Genomic Characterization of Twelve Lytic Bacteriophages Infecting Midgut Bacteria of Aedes aegypti.

Mosquito-borne diseases such as malaria and dengue are global severe public health threats. Due to the lack of efficient control methods, alternative approaches to decreasing arboviral transmitted diseases are prioritized to reduce morbidity and mortality in every endemic region. Mosquito midgut bacteria play an essential role in physiological development, fitness, and the arthropods´ vectorial capacity. Bacteriophages are viruses that infect bacteria and are considered a promising biocontrol method by eliminating midgut microbiota that plays an essential role in mosquitoes´ health. Here, we isolate and identify 22 bacteria from mosquito´s midgut belonging to the genera Mesobacillus, Enterobacter, Klebsiella, Microbacterium, Micrococcus, Pantoea, Serratia, and Staphylococcus, mainly. Twelve phages with lytic activity against Enterobacter, Klebsiella, and Pantoea were also isolated. All 12 phages showed a double-stranded DNA genome, ranging from 36,790 to 149,913 bp, and were taxonomically classified as members of the Drexlerviridae family, Molineuxvirinae, Studiervirinae, and Vequintavirinae subfamilies. Open reading frames associated with phage structure, packing, host lysis, DNA metabolism, and additional functions were predicted in all 12 phage genomes, while tRNAs were predicted in five phage genomes. In addition, the life cycle was predicted as virulent for the 12 phages, and no antibiotic resistance, virulence, allergenic, or lysogenic genes were found in either genome. These findings suggest that the 12 phages have biocontrol potentials; however, it is necessary to elucidate specific bacterial host's roles and then the phages' ability to serve as effective vector control.

First Record of Aedes albopictus in Sinaloa, Mexico.

We report here the discovery of Aedes albopictus for the first time in Sinaloa state, Mexico. The mosquito larvae were collected from small water containers in the urban area of Culiacan city, Sinaloa state. Identification of the species was done primarily by morphology, followed by confirmation with polymerase-chain-reaction-based molecular method.

Replication of Dengue Virus 4 in Plodia interpunctella (Lepidoptera: Pyralidae) Larvae Under Laboratory Conditions.

Background: Developing methods for the isolation and replication of dengue virus (DENV), based on nonhematophagous insect models to assess virus-host interaction, would contribute, for instance, to the creation of drugs or vaccines and eventually to the control of the disease. In this regard, nonhematophagous mosquitoes have been used as biological hosts for the isolation of DENV because they are specific and sensitive to a low viral load and viral particles with low infectivity. However, implementation of these models is mainly affected by the complexity of the establishment of the entomological colonies. Materials and Methods: In this study, the susceptibility of DENV-4 infection in Plodia interpunctella larvae was evaluated. Ten larvae, previously inoculated with supernatant from DENV-4-infected C6/36 cells, were processed to determine viral replication by the optical density and 2-ΔΔCt methods at different time intervals (1 and 7 days postinoculation). Results: A prospective increase in viral replication was observed, which did not influence the survival and development of P. interpunctella. Conclusion: These results demonstrate the infectivity of DENV-4 in P. interpunctella, thus becoming an option as a biological model for the study of this etiological agent.

First Record of Culicoides Occidentalis in Sinaloa, Mexico.

Culicoides species adults were collected in light traps located on the coast of Elota, Sinaloa, Mexico, in February 2022. All specimens were females, and it was determined based on their morphology that they belonged to the Culicoides variipennis complex. The identification of the species was carried out by means of a comparative analysis of genetic sequences of the cytochrome c oxidase subunit I gene, which resulted in C. occidentalis, this being its first report in Sinaloa and its third nationwide.

First Evidence of Horizontal Transmission by Fecal Shedding of Dengue Virus 4 Among Aedes aegypti Larvae (Diptera: Culicidae) Under Laboratory Conditions.

The transmission pathways of dengue virus (DENV) among mosquitoes are a topic that has gained relevance in recent years because they could explain the maintenance of the virus in the wild independently of the human-mosquito horizontal transmission cycle. In this regard, Aedes aegypti larvae exposed to supernatants of C6/36 cells infected with DENV-4 were evaluated for virus excretion in feces and viability of infection in immature stages (larvae). The results demonstrate that larvae excrete DENV-4 in their feces with the potential to at least infect immature individuals of the same species. A horizontal transmission pathway of larvae-larvae DENV-4 under laboratory conditions is suggested.

First Record of Toxorhynchites moctezuma in Sinaloa, Mexico: Notes about its Morphology.

Mosquito larvae were collected in the urban area of the city of Culiacan, Sinaloa, in September of 2020. The immature stages were placed in emergence containers and fed with Aedes aegypti larvae. The adults that emerged from the immature stages were mounted on insect pins and characterized based on their morphology. The species corresponded morphologically to Toxorhynchites moctezuma, making this the first report of the species for the state of Sinaloa, Mexico. Similarities and morphological variations are discussed with previous analysis for this species.

Natural Vertical Transmission of Dengue Virus Serotype 4 in Aedes aegypti Larvae from Urban Areas in Sinaloa, Mexico.

Dengue virus (DENV) is transmitted to humans by the bite of the vector Aedes aegypti. Several researchers have suggested that the mechanism of vertical transmission of DENV in the vector is a key aspect for the prevalence of the virus in the environment and the potentiation of epidemic outbreaks of the disease. In this context and as part of an integrated study of DENV serotypes in mosquitoes of urban areas in Sinaloa, Mexico, the presence of DENV-4 in larval stages of Ae. aegypti was evaluated to demonstrate the vertical transmission of this serotype. In total, 672 larvae of Ae. aegypti were collected in 16 sectors and were grouped into 36 pools, of which 41.66% (15/36 pools) tested positive for DENV-4, with a minimum infection rate = 22.32. The analysis of the obtained sequences showed a 98% similarity to the DENV-4 with sequences previously reported in GenBank. These results show that Ae. aegypti acts as a natural reservoir for DENV-4 in this region.