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 UV­visible 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.

Tackling the growing threat of dengue: Phyllanthus niruri-mediated synthesis of silver nanoparticles and their mosquitocidal properties against the dengue vector Aedes aegypti (Diptera: Culicidae).

Mosquitoes are vectors of devastating pathogens and parasites, causing millions of deaths every year. Dengue is a mosquito-borne viral infection found in tropical and subtropical regions around the world. Recently, transmission has strongly increased in urban and semiurban areas, becoming a major international public health concern. Aedes aegypti (Diptera: Culicidae) is the primary vector of dengue. The use of synthetic insecticides to control Aedes mosquitoes lead to high operational costs and adverse nontarget effects. In this scenario, eco-friendly control tools are a priority. We proposed a novel method to synthesize silver nanoparticles using the aqueous leaf extract of Phyllanthus niruri, a cheap and nontoxic material. The UV-vis spectrum of the aqueous medium containing silver nanostructures showed a peak at 420 nm corresponding to the surface plasmon resonance band of nanoparticles. SEM analyses of the synthesized nanoparticles showed a mean size of 30-60 nm. EDX spectrum showed the chemical composition of the synthesized nanoparticles. XRD highlighted that the nanoparticles are crystalline in nature with face-centered cubic geometry. Fourier transform infrared spectroscopy (FTIR) of nanoparticles exhibited prominent peaks 3,327.63, 2,125.87, 1,637.89, 644.35, 597.41, and 554.63 cm(-1). In laboratory assays, the aqueous extract of P. niruri was toxic against larval instars (I-IV) and pupae of A. aegypti. LC50 was 158.24 ppm (I), 183.20 ppm (II), 210.53 ppm (III), 210.53 ppm (IV), and 358.08 ppm (pupae). P. niruri-synthesized nanoparticles were highly effective against A. aegypti, with LC50 of 3.90 ppm (I), 5.01 ppm (II), 6.2 ppm (III), 8.9 ppm (IV), and 13.04 ppm (pupae). In the field, the application of silver nanoparticles (10 × LC50) lead to A. aegypti larval reduction of 47.6%, 76.7% and 100%, after 24, 48, and 72 h, while the P. niruri extract lead to 39.9%, 69.2 % and 100 % of reduction, respectively. In adulticidal experiments, P. niruri extract and nanoparticles showed LC50 and LC90 of 174.14 and 6.68 ppm and 422.29 and 23.58 ppm, respectively. Overall, this study highlights that the possibility to employ P. niruri leaf extract and green-synthesized silver nanoparticles in mosquito control programs is concrete, since both are effective at lower doses if compared to synthetic products currently marketed, thus they could be an advantageous alternative to build newer and safer tools against dengue vectors.

Green-synthesized silver nanoparticles as a novel control tool against dengue virus (DEN-2) and its primary vector Aedes aegypti.

Dengue is an arthropod-borne viral infection mainly vectored through the bite of Aedes mosquitoes. Recently, its transmission has strongly increased in urban and semi-urban areas of tropical and sub-tropical regions worldwide, becoming a major international public health concern. There is no specific treatment for dengue. Its prevention and control solely depends on effective vector control measures. In this study, we proposed the green-synthesis of silver nanoparticles (AgNP) as a novel and effective tool against the dengue serotype DEN-2 and its major vector Aedes aegypti. AgNP were synthesized using the Moringa oleifera seed extract as reducing and stabilizing agent. AgNP were characterized using a variety of biophysical methods including UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and sorted for size categories. AgNP showed in vitro antiviral activity against DEN-2 infecting vero cells. Viral titer was 7 log10 TCID50/ml in control (AgNP-free), while it dropped to 3.2 log10 TCID50/ml after a single treatment with 20 µl/ml of AgNP. After 6 h, DEN-2 yield was 5.8 log10 PFU/ml in the control, while it was 1.4 log10 PFU/ml post-treatment with AgNP (20 µl/ml). AgNP were highly effective against the dengue vector A. aegypti, with LC50 values ranging from 10.24 ppm (I instar larvae) to 21.17 ppm (pupae). Overall, this research highlighted the concrete potential of green-synthesized AgNP in the fight against dengue and its primary vector A. aegypti. Further research on structure-activity relationships of AgNP against other dengue serotypes is urgently required.

Laboratory Studies of Aedes aegypti Attraction to Ketones, Sulfides, and Primary Chloroalkanes Tested Alone and in Combination with L-Lactic Acid.

The attraction of female Aedes aegypti to single compounds and binary compositions containing L-lactic acid and an additional saturated compound from a set of ketones, sulfides, and chloroalkanes was studied using a triple-cage dual-port olfactometer. These chemical classes were studied because of their structural relation to acetone, dimethyl disulfide, and dichloromethane, which have all been reported to synergize attraction to L-lactic acid. Human odors, carbon dioxide, and the binary mixture of L-lactic acid and CO2served as controls for comparison of attraction responses produced by the binary mixtures. All tested mixtures that contained chloroalkanes attracted mosquitoes at synergistic levels, as did L-lactic acid and CO2. Synergism was less frequent in mixtures of L-lactic acid with sulfides and ketones; in the case of ketones, synergistic attraction was observed only for L-lactic acid combined with acetone or butanone. Suppression or inhibition of attraction response was observed for combinations that contained ketones of C7-C12 molecular chain length (optimum in the C8-C10 range). This inhibition effect is similar to that observed previously for specific ranges of carboxylic acids, aldehydes, and alcohols.

Studies on larvicidal and pupicidal activity of Leucas aspera Willd. (Lamiaceae) and bacterial insecticide, Bacillus sphaericus, against malarial vector, Anopheles stephensi Liston. (Diptera: Culicidae).

The efficacy of whole plant extracts of Leucas aspera and Bacillus sphaericus has been proven against larvicidal and pupicidal activities of the malarial vector, Anopheles stephensi. The present study investigated the larvicidal and pupicidal activity against the first to fourth instar lavae and pupae of the laboratory-reared mosquitoes, A. stephensi. The medicinal plants were collected from the area around Maruthamalai hills, Coimbatore, Tamil Nadu, India. L. aspera whole plant was washed with tap water and shade dried at room temperature. The dried plant materials were powdered by an electric blender. From the powder, 100 g of the plant materials was extracted with 300 ml of organic solvents of ethanol for 8 h using a Soxhlet apparatus. The extracts were filtered through a Buchner funnel with Whatman number 1 filter paper. The crude plant extracts were evaporated to dryness in a rotary vacuum evaporator. The plant extract showed larvicidal and pupicidal effects after 24 h of exposure. All larval instars and pupae have considerably moderate mortality; however, the highest larval mortality was the ethanolic extract of whole plant L. aspera against the first to fourth instar larvae and pupae values of LC(50) = I instar was 9.695%, II instar was 10.272%, III instar was 10.823%, and IV instar was 11.303%, and pupae was 12.732%. B. spaericus against the first to fouth instar larvae and pupae had the following values: I instar was 0.051%, II instar was 0.057%, III instar was 0.062%, IV instar was 0.066%, and for the pupae was 0.073%. No mortality was observed in the control. The present results suggest that the ethanolic extracts of L. aspera and B. sphaericus provided an excellent potential for controlling of malarial vector, A. stephensi.

Biolarvicidal and pupicidal activity of Acalypha alnifolia Klein ex Willd. (Family: Euphorbiaceae) leaf extract and Microbial insecticide, Metarhizium anisopliae (Metsch.) against malaria fever mosquito, Anopheles stephensi Liston. (Diptera: Culicidae).

The present study was to establish of Acalypha alnifolia leaf extract and microbial insecticide, Metarizhium anisopliae on larvicidal and pupicidal properties of against the malaria fever mosquito, Anopheles stephensi. The leaf extract showed larvicidal and pupicidal effects after 24 h of exposure; however, the highest larval and pupal mortality was found in the leaf extract of ethanol A. alnifolia against the 1st to 4th instar larvae and pupae of values LC(50) value of 1st instar was 5.388%, 2nd instar was 6.233%, 3rd instar was 6.884%, 4th instar was 8.594%, and pupae was 10.073%, respectively, and microbial insecticide, M. anisopliae against the 1st to 4th instar larvae and pupae of values LC(50) value of 1st instar was 7.917%, 2nd instar was 10.734%, 3rd instar was 17.624%, 4th instar was 26.590%, and pupae was 37.908%, respectively. Moreover, combined treatment of values of LC(50) value of 1st instar was 3.557%, 2nd instar was 4.373%, 3rd instar was 5.559%, 4th instar was 7.223%, and pupae was 8.542%, respectively. No mortality was observed in the control. The results that the leaves extract of A. alnifolia and microbial insecticide, M. anisopliae is promising as good larvicidal and pupicidal properties of against malaria fever mosquito, A. stephensi. This is an ideal eco-friendly approach for the control of malarial vector, A. stephensi as a vector control programs. Therefore, this study provides first report on the combined effect of mosquitocidal efficacy of this plant extract and fungal pathogen of M. anisopliae against A. stephensi from Southern India.

Mosquitocidal and water purification properties of Cynodon dactylon, Aloe vera, Hemidesmus indicus and Coleus amboinicus leaf extracts against the mosquito vectors.

Ethanolic extracts of Cynodon dactylon, Aloe vera, Hemidesmus indicus and Coleus amboinicus were tested for their toxicity effect on the third-instar larvae of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. The leaves of C. dactylon, A. vera, H. indicus and C. amboinicus were collected from natural habitats (forests) in Western Ghats, Tamil Nadu, India. A total of 250 g of fresh, mature leaves were rinsed with distilled water and dried in shade. The dried leaves were put in Soxhlet apparatus and extract prepared using 100% ethanol for 72 h at 30-40°C. Dried residues were obtained from 100 g of extract evaporated to dryness in rotary vacuum evaporator. Larvicidal properties of ethanolic leaf extracts showed that the extracts are effective as mosquito control agents. The larval mortality was observed after 24 h exposure. No mortality was observed in the control. The median lethal concentration (LC(50)) values observed for the larvicidal activities are 0.44%, 0.51%, 0.59% and 0.68% for extracts of C. dactylon, A. vera, H. indicus and C. amboinicus, respectively. The observed mortality were statistically significant at P < 0.05 level. C. dactylon showed the highest mortality rate against the three species of mosquito larvae in laboratory and field. The selected plants were shown to exhibit water purification properties. Water quality parameters such as turbidity, pH and water clarity were analyzed in the water samples (pre-treatment and post-treatment of plant extracts) taken from the different breeding sites of mosquitoes. Water colour, turbidity and pH were reduced significantly after treatment with C. dactylon (13 HU, 31.5 mg/l and 6.9), H. indicus (13.8 HU, 33 mg/l and 7.1), A. vera (16 HU, 33.8 mg/l and 7.4) and C. amboinicus (21 HU, 35 mg/l and 7.5) extracts. The study proved that the extracts of C. dactylon, A. vera, H. indicus and C. amboinicus have both mosquitocidal and water sedimentation properties.

Laboratory and field evaluation of medicinal plant extracts against filarial vector, Culex quinquefasciatus Say (Diptera: Culicidae).

The present study explored the effects of Jatropha curcas, Hyptis suaveolens, Abutilon indicum, and Leucas aspera tested against third instar larvae of filarial vector, Culex quinquefasciatus. The dried plant materials were powdered by an electrical blender. From each sample, 500 g powder was macerated with 1.5 L of hexane, chloroform, ethyl acetate, and methanol 8h, using Soxhlet apparatus, and filtered. The extracts were concentrated at reduced temperature on a rotary evaporator and stored at a temperature of 4°C. The yield of crude extract was 11.4, 12.2, 10.6, and 13.5 g in hexane, chloroform, ethyl acetate, and methanol, respectively. The hexane, chloroform, ethyl acetate, and methanol extract of J. curcas with LC(50) values of 230.32, 212.85, 192.07, and 113.23 ppm; H. suaveolens with LC(50) values of 213.09, 217.64, 167.59, and 86.93 ppm; A. indicum with LC(50) values of 204.18, 155.53, 166.32, and 111.58 ppm; and L. aspera with LC(50) values of 152.18, 118.29, 111.43, and 107.73 ppm, respectively, against third instar larvae of C. quinquefasciatus. The larval mortality was observed after 24 h of exposure. Maximum larvicidal activity was observed in the methanolic extract followed by ethyl acetate, chloroform, and hexane extract. No mortality was observed in the control. The observed mortality were statistically significant at P < 0.05 level. L. aspera showed the highest mortality rate against the mosquito larvae in laboratory and field. The larval density was decreased after the treatment of plant extracts at the breeding sites (sewage water), and hence, these plant extracts of the suitable alternatives of synthetic insecticides for the mosquito vector management. The present results suggest that the medicinal plants extract was an excellent potential for controlling filarial vector, C. quinquefasciatus.

Effect of application rate and persistence of boric acid sugar baits applied to plants for control of Aedes albopictus.

The use of toxic bait to kill adult Aedes albopictus is a safe and potentially effective alternative to the use of synthetic chemical insecticides. This study was carried out to determine effective concentrations of boric acid needed in sugar bait solutions applied to plant surfaces, and to determine its residual effect in reducing adult mosquito densities. In outdoor tests in 1,100-m3 screened enclosures, landing rates of Ae. albopictus on a human subject and the number of female mosquitoes in mechanical traps were significantly reduced by a 1% boric acid bait compared with the other tested concentrations (0.25%, 0.50%, and 0.75%) and untreated control. Studies of the duration of boric acid activity on plant surfaces were made in 1.4-m3 cages in the laboratory and outdoors in 78-m3 screened enclosures. In the laboratory tests, 1% boric acid bait resulted in >96% mortality in male and female Ae. albopictus for 14 days, whereas in outdoor tests, mosquito landing rates in the treated enclosures were significantly lower than in the control enclosures for 7 days. Also, mosquito mortality responses to boric acid baits between plants with flowers and nonflowers (1.4-m3 cages in the laboratory) were not significantly different. The results of this study suggest that boric acid baits applied to plant surfaces may provide specific data related to the development of an effective point-source-based adjunct/alternative to the use of conventional adulticides for mosquito control.

Effects of body size and nutritional regimen on survival in adult Aedes albopictus (Diptera: Culicidae).

The effects of adult body size and nutritional regimen on the mean lethal time (LT) to death for the 50th (LT50) and 90th centiles (LT90) of large and small male and female Aedes albopictus (Skuse) were determined in the laboratory. The estimated LT50 and the LT90 for large/small females were significantly shorter for test populations receiving water (5.1/3.8 d) or water + blood (6.7/5.0 d) than for those receiving sucrose (44.4/31.7 d) or sucrose + blood (41.4/29.2 d). The estimated LT50 and LT90 for large/small males receiving water (respectively: 3.2/2.5 d and 4.8/3.8 d) were significantly shorter than for those receiving sucrose (respectively: 18.8/15.9 d and 34.9/32.6 d). The availability of sucrose to adult mosquitoes extended the maximum life span of large and small male and female Ae. albopictus by 6-8x when compared with the availability of water or water + blood. Results indicate that sugar availability is more important than blood as a nutritional parameter for survival and longevity of Ae. albopictus in the laboratory.

Partial blood meal, carbohydrate availability, and bloodfeeding-postponement effects on human host avidity and deet repellency in Aedes albopictus.

Host avidity and deet repellency were measured in partially bloodfed Aedes albopictus provided 10% sucrose, water, or nothing when access to a human host was postponed for 1 to 72 h after a partial blood meal. Carbohydrate availability and postfeeding time influenced host avidity, but partial blood meal effects were not significant. Mean host avidity declined significantly between hours 1 and 6 (range 50-18%) but increased significantly between hours 24 (54%) and 72 (68%) after a partial blood meal. Females provided sucrose solution and females denied sucrose or water showed the least (29%) and most (39%) host avidity, regardless of other treatment effects. The longest and shortest deet protection times were 8.5 h against females provided sucrose and 7.3 h against females denied sucrose or water, respectively. Denial of carbohydrate sustenance significantly increased host avidity and deet repellency in partially bloodfed female Ae. albopictus, whereas sucrose availability led to reduced host responding activity and decreased repellency of deet.

Influence of multiple blood meals on gonotrophic dissociation and fecundity in Aedes albopictus.

Gonotrophic dissociation and fecundity in adult female Aedes albopictus affect the transmission of arbovirus and mosquito population dynamics. Female Ae. albopictus bloodfed on guinea pig and human hosts produced significantly (P < 0.05) higher number of eggs (80 and 82/female, respectively) than females fed on chicken (67 eggs/female). Fecundity in mosquitoes that took a double blood meal (chicken and guinea pig), a triple blood meal (3 separate guinea pigs), or mixed blood meals (chicken, guinea pig, and human) was significantly (P < 0.001) higher than in females fed on a single chicken or on 2 separate chickens (refeeding). Gonotrophic dissociation in laboratory colony of Ae. albopictus was first observed and its frequency decreased with multiple blood meals with triple feeding or mixed feeding (3 meals on 3 host types). Blood meal source did not significantly influence gonotrophic dissociation in Ae. albopictus.

Volatile compounds from the integument of White Leghorn Chickens (Gallus gallus domesticus L.): candidate attractants of ornithophilic mosquito species.

Candidate kairomones of ornithophilic mosquito species are reported from GC/MS analysis of compounds from the skin on the back, the feet, and feathers from the back of White Leghorn chickens (Gallus gallus domesticus). Hexane and ether extracts of chicken feathers differ significantly in attractiveness of Culex spp. mosquitoes. The active (hexane) extracts contained an abundance of alcohols, ketones, and diones. The inactive (ether) extracts contained aldehydes, which also were in the hexane extracts. Analysis of hexane extracts from chicken feet, skin, and feathers demonstrated the qualitative similarity in the compounds collected with subtle differences observed in the quantitative amounts of these compounds. Aldehydes and carboxylic acids were detected in a concentrated ether extract of feathers in quantitatively similar ratios within each compound class for the corresponding series of C(6)-C(9 )aldehydes and acids.

Host species diversity and post-blood feeding carbohydrate availability enhance survival of females and fecundity in Aedes albopictus (Diptera: Culicidae).

Aedes albopictus mosquito is an opportunistic blood feeder and has a broad host range. The feeding behavior and habits of this mosquito are liable to increase the transmission potential of arboviruses. The survival and fecundity in A. albopictus fed on different hosts and post-blood meal provision of sugar were investigated in a laboratory-reared colony. Adult survival of caged female A. albopictus that were fed on blood of two different hosts (double meal) was higher than the females fed only on one host (single meal) (mean survival: 70.2+/-9.6 vs. 55.5+/-5.5%, respectively) when held in the laboratory for 72 h after blood feeding. Mean survival of females provided 10% sucrose solution (in water) after a single or double blood meal was higher (90.5+/-6.4% and 89.3+/-6.5%, respectively) than in the respective groups receiving water only following blood feeding (double meal: 49.0+/-9.6%; single meal: 45.3+/-10.9%). Females receiving a double meal were more fecund on average (89.0+/-6.6 eggs) than females provided a single meal (82.3+/-8.2 eggs).

Field evaluation of boric acid- and fipronil-based bait stations against adult mosquitoes.

The effectiveness of boric acid (1%) and fipronil (0.1%) bait stations in reducing the number of laboratory-reared female Aedes aegypti and Ochlerotatus taeniorhynchus mosquitoes released in outdoor screened cages was evaluated. Both toxicants significantly reduced landing rates of the 2 mosquito species on a human subject. However, no significant reduction in the number of adult mosquitoes caught by counterflow geometry (CFG) traps baited with CO2 was observed in the boric acid- and fipronil-treated cages compared with control cage. The 2 bait stations were further evaluated against natural populations of adult mosquitoes in 3 residential yards (each ca. 0.8 ha) in St. Johns County, FL. Both bait stations failed to significantly reduce counts of female mosquitoes landing on a human subject; and the capture rates of adult mosquitoes by CFG traps baited with dry ice in bait-treated and control experimental yards were not significantly different. Further field research is needed on the density and placement of bait stations in order to determine their utility in adult mosquito control programs.

Microsporidiosis (Microsporidia: Culicosporidae) alters blood-feeding responses and DEET repellency in Aedes aegypti (Diptera: Culicidae).

Infection of Aedes aegypti (L.) (Diptera: Culicidae) with Edhazardia aedis (Microsporidia: Culicosporidae) reduced mean human host attraction and landing/probing rates in female mosquitoes by 53 and 62%, respectively, compared with rates in microsporidia-free females. Infection with E. aedis reduced the average weight of unfed female mosquitoes by 4%, caused them to imbibe 23% less blood, and to lay 30% fewer eggs than healthy females. In contrast, E. aedis-infected mosquitoes required 20% more time (>1 h) than healthy females to bite skin treated with 15% DEET. Statistically significant morbidity in E. aedis-infected females was indicated by reductions in host attraction and landing/probing responses, the mass of unfed and blood-engorged females, and fecundity, and by increased DEET repellency.

Laboratory comparison of Aedes aegypti attraction to human odors and to synthetic human odor compounds and blends.

Chemical lures can enhance the ability of traps to collect mosquitoes, selectively target species for capture, and provide a realistic assessment of the species and host-equivalent numbers of mosquitoes present in the local area. One approach to the development of chemical lures is to manufacture blends that comprise odors released in human emanations. These blends need to be safe for use in the environment, desirable from an economic standpoint, and transportable to the field for use in traps. In this report, we compared the attraction of mosquitoes to various chemicals, blends, and odors from humans. Noncompetitive (single-treatment) bioassays established that some blends are equivalent or more attractive to Aedes aegypti than human odors. Competitive bioassays were conducted; these involved simultaneous comparison of 2 treatments: single compounds to binary blends; binary blends to a trinary blend of L-lactic acid, acetone, and dimethyl disulfide; and the trinary blend to human odors from 3 volunteers. The overall trend was that the trinary blend was more attractive than binary blends, and binary blends were more attractive than single compounds. However, human odors were still significantly more attractive than the trinary blend. Therefore, further modifications and refinements to blends will be needed to better compete against human odors.

Efficacy of four trap types for detecting and monitoring Culex spp. in north central Florida.

The effectiveness of four types of mosquito traps at sampling Culex mosquitoes was compared at two north central Florida study sites (a commercial dairy and a swine research unit) with highly eutrophic lagoons that have a history of producing large populations of Culex mosquitoes. Traps evaluated included a John Hock (JH) model 1012 CDC style light trap, JH model 1712 CDC Gravid Trap (GT), and American Biophysics Corporation's Mosquito Magnet-Experimental (MM-X) and commercial model MM-Professional (MM-Pro) traps. The MM-X and MM-Pro traps are based on new counterflow technology. Culex nigripalpus Theobald and Culex quinquefasciatus Say were the two most abundant species collected, and they were the dominant species at the dairy site and swine research unit, respectively. Culex erraticus Dyar & Knabb and Culex salinarius Coquillett also were caught but in much lower numbers than the two dominant species at the swine unit, and rarely at the dairy site. At the dairy site the MM-Pro collection of total female Cx. quinquefasciatus was significantly greater than all other trap types (MM-Pro > GT > MM-X = CDC), and the MM-Pro also caught the most Cx. nigripalpus, but not significantly more than the CDC or MM-X (MM-Pro = CDC = MM-X > GT). At the swine research unit the largest number of female Cx. quinquefasciatus were caught in the MM-X trap, but the only significant difference was with the CDC trap (MM-X = MM-Pro = CT > CDC). For Cx. nigripalpus the CDC trap caught the most females, but these collections were only significantly different from the MM-Pro and GT (CDC = MM-X > MM-Pro > GT). The GT caught significantly more gravid female Cx. quinquefasciatus than all the other trap types at both sites, but collected very few gravid Cx. nigripalpus at either site.

Effects of sublethal exposure to boric acid sugar bait on adult survival, host-seeking, bloodfeeding behavior, and reproduction of Stegomyia albopicta.

Effects of sublethal exposure to 0.1% boric acid sugar bait on adult survival, host-seeking, bloodfeeding behavior, and reproduction of Stegomyia albopicta were studied in the laboratory. Survival of males as well as females was significantly reduced when exposed to the bait, compared to control adults. The host-seeking and bloodfeeding activities in the baited females decreased, but the mean duration of blood engorgement (probing to voluntary withdrawal of proboscis) was not significantly different between the baited and control females. The landing and biting rates (human forearm) were significantly reduced in the baited females compared to nonbaited controls. Fecundity and fertility (based on number of laid eggs per female and percentage egg hatch, respectively) in the baited females were significantly reduced, and ovarian development was retarded. Sublethal exposure to sugar-based boric acid bait has the potential to reduce adult populations of St. albopicta.