Adriana E. Flores

Bio: Adriana E. Flores is an academic researcher from Universidad Autónoma de Nuevo León. The author has contributed to research in topics: Aedes aegypti & Population. The author has an hindex of 18, co-authored 65 publications receiving 1414 citations.

A mutation in the voltage-gated sodium channel gene associated with pyrethroid resistance in Latin American Aedes aegypti.

Abstract: Pyrethroids are commonly used as mosquito adulticides and evolution of resistance to these compounds is a major threat to public health. 'Knockdown resistance' to pyrethroids (kdr) is frequently caused by nonsynonymous mutations in the voltage-gated sodium channel transmembrane protein (para) that reduce pyrethroid binding. Early detection of kdr is critical to the development of resistance management strategies in mosquitoes including Aedes aegypti, the most prevalent vector of dengue and yellow fever viruses. Brengues et al. described seven novel mutations in hydrophobic segment 6 of domain II of para in Ae. aegypti. Assays on larvae from strains bearing these mutations indicated reduced nerve sensitivity to permethrin inhibition. Two of these occurred in codons Iso1011 and Val1016 in exons 20 and 21 respectively. A transition in the third position of Iso1011 encoded a Met1011 replacement and a transversion in the second position of Val1016 encoded a Gly1016 replacement. We have screened this same region in 1318 mosquitoes in 32 additional strains; 30 from throughout Latin America. While the Gly1016 allele was never detected in Latin America, we found two new mutations in these same codons. A transition in the first position of codon 1011 encodes a Val replacement while a transition in the first position of codon 1016 encodes an Iso replacement. We developed PCR assays for these four mutations that can be read either on an agarose gel or as a melting curve. Selection experiments, one with deltamethrin on a field strain from Santiago de Cuba and another with permethrin on a strain from Isla Mujeres, Mexico rapidly increased the frequency of the Iso1016 allele. Bioassays of F(3) offspring arising from permethrin susceptible Val1016 homozygous parents and permethrin resistant Iso1016 homozygous parents show that Iso1016 segregates as a recessive allele in conferring kdr. Analysis of segregation between alleles at the 1011 and 1016 codons in the F(3) showed a high rate of recombination even though the two codons are only separated by a ~250 bp intron. The tools and information presented provide a means for early detection and characterization of kdr that is critical to the development of strategies for resistance management.

Recent rapid rise of a permethrin knock down resistance allele in Aedes aegypti in México.

Abstract: 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 Mexico 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 Mexico 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.

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

Abstract: Aedes aegypti is the primary urban mosquito vector of viruses causing dengue, Zika and chikungunya fevers –for which vaccines and effective 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 space-sprays 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 identified in Brazil and its effect on vgsc was confirmed by electrophysiology. Herein, we screened V410L in 25 Ae. aegypti historical collections from Mexico, the first heterozygote appeared in 2002 and frequencies have increased in the last 16 years alongside V1,016I and F1,534C. Knowledge of the specific vgsc replacements and their interaction to confer resistance is essential to predict and to develop strategies for resistance management.

Mechanisms of insecticide resistance in field populations of aedes aegypti (l.) from quintana roo, southern mexico

Abstract: Potential insecticide-resistance mechanisms were studied with the use of biochemical assays in Aedes aegypti (L.) collected from 5 municipalities representing the north part of Quintana Roo: Benito Juarez, Cozumel, Isla Mujeres, Lazaro Cardenas, and Solidaridad. The activities of α and β esterases, mixed-function oxidases (MFO), glutathione-S-transferase (GST), acethylcholinesterase (AChE), and insensitive acethylcholinesterase (iAChE) were assayed in microplates. Three replicates were performed for each enzyme and 60 males and 60 females were analyzed in each population. The New Orleans (NO) susceptible strain of Ae. aegypti was used as a susceptible reference and the threshold criteria for each enzyme were the highest NO absorbance values. In none of the 6 tests were absorbance values correlated in males and females. α esterases were elevated in Benito Juarez, Cozumel females and in Lazaro Cardenas males and females. β esterases were elevated in Benito Juarez, Cozumel females and in Cozumel and Lazaro Cardenas males. Elevated esterases suggest potential insecticide-resistance mechanisms against organophosphate, carbamate, and some pyrethroid insecticides. Slightly elevated levels of MFOs appeared in Lazaro Cardenas females and in Cozumel, Isla Mujeres, and Solidaridad males. Mechanisms involving iAChE or GST were not apparent.

Prey stage preference and functional response of Euseius hibisci to Tetranychus urticae (Acari: Phytoseiidae, Tetranychidae)

Abstract: The aims of this study were: (a) determine the prey stage preference of female Euseius hibisci (Chant) (Phytoseiidae) at constant densities of different stages of Tetranychus urticae Koch (Tetranychidae), (b) assess the functional response of the predator females to the varying densities of eggs, larvae, or protonymphs of T. urticae, and (c) estimate the functional response of E. hibisci when pollen of Ligustrum ovalifolium was present as well. We conducted experiments on excised pieces of strawberry leaf arenas (Fragaria ananassa) under laboratory conditions of 25 ± 2 °C, 60 ± 5% RH and 12 h photophase. Our results indicated that the predator consumed significantly more prey eggs than other prey stages. Consumption of prey deutonymphs and adults was so low that they were excluded from the non-choice functional response experiments. The functional response on all food items was of type II. The two parameters of the functional response were estimated for each prey type by means of the adjusted non-linear regression model. The highest estimated value a′ (instantaneous rate of discovery) and the lowest value of Th (handling time, including digestion) were found for the predator feeding on prey eggs, and a′ was lowest and Th highest when fed protonymphs. Using the jack-knife method, the values for the functional response parameters were estimated. The values of a′ and Th produced by the model were similar among all prey types except for the eggs, which were different. Using pollen simultaneously with prey larvae decreased the consumption of the latter over the full range of prey densities The suitability of this predator for biological control of T. urticae on strawberry is discussed.

Biology of mosquitoes.

Abstract: 日本には約110種の蚊が産する。その中で医学的に重要なのは, 幼虫(ボウフラ)が人里近くの水域に発生し, 雌成虫がヒトから好んで吸血する種である。西日本ではアカイエカ(南西諸島ではネッタイイエカにおきかわる), チカイエカ, コガタアカイエカ, ヒトスジシマカなどが最も重要である。これらの種は生態がことなるので, その被害に対する効果的対策もことなる。雌成虫が吸血源となる動物を発見して完了するまでの過程は複雑で, わかつていない点もある。

Contemporary status of insecticide resistance in the major Aedes vectors of arboviruses infecting humans.

Abstract: Both Aedes aegytpi and Ae. albopictus are major vectors of 5 important arboviruses (namely chikungunya virus, dengue virus, Rift Valley fever virus, yellow fever virus, and Zika virus), making these mosquitoes an important factor in the worldwide burden of infectious disease. Vector control using insecticides coupled with larval source reduction is critical to control the transmission of these viruses to humans but is threatened by the emergence of insecticide resistance. Here, we review the available evidence for the geographical distribution of insecticide resistance in these 2 major vectors worldwide and map the data collated for the 4 main classes of neurotoxic insecticide (carbamates, organochlorines, organophosphates, and pyrethroids). Emerging resistance to all 4 of these insecticide classes has been detected in the Americas, Africa, and Asia. Target-site mutations and increased insecticide detoxification have both been linked to resistance in Ae. aegypti and Ae. albopictus but more work is required to further elucidate metabolic mechanisms and develop robust diagnostic assays. Geographical distributions are provided for the mechanisms that have been shown to be important to date. Estimating insecticide resistance in unsampled locations is hampered by a lack of standardisation in the diagnostic tools used and by a lack of data in a number of regions for both resistance phenotypes and genotypes. The need for increased sampling using standard methods is critical to tackle the issue of emerging insecticide resistance threatening human health. Specifically, diagnostic doses and well-characterised susceptible strains are needed for the full range of insecticides used to control Ae. aegypti and Ae. albopictus to standardise measurement of the resistant phenotype, and calibrated diagnostic assays are needed for the major mechanisms of resistance.

Catalogue of the Cerambycidae (Coleoptera) of the Neotropical Region. Part II. Subfamily Lamiinae

Abstract: A catalogue of the subfamily Lamiinae (Coleoptera: Cerambycidae) of the Neotropical region is presented. The tribes (36), genera (723), species (4231) and subspecies (60) are listed in alphabetical order. Under each family-group name bibliographical references are given and under each species-group name, data on the type-locality, the acronym of the institution where the type is deposited, the geographical distribution and detailed bibliographical references are provided. Two new combinations are proposed: Urographis eucharis (Bates, 1885), new comb. and Urographis vexillaris (Bates, 1872) new comb., both from Graphisurus LeConte, 1852, not Kirby, 1837. The following new names are given: Alcathousiella new name to replace Alcathous Thomson, 1864, preoccupied by Alcathous Stal, 1863, Hemiptera; Camposiellina new name to replace Camposiella Lane, 1972, preoccupied by Camposiella Hebard, 1924, Orthoptera; Edechthistatus new name to replace Parechthistatus Giesbert, 2001, preoccupied by Parechthistatus Breuning, 1942, Coleoptera; Elytracanthina new name to replace Elytracantha Lane, 1955, preoccupied by Elytracantha Kleine, 1915, Coleoptera; Eranina new name to replace Erana Bates, 1866, preoccupied by Erana Gray, 1840, Aves; Heteresmia new name to replace Esmia Pascoe, 1859, preoccupied by Esmia Leach, 1847, Mollusca; Eupalessa new name to replace Eupales Dillon & Dillon, 1945, preoccupied by Eupales Lefevre, 1885, Coleoptera; Melzerus new name to replace Idiomerus Melzer, 1934, preoccupied by Idiomerus Imms, 1912, Collembola; Midamiella new name to replace Midamus Dillon & Dillon, 1945, preoccupied by Midamus Simon, 1881, Arachnida; Neoamphion new name to replace Amphion Reiche, 1840, preoccupied by Amphion Huebner, 1819, Lepidoptera; Neocolobura new name to replace Colobura Blanchard, 1851, preoccupied by Colobura Billberg, 1820, Lepidoptera; Neohoplonotus new name to replace Hoplonotus Blanchard, 1851, preoccupied by Hoplonotus Schmidt-Goebel, 1846, Coleoptera; Neohylus new name to replace Hylus Dillon & Dillon, 1945, preocuppied by Hylus Van Dyke, 1945, Coleoptera; Neolampedusa new name to replace Lampedusa Dillon & Dillon, 1945, preoccupied by Lampedusa Boettger, 1877, Mollusca; Proseriphus new name to replace Seriphus Bates, 1864, preoccupied by Seriphus Ayres, 1857, Pisces. One new synonym is proposed: Proxepectasis Monne & Giesbert, 1992 = Parepectasoides Breuning, 1979.

Ecology: a prerequisite for malaria elimination and eradication.

Abstract: The Global Malaria Eradication Program, launched in the middle of the last century, over-promised and under-delivered [1]. Decades of pessimism followed, during which malariologists were afraid to even mention the goal of this program by name [2]. The term eradication was often nervously referred to as “the E-word” by a disillusioned community that had learned from bitter experience that optimistic forecasts [3] had been based on an oversimplified view of transmission ecology [4]. Eradication of malaria remains beyond our grasp today, but is nevertheless firmly back on the global health agenda as a long-term target [5].