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Dengue and other Aedes-borne diseases have dramatically increased over the last decades. The Sterile Insect Technique (SIT) has been successfully used as part of integrated pest strategies to control populations of insect-plant and livestock pests and is currently being tested as a potential method to reduce mosquito populations in an environmentally friendly approach. However, during the mass rearing steps needed to produce millions of mosquitoes, egg storage and preservation are essential for a certain amount of time. Eggs of Aedes aegypti have a chorionic pad that functions as a sticky substance to glue them onto the inner walls of larval breeding sites. The chorionic pad is chemically made of hyaluronic acid, a hygroscopic compound, responsible to protect them from desiccation over time. Two commercial products with hygroscopic properties, hydrolyzed collagen, and Hyalurosmooth®, both were tested to assess their ability to prolong egg life storage for A. aegypti and A. albopictus. Results showed that 85–95% of Ae. aegypti eggs were able to hatch up to week 8 after being treated with both hydrophilic compounds, compared with the control 66.3%. These two substances showed promising effects for keeping Ae. aegypti eggs viable during prolonged storage in mass rearing insect production focused on vector control SIT programs.

Aedes aegypti control programs require more sensitive tools in order to survey domestic and peridomestic larval habitats for dengue and other arbovirus prevention areas. As a consequence of the COVID-19 pandemic, field technicians have faced a new occupational hazard during their work activities in dengue surveillance and control. Safer strategies to monitor larval populations, in addition to minimum householder contact, are undoubtedly urgently needed. Drones can be part of the solution in urban and rural areas that are dengue-endemic. Throughout this study, the proportion of larvae breeding sites found in the roofs and backyards of houses were assessed using drone images. Concurrently, the traditional ground field technician’s surveillance was utilized to sample the same house groups. The results were analyzed in order to compare the effectiveness of both field surveillance approaches. Aerial images of 216 houses from El Vergel village in Tapachula, Chiapas, Mexico, at a height of 30 m, were obtained using a drone. Each household was sampled indoors and outdoors by vector control personnel targeting all the containers that potentially served as Aedes aegypti breeding sites. The main results were that the drone could find 1 container per 2.8 found by ground surveillance; however, containers that were inaccessible by technicians in roofs and backyards, such as plastic buckets and tubs, disposable plastic containers and flowerpots were more often detected by drones than traditional ground surveillance. This new technological approach would undoubtedly improve the surveillance of Aedes aegypti in household environments, and better vector control activities would therefore be achieved in dengue-endemic countries.

Background Knockdown resistance (kdr) is the main mechanism that confers resistance to pyrethroids and DDT. This is a product of non-synonymous mutations in the voltage-gated sodium channel (vgsc) gene, and these mutations produce a change of a single amino acid which reduces the affinity of the target site for the insecticide molecule. In Mexico, V410L, V1016I and F1534C mutations are common in pyrethroid-resistant Aedes aegypti (L.) populations. Methods A multiplex PCR was developed to detect the V410L, V1016I and F1534C mutations in Ae. aegypti. The validation of the technique was carried out by DNA sequencing using field populations previously characterized for the three mutations through allele-specific PCR (AS-PCR) and with different levels of genotypic frequencies. Results The standardized protocol for multiplex end-point PCR was highly effective in detecting 15 genotypes considering the three mutations V410L, V1106I and F1534C, in 12 field populations of Ae. aegypti from Mexico. A complete concordance with AS-PCR and DNA sequencing was found for the simultaneous detection of the three kdr mutations. Conclusions Our diagnostic method is highly effective for the simultaneous detection of V410L, V1016I and F1534C, when they co-occur. This technique represents a viable alternative to complement and strengthen current monitoring and resistance management strategies against Ae. aegypti.

Los vectores son animales que transmiten patógenos, entre ellos parásitos, de una persona (o animal) infectada a otra y ocasionan enfermedades graves en el ser humano. Estas enfermedades emergentes y re-emergentes representan un grave problema de salud pública en regiones tropicales y subtropicales, donde gran parte de la población está en riesgo. Los países de escasos recursos son, particularmente, vulnerables al impacto social y económico de estas enfermedades, debido a los recursos limitados en el sector de salud pública para el manejo y prevención de estos padecimientos

Aedes aegypti is the primary urban mosquito vector of viruses causing dengue, Zika and chikungunya fevers –for which vaccines and efective pharmaceuticals are still lacking. Current strategies to suppress arbovirus outbreaks include removal of larval-breeding sites and insecticide treatment of larval and adult populations. Insecticidal control of Ae. aegypti is challenging, due to a recent rapid global increase in knockdown-resistance (kdr) to pyrethroid insecticides. Widespread, heavy use of pyrethroid spacesprays has created an immense selection pressure for kdr, which is primarily under the control of the voltage-gated sodium channel gene (vgsc). To date, eleven replacements in vgsc have been discovered, published and shown to be associated with pyrethroid resistance to varying degrees. In Mexico, F1,534C and V1,016I have co-evolved in the last 16 years across Ae. aegypti populations. Recently, a novel replacement V410L was identifed in Brazil and its efect on vgsc was confrmed by electrophysiology. Herein, we screened V410L in 25 Ae. aegypti historical collections from Mexico, the frst heterozygote appeared in 2002 and frequencies have increased in the last 16 years alongside V1,016I and F1,534C. Knowledge of the specifc vgsc replacements and their interaction to confer resistance is essential to predict and to develop strategies for resistance management.

Background ZIKV is a new addition to the arboviruses circulating in the New World, with more than 1 million cases since its introduction in 2015. A growing number of studies have reported vector competence (VC) of Aedes mosquitoes from several areas of the world for ZIKV transmission. Some studies have used New World mosquitoes from disparate regions and concluded that these have a variable but relatively low competence for the Asian lineage of ZIKV. Methodology/Principal findings Ten Aedes aegypti (L) and three Ae. albopictus (Skuse) collections made in 2016 from throughout Mexico were analyzed for ZIKV (PRVABC59—Asian lineage) VC. Mexican Ae. aegypti had high rates of midgut infection (MIR), dissemination (DIR) and salivary gland infection (SGIR) but low to moderate transmission rates (TR). It is unclear whether this low TR was due to heritable salivary gland escape barriers or to underestimating the amount of virus in saliva due to the loss of virus during filtering and random losses on surfaces when working with small volumes. VC varied among collections, geographic regions and whether the collection was made north or south of the Neovolcanic axis (NVA). The four rates were consistently lower in northeastern Mexico, highest in collections along the Pacific coast and intermediate in the Yucatan. All rates were lowest north of the NVA. It was difficult to assess VC in Ae. albopictus because rates varied depending upon the number of generations in the laboratory. Conclusions/Significance Mexican Ae. aegypti and Ae. albopictus are competent vectors of ZIKV. There is however large variance in vector competence among geographic sites and regions.

Se estudió la capacidad de daño de Prostephanus truncatus para barrenar mazorcas de maíz, en condiciones de campo y su relación con la densidad del insecto en el campo, lejos de los almacenes en tres estados de México, Sonora, Nuevo León y San Luis Potosí. Se estableció una estación de muestro por cuadruplicado en cada estado. Las densidades del insecto se obtuvieron mediante trampas delta cebadas con la feromona, Trunc-call y el daño por el insecto se midió en mazorcas colocadas en jaulas de malla de alambre cercanas a las trampas. Durante un año, cada mes se recogieron las trampas y repusieron por otras nuevas. Uno de los paquetes de mazorcas se recogió cada tres meses y el otro a los seis meses. La densidades de P. truncatus capturados fueron de 649 para San Luis Potosí, 45 para Sonora y 33 para Nuevo León. En ninguno de los tres estados se observó daño en las mazorcas por el barrenador a los 28 días, tampoco a los seis meses en Nuevo León y Sonora, pero sí fueron barrenadas un 15.15% en San Luis Potosí, lo cual coincide con la mayor densidad de insectos capturados.

Background: Free amino acids and acylcarnitines circulating in the blood can be used for diagnosis for metabolic illness and imbalances. To date, the normal reference ranges of amino acids and acylcarnitines in horse peripheral blood have not been established. In this study, the concentrations of 12 amino acids and 26 acylcarnitines were deter‑mined by tandem mass spectrometry in complete blood from 100 healthy horses (50 Quarter horses (QH) [23 males and 27 females] and 50 American Miniature horses (AMH) [15 males and 35 females]) with no signs of metabolic disease. The means and standard deviations were determined and data statistically analyzed. Findings: Concentrations of short, medium, and long chain acylcarnitines were significantly higher in male AMH than in male QH. The concentrations of the amino acids alanine, arginine, glycine, proline (glycogenic), and leucine (ketogenic) were higher in the QH than in the AMH. Female AMH had higher concentrations of propionylcarnitine, leucine, proline, arginine, and ornithine than female QH. Conclusions: Normal reference ranges of amino acids and acylcarnitines were established for AMH and QH. Signifi‑ cant differences were found in concentration of these compounds between breeds and gender.

Background: Aedes aegypti, the ‘yellow fever mosquito’, is the primary vector to humans of dengue and yellow fever flaviviruses (DENV, YFV), and is a known vector of the chikungunya alphavirus (CV). Because vaccines are not yet available for DENV or CV or are inadequately distributed in developing countries (YFV), management of Ae. aegypti remains the primary option to prevent and control outbreaks of the diseases caused by these arboviruses. Permethrin is one of the most widely used active ingredients in insecticides for suppression of adult Ae. aegypti. In 2007, we documented a replacement mutation in codon 1,016 of the voltage-gated sodium channel gene (para) of Ae. aegypti that encodes an isoleucine rather than a valine and confers resistance to permethrin. Ile1,016 segregates as a recessive allele conferring knockdown resistance to homozygous mosquitoes at 5–10 mg of permethrin in bottle bioassays. Methods and Findings: A total of 81 field collections containing 3,951 Ae. aegypti were made throughout Me´xico from 1996 to 2009. These mosquitoes were analyzed for the frequency of the Ile1,016 mutation using a melting-curve PCR assay. Dramatic increases in frequencies of Ile1,016 were recorded from the late 1990’s to 2006–2009 in several states including Nuevo Leo´n in the north, Veracruz on the central Atlantic coast, and Yucata´n, Quintana Roo and Chiapas in the south. From 1996 to 2000, the overall frequency of Ile1,016 was 0.04% (95% confidence interval (CI95) = 0.12%; n = 1,359 mosquitoes examined). The earliest detection of Ile1,016 was in Nuevo Laredo on the U.S. border in 1997. By 2003–2004 the overall frequency of Ile1,016 had increased ,100-fold to 2.7% (60.80% CI95; n = 808). When checked again in 2006, the frequency had increased slightly to 3.9% (61.15% CI95; n = 473). This was followed in 2007–2009 by a sudden jump in Ile1,016 frequency to 33.2% (61.99% CI95; n = 1,074 mosquitoes). There was spatial heterogeneity in Ile1,016 frequencies among 2007–20

Pyrethroid insecticides prolong the opening of voltage-dependent sodium channels in insect nerves to produce instant paralysis and “knock-down.” Many insects have evolved knock-down resistance through nonsynonymous mutations that reduce pyrethroid binding in the channels. In 2006 we discovered one such mutation in the arbovirus mosquito vector Aedes aegypti, called Ile1,016, that confers very high knockdown resistance to the pyrethroid insecticide permethrin in mosquitoes homozygous for this mutation. We examined collections of Ae. aegypti from México during 1996–2009 and found that the overall Ile1,016 frequency increased from <0.1% in 1996–2000, to 2%–5% in 2003–2006, to 38.3%–88.3% in 2007–2009 depending upon collection location. We also demonstrate a strong linear relationship between the frequency of Ile1,016 homozygotes and knockdown rate in bioassays and speculate that widespread use of permethrin-based insecticides in México may be impacting the frequency of Ile1,016. Such a rapid increase is predicted by a simple model of positive directional selection acting on a recessive allele. Unfortunately this model also predicts rapid fixation of Ile1,016 unless there is a negative fitness associated with Ile1,016 in the absence of permethrin and if insecticidal pressure can be reduced.

Los piretroides se aplican con frecuencia como adulticidas de mosquitos y la evolución de la resistencia estos compuestos es la principal amenaza para salud publica. La resistencia ‘knockdown’(kdr) hacia los piretroides es causada frecuentemente por mutaciones no sinónimas en la proteína transmembranal del canal de sodio dependiente de voltaje (para) la cual reduce la unión de los piretroides. La detección temprana de kdr es critica en el desarrollo de estrategias de manejo de resistencia en mosquitos, incluyendo Aedes aegypti, el vector más prevalente de los virus del dengue y la fiebre amarilla. Se encontraron siete mutaciones nuevas en el segmento hidrofóbico 6 del dominio II de para en Ae. aegypti. Los ensayos en larvas que presentan estas mutaciones indicaron una reducida sensibilidad nerviosa a la inhibición por piretroides. Dos de éstos ocurrieron en los codones Iso1011 y Val1016 en los exones 20 y 21 respectivamente. Una transición en la tercera posición de Iso1011 codifica una sustitución a Met1011, y una transversión en la segunda posición de Val1016 codificó una sustitución a Gly1016. Se evaluó esta misma región en 1,318 mosquitos de 32 cepas adicionales, 30 de America Latina. Mientras el alelo Gly1016 no fue detectado en América Latina, se encontraron dos nuevas mutaciones en esos mismos codones. Una transisión en la primera posición del codón 1,011 codifica una sustitución a valina, mientras que una transición en la primera posición del codón 1016 codifica una sustitución a isoleucina. Aquí se desarrollo un ensayo de PCR para estas cuatro mutaciones, y el genotipo puede ser leído en un gel de agarosa o en una curva de desnaturalización. Los experimentos de selección, uno con deltametrina en una cepa de campo proveniente de Santiago de Cuba y otro realizado con permetrina en una ceba de Isla Mujeres, incrementaron rápidamente la frecuencia del alelo Iso1016. Los bioensayos con la descendencia F3 proveniente de los padres homocigotos Val1016 susceptibles

Studies were conducted to determine the host selection patterns of Culex quinquefasciatus in the municipalities of Guadalupe and Escobedo near Monterrey, northeastern Mexico. Mosquitoes were captured inside and outside houses. Chickens and humans were the most common blood sources for all Cx. quinquefasciatus females, accounting for nearby 70% of blood meals. Human blood was detected by enzyme-linked immunosorbent assay in 36.4% and 28.4% of engorged females resting inside houses in Guadalupe and Escobedo, respectively. The proportions of indoor resting females fed on chicken blood were 38.7% and 56.7%, respectively. The weighted and unweighted human blood index (HBI) values were calculated, by using indoor and outdoor data, from the proportions of humanfed mosquitoes. Weighted means (HBI) estimates for Guadalupe and Escobedo were 23.0% and 15.4%, respectively. The forage ratios (FRs) for humans were <1.0 (with or without chicken populations); consequently, it seems that these mosquitoes feed on humans with less frequency in comparison with chickens, horses, and pigs. The FRs for chickens were the highest of all available hosts (1.7 and 3.2), and they were the most abundant hosts in Escobedo, and the second most abundant in Guadalupe, indicating a selective bias of Cx. quinquefasciatus for chickens (i.e. ornithophagic).

Mark–release–recapture experiments were conducted to determine the length of the gonotrophic cycle and rate of survivorship of Culex quinquefasciatus Say in Monterrey, northeastern Mexico. A total of 2,352 field-caught Cx. quinquefasciatus females were marked and released at 8–12 h postemergence in 2 field trials. Sticky ovitraps were used to recapture marked gravid females. One hundred and ten (4.6%) marked females were recaptured during a 12-day sampling period. Recapture rates for the 2 individual trials were 6.4% and 3.5%. The length of the gonotrophic cycle, calculated as the average time between the initial blood meal and the time of recapture of gravid females, was 2–3 days. The first blood-fed mosquitoes were recaptured on the 2nd day postrelease. Gravid egg-laying females were most commonly recaptured at 2–3 days postfeeding. Daily survival estimates for the 2 release dates were of 0.871 and 0.883, respectively.

Se presentan los métodos experimentales más tradicionales que utilizan los practicantes del campo de control biológico, para poder determinar si un enemigo natural (un depredador, parasitoide, parásito o un patógeno) posee capacidad para regular y controlar las poblaciones de los organismos nocivos denominado plagas. Se pone particular énfasis en los casos relacionados con los ecosistemas de mayor estabilidad ecológica, tales como los árboles frutales, donde se manifiesta mayor equilibrio de las poblaciones de organismos.

Desde su introducción al Continente Americano en 1985 Aedes albopictus (Skuse) se ha distribuido en 678 municipios de 25 estados de la Unión Americana. Fue introducida desde Malasia; últimamente se ha ubicado en 866 ciudades de 26 estados de los Estados Unidos. Esta especie es una plaga importante en los estados del Sureste de Estados Unidos. Aedes albopictus es un importante vector de varios virus como Encefalitis Japonesa, Río Ross y Nilo Occidental, además se encuentra en algunos países de Centro y Sudamérica. En México Ae. albopictus se ha distinguido como vector del virus del dengue y su distribución actual ocupa los estados de Coahuila, Nuevo León, Tamaulipas, Veracruz y Chiapas.

The effect of sublethal concentrations (30% lethal concentration [LC30] = 0.41 ppm, LC50 = 1.04 ppm, and LC70 = 2.60 ppm) of VectoBac® 12 aqueous suspension (AS, Bacillus thuringiensis var. israelensis H-14, 600 ITU/mg) on life parameters of Aedes aegypti and its F, progeny (not exposed) was assessed in laboratory tests. Based on the data, it was clear that concentrations of 0.41 ppm of VectoBac significantly shortened the duration of the developmental cycle of the exposed mosquitoes, but not that of the F1 (not exposed). Significant differences were found among the proportions of the age-specific survival between each toxic level, whereas the control did not differ from the treated individuals at the LC50 and LC70. The survival curves of the F1 showed significant differences among the different treatments and with the control. A significant effect was found on the fecundity of adults. Age-specific fecundity was markedly lower for the LC50 and LC70 treatments compared to the LC30 treatment and the control. In general, life parameters were affected inversely and significantly at higher concentrations of VectoBac, both in the exposed population of Ae. aegypti and in the F1 (not exposed).

Cada día la infraestructura y recursos humanos en el país son rebasados por la demanda de la población esto debido a que el crecimiento poblacional tiene un marcado incremento y por otro lado, la eficiente labor del servidor de la salud ha logrado aumentar la esperanza de vida al nacer, todo esto no es proporcional a los recursos disponibles para su atención, por ello es necesario buscar nuevas estrategias mediante las cuales, las acciones encaminadas a preservar la salud lleguen a la población optimizando recursos. En Nuevo León el dengue es una prioridad en Salud Pública por lo cual se buscan nuevas alternativas para su control; la estrategia que se ha utilizado en la entidad a través de los Servicios de Salud es la aplicación de larvicidas mediante la visita domiciliaria o la distribución de este producto en unidades de salud o centros de afluencia poblacional (mercados, centros comerciales, escuelas, etc.), obviamente esta estrategia requiere de una gran movilización de personal, en cambio la Utilización de camiones pipas tratados con Bti reduce el empleo de recursos humanos no siendo así la cobertura de viviendas tratadas. En el presente estudio se probo el bioinsecticida Vectobac 12 AS, formulado a base de Bacillus thuringiensis var israelensis el cual fue aplicado en camiones pipa que distribuyen agua a diversas comunidades del área metropolitana, de tal manera, que una vez que la comunidad recibe dicho recurso, este ya contiene un producto que interrumpirá el ciclo biológico del Aedes aegypti (L) vector del virus del dengue.

Intensive use of the organophosphate insecticide malathion against adults and temephos against larvae of Aedes aegypti in Mexico over the past 30 years has led to problems requiring the use of new larvicides. Toward this objective, Bacillus thuringiensis var. israelensis (Bti), a target-specific and environmentally safer control agent, was evaluated. Laboratory bioassays were done to determine the susceptibility of 2nd- and 3rd-stage larvae of Ae. aegypti to Vectobac® 12 AS (aqueous suspension, 600 ITU/mg). A median lethal concentration of 0.0104 ppm and a 95% lethal concentration of 0.18 ppm were determined after 24 h of exposure to the agent. The values obtained were adjusted for field application and were further tested in the field by the State of Nuevo León, Mexico Vector Control Program. Suspensions of Bti were poured into pipe-water trucks and transferred to domestic 200-gal metal water drums. Larval populations were reduced during a 2-week study period. However, residents complained about a fine dusty film on the water surface. Nevertheless, these results are promising for future Bti field applications.