A major mosquito-borne viral disease outbreak caused by Zika virus (ZIKV) occurred in Bahia, Brazil, in 2015, largely due to transmission by the mosquito, Aedes aegypti (L.). Detecting ZIKV in field samples of Ae. aegypti has proven problematic in some locations, suggesting other mosquito species might be contributing to the spread of ZIKV. In this study, several (five) adult Aedes albopictus (Skuse) mosquitoes that emerged from a 2015 field collection of eggs from Camaçari, Bahia, Brazil, were positive for ZIKV RNA; however, attempts to isolate live virus were not successful. Results from this study suggest that field-collected Ae. albopictus eggs may contain ZIKV RNA that require further tests for infectious ZIKV. There is a need to investigate the role of Ae. albopictus in the ZIKV infection process in Brazil and to study the potential presence of vertical and sexual transmission of ZIKV in this species.

Aedes aegypti, as one of the vectors transmitting several arboviruses, is the main target in mosquito control programs. Permethrin is used to control mosquitoes and Aedes aegypti get exposed due to its overuse and are now resistant. The increasing percentage of permethrin resistant Aedes aegypti has become an important issue around the world and the potential influence on vectorial capacity needs to be studied. Here we selected a permethrin resistant (p-s) Aedes aegypti population from a wild Florida population and confirmed the resistance ratio to its parental population. We used allele-specific PCR genotyping of the V1016I and F1534C sites in the sodium channel gene to map mutations responsible for the resistance. Two important factors, survival rate and vector competence, that impact vectorial capacity were checked. Results indicated the p-s population had 20 times more resistance to permethrin based on LD50 compared to the parental population. In the genotyping study, the p-s population had more homozygous mutations in both mutant sites of the sodium channel gene. The p-s adults survived longer and had a higher dissemination rate for dengue virus than the parental population. These results suggest that highly permethrin resistant Aedes aegypti populations might affect the vectorial capacity, moreover, resistance increased the survival time and vector competence, which should be of concern in areas where permethrin is applied.

Arthropod-borne viruses present important public health challenges worldwide. Viruses such as DENV, ZIKV, and WNV are of current concern due to an increasing incidence and an expanding geographic range, generating explosive outbreaks even in non-endemic areas. The clinical signs associated with infection from these arboviruses are often inapparent, mild, or nonspecific, but occasionally develop into serious complications marked by rapid onset, tremors, paralysis, hemorrhagic fever, neurological alterations, or death. They are predominately transmitted to humans through mosquito bite, during which saliva is inoculated into the skin to facilitate blood feeding. A new approach to prevent arboviral diseases has been proposed by the observation that arthropod saliva facilitates transmission of pathogens. Viruses released within mosquito saliva may more easily initiate host invasion by taking advantage of the host’s innate and adaptive immune responses to saliva. This provides a rationale for creating vaccines against mosquito salivary proteins, especially because of the lack of licensed vaccines against most of these viruses. This review aims to provide an overview of the effects on the host immune response by the mosquito salivary proteins and how these phenomena alter the infection outcome for different arboviruses, recent attempts to generate mosquito salivary-based vaccines against flavivirus including DENV, ZIKV, and WNV, and the potential benefits and pitfalls that this strategy involves.

The Aedes aegypti midgut is crucial for blood digestion, nutrition, reproduction, and pathogen interaction. Using single-cell RNA sequencing, we explored virus infection and transcriptomic changes at the cellular level. We identified 12 distinct cell clusters in the Ae. aegypti midgut post-Zika virus infection, including intestinal stem cells, enteroblasts, enteroendocrine cells (EE), and enterocytes (ECs). The virus was found mainly in specific subsets of ECs and EE. Infection altered transcriptional profiles related to metabolism, signaling, and immune responses. Functional studies highlighted three significantly differentially expressed genes in infected cells. Notably, silencing apolipophorin III reduced virus RNA copy number in the midgut, emphasizing the role of specific genes in viral infection. These findings enhance our understanding of mosquito midgut cell processes during Zika virus infection and suggest potential targets for vector control.

Background: Mosquito-borne dengue virus (DENV) causes major disease worldwide, impacting 50–100 million people every year, and is spread by the major mosquito vector Aedes aegypti. Understanding mosquito physiology, including antiviral mechanisms, and developing new control strategies have become an important step towards the elimination of DENV disease. In the study reported here, we focused on autophagy, a pathway suggested as having a positive influence on virus replication in humans, as a potential antiviral target in the mosquito. Methods: To understand the role played by autophagy in Ae. aegypti, we examined the activation of this pathway in Aag-2 cells, an Ae. aegypti-derived cell line, infected with DENV. Rapamycin and 3-methyladenine, two small molecules that have been shown to affect the function of the autophagy pathway, were used to activate or suppress, respectively, the autophagy pathway. Results: At 1-day post-DENV infection in Aag-2 cells, transcript levels of both the microtubule-associated protein light chain 3-phosphatidylethanolamine conjugate (LC3-II) and autophagy-related protein 1 (ATG1) increased. Rapamycin treatment activated the autophagy pathway as early as 1-h post-treatment, and the virus titer had decreased in the Aag-2 cells at 2 days post-infection; in contrast, the 3-methyladenine treatment did not significantly affect the DENV titer. Treatment with these small molecules also impacted the ATG12 transcript levels in DENV-infected cells. Conclusions: Our studies revealed that activation of the autophagy pathway through rapamycin treatment altered DENV infection in the mosquito cells, suggesting that this pathway could be a possible antiviral mechanism in the mosquito system. Here we provide fundamental information needed to proceed with future experiments and to improve our understanding of the mosquito’s immune response against DENV. Graphical

Florida lies within a subtropical region where the climate allows diverse mosquito species including invasive species to thrive year-round. As of 2021, there are currently 66 state-approved Florida Mosquito Control Districts, which are major stakeholders for Florida public universities engaged in mosquito research. Florida is one of the few states with extensive organized mosquito control programs. The Florida State Government and Florida Mosquito Control Districts have long histories of collaboration with research institutions. During fall 2020, we carried out a survey to collect baseline data on the current control priorities from Florida Mosquito Control Districts relating to (1) priority control species, (2) common adult and larval control methods, and (3) major research questions to address that will improve their control and surveillance programs. The survey data showed that a total of 17 distinct mosquito species were considered to be priority control targets, with many of these species being understudied. The most common control approaches included truck-mounted ultra-low-volume adulticiding and biopesticide-based larviciding. The districts held interest in diverse research questions, with many prioritizing studies on basic science questions to help develop evidence-based control strategies. Our data highlight the fact that mosquito control approaches and priorities differ greatly between districts and provide an important point of comparison for other regions investing in mosquito control, particularly those with similar ecological settings, and great diversity of potential mosquito vectors, such as in Florida. Our findings highlight a need for greater alignment of research priorities between mosquito control and mosquito research. In particular, we note a need to prioritize filling knowledge gaps relating to understudied mosquito species that have been implicated in arbovirus transmission.