Publications by authors named "Immo A Hansen"

46 Publications

A novel Tick Carousel Assay for testing efficacy of repellents on

PeerJ 2021 21;9:e11138. Epub 2021 Apr 21.

Department of Biology, New Mexico State University, Las Cruces, NM, United States of America.

Ticks are important vectors of human and veterinary diseases. A primary way ticks gain access to human hosts is by engaging to clothing. Repellents or acaricides sprayed onto fabric are used to deter ticks' access to human hosts. However, there are a limited amount of standardized laboratory assays that can determine the potency and efficacy of repellents. We present a novel fabric-engagement assay referred to as the 'Tick Carousel Assay'. This assay utilizes fabric brushing past ticks located on an artificial grass patch and measures tick engagements to fabric over time. After screening a variety of tick species, we used the lone star tick ) to test the efficacy of four commonly used active ingredients in repellents: DEET, Picaridin, IR3535, and Oil of Lemon Eucalyptus. Repellency was tested immediately, after three hours, and six hours post application to fabric. Our data show that each repellent we tested significantly reduced the number of tick engagements to fabric for at least 6 hours. We did not find significant differences in repellent efficacy between the four active ingredients tested directly and three hours after application. After six hours, Oil of Lemon Eucalyptus repelled ticks more than the other active ingredients. We show that our Tick Carousel Assay provides an affordable, repeatable, and standardized way to compare and test repellent efficacy on treated fabrics. Our results confirm that commonly used repellents applied to fabric are an effective way to reduce tick engagement.
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http://dx.doi.org/10.7717/peerj.11138DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8067905PMC
April 2021

Long-Term Mosquito culture with SkitoSnack, an artificial blood meal replacement.

PLoS Negl Trop Dis 2020 09 17;14(9):e0008591. Epub 2020 Sep 17.

Department of Biology, New Mexico State University, Las Cruces, New Mexico, United States of America.

The reliance on blood is a limiting factor for mass rearing of mosquitoes for Sterile-Insect-Technique (SIT) and other mosquito-based control strategies. To solve this problem, we have developed SkitoSnack, a formulated diet for Aedes aegypti (L) mosquitoes, as an alternative for vertebrate blood. Here we addressed the question if long-term yellow fever mosquito culture with SkitoSnack resulted in changed life history traits and fitness of the offspring compared to blood-raised mosquitoes. We also explored if SkitoSnack is suitable to raise Asian tiger mosquitos, Aedes albopictus (L.), and the human bed bug, Cimex lectularius (L). We measured life history traits for 30th generation SkitoSnack-raised Ae. aegypti and 11th generation SkitoSnack-raised Ae. albopictus, and compared them with control mosquitoes raised on blood only. We compared meal preference, flight performance, and reproductive fitness in Ae. aegypti raised on SkitoSnack or blood. We also offered SkitoSnack to bed bug nymphs. We found that long-term culture with SkitoSnack resulted in mosquitoes with similar life history traits compared to bovine blood-raised mosquitoes in both species we studied. Also, Ae. aegypti mosquitoes raised on SkitoSnack had similar flight performance compared to blood raised mosquitoes, were still strongly attracted by human smell and had equal mating success. Minimal feeding occurred in bed bugs. Our results suggest that long-term culture with the blood-meal replacement SkitoSnack results in healthy, fit mosquitoes. Therefore, artificial diets like SkitoSnack can be considered as a viable alternative for vertebrate blood in laboratory mosquito culture as well as for mosquito mass production for Sterile-Insect-Technique mosquito control interventions. SkitoSnack was not suitable to induce engorgement of bed bugs.
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http://dx.doi.org/10.1371/journal.pntd.0008591DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7523998PMC
September 2020

Low Levels of Pyrethroid Resistance in Hybrid Offspring of a Highly Resistant and a More Susceptible Mosquito Strain.

J Insect Sci 2020 Jul;20(4)

Department of Biology, New Mexico State University, Las Cruces, NM.

The use of insecticides has been a central approach to control disease-transmitting mosquitoes for the last century. The high prevalence of pyrethroid use as public health insecticides has resulted in the evolution of pyrethroid resistance in many populations of Aedes aegypti (Linnaeus) (Diptera: Culicidae), throughout its global distribution range. Insecticide resistance is often correlated with an associated fitness cost. In this project, we studied the phenotypes of hybrid mosquitoes derived from crossing a pyrethroid-resistant strain of Ae. aegypti (Puerto Rico [PR]) with a more susceptible one (Rockefeller [ROCK]). We first sequenced and compared the para gene of both original strains. We then crossed males from one strain with females of the other, creating two hybrids (Puertofeller, Rockorico). We used a Y-tube choice assay to measure the attraction of these strains towards a human host. We then compared the levels of pyrethroid resistance in the different strains. We found three known resistance mutations in the para gene sequence of the PR strain. In our attraction assays, PR females showed lower attraction to humans, than the ROCK females. Both hybrid strains showed strong attraction to a human host. In the insecticide resistance bottle assays, both hybrid strains showed marginal increases in resistance to permethrin compared to the more susceptible ROCK strain. These results suggest that hybrids of sensitive and permethrin-resistant mosquitoes have an incremental advantage compared to more susceptible mosquitoes when challenged with permethrin. This explains the rapid spread of permethrin resistance that was observed many times in the field.
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http://dx.doi.org/10.1093/jisesa/ieaa060DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7329315PMC
July 2020

Efficacy of Active Ingredients From the EPA 25(B) List in Reducing Attraction of Aedes aegypti (Diptera: Culicidae) to Humans.

J Med Entomol 2020 02;57(2):477-484

Department of Biology, New Mexico State University, Las Cruces, NM.

Mosquitoes of the Aedes genus are vectors for dengue, chikungunya, Zika, and yellow fever viruses. Mosquito repellents are an effective way to prevent mosquito bites and reduce the spread of mosquito-borne diseases. In the early 90s, the U.S. Environmental Protection Agency (EPA) published a list of active ingredients that pose minimum risk to human health that can be used as pesticides or repellents without passing the EPA registration process. The present study examined the efficacy of 21 of the active ingredients listed by the EPA 25 (B) exempt list and five commercially available sprays that only contained active ingredients from the EPA 25(B) list in repelling female Aedes aegypti (L.) females. We performed choice bioassays in a controlled laboratory environment, using a Y-tube olfactometer to determine attraction rates of humans to female Ae. aegypti in the presence of one of the 21 active ingredients and five commercially available repellent sprays. We found that cinnamon oil, peppermint oil, spearmint oil, lemongrass oil, and garlic oil reduced mosquito attraction to human odor. Of the five commercial repellent sprays, only one reduced mosquito attraction for up to 30 min in our assay. The EPA 25 (B) list contains active ingredients that under the conditions of our assay repel Ae. aegypti.
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http://dx.doi.org/10.1093/jme/tjz178DOI Listing
February 2020

occurs in populations in New Mexico and Florida, USA.

Ecol Evol 2019 May 26;9(10):6148-6156. Epub 2019 Apr 26.

Biology Department New Mexico State University Las Cruces New Mexico.

The mosquitoes (L.) and . Skuse are the major vectors of dengue, Zika, yellow fever, and chikungunya viruses worldwide. , an endosymbiotic bacterium present in many insects, is being utilized in novel vector control strategies to manipulate mosquito life history and vector competence to curb virus transmission. Earlier studies have found that is commonly detected in . but rarely detected in . In this study, we used a two-step PCR assay to detect in wild-collected samples of . The PCR products were sequenced to validate amplicons and identify strains. A loop-mediated isothermal amplification (LAMP) assay was developed and used for detecting in selected mosquito specimens as well. We found in 85/148 (57.4%) wild specimens from various cities in New Mexico, and in 2/46 (4.3%) from St. Augustine, Florida. was not detected in 94 samples of from Deer Park, Harris County, Texas. detected in from both New Mexico and Florida was the AlbB strain of . A -positive colony of was established from pupae collected in Las Cruces, New Mexico, in 2018. The infected females of this strain transmitted to their progeny when crossed with males of Rockefeller strain of , which does not carry . In contrast, none of the progeny of Las Cruces males mated to Rockefeller females were infected with .
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http://dx.doi.org/10.1002/ece3.5198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6540660PMC
May 2019

Widespread insecticide resistance in Aedes aegypti L. from New Mexico, U.S.A.

PLoS One 2019 22;14(2):e0212693. Epub 2019 Feb 22.

Department of Biology, New Mexico State University, Las Cruces, NM, United States of America.

Background: Aedes aegypti mosquitoes are vectors of a variety of emerging viral pathogens, including yellow fever, dengue, chikungunya, and Zika virus. This species has established endemic populations in all cities across southern New Mexico sampled to date. Presently, control of Aedes-borne viruses relies on deployment of insecticides to suppress mosquito populations, but the evolution of insecticide resistance threatens the success of vector control programs. While insecticide resistance is quite common in Ae. aegypti field populations across much of the U.S., the resistance status of this species in populations from New Mexico has not previously been assessed.

Results: First, we collected information on pesticide use in cities in southern New Mexico and found that the most commonly used active ingredients were pyrethroids. The use of insecticides with the same mode-of-action over multiple years is likely to promote the evolution of resistance. To determine if there was evidence of resistance in some cities in southern New Mexico, we collected Ae. aegypti from the same cities and established laboratory strains to assess resistance to pyrethroid insecticides and, for a subset of populations, to organophosphate insecticides. F2 or F4 generation mosquitoes were assessed for insecticide resistance using bottle test bioassays. The majority of the populations from New Mexico that we analyzed were resistant to the pyrethroids permethrin and deltamethrin. A notable exception to this trend were mosquitoes from Alamogordo, a city that did not report using pyrethroid insecticides for vector control. We screened individuals from each population for known knock down resistance (kdr) mutations via PCR and found a strong association between the presences of the F1534C kdr mutation in the para gene of Ae. aegypti (homologue to F1534C in Musca domestica L.) and pyrethroid resistance.

Conclusion: High-level pyrethroid resistance is common in Ae. aegypti from New Mexico and geographic variation in such resistance is likely associated with variation in usage of pyrethroids for vector control. Resistance monitoring and management is recommended in light of the potential for arbovirus outbreaks in this state. Also, alternative approaches to mosquito control that do not involve insecticides should be explored.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0212693PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6386485PMC
November 2019

Toward Implementation of Mosquito Sterile Insect Technique: The Effect of Storage Conditions on Survival of Male Aedes aegypti Mosquitoes (Diptera: Culicidae) During Transport.

J Insect Sci 2018 Nov 1;18(6). Epub 2018 Nov 1.

Department of Biology, New Mexico State University, Las Cruces, NM.

Sterile insect technique (SIT) is a promising, environmentally friendly alternative to the use of pesticides for insect pest control. However, implementing SIT with Aedes aegypti (Linnaeus) mosquitoes presents unique challenges. For example, during transport from the rearing facility to the release site and during the actual release in the field, damage to male mosquitoes should be minimized to preserve their reproductive competitiveness. The short flight range of male Ae. aegypti requires elaborate release strategies such as release via Unmanned Aircraft Systems, more commonly referred to as drones. Two key parameters during transport and release are storage temperature and compaction rate. We performed a set of laboratory experiments to identify the optimal temperatures and compaction rates for storage and transport of male Ae. aegypti. We then conducted shipping experiments to test our laboratory-derived results in a 'real-life' setting. The laboratory results indicate that male Ae. aegypti can survive at a broad range of storage temperatures ranging from 7 to 28°C, but storage time should not exceed 24 h. Male survival was high at all compaction rates we tested with a low at 40 males/cm3. Interestingly, results from our 'real-life' shipping experiment showed that high compaction rates were beneficial to survival. This study advances key understudied aspects of the practicalities of moving lab-reared insects into the field and lies the foundation for further studies on the effect of transport conditions on male reproductive fitness.
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http://dx.doi.org/10.1093/jisesa/iey103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6220358PMC
November 2018

Colonized , a Sylvatic New World Mosquito Species, Shows a Low Vector Competence for Zika Virus Relative to .

Viruses 2018 08 16;10(8). Epub 2018 Aug 16.

Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA.

The introduction of Zika virus (ZIKV) to the Americas raised concern that the virus would spill back from human transmission, perpetuated by , into a sylvatic cycle maintained in wildlife and forest-living mosquitoes. In the Americas, species are vectors of sylvatic yellow fever virus (YFV) and are therefore candidate vectors of a sylvatic ZIKV cycle. To test the potential of to transmit ZIKV, and were fed on A129 mice one or two days post-infection (dpi) with a ZIKV isolate from Mexico. were sampled at 3, 4, 5, 7, 14, and 21 days post-feeding (dpf) and were sampled at 14 and 21 dpf. ZIKV was quantified in mosquito bodies, legs, and saliva to measure infection, dissemination, and potential transmission, respectively. Of 69 that fed, ZIKV was detected in only one, in all body compartments, at 21 dpf. In contrast, at 14 dpf 100% of 20 that fed on mice at 2 dpi were infected and 70% had virus in saliva. These data demonstrate that is a competent vector for ZIKV, albeit much less competent than .
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http://dx.doi.org/10.3390/v10080434DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6116206PMC
August 2018

The Effect of SkitoSnack, an Artificial Blood Meal Replacement, on Aedes aegypti Life History Traits and Gut Microbiota.

Sci Rep 2018 07 23;8(1):11023. Epub 2018 Jul 23.

Department of Biology, New Mexico State University, Las Cruces, NM, 88003, USA.

Public health research and vector control frequently require the rearing of large numbers of vector mosquitoes. All target vector mosquito species are anautogenous, meaning that females require vertebrate blood for egg production. Vertebrate blood, however, is costly, with a short shelf life. To overcome these constraints, we have developed SkitoSnack, an artificial blood meal replacement for the mosquito Aedes aegypti, the vector of dengue, Zika and chikungunya virus. SkitoSnack contains bovine serum albumin and hemoglobin as protein source as well as egg yolk and a bicarbonate buffer. SkitoSnack-raised females had comparable life history traits as blood-raised females. Mosquitoes reared from SkitoSnack-fed females had similar levels of infection and dissemination when orally challenged with dengue virus type 2 (DENV-2) and significantly lower infection with DENV-4. When SkitoSnack was used as a vehicle for DENV-2 delivery, blood-raised and SkitoSnack-raised females were equally susceptible. The midgut microbiota differed significantly between mosquitoes fed on SkitoSnack and mosquitoes fed on blood. By rearing 20 generations of Aedes exclusively on SkitoSnack, we have proven that this artificial diet can replace blood in mosquito mass rearing.
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http://dx.doi.org/10.1038/s41598-018-29415-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6056539PMC
July 2018

Corrigendum: RNA-Seq Comparison of Larval and Adult Malpighian Tubules of the Yellow Fever Mosquito Reveals Life Stage-Specific Changes in Renal Function.

Front Physiol 2017 7;8:843. Epub 2017 Nov 7.

Department of Biology, New Mexico State University, Las Cruces, NM, United States.

[This corrects the article on p. 283 in vol. 8, PMID: 28536536.].
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http://dx.doi.org/10.3389/fphys.2017.00843DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5681913PMC
November 2017

Fat Body Organ Culture System in Aedes Aegypti, a Vector of Zika Virus.

J Vis Exp 2017 08 19(126). Epub 2017 Aug 19.

Department of Biology, New Mexico State University; Institute of Applied Biosciences, New Mexico State University;

The insect fat body plays a central role in insect metabolism and nutrient storage, mirroring functions of the liver and fat tissue in vertebrates. Insect fat body tissue is usually distributed throughout the insect body. However, it is often concentrated in the abdomen and attached to the abdominal body wall. The mosquito fat body is the sole source of yolk proteins, which are critical for egg production. Therefore, the in vitro culture of mosquito fat body tissues represents an important system for the study of mosquito physiology, metabolism, and, ultimately, egg production. The fat body culture process begins with the preparation of solutions and reagents, including amino acid stock solutions, Aedes physiological saline salt stock solution (APS), calcium stock solution, and fat body culture medium. The process continues with fat body dissection, followed by an experimental treatment. After treatment, a variety of different analyses can be performed, including RNA sequencing (RNA-Seq), qPCR, Western blots, proteomics, and metabolomics. In our example experiment, we demonstrate the protocol through the excision and culture of fat bodies from the yellow fever mosquito, Aedes aegypti, a principal vector of arboviruses including dengue, chikungunya, and Zika. RNA from fat bodies cultured under a physiological condition known to upregulate yolk proteins versus the control were subject to RNA-Seq analysis to demonstrate the potential utility of this procedure for investigations of gene expression.
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http://dx.doi.org/10.3791/55508DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5614350PMC
August 2017

Short-Range Responses of the Kissing Bug Triatoma rubida (Hemiptera: Reduviidae) to Carbon Dioxide, Moisture, and Artificial Light.

Insects 2017 Aug 29;8(3). Epub 2017 Aug 29.

Department of Entomology, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM 88003, USA.

The hematophagous bug is a species of kissing bug that has been marked as a potential vector for the transmission of Chagas disease in the Southern United States and Northern Mexico. However, information on the distribution of in these areas is limited. Vector monitoring is crucial to assess disease risk, so effective trapping systems are required. Kissing bugs utilize extrinsic cues to guide host-seeking, aggregation, and dispersal behaviors. These cues have been recognized as high-value targets for exploitation by trapping systems. A modern video-tracking system was used with a four-port olfactometer system to quantitatively assess the behavioral response of to cues of known significance. Also, response of adults to seven wavelengths of light-emitting diodes (LED) in paired-choice pitfall was evaluated. Behavioral data gathered from these experiments indicate that nymphs orient preferentially to airstreams at either 1600 or 3200 ppm carbon dioxide and prefer relative humidity levels of about 30%, while adults are most attracted to 470 nm light. These data may serve to help design an effective trapping system for monitoring. Investigations described here also demonstrate the experimental power of combining an olfactometer with a video-tracking system for studying insect behavior.
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http://dx.doi.org/10.3390/insects8030090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5620710PMC
August 2017

RNA-Seq Comparison of Larval and Adult Malpighian Tubules of the Yellow Fever Mosquito Reveals Life Stage-Specific Changes in Renal Function.

Front Physiol 2017 9;8:283. Epub 2017 May 9.

Department of Biology, New Mexico State UniversityLas Cruces, NM, USA.

The life history of presents diverse challenges to its diuretic system. During the larval and pupal life stages mosquitoes are aquatic. With the emergence of the adult they become terrestrial. This shifts the organism within minutes from an aquatic environment to a terrestrial environment where dehydration has to be avoided. In addition, female mosquitoes take large blood meals, which present an entirely new set of challenges to salt and water homeostasis. To determine differences in gene expression associated with these different life stages, we performed an RNA-seq analysis of the main diuretic tissue in , the Malpighian tubules. We compared transcript abundance in 4th instar larvae to that of adult females and analyzed the data with a focus on transcripts that encode proteins potentially involved in diuresis, like water and solute channels as well as ion transporters. We compared our results against the model of potassium- and sodium chloride excretion in the Malpighian tubules proposed by Hine et al. (2014), which involves at least eight ion transporters and a proton-pump. We found 3,421 of a total number of 17,478 (19.6%) unique transcripts with a < 0.05 and at least a 2.5 fold change in expression levels between the two groups. We identified two novel transporter genes that are highly expressed in the adult Malpighian tubules, which have not previously been part of the transport model in this species and may play important roles in diuresis. We also identified candidates for hypothesized sodium and chloride channels. Detoxification genes were generally higher expressed in larvae. This study represents the first comparison of Malpighian tubule transcriptomes between larval and adult mosquitoes, highlighting key differences in their renal systems that arise as they transform from an aquatic filter-feeding larval stage to a terrestrial, blood-feeding adult stage.
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http://dx.doi.org/10.3389/fphys.2017.00283DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5422481PMC
May 2017

Simple and Versatile Detection of Viruses Using Anodized Alumina Membranes.

ACS Sens 2016 May 8;1(5):488-492. Epub 2016 Mar 8.

Department of Chemistry and Biochemistry, New Mexico State University, Las Cruces, New Mexico 88003, United States.

A simple sensor for viral particles based on ionic conductivity through anodized alumina membranes was demonstrated using MS2 bacteriophage as an example. A facile two-point measuring scheme is geared toward realization using a computer's sound card input/output capabilities suitable for a fast and inexpensive point of care testing. The lowest detection concentration down to ~7 pfu/mL and a large dynamic range up to ~2000 pfu/mL were obtained due to physical optimization that included proper length and diameter for the pores, removing the oxide layer at the electrode, as well as the chemical optimization of covalent binding of antibodies to the pore's walls.
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http://dx.doi.org/10.1021/acssensors.6b00003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5434760PMC
May 2016

Efficacy of Some Wearable Devices Compared with Spray-On Insect Repellents for the Yellow Fever Mosquito, Aedes aegypti (L.) (Diptera: Culicidae).

J Insect Sci 2017 Jan;17(1)

Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr, Las Cruces, NM 88003.

The current Zika health crisis in the Americas has created an intense interest in mosquito control methods and products. Mosquito vectors of Zika are of the genus Aedes, mainly the yellow fever mosquito, Aedes aegypti. L. The use of repellents to alter mosquito host seeking behavior is an effective method for the prevention of mosquito-borne diseases. A large number of different spray-on repellents and wearable repellent devices are commercially available. The efficacies of many repellents are unknown. This study focuses on the efficacy of eleven different repellents in reducing the number of Ae. aegypti female mosquitoes attracted to human bait. We performed attraction-inhibition assays using a taxis cage in a wind tunnel setting. One person was placed upwind of the taxis cage and the mosquito movement towards or away from the person was recorded. The person was treated with various spray-on repellents or equipped with different mosquito repellent devices. We found that the spray-on repellents containing N,N-Diethyl-meta-toluamide and p-menthane-3,8-diol had the highest efficacy in repelling mosquitoes compared to repellents with other ingredients. From the five wearable devices that we tested, only the one that releases Metofluthrin significantly reduced the numbers of attracted mosquitoes. The citronella candle had no effect. We conclude that many of the products that we tested that were marketed as repellents do not reduce mosquito attraction to humans.
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http://dx.doi.org/10.1093/jisesa/iew117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5388317PMC
January 2017

Dengue virus serotype 2 infection alters midgut and carcass gene expression in the Asian tiger mosquito, Aedes albopictus.

PLoS One 2017 2;12(2):e0171345. Epub 2017 Feb 2.

Department of Biology, New Mexico State University, Las Cruces, New Mexico, United States of America.

Background: The Asian tiger mosquito, Aedes albopictus is currently an important vector for dengue, chikungunya and Zika virus, and its role in transmission of arthropod-borne viruses (arboviruses) may increase in the future due to its ability to colonize temperate regions. In contrast to Aedes aegypti, the dominant vector of dengue, chikungunya and Zika virus, genetic responses of Ae. albopictus upon infection with an arbovirus are not well characterized. Here we present a study of the changes in transcript expression in Ae. albopictus exposed to dengue virus serotype 2 via feeding on an artificial bloodmeal.

Methodology/principal Findings: We isolated midguts and midgut-free carcasses of Ae. albopictus fed on bloodmeals containing dengue virus as well as controls fed on virus-free control meals at day 1 and day 5 post-feeding. We confirmed infection of midguts from mosquitoes sampled on day 5 post-feeding via RT-PCR. RNAseq analysis revealed dynamic modulation of the expression of several putative immunity and dengue virus-responsive genes, some of whose expression was verified by qRT-PCR. For example, a serine protease gene was up-regulated in the midgut at 1 day post infection, which may potentially enhance mosquito susceptibility to dengue infection, while 14 leucine-rich repeat genes, previously shown to be involved in mosquito antiviral defenses, were down-regulated in the carcass at 5 days post infection. The number of significantly modulated genes decreased over time in midguts and increased in carcasses.

Conclusion/significance: Dengue virus exposure results in the modulation of genes in a time- and site-specific manner. Previous literature on the interaction between mosquitoes and mosquito-borne pathogens suggests that most of the changes that occurred in Ae. albopictus exposed to DENV would favor virus infection. Many genes identified in this study warrant further characterization to understand their role in viral manipulation of and antiviral response of Ae. albopictus.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0171345PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5289563PMC
August 2017

Artificial Diets for Mosquitoes.

Int J Environ Res Public Health 2016 12 21;13(12). Epub 2016 Dec 21.

Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA.

Mosquito-borne diseases are responsible for more than a million human deaths every year. Modern mosquito control strategies such as sterile insect technique (SIT), release of insects carrying a dominant lethal (RIDL), population replacement strategies (PR), and -based strategies require the rearing of large numbers of mosquitoes in culture for continuous release over an extended period of time. Anautogenous mosquitoes require essential nutrients for egg production, which they obtain through the acquisition and digestion of a protein-rich blood meal. Therefore, mosquito mass production in laboratories and other facilities relies on vertebrate blood from live animal hosts. However, vertebrate blood is expensive to acquire and hard to store for longer times especially under field conditions. This review discusses older and recent studies that were aimed at the development of artificial diets for mosquitoes in order to replace vertebrate blood.
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http://dx.doi.org/10.3390/ijerph13121267DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5201408PMC
December 2016

Substrate specificity and transport mechanism of amino-acid transceptor Slimfast from Aedes aegypti.

Nat Commun 2015 Oct 9;6:8546. Epub 2015 Oct 9.

Department of Biology, New Mexico State University, Las Cruces, New Mexico 88003, USA.

Anautogenous mosquitoes depend on vertebrate blood as nutrient source for their eggs. A highly efficient set of membrane transporters mediates the massive movement of nutrient amino acids between mosquito tissues after a blood meal. Here we report the characterization of the amino-acid transporter Slimfast (Slif) from the yellow-fever mosquito Aedes aegypti using codon-optimized heterologous expression. Slif is a well-known component of the target-of-rapamycin signalling pathway and fat body nutrient sensor, but its substrate specificity and transport mechanism were unknown. We found that Slif transports essential cationic and neutral amino acids with preference for arginine. It has an unusual dual-affinity mechanism with only the high affinity being Na(+) dependent. Tissue-specific expression and blood meal-dependent regulation of Slif are consistent with conveyance of essential amino acids from gut to fat body. Slif represents a novel transport system and type of transceptor for sensing and transporting essential amino acids during mosquito reproduction.
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http://dx.doi.org/10.1038/ncomms9546DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4608377PMC
October 2015

The Efficacy of Some Commercially Available Insect Repellents for Aedes aegypti (Diptera: Culicidae) and Aedes albopictus (Diptera: Culicidae).

J Insect Sci 2015 ;15:140

Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM 88003 Molecular Biology Program, New Mexico State University, MSC 3MLS, P.O. Box 30001, Las Cruces, NM 88003 Department of Biology, New Mexico State University, 1200 S. Horseshoe Dr., Las Cruces, NM 88003.

Reducing the number of host-vector interactions is an effective way to reduce the spread of vector-borne diseases. Repellents are widely used to protect humans from a variety of protozoans, viruses, and nematodes. DEET (N,N-Diethyl-meta-toluamide), a safe and effective repellent, was developed during World War II. Fear of possible side effects of DEET has created a large market for "natural" DEET-free repellents with a variety of active ingredients. We present a comparative study on the efficacy of eight commercially available products, two fragrances, and a vitamin B patch. The products were tested using a human hand as attractant in a Y-tube olfactometer setup with Aedes aegypti (Linnaeus) and Aedes albopictus (Skuse), both major human disease vectors. We found that Ae. albopictus were generally less attracted to the test subject's hand compared with Ae, aegypti. Repellents with DEET as active ingredient had a prominent repellency effect over longer times and on both species. Repellents containing p-menthane-3,8-diol produced comparable results but for shorter time periods. Some of the DEET-free products containing citronella or geraniol did not have any significant repellency effect. Interestingly, the perfume we tested had a modest repellency effect early after application, and the vitamin B patch had no effect on either species. This study shows that the different active ingredients in commercially available mosquito repellent products are not equivalent in terms of duration and strength of repellency. Our results suggest that products containing DEET or p-menthane-3,8-diol have long-lasting repellent effects and therefore provide good protection from mosquito-borne diseases.
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http://dx.doi.org/10.1093/jisesa/iev125DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4667684PMC
April 2016

Blood serum and BSA, but neither red blood cells nor hemoglobin can support vitellogenesis and egg production in the dengue vector Aedes aegypti.

PeerJ 2015 5;3:e938. Epub 2015 May 5.

Department of Biology, New Mexico State University , Las Cruces, NM , USA ; Institute for Applied Biosciences, New Mexico State University , Las Cruces, NM , USA ; Molecular Biology Program, New Mexico State University , Las Cruces, NM , USA.

Aedes aegypti is the major vector of dengue, yellow fever and chikungunya viruses that put millions of people in endemic countries at risk. Mass rearing of this mosquito is crucial for strategies that use modified insects to reduce vector populations and transmission of pathogens, such as sterile insect technique or population replacement. A major problem for vector mosquito mass rearing is the requirement of vertebrate blood for egg production since it poses significant costs as well as potential health hazards. Also, regulations for human and animal use as blood source can pose a significant obstacle. A completely artificial diet that supports egg production in vector mosquitoes can solve this problem. In this study, we compared different blood fractions, serum and red blood cells, as dietary protein sources for mosquito egg production. We also tested artificial diets made from commercially available blood proteins (bovine serum albumin (BSA) and hemoglobin). We found that Ae. aegypti performed vitellogenesis and produced eggs when given whole bovine blood, serum, or an artificial diet containing BSA. Conversely, egg production was impaired after feeding of the red blood cell fraction or an artificial diet containing only hemoglobin. We also found that egg viability of serum-fed mosquitoes were comparable to that of whole blood and an iron supplemented BSA meal produced more viable eggs than a meal containing BSA alone. Our results indicate that serum proteins, not hemoglobin, may replace vertebrate blood in artificial diets for mass mosquito rearing.
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http://dx.doi.org/10.7717/peerj.938DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4435475PMC
May 2015

Small mosquitoes, large implications: crowding and starvation affects gene expression and nutrient accumulation in Aedes aegypti.

Parasit Vectors 2015 Apr 28;8:252. Epub 2015 Apr 28.

Department of Biology, New Mexico State University, Las Cruces, NM, USA.

Background: Environmental factors such as temperature, nutrient availability, and larval density determine the outcome of postembryonic development in mosquitoes. Suboptimal temperatures, crowding, and starvation during the larval phase reduce adult mosquito size, nutrient stores and affect vectorial capacity.

Methods: In this study we compared adult female Aedes aegypti, Rockefeller strain, raised under standard laboratory conditions (Large) with those raised under crowded and nutritionally deprived conditions (Small). To compare the gene expression and nutritional state of the major energy storage and metabolic organ, the fat body, we performed transcriptomics using Illumina based RNA-seq and metabolomics using GC/MS on females before and 24 hours following blood feeding.

Results: Analysis of fat body gene expression between the experimental groups revealed a large number of significantly differentially expressed genes. Transcripts related to immunity, reproduction, autophagy, several metabolic pathways; including amino acid degradation and metabolism; and membrane transport were differentially expressed. Metabolite profiling identified 60 metabolites within the fat body to be significantly affected between small and large mosquitoes, with the majority of detected free amino acids at a higher level in small mosquitoes compared to large.

Conclusions: Gene expression and metabolites in the adult fat body reflect the individual post-embryonic developmental history of a mosquito larva. These changes affect nutritional storage and utilization, immunity, and reproduction. Therefore, it is apparent that changes in larval environment due to weather conditions, nutrition availability, vector control efforts, and other factors can affect adult vectorial capacity in the field.
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http://dx.doi.org/10.1186/s13071-015-0863-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4415286PMC
April 2015

Functional characterization of aquaporins and aquaglyceroporins of the yellow fever mosquito, Aedes aegypti.

Sci Rep 2015 Jan 15;5:7795. Epub 2015 Jan 15.

1] Department of Biology, New Mexico State University, Las Cruces, NM [2] Institute for Applied Biosciences, New Mexico State University, Las Cruces, NM [3] Molecular Biology Program, New Mexico State University, Las Cruces, NM.

After taking vertebrate blood, female mosquitoes quickly shed excess water and ions while retaining and concentrating the mostly proteinaceous nutrients. Aquaporins (AQPs) are an evolutionary conserved family of membrane transporter proteins that regulate the flow of water and in some cases glycerol and other small molecules across cellular membranes. In a previous study, we found six putative AQP genes in the genome of the yellow fever mosquito, Ae. aegypti, and demonstrated the involvement of three of them in the blood meal-induced diuresis. Here we characterized AQP expression in different tissues before and after a blood meal, explored the substrate specificity of AQPs expressed in the Malpighian tubules and performed RNAi-mediated knockdown and tested for changes in mosquito desiccation resistance. We found that AQPs are generally down-regulated 24 hrs after a blood meal. Ae. aegypti AQP 1 strictly transports water, AQP 2 and 5 demonstrate limited solute transport, but primarily function as water transporters. AQP 4 is an aquaglyceroporin with multiple substrates. Knockdown of AQPs expressed in the MTs increased survival of Ae. aegypti under dry conditions. We conclude that Malpighian tubules of adult female yellow fever mosquitoes utilize three distinct AQPs and one aquaglyceroporin in their osmoregulatory functions.
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http://dx.doi.org/10.1038/srep07795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4295104PMC
January 2015

Mosquito genomics. Highly evolvable malaria vectors: the genomes of 16 Anopheles mosquitoes.

Science 2015 Jan 27;347(6217):1258522. Epub 2014 Nov 27.

Program of Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.

Variation in vectorial capacity for human malaria among Anopheles mosquito species is determined by many factors, including behavior, immunity, and life history. To investigate the genomic basis of vectorial capacity and explore new avenues for vector control, we sequenced the genomes of 16 anopheline mosquito species from diverse locations spanning ~100 million years of evolution. Comparative analyses show faster rates of gene gain and loss, elevated gene shuffling on the X chromosome, and more intron losses, relative to Drosophila. Some determinants of vectorial capacity, such as chemosensory genes, do not show elevated turnover but instead diversify through protein-sequence changes. This dynamism of anopheline genes and genomes may contribute to their flexible capacity to take advantage of new ecological niches, including adapting to humans as primary hosts.
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http://dx.doi.org/10.1126/science.1258522DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4380271PMC
January 2015

The odorant receptor co-receptor from the bed bug, Cimex lectularius L.

PLoS One 2014 20;9(11):e113692. Epub 2014 Nov 20.

Department of Entomology, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, New Mexico, United States of America.

Recently, the bed bug, Cimex lectularius L. has re-emerged as a serious and growing problem in many parts of the world. Presence of resistant bed bugs and the difficulty to eliminate them has renewed interest in alternative control tactics. Similar to other haematophagous arthropods, bed bugs rely on their olfactory system to detect semiochemicals in the environment. Previous studies have morphologically characterized olfactory organs of bed bugs' antenna and have physiologically evaluated the responses of olfactory receptor neurons (ORNs) to host-derived chemicals. To date, odorant binding proteins (OBPs) and odorant receptors (ORs) associated with these olfaction processes have not been studied in bed bugs. Chemoreception in insects requires formation of heteromeric complexes of ORs and a universal OR coreceptor (Orco). Orco is the constant chain of every odorant receptor in insects and is critical for insect olfaction but does not directly bind to odorants. Orco agonists and antagonists have been suggested as high-value targets for the development of novel insect repellents. In this study, we have performed RNAseq of bed bug sensory organs and identified several odorant receptors as well as Orco. We characterized Orco expression and investigated the effect of chemicals targeting Orco on bed bug behavior and reproduction. We have identified partial cDNAs of six C. lectularius OBPs and 16 ORs. Full length bed bug Orco was cloned and sequenced. Orco is widely expressed in different parts of the bed bug including OR neurons and spermatozoa. Treatment of bed bugs with the agonist VUAA1 changed bed bug pheromone-induced aggregation behavior and inactivated spermatozoa. We have described and characterized for the first time OBPs, ORs and Orco in bed bugs. Given the importance of these molecules in chemoreception of this insect they are interesting targets for the development of novel insect behavior modifiers.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0113692PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4239089PMC
December 2015

Emerging roles of aquaporins in relation to the physiology of blood-feeding arthropods.

J Comp Physiol B 2014 Oct 19;184(7):811-25. Epub 2014 Jun 19.

Department of Biological Sciences, McMicken College of Arts and Sciences, University of Cincinnati, Cincinnati, OH, USA,

Aquaporins (AQPs) are proteins that span plasma membranes allowing the movement of water and small solutes into or out of cells. The type, expression levels and activity of AQPs play a major role in the relative permeability of each cell to water or other solutes. Research on arthropod AQPs has expanded in the last 10 years due to the completion of several arthropod genome projects and the increased availability of genetic information accessible through other resources such as de novo transcriptome assemblies. In particular, there has been significant advancement in elucidating the roles that AQPs serve in relation to the physiology of blood-feeding arthropods of medical importance. The focus of this review is upon the significance of AQPs in relation to hematophagy in arthropods. This will be accomplished via a narrative describing AQP functions during the life history of hematophagic arthropods that includes the following critical phases: (1) Saliva production necessary to blood feeding, (2) Intake and excretion of water during blood digestion, (3) Reproduction and egg development and (4) Off-host environmental stress tolerance. The concentration on these phases will highlight known vulnerabilities in the biology of hematophagic arthropods that could be used to develop novel control strategies as well as research topics that have yet to be examined.
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http://dx.doi.org/10.1007/s00360-014-0836-xDOI Listing
October 2014

Aquaporins are critical for provision of water during lactation and intrauterine progeny hydration to maintain tsetse fly reproductive success.

PLoS Negl Trop Dis 2014 Apr 24;8(4):e2517. Epub 2014 Apr 24.

Department of Epidemiology of Microbial Diseases, Yale School of Public Health, Yale University, New Haven, Connecticut, United States of America.

Tsetse flies undergo drastic fluctuations in their water content throughout their adult life history due to events such as blood feeding, dehydration and lactation, an essential feature of the viviparous reproductive biology of tsetse. Aquaporins (AQPs) are transmembrane proteins that allow water and other solutes to permeate through cellular membranes. Here we identify tsetse aquaporin (AQP) genes, examine their expression patterns under different physiological conditions (blood feeding, lactation and stress response) and perform functional analysis of three specific genes utilizing RNA interference (RNAi) gene silencing. Ten putative aquaporins were identified in the Glossina morsitans morsitans (Gmm) genome, two more than has been previously documented in any other insect. All organs, tissues, and body parts examined had distinct AQP expression patterns. Two AQP genes, gmmdripa and gmmdripb ( = gmmaqp1a and gmmaqp1b) are highly expressed in the milk gland/fat body tissues. The whole-body transcript levels of these two genes vary over the course of pregnancy. A set of three AQPs (gmmaqp5, gmmaqp2a, and gmmaqp4b) are expressed highly in the Malpighian tubules. Knockdown of gmmdripa and gmmdripb reduced the efficiency of water loss following a blood meal, increased dehydration tolerance and reduced heat tolerance of adult females. Knockdown of gmmdripa extended pregnancy length, and gmmdripb knockdown resulted in extended pregnancy duration and reduced progeny production. We found that knockdown of AQPs increased tsetse milk osmolality and reduced the water content in developing larva. Combined knockdown of gmmdripa, gmmdripb and gmmaqp5 extended pregnancy by 4-6 d, reduced pupal production by nearly 50%, increased milk osmolality by 20-25% and led to dehydration of feeding larvae. Based on these results, we conclude that gmmDripA and gmmDripB are critical for diuresis, stress tolerance and intrauterine lactation through the regulation of water and/or other uncharged solutes.
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http://dx.doi.org/10.1371/journal.pntd.0002517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3998938PMC
April 2014

Four-way regulation of mosquito yolk protein precursor genes by juvenile hormone-, ecdysone-, nutrient-, and insulin-like peptide signaling pathways.

Front Physiol 2014 20;5:103. Epub 2014 Mar 20.

Department of Biology, New Mexico State University Las Cruces, NM, USA.

Anautogenous mosquito females require a meal of vertebrate blood in order to initiate the production of yolk protein precursors by the fat body. Yolk protein precursor gene expression is tightly repressed in a state-of-arrest before blood meal-related signals activate it and expression levels rise rapidly. The best understood example of yolk protein precursor gene regulation is the vitellogenin-A gene (vg) of the yellow fever mosquito Aedes aegypti. Vg-A is regulated by (1) juvenile hormone signaling, (2) the ecdysone-signaling cascade, (3) the nutrient sensitive target-of-rapamycin signaling pathway, and (4) the insulin-like peptide (ILP) signaling pathway. A plethora of new studies have refined our understanding of the regulation of yolk protein precursor genes since the last review on this topic in 2005 (Attardo et al., 2005). This review summarizes the role of these four signaling pathways in the regulation of vg-A and focuses upon new findings regarding the interplay between them on an organismal level.
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http://dx.doi.org/10.3389/fphys.2014.00103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3960487PMC
June 2014

The effect of the radio-protective agents ethanol, trimethylglycine, and beer on survival of X-ray-sterilized male Aedes aegypti.

Parasit Vectors 2013 Jul 18;6:211. Epub 2013 Jul 18.

Department of Biology, New Mexico State University, Las Cruces, NM, USA.

Background: Sterile Insect Technique (SIT) has been successfully implemented to control, and in some cases, eradicate, dipteran insect populations. SIT has great potential as a mosquito control method. Different sterilization methods have been used on mosquitoes ranging from chemosterilization to genetically modified sterile male mosquito strains; however, sterilization with ionizing radiation is the method of choice for effective sterilization of male insects for most species. The lack of gentle radiation methods has resulted in significant complications when SIT has been applied to mosquitoes. Several studies report that irradiating mosquitoes resulted in a decrease in longevity and mating success compared to unirradiated males. The present study explored new protocols for mosquito sterilization with ionizing radiation that minimized detrimental effects on the longevity of irradiated males.

Methods: We tested three compounds that have been shown to act as radioprotectors in the mouse model system - ethanol, trimethylglycine, and beer. Male Aedes aegypti were treated with one of three chosen potential radioprotectors and were subsequently irradiated with identical doses of long-wavelength X-rays. We evaluated the effect of these radioprotectors on the longevity of male mosquito after irradiation.

Results: We found that X-ray irradiation with an absorbed dose of 1.17 gy confers complete sterility. Irradiation with this dose significantly shortened the lifespan of male mosquitoes and all three radioprotectors tested significantly enhanced the lifespan of irradiated mosquito males.

Conclusion: Our results suggest that treatment with ethanol, beer, or trimethylglycine before irradiation can be used to enhance longevity in mosquitoes.
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http://dx.doi.org/10.1186/1756-3305-6-211DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3723957PMC
July 2013

RNAi-mediated gene knockdown and in vivo diuresis assay in adult female Aedes aegypti mosquitoes.

J Vis Exp 2012 Jul 14(65):e3479. Epub 2012 Jul 14.

Biology Department, New Mexico State University, USA.

This video protocol demonstrates an effective technique to knockdown a particular gene in an insect and conduct a novel bioassay to measure excretion rate. This method can be used to obtain a better understanding of the process of diuresis in insects and is especially useful in the study of diuresis in blood-feeding arthropods that are able to take up huge amounts of liquid in a single blood meal. This RNAi-mediated gene knockdown combined with an in vivo diuresis assay was developed by the Hansen lab to study the effects of RNAi-mediated knockdown of aquaporin genes on Aedes aegypti mosquito diuresis. The protocol is setup in two parts: the first demonstration illustrates how to construct a simple mosquito injection device and how to prepare and inject dsRNA into the thorax of mosquitoes for RNAi-mediated gene knockdown. The second demonstration illustrates how to determine excretion rates in mosquitoes using an in vivo bioassay.
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http://dx.doi.org/10.3791/3479DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3671835PMC
July 2012