Anopheles Quadrimaculatus Say Research Articles

Abundance, distribution, and dynamics of Anopheles species (Diptera: Culicidae) in Iowa, United States.

Malaria was once endemic in the United States prior to its elimination in 1951. However, due to consistent introductions of travel-associated malaria cases and the presence of several native Anopheles species (Diptera: Culicidae) that are competent vectors of malaria, the potential for local (autochthonous) malaria transmission remains a persistent threat in the United States. While several intermittent cases of local malaria transmission have occurred in the United States in the decades since elimination, the emergence of autochthonous transmission in 4 states in 2023 demonstrates the continued risk for future outbreaks. Moreover, these recent examples also highlight significant gaps in current mosquito surveillance efforts that have predominantly focused on threats of arboviral disease, such that our understanding of Anopheles distributions relies only on historical records and offers limited insight into the ecological factors that influence their abundance. Herein, we summarize mosquito surveillance data collected over the last 20 years (2004-2023) across 59 Iowa counties to provide essential information into the spatial distribution, temporal abundance, and trap preferences of Anopheles species in the state. Further analyses of the 2 most abundant species, Anopheles punctipennis Say and Anopheles quadrimaculatus Say, reveal the additional influence of precipitation and forested habitats in defining An. punctipennis abundance. Together, we believe these results provide an increased understanding of previously neglected Anopheles species that have the potential for autochthonous malaria transmission in Iowa and that can be extended to other regions of the United States to enhance preparedness for future malaria outbreaks.

BEHAVIORAL RESPONSE OF ADULT ANOPHELES QUADRIMACULATUS AND AEDES ALBOPICTUS TO DIFFERENT CARBOHYDRATES IN AN OLFACTOMETER

Eleven different carbohydrates were evaluated to determine the behavioral response of adult Anopheles quadrimaculatus Say and Aedes albopictus Skuse using an olfactometer. The carbohydrates used in the study are arabinose, fructose, glucose, maltose, melezitose, meliniose, raffinose, rhamnose, sucrose, trehalose, and turanose. The results showed that both species of mosquitoes regardless of the sex had significantly higher attraction to arabinose, maltose, meliniose, and trehalose than other 7 carbohydrates tested. Both sexes and both species responded to maltose and trehalose in considerable numbers, and the least responses were to sucrose except by male Ae. albopictus. These findings may provide insights to the development of more effective sugar-based toxic baits for the operational application in mosquito control programs.

Combining DL-Methionine and Bacillus thuringiensis Subspecies israelensis: Prospects for a Mosquito Larvicide.

Simple SummaryWith the increasing threat that mosquito borne diseases pose to public health, the demand for environmentally sustainable pesticides has been increasing in recent years. Pesticides that target the larval stage (i.e., larvicides) are particularly useful for controlling mosquito populations as they strike at the source. Currently, Bacillus thuringiensis subspecies israelensis (BTI) is a commonly used mosquito larvicide but some studies show signs of resistance development. DL-methionine is an essential amino acid that has mosquito larvicidal capabilities, while also having minimal negative effects on non-target organisms in laboratory experiments. In this study, our objective was to evaluate the effect of these two larvicides individually and together at reducing mosquito survival. We found that while DL-methionine was more toxic to Anopheles quadrimaculatus than Aedes aegypti, the opposite was true for BTI. Additionally, when the combination was tested against An. quadrimaculatus larvae at higher concentrations the active ingredients were complementary and the effect was equal to both ingredients alone. However, the active ingredients were antagonistic when tested against Ae. aegypti larvae. These findings are important as they show the potential for DL-methionine and the combination of DL-methionine with BTI to be used as a larvicide against Anopheles mosquitoes, which are responsible for transmitting malaria.Mosquito larvicides can reduce mosquito populations at the source, potentially decreasing biting rates and pathogen transmission. However, there is a growing need for mosquito larvicides that are environmentally sustainable. Bacillus thuringiensis subspecies israelensis (BTI) is a naturally occurring bacterium commonly used as a larvicide to manage mosquito populations. Methionine is an essential amino acid that has demonstrated toxic properties against larval mosquitoes in laboratory experiments, while having minimal effects on non-target organisms. The goal of this study was to evaluate the potential for a novel combination larvicide by testing for compatibility between these two active ingredients. We began by determining the lethal concentration values (LCs) of BTI and DL-methionine against Anopheles quadrimaculatus Say and Aedes aegypti Linnaeus (Diptera: Culicidae) larvae. These bioassays were conducted in glass jars and mortality was observed 48 h post-treatment. We found that while DL-methionine was more toxic to An. quadrimaculatus than Ae. aegypti, the opposite was true for BTI. Then, we used these LCs to conduct bioassays with a combination of BTI and DL-methionine to determine the relationship between the two active ingredients when used against An. quadrimaculatus and Ae. aegypti larvae. The findings of this study demonstrate that BTI and DL-methionine have the potential to be complementary due to their additive properties at higher concentrations and effect levels when tested against An. quadrimaculatus. However, an antagonistic relationship was detected at the concentrations tested with Ae. aegypti. These results are encouraging and imply that a DL-methionine or BTI/DL-methionine combination larvicide could be used in management of Anopheles species.

Methionine as a safe and effective novel biorational mosquito larvicide.

Mosquito larvicides provide a source-reduction strategy to diminish adult females that bite and potentially spread pathogens. Demands are mounting for new and innovative effective biorational larvicides, due to the development of resistance to some currently utilized mosquito larvicides, undesirable non-target effects, and US Environmental Protection Agency (EPA) restrictions. Methionine is a human nutrient essential amino acid that unexpectedly has been shown to be a valuable safe pest management tool against select insect pests that possess alkaline gut physiology. The present study evaluated larvicidal toxicity of methionine in several pestiferous mosquito (Diptera: Culicidae) genera. Concentration-dependent DL-methionine kinetics assays of survival and pupation were conducted in larvae of Aedes albopictus Skuse, Anopheles quadrimaculatus Say, and Culex tarsalis Coquillett in glass jars. High concentrations of DL-methionine yielded 100% mortality for all test species and prevented pupation at a rate equivalent to Bacillus thuringiensis israelensis (Bti) treatments. Concentration kinetics indicated that An. quadrimaculatus was 10-fold more sensitive to DL-methionine than Ae. albopictus and Cx. tarsalis. EPA regulations currently exempt methionine in pesticide formulations applied to agricultural crops. This study demonstrates that methionine is a highly effective mosquito larvicide that can provide a beneficial new biorational, environmentally sustainable tool to control pestiferous mosquitoes. © 2018 Society of Chemical Industry.

Vapor toxicity of five volatile pyrethroids against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles quadrimaculatus (Diptera: Culicidae).

Mosquito mortality has been documented in numerous studies of spatial repellents but the concentration-dependent toxicity of spatial repellent vapors has not been documented. To address this issue, prallethrin, flumethrin, metofluthrin, transfluthrin, and meperfluthrin were selected for comparative study against Aedes albopictus (Skuse), Ae. aegypti (L.), Culex quinquefasciatus Say, and Anopheles quadrimaculatus Say. Mosquito were exposed to vapors of each chemical for 2, 4, and 24 h with mortality recorded at each time point. A second experiment involved exposing mosquitoes to vapors for 2 h, then transferring them to untreated holding containers and held for 24 h. For these mosquitoes, readings were only taken after 24 h to allow for metabolic detoxification and recovery. LC50 and LC90 data indicated that transfluthrin and meperfluthrin had the greatest toxicity across all species, followed by metofluthrin, prallethrin, and flumethrin. Our findings, through the direct comparison of these compounds, suggest that transfluthrin, meperfluthrin, and metofluthrin be considered for further development. The vapor toxicity for the aforementioned compounds significantly exceeds prallethrin, which is currently market available as an adulticidal active ingredient in public health pest control. © 2018 Society of Chemical Industry.

Development of an autodissemination strategy for the deployment of novel control agents targeting the common malaria mosquito, Anopheles quadrimaculatus say (Diptera: Culicidae)

BackgroundThe reduced efficacy of current Anopheline mosquito control methods underscores the need to develop new methods of control that exploit unique target sites and/or utilizes novel deployment methods. Autodissemination methodologies using insect growth regulators (IGRs) is growing in interest and has been shown to be effective at controlling Aedes mosquitoes in semi-field and field environments, yet little information exists for Anopheline mosquitoes. Therefore, we tested the hypothesis that female-driven autodissemination of an IGR combined with a new mechanism of action insecticide (Kir channel inhibitor) could be employed to reduce Anopheline populations.MethodologyWe studied the ability of three IGRs to be transferred to the larval habitat during oviposition in laboratory and semi-field environments. Adult mosquitoes were exposed to the chemicals for 4 hours immediately after blood feeding and efficacy was tested using classical methodologies, including adult emergence inhibition and High Performance Liquid Chromatography (HPLC). A complete autodissemination design was tested in a semi-field environment.Principal findingsLarval survivability and adult emergence were significantly reduced in habitats that were visited by novaluron treated adults, but no statistical differences were observed with pyriproxyfen or triflumuron. These data suggested novaluron, but not pyriproxyfen or triflumuron, was horizontally transferred from the adult mosquito to the larval habitat during oviposition. HPLC studies supported the toxicity data and showed that novaluron was present in the majority of larval habitats, suggesting that novaluron can be horizontally transferred by Anopheles quadrimaculatus. Importantly, the combination of novaluron and the Kir channel inhibitor, VU041, was capable of reducing adult and larval populations in semi-field environments.ConclusionsNovaluron can be transferred to the adult at a greater efficacy and/or is not degraded as quickly during the gonotropic cycle when compared to pyriproxyfen or triflumuron. Pending field confirmation, autodissemination approaches with novaluron may be a suitable tool to manage Anopheles populations.

Electrophysiological Responses of Gustatory Receptor Neurons on the Labella of the Common Malaria Mosquito, Anopheles quadrimaculatus (Diptera: Culicidae).

We recorded electrical responses from sensory cells associated with gustatory sensilla on the labella of female Anopheles quadrimaculatus Say to salt, sucrose, quinine (a feeding deterrent), and the insect repellent, N,N-diethyl-3-methylbenzamide (DEET). A salt-sensitive cell responded to increasing concentrations of sodium chloride. A second cell was activated by increasing sucrose concentrations, while quinine, DEET, or a mixture of quinine + DEET elicited spike activity from a third cell, an apparent bitter- or deterrent-sensitive cell. Both quinine and DEET suppressed activity of the sugar-sensitive cell; sucrose suppressed activity of the bitter- or deterrent-sensitive cell. These results demonstrate separate gustatory pathways for a feeding stimulant and aversive contact cues mediated through distinct sensory inputs on the labellum. This sensory appendage may serve as a useful target to disrupt feeding behavior in this and other anopheline species, which transmit diseases like malaria to human populations.

Expression Profiles and RNAi Silencing of Inhibitor of Apoptosis Transcripts in Aedes, Anopheles, and Culex Mosquitoes (Diptera: Culicidae).

Effective mosquito control is vital to curtail the devastating health effects of many vectored diseases. RNA interference (RNAi)-mediated control of mosquitoes is an attractive alternative to conventional chemical pesticides. Previous studies have suggested that transcripts for inhibitors of apoptosis (IAPs) may be good RNAi targets. To revisit and extend previous reports, we examined the expression of Aedes aegypti (L.) IAPs (AaeIAPs) 1, 2, 5, 6, 9, and a viral IAP-associated factor (vIAF) as well as Anopheles quadrimaculatus Say and Culex quinquefasciatus Say IAP1 homologs (AquIAP1 and CquIAP1) in adult females. Expression profiles of IAPs suggested that some older female mosquitoes had significantly higher IAP mRNA levels when compared to the youngest ones. Minor differences in expression of AaeIAPs were observed in mosquitoes that imbibed a bloodmeal, but the majority of the time points (up to 48 h) were not significantly different. Although in vitro experiments with the Ae. aegypti Aag-2 cell line demonstrated that the various AaeIAPs could be effectively knocked down within one day after dsRNA treatment, only Aag-2 cells treated with dsIAP1 displayed apoptotic morphology. Gene silencing and mortality were also evaluated after topical application and microinjection of the same dsRNAs into female Ae. aegypti. In contrast to previous reports, topical administration of dsRNA against AaeIAP1 did not yield a significant reduction in gene expression or increased mortality. Knockdown of IAP1 and other IAPs by microinjection did not result in significant mortality. In toto, our findings suggest that IAPs may not be suitable RNAi targets for controlling adult mosquito populations.

Larvicidal and Biting Deterrent Activity of Essential Oils of Curcuma longa, Ar-turmerone, and Curcuminoids Against Aedes aegypti and Anopheles quadrimaculatus (Culicidae: Diptera).

Essential oils and extract of Curcuma longa, ar-turmerone, and curcuminoids were evaluated for their larvicidal and deterrent activity against mosquitoes. Ar-turmerone and curcuminoids constituted 36.9, 24.9 and 50.6% of rhizome oil, leaf oil, and rhizome extract, respectively. Ar-turmerone was the major compound of the rhizome oil (36.9%) and leaf oil (24.9%). The ethanolic extract had 15.4% ar-turmerone with 6.6% bisdesmethoxycurcumin, 6.1% desmethoxycurcumin, and 22.6% curcumin. In in vitro studies, essential oils of the leaf (biting deterrence index [BDI] = 0.98), rhizome (BDI = 0.98), and rhizome ethanolic extract (BDI = 0.96) at 10 µg/cm(2) showed biting deterrent activity similar to DEET at 25 nmol/cm(2) against Aedes aegypti L. Among the pure compounds, ar-turmerone (BDI = 1.15) showed the biting deterrent activity higher than DEET at 25 nmol/cm(2) whereas the activity of other compounds was lower than DEET. In Anopheles quadrimaculatus Say, only ar-turmerone showed deterrent activity similar to DEET. In dose-response bioassay, ar-turmerone showed significantly higher biting deterrence than DEET at all the dosages. Ar-turmerone, at 15 nmol/cm(2), showed activity similar to DEET at 25 nmol/cm(2) and activity at 5 nmol/cm(2) was similar to DEET at 20 and 15 nmol/cm(2). Leaf essential oil with LC(50) values of 1.8 and 8.9 ppm against larvae of An. quadrimaculatus and Ae. aegypti, respectively, showed highest toxicity followed by rhizome oil and ethanolic extract. Among the pure compounds, ar-turmerone with LC(50) values of 2.8 and 2.5 ppm against larvae of An. quadrimaculatus and Ae. aegypti, respectively, was most toxic followed by bisdesmethoxycurcumin, curcumin, and desmethoxycurcumin.

Essential Oils of Echinophora lamondiana (Apiales: Umbelliferae): A Relationship Between Chemical Profile and Biting Deterrence and Larvicidal Activity Against Mosquitoes (Diptera: Culicidae).

The essential oils from the flower, leaf, and stem of Echinophora lamondiana B.Yildiz et Z.Bahcecioglu were analyzed by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. In total, 41, 37, and 44 compounds were identified, which accounted for 98.0, 99.1, and 97.0% of flower, leaf, and stem essential oils, respectively. The monoterpenic hydrocarbons were found to be high in all samples of the essential oils. The major components of essential oils from flower, leaf, and stem of E. lamondiana were δ-3-carene (61.9, 75.0, and 65.9%, respectively), α-phellandrene (20.3, 14.1, and 12.8%, respectively), and terpinolene (2.7, 3.3, and 2.9%, respectively). Flower and leaf essential oils and terpinolene produced biting deterrence similar to 25 nmol/cm(2) N, N-diethyl-meta-toluamide (DEET; 97%) against Aedes aegypti (L.) and Anopheles quadrimaculatus Say. Compounds (+)-δ-3-carene, (R)-(-)-α-phellandrene, and water-distilled essential oils were significantly less repellent than DEET. Among essential oils, leaf oil was the least toxic of the oils, with an LC50 value of 138.3 ppm, whereas flower essential oil killed only 32% larvae, and no mortality of stem oil at highest tested dosages against Ae aegypti was observed. Terpinolene and α-phellandrene showed higher toxicity than δ-3-carene in both the species. In contrast to Ae. aegypti, all the essential oils showed toxicity in An. quadrimaculatus, and toxicity was higher in leaf oil than the other two oils. These results could be useful in finding new, safe, and more effective natural biopesticides and biting deterrent or repellents against Ae. aegypti.

Biting deterrence, repellency, and larvicidal activity of Ruta chalepensis (Sapindales: Rutaceae) essential oil and its major individual constituents against mosquitoes.

The essential oil from aerial parts of Ruta chalepensis L. (Sapindales: Rutaceae) was obtained by hydrodistillation, and its chemical profile was identified using gas chromatography and gas chromatography-mass spectrometry. Compounds, 2-undecanone (43.2%), 2-nonanone (27.9%), and 2-nonyl acetate (10.6%) were the major constituents of the oil. Biting deterrent activity of R. chalepensis essential oil at 10 and 50 microg/cm2, 2-undecanone at 8.5 microg/cm2, 2-nonanone at 9 microg/cm2, and 2-nonyl acetate at 9.3 microg/cm2 was similar to DEET (N, N-diethyl-meta-toluamide) at 4.8 microg/cm2, against Aedes aegypti L. Biting deterrent activity of R. chalepensis oil at 50 microg/cm2 against Anopheles quadrimaculatus Say was statistically similar to DEET at 4.8 microg/cm2, whereas the activity was lower in the other compounds tested. In cloth patch assay, R. chalepensis essential oil was effective at 187 microg/cm2, whereas 2-undecanone was effective at 108.9 microg/cm2 against Ae. aegypti. In larval bioassays, 2-undecanone showed similar toxicity whereas toxicity of R. chalepensis essential oil and 2-nonanone was higher at 24-h posttreatment at the LD50 in An. quadrimaculatus than Ae. aegypti. This study revealed that R. chalepensis essential oil and its major compounds were active biting deterrents against Ae. aegypti at higher application rates whereas only the essential oil showed activity similar to DEET against An. quadrimaculatus. 2-undecanone was the most active compound in in vivo repellency bioassay against Ae. aegypti. Chemical composition of R. chalepensis essential oil varies because of plant production and harvest practices, and the activity level of the essential oil may depend on the source of the sample.

Prevalence of <I>Dirofilaria immitis</I> (Nematoda: Filarioidea) in Mosquitoes From Northeast Arkansas, the United States

A mosquito survey was conducted to identify which species of mosquitoes carry Dirofilaria immitis (Leidy) (Nematoda: Filarioidea), dog heartworm, in northeast Arkansas. Using polymerase chain reaction, mosquitoes were analyzed for D. immitis, Dirofilaria repens Railliet & Henry, and Acanthocheilonema dracunculoides Cobbold. Mosquitoes were collected from April to October 2009 using black light ultraviolet traps baited with dry ice. Sixteen mosquito species were identified. D. immitis was identified in nine mosquito species, which included Aedes vexans (Meigen), Anopheles quadrimaculatus Say, Anopheles punctipennis (Say), Culex pipiens quinquefasciatus Say, Culex erraticus (Dyer & Knab), Culiseta inornata (Williston), Psorophora columbiae (Dyer & Knab), Psorophora ferox (Humboldt), and Psorophora howardii Coquillett. No D. repens or A. dracunculoides DNA was amplified. Of the 1,212 mosquito pools tested, 7.3% were positive for D. immitis. Frequency of D. immitis infections from six collection sites ranged from 2.1 to 19.4%. Ae. vexans and An. quadrimaculatus were the two most abundant species, composing 58.7 and 23.7% of the total mosquitoes collected, with 9.6 and 6.9% of pools positive for D. immitis, respectively. To investigate localized vector infection rates of D. immitis, mosquitoes were collected from inside the kennel of a heartworm-positive dog. Of the 114 mosquitoes collected, 84 (73.7%) were positive for D. immitis. The frequency of D. immitis-infected mosquitoes collected near a heartworm-positive dog was considerably higher than in the original six collection sites, suggesting a single heartworm-positive dog potentially increases infection pressure on susceptible animals sharing mosquito exposure.

<I>Aedes aegypti</I> (Diptera: Culicidae) Biting Deterrence: Structure-Activity Relationship of Saturated and Unsaturated Fatty Acids

In this study we evaluated the biting deterrent effects of a series of saturated and unsaturated fatty acids against Aedes aegypti (L), yellow fever mosquito (Diptera: Culicidae) using the K & Dbioassay module system. Saturated (C6:0 to C16:0 and C18:0) and unsaturated fatty acids (C11:1 to C14:1, C16:1, C18:1, and C18:2) showed biting deterrence index (BDI) values significantly greater than ethanol, the negative control. Among the saturated fatty acids, mid chain length acids (C10:0 to C13:0) showed higher biting deterrence than short (C6:0 to C9:0) and long chain length acids (C14:0 to C18:0), except for C8:0 and C16:0 that were more active than the other short and long chain acids. The BDI values of mid chain length acids (C10:0 to C13:0) were not significantly less than N, N-diethyl-meta-toluamide (DEET), the positive control. Among the unsaturated fatty acids, C11:1 showed the highest activity (BDI = 1.05) and C18:2 had the lowest activity (BDI = 0.7). In C11:1, C12:1, and C14:1 BDI values were not significantly less than DEET. After the preliminary observations, residual activity bioassays were performed on C11:0, C12:0, C11:1, and C12:1 over a 24-h period. All the fatty acids (C11:0, C12:0, C11:1, and C12:1) and DEET showed significantly higher activity at all test intervals than the solvent control. At treatment and 1-h posttreatment, all fatty acids showed proportion not biting (PNB) values not significantly less than DEET. At 3-, 6-, and 12-h posttreatment, all fatty acids showed PNB values significantly greater than DEET. At 24-h posttreatment, only the PNB value for C12:0 was significantly higher than DEET. The dose-responses of C12:0 and DEET were determined at concentrations of 5-25 nmol/cm2. As in the residual activity bioassays, the PNB values for C12:0 and DEET at 25 nmol/cm(2) were not significantly different. However, at lower concentrations, the PNB values for C12:0 were significantly greater than DEET. These results clearly indicate that mid chain length fatty acids not only have levels of biting deterrence similar to DEET at 25 nmnol/cm(2) in our test system, but also appeared to be more persistent than DEET. In contrast, in vivo cloth patch assay system showed that the mid-chain length fatty acids, C11:0, C11:1, C12:0, and C12:1 had minimum effective dose (MED) values greater than DEET against Ae. aegypti and their relative repellency varied according to species tested. The MED values of 120 (C11:0), 145 (C12:0) and 116 (C11:1) nmol/cm(2) against Anopheles quadrimaculatus Say, indicated that these acids were not as potent as DEET with a MED of 54 nmol/cm(2). The MED ratio of the C11:0 and C11:1 for all three mosquito species indicated the C11 saturated and unsaturated acids as more repellent than their corresponding C12:0 and C12:1 homologues.

Relationship between mosquito (Diptera: Culicidae) landing rates on a human subject and numbers captured using CO2-baited light traps

Capture rates of insectary-reared female Aedes albopictus (Skuse), Anopheles quadrimaculatus Say, Culex nigripalpus Theobald, Culex quinquefasciatus Say and Aedes triseriatus (Say) in CDC-type light traps (LT) supplemented with CO2 and using the human landing (HL) collection method were observed in matched-pair experiments in outdoor screened enclosures. Mosquito responses were compared on a catch-per-unit-effort basis using regression analysis with LT and HL as the dependent and independent variables, respectively. The average number of mosquitoes captured in 1 min by LT over a 24-h period was significantly related to the average number captured in 1 min by HL only for Cx. nigripalpus and Cx. quinquefasciatus. Patterns of diel activity indicated by a comparison of the mean response to LT and HL at eight different times in a 24-h period were not superposable for any species. The capture rate efficiency of LT when compared with HL was ≤15% for all mosquitoes except Cx. quinquefasciatus (43%). Statistical models of the relationship between mosquito responses to each collection method indicate that, except for Ae. albopictus, LT and HL capture rates are significantly related only during certain times of the diel period. Estimates of mosquito activity based on observations made between sunset and sunrise were most precise in this regard for An. quadrimaculatus and Cx. nigripalpus, as were those between sunrise and sunset for Cx. quinquefasciatus and Ae. triseriatus.

Insecticidal potency of novel compounds on multiple insect species of medical and veterinary importance

Vector-borne diseases continue to present significant threats to human, animal and plant health. Mosquitoes, houseflies, sand flies and stable flies are well-known vectors of several human and animal pathogens. The toxicity of selected semiochemicals with molecular structures indicative of insecticidal activity was determined against these insect species with the aim of developing novel insecticides toxic to multiple insect species. Three semiochemicals, namely beta-damascone, cyclemone A and melafleur, showed remarkable toxicity to three mosquitoes, Aedes aegypti L., Ae. albopictus (Skuse) and Anopheles quadrimaculatus Say, the housefly, Musca domestica L., the stable fly, Stomoxys calcitrans L., and the sand fly, Lutzomyia shannoni (Dyar). The chemicals were equally toxic to several field-collected permethrin-tolerant housefly strains. When formulated as 500 mL L(-1) emulsifiable concentrates, the chemicals demonstrated stability and toxicity on filter paper and camouflage military fabrics, with persistence up to 8 days under laboratory conditions. The chemicals were equally effective under field conditions when evaluated on unpainted plywood panels, although a higher dosage was required under field conditions to achieve similar efficacy. Laboratory quantification of LC(50) values and field efficacy of three semiochemicals as formulated compounds on mosquitoes, houseflies, stable flies and sand flies showed that these semiochemicals could serve as potent insecticides for multiple insect species.

Potential for North American Mosquitoes (Diptera: Culicidae) to Transmit Rift Valley Fever Virus

To determine which arthropods should be targeted for control should Rift Valley fever virus (RVFV) be detected in North America, we evaluated Culex erraticus (Dyar and Knab), Culex erythrothorax Dyar, Culex nigripalpus Theobald, Culex pipiens L., Culex quinquefasciatus Say, Culex tarsalis Coquillett, Aedes dorsalis (Wiedemann), Aedes vexans (Meigen), Anopheles quadrimaculatus Say, and Culicoides sonorensis Wirth and Jones from the western, midwestern, and southern United States for their ability to transmit RVFV. Female mosquitoes were allowed to feed on adult hamsters inoculated with RVFV, after which engorged mosquitoes were incubated for 7-21 d at 260C, then allowed to refeed on susceptible hamsters, and tested to determine infection, dissemination, and transmission rates. Other specimens were inoculated intrathoracically, held for 7 d, and then allowed to feed on a susceptible hamster to check for a salivary gland barrier. When exposed to hamsters with viremias > or =10(8.8) plaque-forming units/ml blood, Cx. tarsalis transmitted RVFV efficiently (infection rate = 93%, dissemination rate = 56%, and estimated transmission rate = 52%). In contrast, when exposed to the same virus dose, none of the other species tested transmitted RVFV efficiently. Estimated transmission rates for Cx. erythrothorax, Cx. pipiens, Cx. erraticus, and Ae. dorsalis were 10, 8, 4, and 2%, respectively, and for the remaining species were < or = 1%. With the exception of Cx. tarsalis and Cx. pipiens, all species tested had moderate to major salivary gland barriers. None of the C. sonorensis became infected and none of the An. quadrimaculatus tested transmitted RVFV by bite, even after intrathoracic inoculation, indicating that these species would not be competent vectors of RVFV. Although Ae. vexans from Florida and Louisiana were relatively efficient vectors of RVFV, specimens of this species captured in Colorado or California were virtually incompetent, illustrating the need to evaluate local population for their ability to transmit a pathogen. In addition to laboratory vector competence, factors such as seasonal density, host feeding preference, longevity, and foraging behavior should be considered when determining the potential role that these species could play in RVFV transmission.

Resurrection of Two Species From Synonymy of &lt;I&gt;Anopheles&lt;/I&gt; (&lt;I&gt;Nyssorhynchus&lt;/I&gt;) &lt;I&gt;strodei&lt;/I&gt; Root, and Characterization of a Distinct Morphological Form From the Strodei Complex (Diptera: Culicidae)

Anopheles albertoi Unti and Anopheles arthuri Unti are revived from the synonymy with Anopheles strodei Root, and a distinct morphological form (designated in this study as Anopheles CP Form) from the Strodei Complex of Anopheles (Nyssorhynchus) is characterized. The male genitalia of An. arthuri and An. albertoi are described and illustrated for the first time. An. strodei, An. arthuri, and An. albertoi were first distinguished based on scanning electron microphotos of the eggs, and then each egg type was associated with diagnostic characters of the male genitalia. Identification of Anopheles CP Form was based on morphological characters of the male genitalia, characterized and illustrated in this study. Molecular phylogenetic analysis was most clear when an outgroup was not included, in which case using the nuclear white gene, or the white gene in combination with the mitochondrial cytochrome c oxidase subunit I (COI) gene, clearly separated these four taxa. When Anopheles quadrimaculatus Say and Anopheles stephensi Liston were included as an outgroup, combined white and COI data resolved An. strodei and An. albertoi, whereas An. arthuri was not well resolved. The single sequence of Anopheles CP Form was recovered well separated from other groups in all analyses.

Resurrection of Two Species From Synonymy of Anopheles (Nyssorhynchus) strodei Root, and Characterization of a Distinct Morphological Form From the Strodei Complex (Diptera: Culicidae)

Abstract Anopheles albertoi Unti and Anopheles arthuri Unti are revived from the synonymy with Anopheles strodei Root, and a distinct morphological form (designated in this study as Anopheles CP Form) from the Strodei Complex of Anopheles (Nyssorhynchus) is characterized. The male genitalia of An. arthuri and An. albertoi are described and illustrated for the first time. An. strodei, An. arthuri, and An. albertoi were first distinguished based on scanning electron microphotos of the eggs, and then each egg type was associated with diagnostic characters of the male genitalia. Identification of Anopheles CP Form was based on morphological characters of the male genitalia, characterized and illustrated in this study. Molecular phylogenetic analysis was most clear when an outgroup was not included, in which case using the nuclear white gene, or the white gene in combination with the mitochondrial cytochrome c oxidase subunit I (COI) gene, clearly separated these four taxa. When Anopheles quadrimaculatus Say and Anopheles stephensi Liston were included as an outgroup, combined white and COI data resolved An. strodei and An. albertoi, whereas An. arthuri was not well resolved. The single sequence of Anopheles CP Form was recovered well separated from other groups in all analyses.

Male accessory gland proteins induce female monogamy in anopheline mosquitoes

The role of male accessory gland (MAG) secretions in inducing refractoriness to further mating in mosquitoes (Diptera: Culicidae) was established in the late 1960s. In a set of simple experiments, MAG extract was injected intra-thoraxically into the hemocoel of virgin Aedes aegypti (L.), Culex pipiens pipiens (L.) and Anopheles quadrimaculatus Say females. This subsequently caused most females to remain unmated when exposed to males. For anophelines these findings were later challenged by a study involving intra-abdominal injections of MAG extracts into Anopheles gambiae Giles s.l. and Anopheles albimanus Wiedmann females, which failed to induce refractoriness to further mating. These findings led to controversy about the respective role of sperm and accessory gland peptides in inducing female monogamy in Anopheles and are at odds with our current understanding of the mating process in Drosophila spp. (Diptera: Drosophillidae) and other dipterans. Here we confirm the function of MAG secretions in anophelines experimentally by showing that intra-thoracic injections in Anopheles stephensi Liston and in the M and S molecular forms of An. gambiae s.s. result in the expected female monogamy. Cross-injections of MAG extracts between the M and S molecular forms of An. gambiae, two cryptic taxa within An. gambiae s.s. which are thought to be undergoing incipient speciation, also elicited effective refractoriness, suggesting that the two sub-taxa have not diverged with regard to sex peptides responsible for female monogamy. Importantly, this also suggests that the rare cases of re-mating following cross-mating observed in this species may not be a form of reproductive barrier between molecular forms.

Identification of bloodmeals in Anopheles quadrimaculatus and Anopheles punctipennis from eastern equine encephalitis virus foci in northeastern U.S.A.

The host-feeding patterns of Anopheles quadrimaculatus Say and Anopheles punctipennis (Say) were examined in order to evaluate their potential contributions to the transmission of eastern equine encephalitis virus (EEEv) and other arboviruses in the northeastern U.S.A. Engorged mosquitoes of the two species were collected from EEEv foci in central New York (NY) and throughout New Jersey (NJ), and their bloodmeals were identified using a polymerase chain reaction (PCR)-based assay and sequencing portions of the mitochondrial cytochrome b gene. Analysis of 131 An. quadrimaculatus and 107 An. punctipennis from NY revealed that 97.7% and 97.2%, respectively, had acquired blood solely from mammalian hosts. Similarly, examination of 288 An. quadrimaculatus and 127 An. punctipennis from NJ showed 100% and 96.0%, respectively, contained mammalian-derived bloodmeals. Mosquitoes containing mixed bloodmeals from both avian and mammalian hosts were detected in 1.6% of An. quadrimaculatus from NY, and 2.8% and 4.0% of An. punctipennis from NY and NJ, respectively. White-tailed deer (Odocoileus virginianus) constituted the most common vertebrate host for these anopheline mosquitoes, accounting for 85.8-97.7% of all bloodmeals identified. The predominance of white-tailed deer as a source of bloodmeals supports enzootic amplification of deer-associated arboviruses in this region, including Jamestown Canyon, Cache Valley and Potosi viruses. One horse- and two human-derived bloodmeals were also detected in An. quadrimaculatus collected in NJ. Limited avian-derived bloodmeals were detected from mourning dove (Zenaida macroura), sharp-shinned hawk (Accipiter striatus) and house finch (Carpodacus mexicanus), mostly in mixed bloodmeals. Occasional feeding on avian hosts suggests that these mosquitoes may participate as epizootic-epidemic bridge vectors of EEEv from viraemic birds to mammalian hosts of concern, including horses and humans. An isolate of EEEv was recovered from the head and thorax of an An. punctipennis mosquito collected in NY.