Aedes Albopictus Larvae Research Articles

Curzerene, trans-β-elemenone, and γ-elemene as effective larvicides against Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus: toxicity on non-target aquatic predators.

A wide number of studies dealing with mosquito control focus on toxicity screenings of whole plant essential oils, while limited efforts shed light on main molecules responsible of toxicity, as well as their mechanisms of action on non-target organisms. In this study, GC-MS shed light on main essential oil components extracted from leaves of the Suriname cherry Eugenia uniflora, i.e., curzerene (35.7%), trans-β-elemenone (11.5%), and γ-elemene (13.6%), testing them on Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus larvae. Non-target toxicity experiments were carried out on four species of aquatic larvivorous organisms, including fishes, backswimmers, and waterbugs. The essential oil from E. uniflora leaves tested on An. subpictus, Ae. Albopictus, and Cx. tritaeniorhynchus showed LC50 of 31.08, 33.50, and 36.35μg/ml, respectively. Curzerene, trans-β-elemenone, and γ-elemene were extremely toxic to An. subpictus (LC50=4.14, 6.13, and 10.53μg/ml), Ae. albopictus (LC50=4.57, 6.74, and 11.29μg/ml), and Cx. tritaeniorhynchus (LC50=5.01, 7.32, and 12.18μg/ml). The essential oil from E. uniflora leaves, curzerene, trans-β-elemenone, and γ-elemene showed low toxicity to larvivorous fishes, backswimmers, and waterbugs, with LC50 ranging from 303.77 to 6765.56μg/ml. Predator safety factor (PSF) ranged from 55.72 to 273.45. Overall, we believe that curzerene isolated from the essential oil from E. uniflora leaves can represent an ideal molecule to formulate novel mosquito larvicides, due to its extremely low LC50 on all tested mosquito vectors (4.14-5.01μg/ml), which far encompasses most of the botanical pesticides tested till now. Notably, the above-mentioned LC50 did not damage the four aquatic predators tested in this study.

Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer

Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.

IdentificationofLarvicidalConstituentsofthe EssentialOilofEchinopsgrijsii Rootsagainstthe ThreeSpeciesofMosquitoes.

The screening of Chinese medicinal herbs for insecticidal principles showed that the essential oil of Echinops grijsii Hance roots possessed significant larvicidal activity against mosquitoes. The essential oil was extracted via hydrodistillation and its constituents were determined by gas chromatography-mass spectrometry (GC-MS) analysis. GC-MS analyses revealed the presence of 31 components, with 5-(3-buten-1-yn-1-yl)-2,2′-bithiophene (5-BBT, 27.63%), α-terthienyl (α-T, 14.95%), 1,8-cineole (5.56%) and cis-β-ocimene (5.01%) being the four major constituents. Based bioactivity-directed chromatographic separation of the essential oil led to the isolation of 5-BBT, 5-(4-isovaleroyloxybut-1-ynyl)-2,2′-bithiophene (5-IBT) and α-T as active compounds. The essential oil of E. grijsii exhibited larvicidal activity against the fourth instar larvae of Aedes albopictus, Anopheles sinensis and Culex pipiens pallens with LC50 values of 2.65 μg/mL, 3.43 μg/mL and 1.47 μg/mL, respectively. The isolated thiophenes, 5-BBT and 5-IBT, possessed strong larvicidal activity against the fourth instar larvae of Ae. albopictus (LC50 = 0.34 μg/mL and 0.45 μg/mL, respectively) and An. sinensis (LC50 = 1.36 μg/mL and 5.36 μg/mL, respectively). The two isolated thiophenes also had LC50 values against the fourth instar larvae of C. pipiens pallens of 0.12 μg/mL and 0.33 μg/mL, respectively. The findings indicated that the essential oil of E. grijsii roots and the isolated thiophenes have an excellent potential for use in the control of Ae. albopictus, An. sinensis and C. pipiens pallens larvae and could be used in the search for new, safer and more effective natural compounds as larvicides.

Mosquito (Diptera: Culicidae) Habitat Surveillance by Android Mobile Devices in Guangzhou, China.

In 2014, Guangzhou City, South China, suffered from its worst outbreak of dengue fever in decades. Larval mosquito habitat surveillance was carried out by using android mobile devices in four study sites in May 2015. The habitats with larval mosquitoes were recorded as photo waypoints in OruxMaps or in videos. The total number of potential mosquito habitats was 342, of which 166 (49%) were found to have mosquito larvae or pupae. Small containers were the most abundant potential habitats, accounting for 26% of the total number. More mosquito larvae and pupae, were found in small containers than in other objects holding water, for example, potted or hydroponic plants (p < 0.05). Mosquito larvae were collected from all plastic road barriers, used tires, and underground water. Aedes albopictus larvae were found from small and large containers, stumps, among others. The overall route index (RI) was 11.3, which was 14.2 times higher than the grade C criteria of the National Patriotic Health Campaign Committee (NPHCC), China. The higher RIs were found from the bird and flower markets, schools, and underground parking lots. The results indicated that Android mobile devices are a convenient and useful tool for surveillance of mosquito habitats, and the enhancement of source reduction may benefit the prevention and control of dengue vector mosquitoes.

Reducing the Risk of Zika and other Arboviruses by Rapidly Eliminating Aedes albopictus Larvae from Tires Using a Spray Formulation of Bacillus thuringiensis israelensis.

The Asian tiger mosquito (Aedes albopictus) likely arrived in the United States through the importation of used tires. The Asian tiger mosquito is a competent of several arboviruses and with the recent introduction of Zika virus into North America finding methods to control this species is vital. The rapid action of a spray formulation of Bacillus thuringiensis israelensis using Entobac with Aquabac XT is discussed. There was significant reduction of larvae was achieved in less than seven days in the test site whereas the control site showed no significant change.Entobac is currently the only Bti formulation available that controls both adult and larvae mosquitoes. Entobac is also the only Bti formulation that can be utilized in the five principle methods of dispersal; 1) hand tossed 2) backpack spray, 3) truck mounted spray, 4) aerial spray and 5) bait station.

Evaluation of different formulations of IGRs against Aedes albopictus and Culex quinquefasciatus (Diptera: Culicidae)

ObjectiveTo test the relative efficacy of pyriproxyfen and methoprene on mortality, deformity, inhibition and emergence to adult stages of Culex quinquefasciatus and Aedes albopictus. MethodsSerial dilutions (0.01–0.05 mg/L) of methoprene, pyriproxyfen 0.5 water dispersible granules (WDG) and pyriproxyfen 1.0 WDG were used to assess mortality and inhibition of 3rd instar larvae of Aedes albopictus and Culex quinquefasciatus. Each concentration and control was replicated four times in completely randomized design. Data on larval mortality, growth inhibition, deformities and adult's emergence was recorded weekly. On the basis of best comparative performance, the efficacy of pyriproxyfen 1.0 WDG at 0.1 g/m3 was also tested in the field by collecting treated water samples monthly for 1–6 months after field application. Twenty five 3rd instar larvae of Aedes and Culex spp. of the same cohorts were used for bioassays and compared with larvae in control cups containing 1 L of untreated tap water. ResultsResults revealed variations in fatality of different insect growth regulators (IGRs) to the 3rd instar larvae of Culex and Aedes mosquitoes. Among the IGRs, pyriproxyfen 1.0 WDG was found best that exhibited significantly high emergence inhibition against Culex and Aedes spp. Based on the results, the IGRs were classified in terms of the tested parameters in order of pyriproxyfen 1.0 WDG > pyriproxyfen 0.5 WDG > methoprene. In case of field studies, pyriproxyfen 1.0 WDG, pool data of the entire target treated sites showed minimum adult emergence from water sampled of habitats treated with 0.1 g/m3 of pyriproxyfen 1.0 WDG. ConclusionsIt is thus concluded that IGRs can be utilized as environment friendly control measures for Culex and Aedes spp. of mosquitoes on small and large scale. This will reduce the use of conventional insecticides by the public health authorities and help in reducing selection pressure of insecticides.

Seasonal variation and bioactivity of the essential oils of two Juniperus species against Aedes (Stegomyia) albopictus (Skuse, 1894).

The seasonal variation in respect to the yield and chemical composition of 24 essential oils (EOs) isolated from various parts (leaves and fruits) of two indigenous Greece Juniperus species (family Cupressaceae), namely Juniperus drupacea and Juniperus phoenica, were determined by GC and GC/MS analysis. The larvicidal properties of these EOs were evaluated against 3rd and early 4th instar larvae of Aedes (Stegomyia) albopictus (Skuse, 1894) at one screening dose (29mgL(-1)). Moreover, the repellent activity against adult mosquitoes was also evaluated at one screening dose. The analytical data indicated that the EOs mainly consisted of monoterpenes, mostly cyclic and only occasionally aliphatic and to a lesser percent diterpenes. The EOs yield was sharply increased when the plant material was subjected to pre-treatment before steam distillation. Finally, the influence of plant material collection period on their yield and chemical content was also determined. Bioactivity assessments indicated that three EOs possess very potent larvicidal properties and 12 EOs display significant repellent activities since they were proved to be "DEET-like." Therefore, they represent an inexpensive source of natural mixtures of larvicidal and repellent mixture of natural compounds, with potentials for application for utilization in mosquito control schemes in order to prevent the expansion of viral infections.

Susceptibility of Aedes albopictus from dengue outbreak areas to temephos and Bacillus thuringiensis subsp. israelensis

ObjectiveTo monitor the current duration of the application rates in vector programme and the level of Aedes albopictus larvae susceptibility from three selected areas in northeast district of Penang on two selected larvicides, temephos and Bacillus thuringiensis subsp. israelensis (Bti) which are commonly used by Penang Health Department for vector control. MethodsThe mosquito larvae were tested against two types of larvicides: (1) temephos (Abate®) with diagnostic dosage (0.012 mg/L) and operational dosage (1 mg/L) and (2) Bacillus thuringiensis subsp. israelensis (VectoBac® WG) with operational dosage ranging from 6000 international toxic units per L to 24000 international toxic unit per L. A total of 20 late third and early forth instar larvae were selected and transferred into paper cup sized 300 mL using wide-mouthed pipette. The larvae were distributed into each 300 mL paper cup containing 50 mL of aged tap water. The experiment was replicated five times for each concentration tested. Each test was repeated three times. The mortality was recorded after 24 h of exposure and recorded lethal time was based on 2 h for temephos and 6 h for Bti. The control consisted of ethanol for temephos and only seasoned water for Bti. ResultsThe result showed that Aedes albopictus from Flat Hamna, Kampung Sungai Gelugor and Kampung Tanjung Tokong were still susceptible to Bti and temephos. However, higher lethal time and resistance ratio were detected in strain from Flat Hamna which was a known dengue hot spot area in northeast of Penang. ConclusionsThe application of temephos and Bti in vector control activity in these selected localities is still relevant in the control of Aedes larvae populations.

Clerodendrum chinense-mediated biofabrication of silver nanoparticles: Mosquitocidal potential and acute toxicity against non-target aquatic organisms

Mosquito-borne diseases represent a deadly threat for millions of people worldwide. However, the use of synthetic insecticides to control Culicidae may lead to high operational costs and adverse non-target effects. Plant-borne compounds have been proposed for rapid extracellular synthesis of mosquitocidal nanoparticles. Their impact against biological control agents of mosquito larval populations has been poorly studied. In this study, we synthesized silver nanoparticles (Ag NPs) using the Clerodendrum chinense leaf extract as reducing and stabilizing agent. The biosynthesis of AgNP was confirmed analyzing the excitation of surface Plasmon resonance using ultraviolet–visible (UV–vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was determined by energy dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy analysis investigated the identity of secondary metabolites, which may act as Ag NP capping agents. The acute toxicity of C. chinense leaf extract and biosynthesized Ag NP was evaluated against larvae of Anopheles subpictus, Aedes albopictus and Culex tritaeniorhynchus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against A. subpictus, A. albopictus, and C. tritaeniorhynchus with LC50 values of 10.23, 11.10 and 12.38μg/mL, respectively. Biosynthesized Ag NPs were found safer to non-target organisms Diplonychus indicus, Anisops bouvieri and Gambusia affinis, with respective LC50 values ranging from 647.05 to 6877.28μg/ml. Overall, our results highlight that C. chinense-fabricated Ag NP are a promising and eco-friendly tool against larval populations of mosquito vectors of medical and veterinary importance, with negligible toxicity against non-target aquatic organisms.

Facile biosynthesis of silver nanoparticles using Barleria cristata: mosquitocidal potential and biotoxicity on three non-target aquatic organisms.

Mosquitoes (Diptera: Culicidae) act as vectors of important pathogens and parasites, such as malaria, dengue, chikungunya, Japanese encephalitis and lymphatic filariasis. The use of synthetic mosquitocides often leads to high operational costs and adverse non-target effects. Recently, plant-borne compounds have been proposed for rapid extracellular biosynthesis of mosquitocidal nanoparticles. However, the impact of these nanomosquitocides against biological control agents of mosquito larval populations has been poorly studied. In this research, we biosynthesized silver nanoparticles (Ag NP) using the Barleria cristata leaf extract as a reducing and stabilizing agent. The biosynthesis of Ag NP was confirmed analyzing the excitation of surface plasmon resonance using ultraviolet-visible (UV-vis) spectrophotometry. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed the clustered and irregular shapes of Ag NP. The presence of silver was confirmed by energy-dispersive X-ray (EDX) spectroscopy. Fourier transform infrared (FTIR) spectroscopy investigated the identity of secondary metabolites, which may also act as Ag NP capping agents. The acute toxicity of B. cristata leaf extract and biosynthesized Ag NP was evaluated against larvae of Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Compared to the leaf aqueous extract, biosynthesized Ag NP showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with lethal concentration (LC)50 values of 12.46, 13.49, and 15.01 μg/mL, respectively. Notably, biosynthesized Ag NP were found safer to non-target organisms Diplonychus indicus, Anisops bouvieri, and Gambusia affinis, with respective LC50 values ranging from 633.26 to 866.92 μg/mL. Overall, our results highlight that B. cristata-fabricated Ag NP are a promising and eco-friendly tool against young instar populations of mosquito vectors of medical and veterinary importance.

Novel synthesis of silver nanoparticles using Bauhinia variegata: a recent eco-friendly approach for mosquito control.

Mosquito vectors are responsible for transmitting diseases such as malaria, dengue, chikungunya, Japanese encephalitis, dengue, and lymphatic filariasis. The use of synthetic insecticides to control mosquito vectors has caused physiological resistance and adverse environmental effects, in addition to high operational cost. Biosynthesis of silver nanoparticles has been proposed as an alternative to traditional control tools. In the present study, green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Bauhinia variegata by reduction of Ag(+) ions from silver nitrate solution has been investigated. The bioreduced silver nanoparticles were characterized by UV–visible spectrophotometry, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDX), and X-ray diffraction analysis (XRD). Leaf extract and synthesized AgNPs were evaluated against the larvae of Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus. Compared to aqueous extract, synthesized AgNPs showed higher toxicity against An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 and LC90 values of 41.96, 46.16, and 51.92 μg/mL and 82.93, 89.42, and 97.12 μg/mL, respectively. Overall, this study proves that B. variegata is a potential bioresource for stable, reproducible nanoparticle synthesis and may be proposed as an efficient mosquito control agent.

Laboratory evaluation of aqueous leaf extract of Tephrosia vogelii against larvae of Aedes albopictus (Diptera: Culicidae) and non-target aquatic organisms

Mosquito control using insecticides has been the most successful intervention known to reduce malaria prevalence or incidence. However, vector control is facing a threat due to the emergence of resistance to synthetic insecticides. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. In this research, the leaf aqueous leachate of Tephrosia vogelii was evaluated for its toxicity against larvae of the most invasive mosquito worldwide, Aedes albopictus (Diptera: Culicidae), and toward adults of the water flea, Daphnia magna (Cladocera: Crustacea) and Oreochromis niloticus, two non-target aquatic organisms that share the same ecological niche of A. albopictus. The leaf aqueous leachate of T. vogelii was evaluated against fourth-instar larvae, non-blood fed 3–5 days old laboratory strains of A. albopictus under laboratory condition. In addition, the objective of the present work was to study the environmental safety evaluation for aquatic ecosystem. Mortality was then recorded after 7d exposure. The leaf aqueous leachate of T. vogelii showed high mosquitocidal activity against larvae of A. albopictus, with a LC50=1.18μg/mL. However, it had a remarkable acute toxicity also toward adults of the non-target arthropod D. magna, with a LC50=0.47μg/L and O. niloticus with a LC50=5.31μg/L. The present findings have important implications in the practical control of mosquito larvae in the aquatic ecosystem, as the medicinal plants studied are commonly available in large quantities. The extract could be used in stagnant water bodies for the control of mosquitoes acting as vector for many communicable diseases.

Biological control of Asian tiger mosquito, Aedes albopictus (Diptera: Culicidae) using Metarhizium anisopliae JEF-003 millet grain

Mosquitoes have been becoming serious vectors worldwide thus effective and safe control strategies should be established. Entomopathogenic fungi can be alternative controlling agents by substituting chemical insecticides. Herein we assayed 12 soil-borne entomopathogenic fungi against Asian tiger mosquito (Aedes albopictus) larvae in laboratory conditions and tried to establish an effective application method using millet granular formulation (GR). Twelve fungal isolates which belong to 6 genera (Beauveria, Cordyceps, Metarhizium, Paecilomyces, Purpureocillium and Verticillium) were assayed; M. anisopliae JEF-003 showed the fastest mosquitocidal activity, approximately 73% mortality rate at 2days post-inoculation (dpi.) and >90% mortality rate at 5dpi. Conidia of M. anisopliae JEF-003 also showed a dosage dependent activity at 1×105, 1×106 and 1×107conidiaml−1. Hyphal growth of M. anisopliae JEF-003 in the Ae. albopictus larvae was observed by infection of an M. anisopliae JEF-003 EGFP-transformant, which was generated by restriction enzyme-mediated integration (REMI) method. GR of M. anisopliae JEF-003 showed high virulence to Ae. albopictus larvae (>90% mortality) after 5days of application. These results suggest that M. anisopliae JEF-003 has a potential to control A. albopictus larvae and GR can be practically used for management of the serious vector in water environment.

Detection of Transovarial Dengue Virus with RT-PCR in Aedes albopictus (Skuse) Larvae Inhabiting Phytotelmata in Endemic DHF Areas in West Sumatra, Indonesia

Transovarial dengue virus detection by RT-PCR in Ae.albopictus larvae that inhabit Phytotelmata has been conducted in several dengue endemic areas in West Sumatra. The purpose of this study was to determine whether larval Ae. albopictus inhabiting Phytotelmata is a potential transmitter of Dengue Hemorrhagic Fever (DHF). The results concluded that Ae.albopictus larvae which inhabited Phytotelmata positively contained two serotypes of dengue virus (DEN-1) and (DEN-4) which has the potential to transmit and spread DHF.

Larvicidal activity of the essential oil of Youngia japonica aerial parts and its constituents against Aedes albopictus.

The aim of this study was to evaluate the larvicidal activity of the essential oil of Youngia japonica aerial parts against the larvae of Aedes albopictus and to isolate any active compounds from the oil. Gas chromatography-mass spectrometry (GC-MS) analyses revealed the presence of 31 compounds, with menthol (23.53%), α-asarone (21.54%), 1,8-cineole (5.36%), and caryophyllene (4.45%) as the major constituents. Bioactivity-directed chromatographic separation of the oil led to the isolation of menthol and α-asarone as active compounds. The essential oil of Y. japonica exhibited larvicidal activity against the fourth instar larvae of A. albopictus with an LC₅₀ value of 32.45 μg/mL. α-Asarone and menthol possessed larvicidal activity against the fourth instar larvae of A. albopictus with LC₅₀ values of 24.56 μg/mL and 77.97 μg/mL, respectively. The results indicate that the essential oil of Y. japonica aerial parts and the two constituents can be potential sources of natural larvicides.

Evaluating the toxicity of oil of lemon eucalyptus, Corymbia citriodora (Hook.), against larvae of the Asian tiger mosquito and non-target fish and larval amphibians

We evaluated the toxicity of oil of lemon eucalyptus (OLE) against larvae of the tiger mosquito Aedes (Stegomya) albopictus (Skuse, 1895) (Diptera: Culicidae) and non-target aquatic vertebrates, the fish Gambusia affinis (Baird and Girard, 1853) and the tapole of the frog Pelophylax perezi (Lopez-Seodane, 1885). The water-mixture of OLE was effective as a larvicide and lethal to both mosquitofish and tadpoles in the short-term. The water-mixture left in the open air over a week had no effect on larvae. Pure OLE released on the water surface killed larvae at very low concentrations irrespectively of the volume of water medium. OLE seems a useful compound to be used against tiger mosquito larvae especially in mosquito breeding sites isolated from native ecosystems.

Scanning Electron Microscopy and Molecular Characterization of Aedes albopictus (Skuse)

Scanning electron microscopy and molecular characterization of Aedes albopictus larvae were done. Analysis of 28S rRNA gene sequence of Aedes albopictus Burdwan-SNC1 (KC208593) revealed comparatively higher GC content. Phylogenetic tree was prepared using the Neighbor-Joining (NJ) method. Phylogenetic tree revealed that Aedes albopictus Burdwan-SNC1 (KC208593) branched with the cluster containing of Aedes palauensis A26, Aedes hensilli A25, Aedes riversi A51A, Aedes dybasi A28, Aedes galloisi A77, Aedes flavopictus A47, Aedes albopictus A22, Aedes albopictus A34, Aedes albopictus MQSRNAGN and also branched with the cluster containing Aedes aegypti A20 and Aedes wadai A85. Scanning electron micrographs of Aedes albopictus larvae revealed that the structural complexity and number of both comb scales and pecten spines increased with larval growth and development. Similar results were revealed by anal papillae of abdominal segments.

Fluctuation of diptera larvae in phytotelmata and relation with climate variation in West Sumatra Indonesia.

Research of fluctuations in Diptera's larvae in Phytotelmata had been conducted at three locations in West Sumatra, Indonesia; Padang, Bukittinggi and Payakumbuh; which aimed to determine the number and fluctuations Diptera larvae in Phytotelmata. The results obtained; the highest number of individual larvae Diptera in Phytotelmata was 7109 Aedes albopictus larvae (49.56%), followed by larvae of Culex tritaeniorhynchus with 2409 individuals (16.80%). Larvae fluctuated every month and tent to increase in November and December. There was no difference in the number of Diptera larvae individuals inhabiting pandan, taro, and pineapple, but there were significant differences between the three types of Phytotelmata (pandanus, taro and pineapple) with bamboo (p < 0.05). Number of individual larvae in Phytotelmata negatively correlated with temperature and rainfall, but positively correlated with humidity (r = 0.44: p < 0.05).

Sublethal effects of atrazine and glyphosate on life history traits of Aedes aegypti and Aedes albopictus (Diptera: Culicidae).

Although exposure of mosquito larvae to agricultural chemicals such as herbicides is common and widespread, our understanding of how these chemicals affect mosquito ecology and behavior is limited. This study investigated how an environmentally relevant concentration of two herbicides, atrazine and glyphosate, affects mosquito life history traits. One hundred and fifty (150) first instar Aedes (Stegomyia) aegypti (L.) or Aedes (Stegomyia) albopictus (Skuse) larvae were reared in 1.6 L of live oak leaf (Quercus virginiana) infusion in the presence (5 mg/L) or absence (0 mg/L) of atrazine or glyphosate. The containers were monitored daily to determine the emergence rates, sex ratio, male and female emergence times, and female body size. Emergence rates of A. aegypti from atrazine treatment were significantly higher relative to either glyphosate or control treatments (A. aegypti: atrazine = 93 ± 6% (±95% CI), glyphosate = 82 ± 5%, control = 78 ± 5%), while emergence rates of A. albopictus in atrazine treatments were significantly higher than in glyphosate treatments but not in controls (A. albopictus: atrazine = 84 ± 5 %, glyphosate = 76 ± 4%, control = 78 ± 4%). For both mosquito species, a sex ratio distortion with male bias was observed in control and glyphosate treatments, but not in atrazine treatments (A. aegypti: atrazine = 0.90 ± 0.17 (±SE), glyphosate = 1.63 ± 0.21, control = 1.69 ± 0.26; A. albopictus: atrazine = 1.09 ± 0.08, glyphosate = 1.88 ± 0.12, control = 1.37 ± 0.11). Emergence times for both sexes of the two mosquito species were significantly longer in atrazine treatments compared to glyphosate or control treatments (A. aegypti: females: atrazine = 11.20 ± 0.50 (days ± 95 % CI), glyphosate = 9.71 ± 0.23, control = 9.87 ± 0.21; males: atrazine = 9.46 ± 0.27, glyphosate = 8.80 ± 0.25, control = 8.85 ± 0.24; A. albopictus: females: atrazine = 17.40 ± 1.70, glyphosate = 12.4 ± 0.40, control = 12.5 ± 0.30; males: atrazine = 12.96 ± 0.41, glyphosate = 10.48 ± 0.24, control = 10.64 ± 0.37). For A. albopictus but not A. aegypti, adult females from atrazine treatment had significantly longer wing lengths compared to those from glyphosate or control treatments (A. albopictus: atrazine = 3.06 ± 0.07 (mm ± 95% CI), glyphosate = 2.80 ± 0.07, control = 2.83 ± 0.06). These results demonstrate the potential for atrazine, a widely used herbicide, to influence epidemiologically relevant life history traits of mosquitoes.

The Importance of Oxidases in the Tolerance of Deciduous Leaf Infusions by Aedes (Stegomyia) aegypti and Aedes (Stegomyia) albopictus (Diptera: Culicidae)

Aedes (Stegomyia) aegypti (L.) and Aedes (Stegomyia) albopictus (Skuse) larvae rely on oxidases to reduce toxicity of water soluble toxins from some senescent tree leaf infusions. The mortality of third instar Ae. aegypti larvae in live oak and pin oak leaf infusions increased significantly in the presence of piperonyl butoxide (PBO), a broad inhibitor of cytochrome P450s (CYPs). In contrast, PBO treatment did not increase mortality in water controls or infusions of northern red oak or sugar maple leaf infusions for Ae. aegypti larvae. A similar pattern was observed for Ae. albopictus larvae, that is, an increase in mortality when CYPs were inhibited in live oak leaf infusions and no increase in sugar maple leaf infusions or water controls. However, the fresh live oak leaf infusion (5 d old) was the most toxic infusion to Ae. aegypti, but appeared less toxic to Ae. albopictus than the older infusions. A direct comparison of survival between the two Aedes species revealed Ae. aegypti exhibited a greater mortality than Ae. albopictus in PBO-treated live oak leaf infusions. These findings suggest that toxic components of some leaf litter in larval habitats may impose cryptic energy costs (detoxification).