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Entomological research is vital for shaping strategies to control mosquito vectors. Its significance also reaches into environmental management, aiming to prevent inconveniences caused by non-vector mosquitoes like the Mansonia Blanchard, 1901 mosquito. In this study, we carried out a five-year (2019-2023) monitoring of these mosquitoes at ten sites in Porto Velho, Rondônia, using SkeeterVac SV3100 automatic traps positioned between the two hydroelectric complexes on the Madeira River. Throughout this period, we sampled 153,125 mosquitoes, of which the Mansonia genus accounted for 54% of the total, indicating its prevalence in the region. ARIMA analysis revealed seasonal patterns of Mansonia spp., highlighting periods of peak density. Notably, a significant decreasing trend in local abundance was observed from July 2021 (25th epidemiological week) until the end of the study. Wind speed was observed to be the most relevant meteorological factor influencing the abundance of Mansonia spp. especially in the Joana D'Arc settlement, although additional investigation is needed to comprehensively analyze other local events and gain a deeper understanding of the ecological patterns of this genus in the Amazon region.

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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.

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BACKGROUND: Malaria is a public health concern in the Amazonian Region, where Anopheles darlingi is the main vector of Plasmodium spp. Several studies hypothesised the existence of cryptic species in An. darlingi, considering variations in behaviour, morphological and genetic aspects. Determining their overall genetic background for vector competence, insecticide resistance, and other elements is essential to better guide strategies for malaria control. OBJECTIVES: This study aimed to evaluate the molecular diversity in genes related to behaviour and insecticide resistance, estimating genetic differentiation in An. darlingi populations from Amazonian localities in Brazil and Pacific Colombian region. METHODS: We amplified, cloned and sequenced fragments of genes related to behaviour: timeless (tim) and period (per), and to insecticide resistance: voltage-gated sodium channel (Na V ) and acetylcholinesterase (ace-1) from 516 An. darlingi DNA samples from Manaus, Unini River, Jaú River and Porto Velho - Brazil, and Chocó - Colombia. We discriminated single nucleotide polymorphisms (SNPs), determined haplotypes and evaluate the phylogenetic relationship among the populations. FINDINGS: The genes per, tim and ace-1 were more polymorphic than Na V . The classical kdr and ace-1 R mutations were not observed. Phylogenetic analyses suggested a significant differentiation between An. darlingi populations from Brazil and Colombia, except for the Na V gene. There was a geographic differentiation within Brazilian populations considering per and ace-1. CONCLUSIONS: Our results add genetic data to the discussion about polymorphisms at population levels in An. darlingi. The search for insecticide resistance-related mechanisms should be extended to more populations, especially from localities with a vector control failure scenario.

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BACKGROUND: Most cases of malaria in Brazil are concentrated in the Amazon region. One of the vector control alternatives recommended by the WHO is the long-lasting insecticidal net (LLIN). This tool is used in the nine federal states of the Brazilian Legal Amazon, where LLINs are essential for reducing vector density and disease transmission as they prevent contact between the mosquito and the individual. The objective of this study was to evaluate the residuality and use of LLIN insecticides in different health regions in a city located in the Brazilian Amazon. METHODS: A total of 17,027 LLINs were installed in the third, fifth and ninth health regions of the municipality of Porto Velho, Rondonia State, Brazil. The LLINs were of two types: Olyset (permethrin), for around the bed, and Interceptor (alphacypermethrin), for around hammocks. The residuality of 172 LLINs was evaluated using cone bioassays to verify the mortality rate of the mosquito Nyssorhynchus darlingi, over a period of 2 years. Structured questionnaires on the acceptance and use of LLINs were distributed to the participating population (n = 391), covering a total sample of 1147 mosquito nets. The mortality rate was evaluated both in terms of days after LLIN installation and the type of insecticide used. Statistical analyses were based on analysis of variance (ANOVA) and Chi-square and were performed using the SPSS statistical program. RESULTS: For the Ny. darlingi mosquito, Interceptor-type LLINs showed residual efficacy, with mortality rates ≥ 80% during the 2-year study period, as determined by the WHO. In contrast, Olyset-type LLINs were associated with a reduction in mortality rates, with 76% and 45% mortality rates in the last two assessments, which occurred during the last 6 months of the study period. Based on the structured questionnaires, the acceptance rate, i.e. percentage of individuals accepting the permanence of the 1147 LLINs sampled, in the three health regions of Porto Velho was 93.8% (of 1076 LLINs). CONCLUSION: The alphacypermethrin-impregnated LLIN was more effective than the LLIN impregnated with permethrin. The results indicate that the correct use of mosquito nets-and consequently the protection of the population-needs to be supported by health promotion actions. These initiatives are considered to be essential for the success of this vector control strategy. New studies that consider the monitoring of the placement of mosquito nets are necessary to provide effective support in the correct use of this methodology.

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BACKGROUND Malaria is a public health concern in the Amazonian Region, where Anopheles darlingi is the main vector of Plasmodium spp. Several studies hypothesised the existence of cryptic species in An. darlingi, considering variations in behaviour, morphological and genetic aspects. Determining their overall genetic background for vector competence, insecticide resistance, and other elements is essential to better guide strategies for malaria control. OBJECTIVES This study aimed to evaluate the molecular diversity in genes related to behaviour and insecticide resistance, estimating genetic differentiation in An. darlingi populations from Amazonian localities in Brazil and Pacific Colombian region. METHODS We amplified, cloned and sequenced fragments of genes related to behaviour: timeless (tim) and period (per), and to insecticide resistance: voltage-gated sodium channel (Na V ) and acetylcholinesterase (ace-1) from 516 An. darlingi DNA samples from Manaus, Unini River, Jaú River and Porto Velho - Brazil, and Chocó - Colombia. We discriminated single nucleotide polymorphisms (SNPs), determined haplotypes and evaluate the phylogenetic relationship among the populations. FINDINGS The genes per, tim and ace-1 were more polymorphic than Na V . The classical kdr and ace-1 R mutations were not observed. Phylogenetic analyses suggested a significant differentiation between An. darlingi populations from Brazil and Colombia, except for the Na V gene. There was a geographic differentiation within Brazilian populations considering per and ace-1. CONCLUSIONS Our results add genetic data to the discussion about polymorphisms at population levels in An. darlingi. The search for insecticide resistance-related mechanisms should be extended to more populations, especially from localities with a vector control failure scenario.

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BACKGROUND: The development of resistance against insecticides in Aedes aegypti can lead to operational failures in control programs. Knowledge of the spatial and temporal trends of this resistance is needed to drive effective monitoring campaigns, which in turn provide data on which vector control decision-making should be based. METHODS: Third-stage larvae (L3) from the F1 and F2 generations of 39 Peruvian field populations of Ae. aegypti mosquitoes from established laboratory colonies were evaluated for resistance against the organophosphate insecticide temephos. The 39 populations were originally established from eggs collected in the field with ovitraps in eight departments of Peru during 2018 and 2019. Dose-response bioassays, at 11 concentrations of the insecticide, were performed following WHO recommendations. RESULTS: Of the 39 field populations of Ae. aegypti tested for resistance to temephos , 11 showed high levels of resistance (resistance ratio [RR] > 10), 16 showed moderate levels of resistance (defined as RR values between 5 and 10) and only 12 were susceptible (RR < 5). The results segregated the study populations into two geographic groups. Most of the populations in the first geographic group, the coastal region, were resistant to temephos, with three populations (AG, CR and LO) showing RR values > 20 (AG 21.5, CR 23.1, LO 39.4). The populations in the second geographic group, the Amazon jungle and the high jungle, showed moderate levels of resistance, with values ranging between 5.1 (JN) and 7.1 (PU). The exception in this geographic group was the population from PM, which showed a RR value of 28.8 to this insecticide. CONCLUSIONS: The results of this study demonstrate that Ae. aegypti populations in Peru present different resistance intensities to temephos, 3 years after temephos use was discontinued. Resistance to this larvicide should continue to be monitored because it is possible that resistance to temephos could decrease in the absence of routine selection pressures.

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BACKGROUND: Botanical substances such as essential oils (EOs) have demonstrated insecticidal properties and are a valid option for vector control. However, free EOs are unreliable as mosquito larvicides due their easy degradation by environmental exposure to ultraviolet light and higher temperatures. Here, we assessed the efficacy of a mosquito larvicide based on orange oil in a yeast-based delivery system against Aedes aegypti strains with different resistance status towards chemical neurotoxic insecticides. This larvicide preparation was physicochemically characterized in a previous report. METHODS: Larvae of four Ae. aegypti strains from different regions of Brazil and different resistance profiles for deltamethrin (pyrethroid) and temephos (organophosphate) were tested against yeast-encapsulated orange oil (YEOO) in laboratory conditions for measurement of LC50 and LC90 values. The same assays were performed with the Belo Horizonte strain under environmental conditions (natural light and temperature). The resistance profiles of these strains were compared to the Rockefeller reference strain in all conditions. RESULTS: YEOO was found to be a highly active larvicide (LC50 < 50 mg/L) against all Ae. aegypti strains tested in both laboratory conditions (LC50 = 8.1-24.7 mg/L) and environmental conditions with natural light and temperature fluctuation (LC50 = 20.0-49.9 mg/L). Moreover, all strains were considered susceptible (RR < 5) to YEOO, considering resistance ratios calculated based on the Rockefeller strain. The resistance ratios were only higher than 2.5 for LC90-95 of Belo Horizonte in the laboratory, probably due the higher heterogeneity associated with older egg papers (> 5 months). CONCLUSION: YEOO demonstrates high larvicidal activity against Ae. aegypti strains with resistant phenotypes for deltamethrin (PY) and temephos (OP). This larvicidal activity suggests the potential for the development of YEOO as an alternative intervention to synthetic insecticides in integrated vector management programs, for populations with resistance to commonly used insecticides.

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Vector control largely relies on neurotoxic chemicals, and insecticide resistance (IR) directly threatens their effectiveness. In some cases, specific alleles cause IR, and knowledge of the genetic diversity and gene flow among mosquito populations is crucial to track their arrival, rise, and spread. Here we evaluated Aedes aegypti populations' susceptibility status, collected in 2016 from six different municipalities of Rio de Janeiro state (RJ), to temephos, pyriproxyfen, malathion, and deltamethrin. We collected eggs of Ae. aegypti in Campos dos Goytacazes (Cgy), Itaperuna (Ipn), Iguaba Grande (Igg), Itaboraí (Ibr), Mangaratiba (Mgr), and Vassouras (Vsr). We followed the World Health Organization (WHO) guidelines and investigated the degree of susceptibility/resistance of mosquitoes to these insecticides. We used the Rockefeller strain as a susceptible positive control. We genotyped the V1016I and F1534C knockdown resistance (kdr) alleles using qPCR TaqMan SNP genotyping assay. Besides, with the use of Ae. aegypti SNP-chip, we performed genomic population analyses by genotyping more than 15,000 biallelic SNPs in mosquitoes from each population. We added previous data from populations from other countries to evaluate the ancestry of RJ populations. All RJ Ae. aegypti populations were susceptible to pyriproxyfen and malathion and highly resistant to deltamethrin. The resistance ratios for temephos was below 3,0 in Cgy, Ibr, and Igg populations, representing the lowest rates since IR monitoring started in this Brazilian region. We found the kdr alleles in high frequencies in all populations, partially justifying the observed resistance to pyrethroid. Population genetics analysis showed that Ae. aegypti revealed potential higher migration among some RJ localities and low genetic structure for most of them. Future population genetic studies, together with IR data in Ae aegypti on a broader scale, can help us predict the gene flow within and among the Brazilian States, allowing us to track the dynamics of arrival and changes in the frequency of IR alleles, and providing critical information to improving vector control program.

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Insecticide resistant Aedes populations have recently been reported in Pakistan, imposing a threat to their control. We aimed to evaluate the susceptibility of Aedes aegypti and Aedes albopictus populations from Lahore to WHO-recommended insecticides and to investigate metabolic and target-site resistance mechanisms. For this purpose, we first carried out bioassays with the larvicides temephos and pyriproxyfen, and the adulticides malathion, permethrin, deltamethrin, alpha-cypermethrin, and etofenprox. We looked for Knockdown resistance mutations (kdr) by qPCR, High-Resolution Melt (HRM), and sequencing. In order to explore the role of detoxifying enzymes in resistance, we carried out synergist bioassay with both species and then checked the expression of CYP9M6, CYP9J10, CYP9J28, CYP6BB2, CCAe3a, and SAP2 genes in Ae. aegypti. Both species were susceptible to organophosphates and the insect growth regulator, however resistant to all pyrethroids. We are reporting the kdr haplotypes 1520Ile + 1534Cys and T1520 + 1534Cys in high frequencies in Ae. aegypti while Ae. albopictus only exhibited the alteration L882M. PBO increased the sensitivity to permethrin in Ae. aegypti, suggesting the participation of P450 genes in conferring resistance, and indeed, CYP928 was highly expressed. We presume that dengue vectors in Lahore city are resistant to pyrethroids, probably due to multiple mechanisms, such as kdr mutations and P450 overexpression.

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Aedes (Stegomyia) aegypti (Linnaeus, 1762) is a mosquito species of significant medical importance. The use of this vector in research studies usually requires a large number of mosquitoes as well as rearing and maintenance in a laboratory-controlled environment. However, laboratory conditions may be different from field environments, presenting stressful challenges such as low food concentration, especially during larval stages, which may, in turn, impair vector biology. Therefore, we tested herein if larval food availability (0.004, 0.009, 0.020, and 0.070% diets) would affect overall adult insect fitness. We observed slower development in mosquitoes fed a 0.004% diet 15 d post-eclosion (DPE) and shorter mean time in mosquitoes fed a 0.020% diet (7 DPE). Larval diet and adult mosquito weight were positively correlated, and heavier females fed higher larval diets exhibited greater blood feeding capacity and oviposition. In addition, larval diet concentrations led to median adult lifespan variations (male/female in days-0.004%: 30 ± 1.41, 45 ± 1.3; 0.009%: 31.5 ± 1.33, 41 ± 1.43; 0.020%: 26 ± 1.18, 41 ± 1.45; 0.070%: 29 ± 1.07, 44 ± 1.34), reduced tolerance to deltamethrin (1 mg/m2) and changes in detoxification enzyme activities. Moreover, in the larval 0.070% diet, females presented higher Zika susceptibility (plaque-forming unit [PFU]: 1.218 × 106) compared with other diets (0.004%: 1.31 × 105; 0.009%: 2.0 × 105; 0.020%: 1.25 × 105 PFU). Altogether, our study demonstrates that larval diet restriction results not only in larval developmental arrest but also in adult fitness impairment, which must be considered in future assessments.

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