Adriana E. Flores-Suarez

GONOTROPHIC CYCLE AND SURVIVORSHIP OF CULEX QUINQUEFASCIATUS (DIPTERA: CULICIDAE) USING STICKY OVITRAPS IN MONTERREY, NORTHEASTERN MEXICO

ABSTRACT 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.

Local Evolution of Pyrethroid Resistance Offsets Gene Flow among Aedes aegypti Collections in Yucatan State, Mexico

The mosquito Aedes aegypti is the major vector of the four serotypes of dengue virus (DENV1-4). Previous studies have shown that Ae. aegypti in Mexico have a high effective migration rate and that gene flow occurs among populations that are up to 150 km apart. Since 2000, pyrethroids have been widely used for suppression of Ae. aegypti in cities in Mexico. In Yucatan State in particular, pyrethroids have been applied in and around dengue case households creating an opportunity for local selection and evolution of resistance. Herein, we test for evidence of local adaptation by comparing patterns of variation among 27 Ae. aegypti collections at 13 single nucleotide polymorphisms (SNPs): two in the voltage-gated sodium channel gene para known to confer knockdown resistance, three in detoxification genes previously associated with pyrethroid resistance, and eight in putatively neutral loci. The SNPs in para varied greatly in frequency among collections, whereas SNPs at the remaining 11 loci showed little variation supporting previous evidence for extensive local gene flow. Among Ae. aegypti in Yucatan State, Mexico, local adaptation to pyrethroids appears to offset the homogenizing effects of gene flow.

Host-feeding preference of Culex quinquefasciatus in Monterrey, northeastern Mexico.

ABSTRACT 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).

Chikungunya Fever in Patients from Northeastern Mexico

Abstract. Chikungunya fever is a viral disease transmitted to humans by Aedes aegypti (L.), and Aedes albopictus (Skuse). The disease is characterized by sudden onset of fever usually accompanied by joint pain. The diagnostic is made by RT-qPCR of the virus genome or serological tests to confirm the presence of IgM and IgG anti-Chikungunya antibodies. A descriptive study was done with serum samples of patients with clinical symptoms of Chikungunya fever referred to the Laboratorio Estatal de Salud Publica de Nuevo Leon, northeastern Mexico. From 101 samples, 41 were positive for Chikungunya virus. The median age of the patients was 31 years old, of which 19 were females and 22 males. Thirty-one of the positive cases had traveled history to others states of Mexico: Guerrero (11), Chiapas (seven), Veracruz (seven), Oaxaca (four), Quintana Roo (one), and Yucatan (one). The most frequent signs in the patients were 92.7% (38) headache, 85.4% (35) myalgia, 73.2% (30) exanthema, 70.7% (29) arthralgia, 68.3% (28) retro-ocular pain. Five serum samples were registered with co-infection with dengue and Chikungunya virus. RNA was extracted from the positive samples, and cDNA was synthesized. The E2 segment of the virus genome was amplified by PCR, cloned, and genotyped. Chikungunya virus genotypes identified in patients from northeastern Mexico differed from those previously reported from other regions of Mexico.

Profiles of Amino Acids and Acylcarnitines Related with Insecticide Exposure in Culex quinquefasciatus (Say).

Culex quinquefasciatus Say is a vector of many pathogens of humans, and both domestic and wild animals. Personal protection, reduction of larval habitats, and chemical control are the best ways to reduce mosquito bites and, therefore, the transmission of mosquito-borne pathogens. Currently, to reduce the risk of transmission, the pyrethroids, and other insecticide groups have been extensively used to control both larvae and adult mosquitoes. In this context, amino acids and acylcarnitines have never been associated with insecticide exposure and or insecticide resistance. It has been suggested that changes in acylcarnitines and amino acids profiles could be a powerful diagnostic tool for metabolic alterations. Monitoring these changes could help to better understand the mechanisms involved in insecticide resistance, complementing the strategies for managing this phenomenon in the integrated resistance management. The purpose of the study was to determine the amino acids and acylcarnitines profiles in larvae of Cx. quinquefasciatus after the exposure to different insecticides. Bioassays were performed on Cx. quinquefasciatus larvae exposed to the diagnostic doses (DD) of the insecticides chlorpyrifos (0.001 μg/mL), temephos (0.002 μg/mL) and permethrin (0.01 μg/mL). In each sample, we analyzed the profile of 12 amino acids and 31 acylcarnitines by LC-MS/MS. A t-test was used to determine statistically significant differences between groups and corrections of q-values. Results indicates three changes, the amino acids arginine (ARG), free carnitine (C0) and acetyl-carnitine (C2) that could be involved in energy production and insecticide detoxification. We confirmed that concentrations of amino acids and acylcarnitines in Cx. quinquefasciatus vary with respect to different insecticides. The information generated contributes to understand the possible mechanisms and metabolic changes occurring during insecticide exposure.

Mining the Alkhumra Hemorrhagic Fever Virus Genomes in 2015

Abstract. Alkhurma hemorrhagic fever virus was first isolated at Jeddah, Saudi Arabia, in the early 1990s, and identified as a member of the Flaviviridae family. The virus has been confirmed only in the sand tampan tick, Ornithodoros savignyi (Audouin), and camel tick, Hyalomma dromedarii Koch. Symptoms of infection include headache, joint and muscle pain, vomiting, and thrombocytopenia, leading to hemorrhagic fever, which can cause death. The purpose of this article was to make a genomic-mined Alkhurma hemorrhagic fever virus from the genomic sequences previously reported in GenBank of NCBI. Genomes were divided into peptides, and different evolutionary parameters were derived using bioinformatics tools. The individual behavior of each of the peptides encoded in the genome of Alkhurma hemorrhagic fever virus is specific; the rate of change indicates different kinds of evolutionary pressure. Complete genome and NS3 protein are under positive selection (dN > dS, p < 0.05), while purifying selection is the main force that drives the evolution of envelope and NS5 proteins (dN < dS, p < 0.05). The spread of viruses such as Alkhurma hemorrhagic fever virus can be catastrophic if they affect the global population without antibodies. Genomic mining of Alkhurma hemorrhagic fever virus provides a powerful tool to design new strategies focused on variable regions of the genome in case of spread.

Current Status of the Insecticide Resistance in Aedes aegypti (Diptera: Culicidae) from Mexico

The mosquito Aedes aegypti (Diptera: Culicidae) is the primary vector of dengue in Mexi‐ co and lately virus Chikungunya, although Aedes albopictus is widely distributed; its role in both diseases’ transmission has not been confirmed. The control of mosquitoes in Mex‐ ico includes source reduction consisting in the elimination of containers that are favorable sites for oviposition and development of the aquatic stage. The use of insecticides is to control larvae and adulticides as outdoor ultra-low volume applications and indoor re‐ sidual spray and more recently impregnated materials. The health department regulates the use of insecticides, and such regulations are revised and adapted over time. Since 1999, the vector control regulations gave preference to the use of pyrethroids, a perme‐ thrin-based formulation to control adult forms. This insecticide was used as the only adulticide in Mexico for more than 10 years. The consequences of this actions have evolved in a widespread and strong resistance to other insecticides, mainly pyrethroids. We include in this revision evidence of resistance reported in Ae. aegypti in Mexico.

Molecular Cloning, Sequence Analysis, and Gene Expression of the Circadian Clock Gene Period in Culex quinquefasciatus Say (Diptera: Culicidae)

Abstract. In prokaryotes and eukaryotes, the Period (PER) gene is important for the circadian clock that regulates some rhythmic biochemical, physiological, and behavioral processes. PER messenger amplification was done by RT-PCR from southern house mosquito, Culex quinquefasciatus Say, larvae collected at three locations in the State of Nuevo Leon, northeastern Mexico. The amplified products were cloned, sequenced, and compared/analyzed with those of other species of mosquitoes. A 3,093-bp amplified product was synthesized by PCR, which is the complete coding DNA sequence (3,027 bp) of PER encoding an open reading frame of 996 amino acid residues and much smaller than the orthologous in other mosquitoes analyzed. No other simultaneous amplification was visualized; thus, possible alternative splicings were discarded or at least not detected by the method. Because PER is a widely conserved gene in prokaryotes and eukaryotes and maintaining colonies of southern house mosquitoes is relativity easy, determining the sequence of the gene in the mosquito provides the possibility of using the gene as a model and generating data on the role in the circadian clock.

Molecular Cloning and Characterization of the Circadian Clock Timeless Gene in Culex quinquefasciatus Say (Diptera: Culicidae)

Abstract. In eukaryotes, the timeless (TIM) gene plays a fundamental role in the control of the circadian clock by regulating several biochemical, physiological, and behavioral processes. RT-PCR was used to amplify TIM mRNA from larval southern house mosquito, Culex quinquefasciatus Say, from three locations in the State of Nuevo Leon in northeastern Mexico. The 3062 bp TIM cDNA was assembled from three overlapping PCRs that were cloned and sequenced. DNA sequence analysis used amplified cDNA fragments to complete coding the DNA sequence (2991 bp). Tim ORF consisting of 996 codons was shorter than the orthologous genes from other mosquito species. A series of deletions in the core sequence of TIM were detected. No other amplification products were visualized, and thus, the possibility of alternative spliced mRNA species was discarded. Because TIM is a widely conserved gene in eukaryotes, and maintaining colonies of Cx. quinquefasciatus is easy, determining the sequence of the TIM gene in the mosquito provides the possibility of its use as a model for circadian clock experimentation.

Análisis de la Distribución Espacial y Temporal de los Casos de Dengue (2009–2012) Mediante un Sistema de Información Geográfica en el Área Metropolitana de Monterrey, NL, México

Resumen. El objetivo fue generar mapas de casos de dengue mediante un Sistema de Información Geográfica (SIG) en el área metropolitana de Monterrey (AMMty), Nuevo León, México indicando las zonas de riesgo. Las muestras positivas a una de las pruebas para dengue, que realiza el Laboratorio Estatal de Salud Pública (LESP) se tomaron como casos. Los casos fueron agrupados en área geoestadística básica (AGEBs). Se definieron AGEBs brote y semana brote. Se presentaron 114 AGEBs Brote y 33 Semanas Brote. Las AGEBs fueron ubicadas en cinco niveles de riesgo: Muy alto, Alto, Mediano, Bajo y en Riesgo. Las AGEBs incluidas en Muy alto y Alto Riesgo abarcaron el 7.9% de las AGEBs y 41.4% casos. Con mayor frecuencia durante las semanas 38–45, temporada de lluvia. En base a estos resultados el AMMty debe considerase endémica.