DIFFERENTIAL TOXICITY OF PYRETHROID AND ORGANOPHOSPHATE INSECTICIDES TO THE HONEY BEE, APIS MELLIFERA AND THE YELLOW FEVER MOSQUITO, AEDES AEGYPTI

Six insecticide active ingredients (AIs) and five commercial insecticide formulations were applied by topical application and onto filter paper strips to determine differential toxicity to Aedes aegypti (L.) and Apis mellifera (L.), and to evaluate their potential use in future insecticide resistance monitoring surveys. For topical application, 0.1 or 1 µl of the technical insecticide solution was applied to the Ae. aegypti and A. mellifera thorax, respectively. For insecticide-impregnated strips the insecticide amount varied, according with the commercial formulation. By topical application deltamethrin was the most toxic AI (LD 50 = 0.057 µg/g) to Ae. aegypti and prallethrin was least toxic (LD 50 = 19.42 µg/g). For A. mellifera, the most toxic AIs were deltamethrin (LD 50 = 0.013 µg/g) and bifenthrin (LD50 = 0.156 µg/g); and the least toxic was chlorpyrifos (LD 50 = 3.246 µg/g). When the insecticide-impregnated papers method was used, Mosquitomist Two (chlorpyrifos 24.6%) was the most toxic insecticide for Ae. aegypti (LC50 = 0.024 µg/cm2 ), and Aqualuer (permethrin 20.6%, PBO 20.6%) was least toxic (LC50 = 0.408 µg/cm2 ). For A. mellifera the most toxic commercial insecticide formulations were Talstar (bifenthrin 7.9%; LC50 = 0.288 µg/cm2 ) and Mosquitomist Two (LC50 = 0.299 µg/cm2 ), with no significant differences, and the least toxic commercial formulation was Deltagard (deltamethrin 2.0%; LC50 = 15.084 µg/cm2 ). By topical application, more than 28 times of chlorpyrifos was needed to obtain the same mortality in A. mellifera as in Ae. aegypti. When using the insecticide-impregnated paper method, more than 206 times of Deltagard was needed to obtain the same mortality in A. mellifera as in Ae. aegypti. Even though Mosquitomist Two was the most toxic insecticide for both insect species, the honey bees were >12 times more tolerant to this insecticide, compared with the mosquitoes.

PERFORMANCE OF THE ATRAKTA™ MOSQUITO LURE IN COMBINATION WITH DYNATRAP® (MODELS DT160 AND DT700) AND A CDC TRAP (MODEL 512)

The performance of the three-part mosquito lure ATRAKTA (1-octen-3-ol, ammonium bicarbonate, and lactic acid) was evaluated in two DynaTrap commercial mosquito traps (models DT160 and DT700) as well as in one model of CDC trap (model 512). Lures were evaluated fresh from the factory, after being aged in functioning traps under field conditions, and after prolonged storage in the packaging (aged for 30 days aged in functioning traps before being tested in the DynaTrap models; and two years stored in the packaging before being tested in CDC traps). The primary study questions were whether the addition of lures would increase efficacy of various trap types and whether lures would retain effectiveness after a lengthy stay on the shelf or in traps. To do this, traps with no lures, new lures and old lures were used to trap three mosquito species (Aedes albopictus, Culex quinquefasciatus, and Anopheles gambiae) in the field in West Africa Mali, the first two species are also common North American nuisance mosquitoes. The addition of ATRAKTA lures aged 30 days to both DynaTrap® models, and ATRAKTA lures aged two years in the packaging to the CDC trap significantly increased catches of female Cx. quinquefasciatus and Ae. albopictus mosquitoes. Aged lures did not significantly lose their attraction in comparison to lures fresh from the factory. The addition of lures to traps resulted in slight increases in catches of An. gambiae, but these were not statistically significant. No effect of any lures on males was observed.

RELATIONSHIP OF PRECIPITATION AND HABITAT TO THE SPATIAL AND TEMPORAL ABUNDANCE OF AEDES ATLANTICUS AND AEDES INFIRMATUS IN ST. JOHNS COUNTY, FLORIDA

The purpose of this study was to perform descriptive and inferential analyses to better understand the presence of the abundant mosquito species Aedes atlanticus and Aedes infirmatus in St. Johns County, northeastern Florida. Historical surveillance data (2010-2019) obtained from Anastasia Mosquito Control District of St. Johns County, St. Augustine, FL, was organized to graph temporal mosquito abundance trends and inverse distance weighted (IDW) interpolation was used to map spatial distribution patterns of mosquitoes. Precipitation and habitat composition were investigated as spatiotemporal predictors of mosquito abundance using Pearson’s correlation statistics. There were considerable and inconsistent fluctuations in the population abundance of Ae. atlanticus and Ae. infirmatus across and within individual surveillance seasons during the last decade. Precipitation was significantly associated with total county-wide mosquito population counts by season (Ae. atlanticus, R = 0.810, p = 0.005; Ae. infirmatus, R = 0.850, p = 0.002), while the association with weekly mosquito population trends was inconsistently significant across species, lag time, and years. The proportion of surrounding land covered by upland forest, water, and agriculture was associated with species abundance at the spatial level of individual trap sites. Overall, the results identify that Ae. atlanticus and Ae. infirmatus share a spatiotemporal relationship and are similarly impacted by rainfall and habitat type. Findings of the study might help to inform improved surveillance by integrating IDW estimation maps with current district resources and improved knowledge of species’ ecology.

FIELD COMPARISON OF AUTOCIDAL GRAVID OVITRAPS AND IN2CARE TRAPS AGAINST AEDES AEGYPTI IN DOWNTOWN SAINT AUGUSTINE, NORTHEASTERN FLORIDA

Mosquito Control programs are utilizing cost-effective long term autocidal gravid traps because they minimize labor needs while targeting the gravid population of container-breeding mosquitoes. This field study compared the efficacy of the In2Care Mosquito Trap and the Centers for Disease Control and Prevention autocidal gravid ovitrap (CDC-AGO). The study consisted of two control and two treatment sites, and each treatment site had either 100 In2Care Mosquito Traps or 100 CDC-AGOs. Aedes aegypti populations in each site were monitored using Biogent (BG) Sentinel 2 mosquito traps and ovitraps. Analysis of pre- and post-treatment data indicated no significant difference in adult mosquito populations detected by BG traps from either the In2Care or CDC-AGO sites. However, the mean number of eggs collected by ovitraps showed significant reduction in both trap type treated areas posttreatment, compared to pre-treatment. Furthermore, the mean number of egg collections from the In2Care mosquito trap treated area was much less than the collection from the CDC-AGO trap treated area post-treatment.

EVALUATION OF D-ALLETHRIN IN THE THERMACELL MOSqUITO REPELLENT DEVICE AGAINST THE LONE STAR TICK UNDER LABORATORY CONDITIONS

D-allethrin vapor generated from a personal mosquito repellent device (Thermacell MR300) was evaluated for its effectiveness to repel the lone star tick, Amblyomma americanum (adults and nymphs) when released at tick body level in a wind tunnel and in an olfactometer. In the wind tunnel 48.5% of ticks moved upwind when only attractant lure was present, while only 30.8% moved upwind when d-allethrin repellent was present with the lure. In the olfactometer strong repellency of d-allethrin vapor to adults was observed, but the effect was reduced with nymphs. Results of this study showed that d-allethrin vapor generated by the Thermacell MR300 pad could be used to reduce movement of ticks towards a host under some conditions.

CONSIDERATIONS OF MORPHOLOGIC OBSERVATIONS OF MOSQUITO SPECIES FROM IDENTIFYING COMPLETE SAMPLES IN PANAMA CITY BEACH, FLORIDA

In Panama City Beach, Florida, thirteen mosquito species have been recently registered into public health data banks over the span of 7 years [2014-2020], ten species within their published geographic range and three species outside of their noted geographic range. The underreporting is likely due to past identification practices of sub-sampling and aliquoting surveillance collections while only recording the top-most three abundant species for control application thresholds. However, these thirteen species have not been recorded in this area by public health operations up until their respective record timelines. Timelines of identification, species specific character states, the dynamic of identifying similar species and alternate identification methods are discussed. As of 2020, 10 genera and 50 species within Diptera: Culicidae are recorded in Panama City Beach, FL, U.S.A.

EVALUATION OF ORANGE OIL APPLIED BY THREE BACKPACK SPRAYERS AGAINST AEDES AEGYPTI AND CULEX QUINQUEFASCIATUS

A solvent orange oil has been used to mix with permethrin and PBO as a commercial adulticide product called Aqualure® 20-20 for control of adult mosquitoes. The orange oil at 2.7% and 3.5% sprayed by three backpack sprayers, Hudson battery operated sprayer modified with a Solo nozzle, hand pump sprayer Solo-425, and Birchmeire battery operated sprayer, against caged adult female Aedes aegypti Linn. and Culex quinquefasciatus Say resulted in 89%–100% mortality of Ae. aegypti and 100% mortality of Cx. quinquefasciatus. The three different backpack sprayers did not show any significant differences in the percent mortality. Our test results demonstrate that orange oil alone at a high dose (3.5 %) showed effective insecticidal characteristics against both species of adult mosquitoes.

EFFECT OF COPPER SULPHATE PENTAHYDRATE ON MOSQUITO LARVAL AEDES AEGYPTI, CULEX QUINQUEFASCIATUS, AND ANOPHELES QUADRIMACULATUS IN LABORATORY AND UNDER SEMI-FIELD CONDITIONS

Mosquito larval control has been conducted by various chemicals and biological agents to reduce mosquito population and mosquito-borne diseases. The larvicidal efficacy of Copper sulphate pentahydrate (CuSO4 ·5H2 O) on Aedes aegypti, Culex quinquefasciatus and Anopheles quadrimaculatus was evaluated separately in the laboratory and semi-field conditions. Different concentrations of CuSO4 ·5H2 O (ranging from 1 to 20 ppm) were tested against third (3rd ) instar larvae. Larval mortality was observed at 24, 48 & 72h after exposure and the LC 50 values were determined. In both conditions, larval mortality showed concentration and time dependent correlations i.e. larval mortality was higher with increasing concentration CuSO4 ·5H2 O and exposure time. No mortality was observed in the control (0 ppm). Of the three species tested, Cx. quinquefasciatus and An. quadrimaculatus were more sensitive to CuSO4 ·5H2 O than Ae. aegypti. It was demonstrated that 1.5 -2.25 ppm of CuSO4 ·5H2 O killed more than 50% of Cx. quinquefasciatus and An. quadrimaculatus larvae at 72 h in both laboratory and semi-field conditions, whereas Ae. aegypti could survive easily in these concentrations. Besides, CuSO4 ·5H2 O showed more toxicity to larvae in semi-field conditions than laboratory studies. These results suggest that CuSO4 ·5H2 O could be used as a potential larvicide especially for Cx. quinquefasciatus and An. quadrimaculatus as a low-cost alternative larvicidal agent. Further studies will be needed to confirm its effectiveness in large scale field trials.

FIELD EVALUATION OF TALSTAR (BIFENTHRIN) RESIDENTIAL BARRIER TREATMENTS ALONE AND IN CONJUNCTION WITH MOSQUITO MAGNET LIBERTY PLUS TRAPS IN CEDAR KEY, FLORIDA

The effectiveness of bifenthrin applications to vegetation with and without commercial mosquito traps (Mosquito Magnet Liberty Plus) was evaluated against Culicoides biting midges in a residential coastal area located in Cedar Key, Florida. Efficacy evaluations were determined by surveillance trap collections and modified landing rate counts. In general, all treatments provided significant reduction from Culicoides biting midge pressure when compared with untreated yards with no traps (control). However, the combination of bifenthrin and Liberty Plus traps proved to be the most successful in reducing Culicoides compared with yards with only a Liberty Plus trap. Yards treated with bifenthrin alone or in combination with the Liberty Plus trap were more successful than controls, suggesting that Culicoides biting midge population suppression may be obtained through barrier application alone.

BARRIER TREATMENTS USING COMBINED LAMBDA-CYHALOTHRIN AND PYRIPROXYFEN REDUCE PERIDOMESTIC AEDES MOSQUITOES IN A SUBTROPICAL ENVIRONMENT

Barrier treatment of vegetation using lambda-cyhalothrin has been shown to be effective at reducing adult mosquito populations in the US. However, recent investigations have indicated that standard residual adulticide barrier treatments may be enhanced when combined with an insect growth regulator targeting immature stages that could be transferred to immature habitat by adults contacting treated surfaces. We conducted field trials at residential sites in a subtropical urban environment in north central Florida treating blocks of vegetation with residual sprays of lambda-cyhalothrin (Demand® CS) and pyriproxyfen (Archer®) alone and in combination treatments to determine their efficacy against peridomestic mosquitoes. The combined treatment resulted in consistent approximately 100% reduction in Aedes mosquito eggs for 16 wk post-treatment compared to not significantly lower but more variable reductions at alone treatment sites.