The neovolcanic axis is a barrier to gene flow among Aedes aegypti populations in Mexico that differ in vector competence for Dengue 2 virus.

The Neovolcanic axis (NVA) traverses Mexico at the 19th parallel and is considered to be a geographic barrier to many species. We have demonstrated that the intersection of the NVA with the coast in Veracruz state is a barrier to gene flow in Ae. aegypti. This was unexpected because the intersection of the NVA with the Pacific Coast is not a barrier to gene flow. Further studies to identify the actual mechanism(s) that is(are) contributing to the lack of gene flow will provide important information on the trafficking potential of Ae. aegypti, which will be of great value to Ae. aegypti control programs. There are significant differences in vector competence for dengue virus between mosquitoes north and south of the NVA, but the epidemiological significance of these finding remains to be determined. Future studies will determine if, for example, the genes that condition midgut infection and vector competence of Ae. aegypti populations provide biomarkers for risk of dengue transmission. Such biomarkers could be of great value to control programs in resource limited environments by allowing targeting of vector control efforts to areas at most risk for epidemic dengue and dengue hemorrhagic fever

Parallel evolution of vgsc mutations at domains IS6, IIS6 and IIIS6 in pyrethroid resistant Aedes aegypti from Mexico

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

Fecundity and morphological description of the eggs of Psorophora cyanescens (Coquillett, 1902) (Diptera: Culicidae) by scanning electron microscopy

Taxonomic studies on mosquitoes are based on the morphological description of larvae and adults. However, few studies have focused on the morphological description of eggs despite their taxonomic value. The description of mosquito eggs by scanning electron microscopy (SEM) allows more detailed descriptions of the ornamentation of the egg, which can provide diagnostic characters of the species. The objective of the work was to describe the eggs of Psorophora cyanescens by SEM and provide fecundity data for the species. In general, Ps. cyanescens eggs are elliptical and very wide. The exochorion is characterized by polygon pattern, where each polygon consists of longitudinal ridges joined by cross-ridges defining regular "hexagonal" areas. Each longitudinal ridge consisting by a small tubercle. The small tubercles are irregular, rectangular, rounded, or tubular. The ornamentation of the exochorion also has long and conical tubercles throughout the egg region. The micropylar apparatus located in the anterior region of the egg has a prominent, continuous and thickness collar. Psorophora cyanescens laid mature eggs at 2.5 days post-feeding. The mean number of eggs per female was 82.20 (± 13.31). This is the first study that describes the ultrastructure of the morphology of the eggs of Ps. cyanescens by SEM. With the contribution of the present work, there are five species of the genus Psorophora whose eggs morphology is described by SEM: Ps. albigenu, Ps. albipes, Ps. columbiae, Ps. cyanescens, and Ps. ferox.Los estudios taxonómicos sobre mosquitos se basan en la descripción morfológica de larvas y adultos. Sin embargo, son pocos los estudios enfocados en la descripción morfológica de los huevos a pesar de su valor taxonómico. La descripción de los huevos de mosquitos mediante microscopía electrónica de barrido (MEB) permite obtener imágenes más detalladas de la ornamentación del huevo, los cuales pueden proporcionar caracteres diagnósticos de la especie. El objetivo del trabajo fue describir los huevos de Psorophora cyanescens por MEB y proporcionar datos de fecundidad de la especie. En general, los huevos de Ps. cyanescens son de forma elíptica y muy anchos. El exocorión se caracteriza por un patrón de polígono, donde cada polígono consta de crestas longitudinales unidas por crestas cruzadas que definen áreas "hexagonales" regulares. Cada cresta longitudinal consiste en un pequeño tubérculo. Los pequeños tubérculos son irregulares, rectangulares, redondeados o tubulares. La ornamentación del exocorión también presenta largos tubérculos cónicos en toda la región del huevo. El aparato micropilar ubicado en la región anterior del huevo tiene un collar prominente, continuo y grueso. Psorophora cyanescens puso huevos maduros a los 2.5 días después de la alimentación sanguínea. El número promedio de huevos por hembra fue de 82.20 (± 13.31). Este es el primer estudio que describe la ultraestructura de la morfología de los huevos de Ps. cyanescens mediante MEB. Con el aporte del presente trabajo, son cinco las especies del género Psorophora que cuentan con la descripción de la morfología de los huevos mediante MEB: Ps. albigenu, Ps. albipes, Ps. columbiae, Ps. cyanescens, and Ps. ferox