Comparison of entomological impacts of two methods of intervention designed to control Anopheles gambiae s.l. via swarm killing in Western Burkina Faso.

Outdoor biting constitutes a major limitation of current vector control based primarily on long-lasting insecticidal nets and indoor residual spraying, both of which are indoor interventions. Consequently, malaria elimination will not be achieved unless additional tools are found to deal with the residual malaria transmission and the associated vector dynamics. In this study we tested a new vector control approach for rapidly crashing mosquito populations and disrupting malaria transmission in Africa. This method targets the previously neglected swarming and outdoor nocturnal behaviors of both male and female Anopheles mosquitoes. It involved accurate identification and targeted spraying of mosquito swarms to suppress adult malaria vector populations and their vectorial capacities. The impact of targeted spraying was compared to broadcast spraying and evaluated simultaneously. The effects of the two interventions were very similar, no significant differences between targeted spraying and broadcast spraying were found for effects on density, insemination or parity rate. However, targeted spraying was found to be significantly more effective than broadcast spraying at reducing the number of bites per person. As expected, each intervention had a highly significant impact upon all parameters measured, but the targeted swarm spraying required less insecticide.

A Field Efficacy Evaluation of In2Care Mosquito Traps in Comparison with Routine Integrated Vector Management at Reducing Aedes aegypti.

Aedes aegypti is the predominant vector of dengue, chikungunya, and Zika viruses. This mosquito is difficult to control with conventional methods due to its container-inhabiting behavior and resistance to insecticides. Autodissemination of pyriproxyfen (PPF), a potent larvicide, has shown promise as an additional tool to control Aedes species in small-scale field trials. However, few large-scale field evaluations have been conducted. We undertook a 6-month-long large-scale field study to compare the effectiveness and operational feasibility of using In2Care Mosquito Traps (In2Care Traps, commercially available Aedes traps with PPF and Beauveria bassiana) compared to an integrated vector management (IVM) strategy consisting of source reduction, larviciding, and adulticiding for controlling Ae. aegypti eggs, larvae, and adults. We found that while the difference between treatments was only statistically significant for eggs and larvae (P < 0.05 for eggs and larvae and P > 0.05 for adults), the use of In2Care Traps alone resulted in 60%, 57%, and 57% fewer eggs, larvae, and adults, respectively, collected from that site compared to the IVM site. However, In2Care Trap deployment and maintenance were more time consuming and labor intensive than the IVM strategy. Thus, using In2Care Traps alone as a control method for large areas (e.g., >20 ha) may be less practical for control programs with the capacity to conduct ground and aerial larviciding and adulticiding. Based on our study results, we conclude that In2Care Traps are effective at suppressing Ae. aegypti and have the most potential for use in areas without sophisticated control programs and within IVM programs to target hotspots with high population levels and/or risk of Aedes-borne pathogen transmission.

Aerial ULV control of Aedes aegypti with naled (Dibrom) inside simulated rural village and urban cryptic habitats.

We conducted aerial fixed wing ultra low volume (ULV) spray trials with naled to investigate penetration of exposed and simulated cryptic habitat within opened buildings, partially sealed buildings, and outdoor locations targeting sentinel adult Aedes aegypti mosquitoes in north central Florida. Mortality was observed in open and closed buildings and outdoors, even in mosquitoes placed in cryptic habitats. Observations on the impact of building type, mosquito exposure method such as placement in cryptic habitat, and spray nozzle size on mosquito mortality are described and analyzed.

Evaluating the Vector Control Potential of the In2Care® Mosquito Trap Against Aedes aegypti and Aedes albopictus Under Semifield Conditions in Manatee County, Florida.

Successful integrated vector management programs may need new strategies in addition to conventional larviciding and adulticiding strategies to target Aedes aegypti and Ae. albopictus, which can develop in small, often cryptic, artificial and natural containers. The In2Care® mosquito trap was recently developed to target and kill larval and adult stages of these invasive container-inhabiting Aedes mosquitoes by utilizing autodissemination. Gravid females that visit the trap pick up pyriproxyfen (PPF) that they later transfer to nearby larval habitats as well as Beauveria bassiana spores that slowly kill them. We assessed the efficacy of the In2Care mosquito trap in a semifield setting against locally sourced strains of Ae. aegypti and Ae. albopictus. We found that the In2Care mosquito trap is attractive to gravid Ae. aegypti and Ae. albopictus females and serves as an egg sink, preventing any adult emergence from the trap (P = 0.0053 for both species). Adult females successfully autodisseminated PPF to surrounding water-filled containers, leading to a statistically significant reduction in new mosquito emergence (P ≤ 0.0002 for both species). Additionally, we found effective contamination with Beauveria bassiana spores, which significantly reduced the survivorship of exposed Ae. aegypti and Ae. albopictus (P ≤ 0.008 for both species in all experimental setups). In summary, the In2Care mosquito trap successfully killed multiple life stages of 2 main mosquito vector species found in Florida under semifield conditions.

Tuning the excited state of water-soluble Ir(III)-based DNA intercalators that are isostructural with [Ru(II)(NN)2(dppz)] light-switch complexes.

The synthesis of two new Ir(III)  complexes which are effectively isostructural with well-established [Ru(NN)2(dppz)](2+) systems is reported (dppz=dipyridophenazine; NN=2,2'-bipyridyl, or 1,10-phenanthroline). One of these Ir(III) complexes is tricationic and has a conventional N6 coordination sphere. The second dicationic complex has a N5C coordination sphere, incorporating a cyclometalated analogue of the dppz ligand. Both complexes show good water solubility. Experimental and computational studies show that the photoexcited states of the two complexes are very different from each other and also differ from their Ru(II) analogues. Both of the complexes bind to duplex DNA with affinities that are two orders of magnitude higher than previously reported Ir(dppz)-based systems and are comparable with Ru(II)(dppz) analogues.

Nontarget effects of aerial mosquito adulticiding with water-based unsynergized pyrethroids on honey bees and other beneficial insects in an agricultural ecosystem of north Greece.

We assessed the nontarget effects of ultra-low-volume (ULV) aerial adulticiding with two new water-based, unsynergized pyrethroid formulations, Aqua-K-Othrine (FFAST antievaporant technology, 2% deltamethrin) and Pesguard S102 (10% d-phenothrin). A helicopter with GPS navigation technology was used. One application rate was tested per formulation that corresponded to 1.00 g (AI)/ha of deltamethrin and 7.50 g (AI)/ha of d-phenothrin. Three beneficial nontarget organisms were used: honey bees (domesticated hives), family Apidae (Apis mellifera L.); mealybug destroyers, family Coccinellidae (Cryptolaemus montrouzieri Mulsant); and green lacewings, family Chrysopidae (Chrysoperla carnea (Stephens)). No significant nontarget mortalities were observed. No bees exhibited signs of sublethal exposure to insecticides. Beehives exposed to the insecticidal applications remained healthy and productive, performed as well as the control hives and increased in weight (25-30%), in adult bee population (14-18%), and in brood population (15-19%).

Droplet sampling of an oil-based and two water-based antievaporant ultra-low volume insecticide formulations using Teflon- and magnesium oxide-coated slides.

We estimated the diameters below which 50% and 90% of the volume of droplets exist (Dv50 and Dv90, respectively) of 1 oil-based (Permanone 30-30) and 2 water-based (AquaReslin, Aqua-K-Othrine) antievaporant aerosols (with the Film Forming Aqueous Spray Technology [FFAST]) using Teflon- and magnesium oxide (MgO)-coated slides and determined whether the aging of the droplets on the slides (up to 60 min) exhibited any significant effect on Dv50 and Dv90 calculations. There were no significant differences in either Dv50 or Dv90 estimates on MgO-coated slides at 0 min and 60 min for all 3 products tested. On Teflon-coated slides, the only product that showed significant difference between 0 min and 60 min in both Dv50 and Dv90 estimates was Aqua-K-Othrine, perhaps due to a difference in formulation components. Specifically, both values corresponding to Dv50 and Dv90 at 60 min decreased by approximately 50% when compared to the values at 0 min. For the other 2 products, AquaReslin and Permanone, aging of droplets on Teflon up to 60 min did not have any significant effect on Dv50 and Dv90 values. To further investigate the behavior of Aqua-K-Othrine droplets on Teflon-coated slides we observed the droplets immediately after spraying and at 10-min intervals under different conditions of temperature and humidity. The majority of the shrinkage occurred within the 1st 10 min after impaction on the slides under all conditions tested. So in most field situations where slides are read several hours or days after collection, this shrinkage would not be observed. The MgO-coated slides should be the preferred field method for sampling droplets of Aqua-K-Othirne with the FFAST antievaporant technology.

Efficacy of aerial ultra-low volume applications of two novel water-based formulations of unsynergized pyrethroids against riceland mosquitoes in Greece.

We assessed the efficacy of ultra-low volume aerial adulticiding with 2 new water-based, unsynergized formulations of Aqua-K-Othrin (2% deltamethrin) and Pesguard S102 (10% d-phenothrin) against the riceland mosquitoes of Greece. A helicopter with Global Positioning System (GPS) navigation, real-time weather recording, and spray dispersal modeling (AgDISP) was utilized to accurately treat the experimental blocks by adjusting spray line positions to changing meteorological conditions. Two application rates were applied per formulation that corresponded to 0.75 and 1.00 g AI/ha of deltamethrin and 7.50 and 10.00 g AI/ha of d-phenothrin. The mosquitoes used for the trials were the main nuisance species found in rice field areas of Thessaloniki, which were primarily Aedes caspius, followed by Culex modestus and Anopheles sacharovi. Overall mean mortality of caged mosquitoes was 69.2% and 64.8% for deltamethrin and d-phenothrin, respectively. Mean population decrease in wild mosquito populations within the treatment areas was 76.5% and 78% for deltamethrin and d-phenothrin, respectively. The AgDISP dispersal model, coupled with GPS navigation and real-time weather recording, enabled accurate placement of the spray cloud such that the majority of the treatment area received sufficiently high droplet densities to result in uniform caged-mosquito mortality across all sampling sites.

Prediction, assessment of the Rift Valley fever activity in East and Southern Africa 2006-2008 and possible vector control strategies.

Historical outbreaks of Rift Valley fever (RVF) since the early 1950s have been associated with cyclical patterns of the El Niño/Southern Oscillation (ENSO) phenomenon, which results in elevated and widespread rainfall over the RVF endemic areas of Africa. Using satellite measurements of global and regional elevated sea surface temperatures, elevated rainfall, and satellite derived-normalized difference vegetation index data, we predicted with lead times of 2-4 months areas where outbreaks of RVF in humans and animals were expected and occurred in the Horn of Africa, Sudan, and Southern Africa at different time periods from September 2006 to March 2008. Predictions were confirmed by entomological field investigations of virus activity and by reported cases of RVF in human and livestock populations. This represents the first series of prospective predictions of RVF outbreaks and provides a baseline for improved early warning, control, response planning, and mitigation into the future.

A droplet collection device and support system for ultra-low-volume adulticide trials.

A supporting stand to suspend rotating impactors and mosquito cages is a requirement for field tests during pesticide efficacy trials. We present schematics for a collection device and associated support system for sampling droplets of ultra-low-volume (ULV) sprays during mosquito adulticide applications. This system offers the advantages of cost efficiency, increased ease of deployment, off-season storage, visibility, stability, and ULV collection efficacy. Use of this system ensures that droplet collection and meteorological equipment is at appropriate and consistent heights between trials. The 2 arms of the support allow for placement of multiple cages, light-emitting or reflecting devices, and wind-indicating ribbons to be attached to the station. The support described makes possible deployment of stations over a wider variety of terrains, increasing the extent of field trials. Presentation of the simple design and fabrication of the rotating collection device (impactor), T-station, and its support is provided.

Identification of two mosquitocidal Bacillus cereus strains showing different host ranges.

Mosquitocidal bacteria, M413 and C32 have been isolated from sediment samples collected from woodland and ditch, respectively. Gas chromatographic analysis of fatty acids methyl esters (GC-FAME) and 16S rRNA gene sequence alignment results showed these isolates belong to Bacillus cereus. The SDS-PAGE analysis of sporulated cultures of both isolates showed two major bands very similar in size. Interestingly, however, M413 is mainly toxic to 4th instars of Ochlerotatus taeniorhynchus whereas C32 is to those of Culex quinquefasciatus.

Characterization of a new ultra-low volume fuselage spray configuration on Air Force C-130H airplane used for adult mosquito control.

The US Air Force (USAF) tested a new fuselage boom configuration on the C-130H airplane. We used into-the-wind and crosswind field trials to characterize a BVA oil (BVA Inc, Wixom, MI) droplet spectra produced by fuselage booms with flat-fan nozzles (8001, 8005) at the Air Force Range at Avon Park, FL. Across all trials, median droplet diameter (DV50) for 8001 and 8005 nozzles were 11.4 microm and 54.3 microm, respectively. For 8005 nozzles 22% of droplets collected were 7 microm to 25 microm size range while 75% of droplets from 8001 nozzles were < 7 microm. Fuselage configuration parameters and field data were also used as input variables into the Agricultural Dispersal (AGDISP) computer model to predict aerosol deposition and droplet fate. AGDISP predictions were compared with field data from crosswind tests and the model was found to fit reasonably well to empirical data. However, AGDISP predictions were better correlated with empirical findings for larger droplets than smaller droplets and for locations closer to the release point than further downwind.

Canopy effects droplet size distribution and meteorological change.

Wind speed fluctuations measured via a 3-dimensional sonic anemometer recording at 10 Hz returned detailed information both above and within the canopy. The information returned facilitated detailed descriptions of atmospheric energy. In short, large energetic motions equal spray transfer into the target zone, the plant canopy. Data are presented on the physical and biological characterization of spray flux. When nontarget mortality was high the conditions were stable, and large volumes of pesticide descended via aircraft vortices and sedimentation. On the neutral night where there was turbulence in the atmosphere a large proportion of the spray was transported from the target, by winds at altitude. Therefore nontarget mortality and the overall volume entering the canopy were low. That chemical, however, which did enter the canopy was well mixed and transported horizontally as opposed to the more vertical sedimentation on the stable night creating more consistent control.

Minimizing the impact of the mosquito adulticide naled on honey bees, Apis mellifera (Hymenoptera: Apidae): aerial ultra-low-volume application using a high-pressure nozzle system.

The impact of the mosquito adulticide naled on honey bees, Apis mellifera L., was evaluated by exposing test beehives to nighttime aerial ultra-low-volume (ULV) applications using a high-pressure nozzle system. The tests were conducted during routine mosquito control missions at Manatee County, Florida, in summer 2000. Two treatment sites were sprayed a total of four times over a 10-wk period. Honey bees, which clustered outside of the hive entrances, were subjected to naled exposure during these mosquito control sprays. The highest average naled ground deposition was 2,688 microg/m2 at the Port Manatee site, which resulted in statistically significant bee mortality (118) compared with the controls. At the Terra Ceia Road site, an intermediate level of naled deposition was found (1,435 microg/m2). For this spray mission, the range of dead bees per hive at Terra Ceia was 2 to 9 before spraying and 5 to 36 after naled application. Means of all other naled ground depositions were < 850 microl/m2. We concluded that substantial bee mortality (> 100 dead bees) resulted when naled residue levels were > 2,000 kg/m2 and honey bees were clustered outside of the hive entrances during mosquito adulticide applications. Compared with the flat-fan nozzle systems currently used by most of Florida's mosquito control programs, the high-pressure nozzle system used in this experiment substantially reduced environmental insecticide contamination and lead to decreased bee mortality. Statistical analysis also showed that average honey yield at the end of the season was not significantly reduced for those hives that were exposed to the insecticide.