microorganisms on the vectorial competence of G. m. submorsistans. Methods: Tsetse flies were captured using biconical traps. DNA was extracted from tsetse body using the resin chelex. Sodalis glossinidius and Wolbachia were investigated by PCR using specific primers for pSG 2 and wsp genes. Comparisons between S. glossinidius and Wolbachia infections were performed according to sex and sampling periods and association studies between trypanosome infections and S. glossinidius or Wolbachia were performed. Results: From 345 G. m. submorsitans analyzed, 9.0% and 14.5% were respectively infected with S. glossinidius and Wolbachia. Only 2.31% of all tsetse flies hosted the 2 bacteria. Of all trypanosome-infected flies, 7.1% and 9.8% hosted respectively S. glossinidius and Wolbachia. No association was observed between Wolbachia and trypanosomes while significant association (r = 4.992; P = 0.025) was found between S. glossinidius and trypanosome infections. Although significant association (r = 3.147; P = 0.043) was observed between S. glossinidius and T. simiae, none was found with T. congolense or T. godfreyi. Conclusion: This study revealed S. glossinidius and Wolbachia in wild population of G. m. submorsitans of lake Iro. It showed that few tsetse flies are co-infected by Wolbachia and S. glossinidius. The presence of S. glossinidius seems to favor trypanosome infections while Wolbachia has probably no effect. Decrypting the tripartite association requires to investigate the relationship between haplotypes or genotypes of Wolbachia and/or S. glossiniduis and trypanosome infections.

Control Strategy for Aedes aegypti (Linnaeus, 1762) Population

The mosquito Aedes aegypti (Diptera: Culicidae), is adapted to different environments, mainly urban ones. They have a high degree of vectorial competence for viral diseases, especially Dengue, the arbovirus with the highest number of cases in the world. The adaptive ability of this insect and the abundance of breeding sites have undermined attempts at population’s control, resulting in a high degree of infestation in many regions of the world, resulting in a Dengue endemic. It is important to understand the different nuances of the insect in order to understand the adaptive capacity of this vector, through the knowledge of his behavior, to propose new strategies and engagement of population in proactive actions that allow the population control of this vector, especially in periods of greater proliferation. This chapter discusses population control strategies, in different scenarios and carried out by different researchers, mainly in Brazil.

A study of residual bio-efficacy of Inesfly 5AIGR and Inesfly 5AIGRNG insecticidal paints on Adult Anopheles gambiae complex mosquitoes on treated wall surfaces in Nigeria Communities: Masaka and Gidan-Zakara

BackgroundSince insecticides are commonly used in agriculture/cultivation and in vector control, they are frequently found in agricultural water bodies, where mosquito larvae are exposed. Although their concentration is often so low as not to kill the larvae, they affect the development of the mosquitoes. In particular, their effects may be transmitted to adults to influence their characteristics of life-history and their vectorial competence for arboviruses infection and malaria. Such effects on vectorial competence of sub-lethal doses of insecticides are likely to be related to their impact on immune response. Insecticide exposure influences the immune response of insects in several ways. Organophosphates and organochlorines affect the number of hemocytes (for phagocytosis) However, it is not known whether larvae exposure will impact the immune response of adults.MethodAssessment of the bio-efficacy and residual activities of insecticides sprayed, wall surface using CDC wall cone bioassay test. Entomological indices with Anopheles species collection was measured to determined vectorial involvement and residual bio-efficacy of of Inesfly 5AIGR/ Inesfly 5AIGRNG insecticidal paints on Adult Anopheles gambiae complex mosquitoes on treated wall surfaces in at both communities (Masaka and Gidan Zakara) from January to April and May through June, 2018. A bio-assay cone test was carried out at various wall surfaces/height treated with above named insecticidal paints at parameters of 0.5meter, 1meter, and 1.5meter respectively.ResultIn both communities the knockdown/mortality threshold fluctuates (94%-99%.) indicating the state of resistance and susceptible, however, in the month of May and June at Gidan-Zakara, the knockdown/mortality of mosquitoes after 24hrs was 90%-100%.The seasonal abundance of mosquito population was generally observed to decrease between the month of January through April, 2018 and increases during the onset of rains in the months of April through June, 2018. There was no significance difference in the seasonal abundance of mosquitoes and the efficacy of Inesfly 5AIGR and Inesfly 5AIGRNG insecticide paints (F= 0.958> 0.435 and F 1.515>0.293. Similarly no significant difference in the residual efficacy and the malaria vector mortality (F=2.286>0.183) and in June (F1.549>0.287). The residual Inesfly paints were effective, given that 98%-100% malaria vector were susceptible. ConclusionThe malaria vectorial competence of Anopheles species were 98% - 100% susceptible to residual ‘1NESFLY’ paints (5AIGR and 5AIGRNG) at various wall parameters of 0.5meters, 1meter and 1.5meters in the studied communities in central Nigetia. It is also imperative to state that the trial paints were in compliance with animals and human tolerance levels/standards during the during the trial periods, and fulfils the WHO criteria of insecticidal bio-efficacy (mortality >80%).

Zika virus replication in the mosquito Culex quinquefasciatus in Brazil

Zika virus (ZIKV) is a flavivirus that has recently been associated with increased incidence of neonatal microcephaly and other neurological disorders. The virus is primarily transmitted by mosquito bite, although other routes of infection have been implicated in some cases. The Aedes aegypti mosquito is considered to be the main vector to humans worldwide, but there is evidence of other mosquito species, including Culex quinquefasciatus, playing a role in the Brazilian outbreak. To test this hypothesis, we experimentally compared the vectorial competence of laboratory-reared A. aegypti and C. quinquefasciatus. We found ZIKV in the midgut, salivary glands, and saliva of artificially fed C. quinquefasciatus. Additionally, we collected ZIKV-infected C. quinquefasciatus from urban areas of high microcephaly incidence in Recife, Brazil. Take into account; these findings indicate that there may be a wider range of vectors for ZIKV than anticipated.