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Background: Aedes aegypti is associated with dengue, Zika, and chikungunya transmission. These arboviruses are responsible for national outbreaks with severe public health implications. Vector control is one of the tools used to prevent mosquito proliferation, and SumiLarv® 2MR is an alternative commercial product based on pyriproxyfen for larval/pupal control. In this study, the residual effectiveness of SumiLarv® 2MR in different regions of Brazil was evaluated in simulated field conditions. Methods: We conducted a multicenter study across four Brazilian states—Amapá, Pernambuco, Rio de Janeiro, and São Paulo—given the importance to the country's climatic variances in the north, northeast, and southeast regions and their influence on product efficiency. The populations of Ae. aegypti from each location were held in an insectary. Third-instar larvae (L3) were added every 2 weeks to water containers with SumiLarv® 2MR discs in 250-, 500- and 1000-l containers in Amapá and Rio de Janeiro, and 100-l containers in Pernambuco and São Paulo, using concentrations of 0.04, 0.08, and 0.16 mg/l. Results: Adult emergence inhibition over 420 days was observed in all tests conducted at a concentration of 0.16 mg/l; inhibition for 308–420 days was observed for 0.08 mg/l, and 224–420 days for 0.04 mg/l. Conclusions: Sumilarv® 2MR residual activity demonstrated in this study suggests that this new pyriproxyfen formulation is a promising alternative for Aedes control, regardless of climatic variations and ideal concentration, since the SumiLarv® 2MR showed adult emergence inhibition of over 80% and residual activity greater than 6 months, a period longer than that recommended by the Ministry of Health of Brazil between product re-application in larval breeding sites. [ABSTRACT FROM AUTHOR]

Background: Mosquito-borne diseases are rapidly spreading to vast territories, putting at risk most of the world's population. A key player in this scenario is Aedes aegypti, a hematophagous species which hosts and transmits viruses causing dengue and other serious illnesses. Since vector control strategies relying only on insecticides have proven unsustainable, an alternative method involving the release of Wolbachia-harboring individuals has emerged. Its successful implementation vastly depends on how fit the released individuals are in the natural habitat, being able to mate with wild populations and to spread Wolbachia to subsequent generations. In mosquitoes, an important aspect of reproductive fitness is the acoustic communication between males and females, which translates to interactions between harmonic frequencies in close proximity flight. This study aimed to characterize the flight tone produced by individuals harboring Wolbachia, also evaluating their ability to establish stable acoustic interactions. Methods: Wild-type (WT) and Wolbachia-harboring specimens (wMelBr) were thorax-tethered to blunt copper wires and placed at close proximity to sensitive microphones. Wing-beat frequencies (WBFs) were characterized at fundamental and harmonic levels, for both single individuals and couples. Harmonic interactions in homogeneous and heterogeneous couples of WT and wMelBr variants were identified, categorized and quantified accordingly. Results: In tethered 'solo' flights, individuals harboring Wolbachia developed WBFs, differing slightly, in a sex-dependent way, from those of the WT strain. To test the ability to form harmonic 'duets', tethered couples of wMelBr and WT individuals were shuffled in different sex pairs and had their flight tones analyzed. All couple types, with WT and/or wMelBr individuals, were able to interact acoustically in the frequency range of 1300-1500 Hz, which translates to the convergence between male's second harmonic and female's third. No significant differences were found in the proportions of interacting couples between the pair types. Surprisingly, spectrograms also revealed the convergence between alternative harmonic frequencies, inside and outside the species putative hearing threshold. Conclusions: Wolbachia infection leads to small sex-dependent changes on the flight tones of Ae. aegypti, but it does not seem to prevent the stereotyped harmonic interaction between males and females. Therefore, when released in the natural habitat to breed with native individuals, Wolbachia-harboring individuals shall be fit enough to meet the criteria of acoustically-related mating behavior and promote bacteria dispersion effectively. [ABSTRACT FROM AUTHOR]

Background: Knockdown resistance (kdr), caused by alterations in the voltage-gated sodium channel (NaV), is one of the mechanisms responsible for pyrethroid (PY) resistance. In the Asian tiger mosquito, Aedes albopictus, at least four different mutations were described in the IIIS6 NaV segment in populations from Asia, North America and Europe. In contrast, in Aedes aegypti at least 12 non-synonymous mutations have been reported at nine different codons, mostly in the IIS6 and IIIS6 NaV segments. The Phe1534Cys kdr mutation in the IIIS6 NaV segment is the most prevalent in populations of Ae. aegypti worldwide, also found in Ae. albopictus from Singapore. Herein, we investigated the DNA diversity corresponding to the IIS6 and IIIS6 NaV segments in natural populations of Ae. albopictus from Brazil. Methods: DNA from eight Brazilian Ae. albopictus natural populations were individually extracted and pooled by states of origin, amplified, cloned and sequenced for the corresponding IIS6 and IIIS6 NaV segments. Additionally, samples from each location were individually genotyped by an allelic specific PCR (AS-PCR) approach to obtain the genotypic and allelic frequencies for the 1534 NaV site. Results: No non-synonymous substitutions were observed in the IIS6 sequences. However, the Phe1534Cys kdr mutation was evidenced in the Ae. albopictus NaV IIIS6 segment sequences from Paraná (PR) and Rondônia (RO) states, but not from Mato Grosso (MT) state. The 1534Cyskdr allele varied from 3% (Marilena/PR and Porto Velho/RO) to 10% (Foz do Iguaçu/PR). To our knowledge, this paper reports the first occurrence and provides distribution data of a possible kdr mutation in Ae. albopictus in South America. Conclusion: The emergence of a likely kdr mutation in Ae. albopitus natural populations is a signal of alert for vector control measures since PY are the most popular insecticides adopted by residents. Additionally, once the kdr allele is present, its frequency tends to increase faster under exposition to those compounds. Although the Asian tiger mosquito is not incriminated as an important vector of dengue, chikungunya and Zika viruses in South America, its importance in this regard has been extensively discussed since Ae. albopictus is rapidly spreading and can also migrate between sylvatic and urban environments. Therefore, insecticide resistance monitoring initiatives should also be extended to Ae. albopictus in Brazil in order to maintain chemical compounds as an efficient vector control tool when needed. [ABSTRACT FROM AUTHOR]