Beatriz Lopez-Monroy

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.

Dengue is a mosquito-borne viral disease transmitted by Aedes aegypti, the main vector in the Americas. The lack of effective antiviral treatments, limited vaccine coverage, and the increasing resistance of mosquitoes to conventional insecticides emphasize the need for alternative vector control strategies. Plant-derived larvicides represent a promising and eco-friendly approach. This study characterized the phytochemical profile of Persea americana Mill. (var. Lorena) and evaluated its larvicidal activity against Ae. aegypti (Rockefeller strain). The phytochemical profile was assessed through qualitative screening, UV-Vis spectrophotometry, and UHPLC analysis. Larvicidal activity was evaluated against third-instar larvae of Ae. aegypti (Rockefeller strain) and the median lethal concentration (LC₅₀) values were determined. Preliminary screening of ethanolic extracts revealed the presence of various secondary metabolites of pharmacological relevance, including alkaloids, coumarins, tannins, flavonoids, saponins, triterpenes/sterols, and quinones. UV-Vis spectra displayed distinct absorption patterns, with a prominent peak near 260 nm, consistent with the presence of aromatic compounds. UHPLC profiling revealed high chemical diversity across different plant parts, with 70, 98, 71, and 52 peaks (above 1 × 10⁵ intensity) detected in seed, flower, pulp, and leaf extracts, respectively. Larvicidal bioassays showed significant activity, particularly in the seed extract, with LC₅₀ values (µg/mL) of 3.8 (3.3–4.1) for seeds, 22.4 (21.8–23.9) for flowers, 23.0 (21.5–24.6) for pulp, and 29.7 (28.1–31.2) for leaves. This study highlights the larvicidal potential of ethanolic extracts from P. americana (var. Lorena), with the seed extract exhibiting the highest chemical diversity and bioactivity against Ae. aegypti larvae. The detection of key secondary metabolites, including flavonoids, alkaloids, and saponins, supports the development of an effective, plant-based larvicide for sustainable vector control strategies.

Incluimos la presencia de Culex lactator, Cx. apicalis y Toxorhynchites rutilus septentrionalis en Nuevo León. Con la adición de los nuevos registros para el estado, se eleva la diversidad a 72 especies, siendo el género Aedes los de mayor diversidad en Nuevo León con 22 especies y Culex con 18 especies en Nuevo León.

La selección de sitios de oviposición por parte de las hembras de mosquitos es un proceso multifactorial que integra señales químicas, factores físicos y adaptaciones evolutivas. Este comportamiento no solo asegura la supervivencia de la descendencia, sino que también tiene implicaciones críticas en la transmisión de enfermedades como el dengue, malaria y Zika, entre otras. Este artículo explora los mecanismos involucrados en la selección de sitios de oviposición, destacando el papel de las señales químicas, su integración con factores físicos y procesos ecológicos. También se aborda cómo la urbanización y el cambio climático han alterado significativamente los patrones de oviposición, generando hábitats artificiales y modificando la dinámica poblacional de los mosquitos. Finalmente, se analiza cómo estos conocimientos han impulsado el desarrollo de herramientas innovadoras de control vectorial, incluyendo ovitrampas autocidas, dispositivos autodiseminadores y materiales novedosos como hidrogeles y semioquímicos para atraer o repeler hembras grávidas. Estas estrategias integradas ofrecen herramientas efectivas para la vigilancia, reducción de poblaciones vectoriales y mitigación de enfermedades transmitidas por mosquitos.

El desarrollo del sistema CRISPR ha marcado un hito en la entomología, al proporcionar una herramienta poderosa para la edición genómica precisa. Esta tecnología ha revolucionado la investigación en insectos, permitiendo estudios detallados sobre funciones genéticas y facilitando el desarrollo de nuevas estrategias de control de plagas. CRISPR ha sido clave en la mutagénesis dirigida de varios insectos, revelando aspectos cruciales de su biología, como la pigmentación, el desarrollo y la metamorfosis. Además, ha abierto nuevas posibilidades para el manejo de plagas mediante la creación de insectos genéticamente modificados capaces de reducir poblaciones de plagas de manera efectiva. La expansión del uso de CRISPR a especies no tradicionales ha permitido avances significativos en su estudio y manejo, mostrando su potencial en áreas como la conservación y el control de artrópodos de importancia médica, veterinaria y agrícola.

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.

Triatoma species from the phyllosoma subcomplex are sympatrically distributed and include some of the main vectors of Chagas disease in Mexico. Species within this subcomplex, including Triatoma pallidipennis, T. mazzottii, T. picturata, and T. longipennis, have shown resistance to pyrethroid insecticides, associated with mutations in the para gene of the voltage gate sodium channel (VGSC) and the activity of detoxifying enzymes such as β-esterases and glutathione s-transferases (GST). In this study, we evaluated resistance to deltamethrin in hybrids of T. pallidipennis × T. mazzottii (T.pal × T.maz) and T. pallidipennis × T. picturata (T.pal × T.pic) under laboratory conditions, and the inheritance was determined based on the degree of dominance (DO). Additionally, associated resistance mechanisms were analyzed, including detoxifying enzymes and knockdown resistance (kdr) mutations. High levels of resistance to deltamethrin were found in the hybrids of T.pal × T.maz when compared with the susceptible strain of T. mazzottii (RR₅₀ = 17.50). Dominance levels calculated for each hybrid showed values < − 1, confirming that resistance to deltamethrin was recessive. Hybrids exhibited reduced α-, β-esterases, and cytochrome P₄₅₀ mixed-function oxidases (MFO) activity. However, both hybrids showed significantly increased GST activity, particularly in T.pal × T.pic, suggesting enhanced detoxification through this pathway. The kdr mutation A943V, present in T. mazzottii, was found in T.pal × T.maz hybrids. These results emphasize the importance of considering hybridization in resistance management programs and its potential impact on the success of insecticide-based control measures.

Although integrated management and control programs implement intense control measures for adult, pupal, larval, and breeding sites during outbreaks, there is a lack of studies to understand the role of the vector egg stage in disease dynamics. This study aimed to assess the dry season quiescent Aedes aegypti and Aedes albopictus egg populations in houses and backyards in Tapachula, southern Mexico. Two hundred and fifty ovitraps were placed in 125 homes in the Las Americas neighborhood. A total of 7290 eggs were collected from 211 (84.4%) ovitraps. Only 5667 (77.7%) hatched under insectary water immersion and food supply conditions, with 4031 (71.1%) identified as Ae. aegypti, and 1636 (28.8%) as Ae. albopictus, respectively. The remaining 1623 (22.3%) did not hatch due to Delayed Hatching and/or quiescence tropical stage. Eighty-three larval containers were sampled with desiccated eggs during the dry season; most of them were described as trash waste because larvicides are only used for larger containers of 5–10 L. Evolutionary characteristics for the two species including partial egg hatching, ambient-regulated quiescence, the ability of the embryo to survive for a more extended period intra-seasonally, the egg sticking to inner container walls, demands urgent operational research to achieve successful egg-proof larval container methods.

The lack of a Dengue vaccine and pharmacological antiviral drugs has made Vector Control Programs the primary resource in the fight against arboviral diseases. Although Integrated Management and Control programs implement intense control measures for adult, pupal, larval, and breeding sites during outbreaks, there is a lack of studies to understand the role of the vector egg stage in disease dynamics. This study aimed to assess the dry season quiescent Aedes aegypti and Aedes albopictus egg populations in houses and backyards in the tropical city of Tapachula, southern Mexico. Two hundred fifty ovitraps were placed in 125 homes in the Las Americas neighborhood. A total of 7,290 eggs were collected from 211 (84.4%) ovitraps, with 4,031 (71.1%) identified as Ae—aegypti, and 1,636 (28.8%) as albopictus, respectively. Eighty-three larval sites were sampled with desiccated eggs during the dry season; most of them were described as trash-like because larvicides are only used for larger containers of 5-10 L. Evolutionary characteristics for the two species include rapid and delayed hatching of eggs, ambient-regulated quiescence, the ability of the embryo to survive for a more extended period intra-seasonally, and the sticking of egg walls to container walls. This demands urgent operational research to achieve successful egg-proof larval container methods.