BACKGROUND: The control of Aedes aegypti (L.), the main urban vector that causes arboviral diseases such as dengue, Chikungunya and Zika, has proved to be a challenge because of a rapid increase in insecticide resistance. Therefore, adequate monitoring of insecticide resistance is an essential element in the control of Ae. aegypti and the diseases it transmits. We estimated the frequency and intensity (Resistance Frequency Rapid Diagnostic Test [F‐RDT] and Resistance Intensity Rapid Diagnostic Test [I‐RDT]) of pyrethroid resistance in populations of Ae. aegypti from Mexico using the bottle bioassay and results were related to the frequencies of knockdown resistance ( kdr ) mutations V1016I and F1534C. RESULTS: All populations under study were resistant to the pyrethroids: bifenthrin (99%), d ‐( cis – trans )‐phenothrin (6.3% cis , 91.7% trans ) and permethrin (99.5%) according to F‐RDT, and showed moderate to high‐intensity resistance at 10× the diagnostic dose (DD) in I‐RDT. Frequencies of the kdr mutation V1016I in Ae. aegypti populations were correlated with moderate permethrin resistance at 10× DD, whereas F1534C mutation frequencies were correlated with high bifenthrin resistance at 5× DD. Both I1016 and C1535 were highly correlated with high‐intensity phenothrin resistance at 1× to 10× DD. CONCLUSIONS: This study showed that high frequencies of kdr mutations V1016I and F1534C are reflected in the results of F‐RDT and I‐RDT tests. Bioassays in conjunction with the characterization of genetic resistance mechanisms are indispensable in the strategic and rational management of resistance in mosquitoes. © 2018 Society of Chemical Industry

Organic synthetic insecticides continue to be part of the arsenal for combating vector-borne diseases in Mexico. Larvicides are a fundamental part of the process in programs for mosquito control, temephos being one of the most widely used in Mexico. In the present study, we analyzed the frequency of temephos resistance in twenty-three Aedes aegypti populations using the discriminating concentration (DC) of 0.012 mg/L. We also tested 5× DC (0.6 mg/L) and 10× DC (0.12 mg/L) of temephos. The resistance distribution to temephos was interpolated to unsampled sites using the inverse distance weighting (IDW) method. The populations of Ae. aegypti showed a high frequency of resistance (1× DC) with mortality rates below 93% in 22 of the 23 populations analyzed. Moderate resistance intensity (5× DC) was found in 78% of the populations, and high intensity (10× DC) in 30%. Predicted mortality was below 60% in the populations of the Pacific Coast, along the Gulf of Mexico, and in the state of Coahuila in Northeastern Mexico in relation to 1× DC; the Pacific Coast and Northeast patterns hold for 5× and 10× DC. The results suggest the need for rotation of the larvicide to effectively control the larval populations of the vector in the country.

The growing resistance of Aedes aegypti (L.) to conventional insecticides presents a major challenge in arbovirus control, necessitating the exploration of alternative insecticidal chemistries. Spiromesifen, derived from spirocyclic tetronic acids, is widely used against agricultural pests and is crucial in resistance management due to its unique lipid synthesis inhibition. This study evaluates the insecticidal activity of spiromesifen against temephos-resistant Ae. aegypti populations, focusing on larval body weight, volume, biochemical composition, and adult female reproductive potential. Spiromesifen demonstrated effective larvicidal activity, significantly reducing adult emergence. Resistance to spiromesifen was not observed, with resistance ratios (RR₅₀, RR₉₀) ranging from 0.36- to 3.31-fold. Larvae exposed to LC₅₀ showed significant reductions in body weight and volume, and reduced carbohydrate, lipid, and protein contents. Enhanced catalase activity and malondialdehyde levels indicated increased oxidative stress and lipid peroxidation, highlighting its effects on lipid metabolism. Spiromesifen also exhibited sterilizing effects, significantly reducing fecundity and fertility in adult females, thereby impacting Ae. aegypti reproductive capacity. These findings highlight the potential of spiromesifen as a component of integrated vector management strategies, especially in regions with prevalent insecticide resistance in Ae. aegypti, serving as an effective larvicide and impacting adult reproductive outcomes.

The increasing prevalence of insecticide resistance in Aedes aegypti threatens the effectiveness of chemical vector control and highlights the need for alternative approaches targeting mosquito behavior. This study evaluated the oviposition deterrent and larvicidal activity of Salvia munzii essential oil against insecticide-susceptible (New Orleans; NO) and insecticide-resistant (Escobedo) Ae. aegypti strains. The essential oil, dominated by camphor (29.6%), 1,8-cineole (20.8%), and limonene (16.7%), was assessed through laboratory and semi-field bioassays. Larvicidal activity yielded LC₅₀ values of 184.38 µg mL⁻¹ for the susceptible strain and 305.04 µg mL⁻¹ for the resistant strain, with a resistance ratio of 1.65, indicating susceptibility. Oviposition deterrence was quantified using the Oviposition Activity Index (OAI), and median repellent concentrations (RC₅₀) were estimated. Under laboratory conditions, RC₅₀ values were 1.65 µg mL⁻¹ for the NO strain and 1.73 µg mL⁻¹ for the Escobedo strain. Under semi-field conditions, the RC₅₀ for the Escobedo strain decreased to 0.62 µg mL⁻¹. Deterrent activity increased with concentration and persisted for up to 40 days, particularly at higher doses. These results demonstrate that S. munzii essential oil exhibits both larvicidal and oviposition deterrent activity against Ae. aegypti, including a pyrethroid-resistant population, under laboratory and semi-field conditions. The findings support further evaluation of S. munzii essential oil as a potential complementary tool for integrated vector management strategies.

Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mexico and Central America, found across a range of habitats from sylvatic to domestic. Vector control has relied heavily on indoor residual spraying with pyrethroids; however, reinfestation and emerging resistance have limited its long-term effectiveness. In this study, we analyzed the genetic diversity and population structure of T. dimidiata from Veracruz, Oaxaca, and Yucatan using mitochondrial markers (cyt b and ND4) and screened for knockdown resistance (kdr)-type mutations in the voltage-gated sodium channel (VGSC) gene. High haplotype diversity and regional differentiation were observed, with most genetic variation occurring between populations. The ND4 marker provided greater resolution than cyt b, revealing ten haplotypes and supporting evidence of recent population expansion. Haplotype networks showed clear geographic segregation, particularly between populations east and west of the Isthmus of Tehuantepec. The L925I mutation, highly associated with pyrethroid resistance, was detected for the first time in Mexican populations of T. dimidiata, albeit at low frequencies. These findings highlight the importance of integrating population genetic data and resistance surveillance into regionally adapted vector control strategies for Chagas disease.