Robert L. Aldridge

Longevity and Efficacy of Bifenthrin Treatment on Desert-Pattern US Military Camouflage Netting Against Mosquitoes in a Hot-Arid Environment

Abstract The current Department of Defense pest management system does not provide adequate protection from arthropod disease vectors to personnel deployed in support of US military operations. We hypothesized that military camouflage netting, ubiquitous around living and working areas in current US military operations in Africa and the Middle East, treated with a residual pesticide such as bifenthrin may reduce the presence of biting insects and improve the military pest management system. In this study, we examined the longevity and efficacy of bifenthrin applied to camouflage netting material at the maximum label rate of 0.03 liter formulation (7.9% AI) per 92.9 m2 against field populations of mosquitoes in southern California in a hot-arid environment similar to regions of Iraq, Afghanistan, and the Horn of Africa. We showed that bifenthrin treatment of camouflage netting was effective at reducing mosquito populations, predominantly Psorophora columbiae and Aedes vexans, by an average of up to 46% for 56 days, and could cause as much as 40% mortality in Culex quinquefasciatus in laboratory bioassays for nearly 2 months postapplication. These population reductions could translate to commensurate reductions in risk of exposure to mosquito-borne pathogens, and could potentially be effective against sand flies and filth flies.

Impact of Topical Application Site On the Efficacy of Permethrin and Malathion To Culex quinquefasciatus

Abstract Although insecticide spray droplets will potentially impinge on many exoskeletal body regions, traditional mosquito topical bioassays focus insecticide application to the mesothoracic pleural or dorsal area. Concentrations of permethrin and malathion found in droplets from ultra-low volume and low-volume sprays were evaluated for efficacy against adult Culex quinquefasciatus using a topical application bioassay. Results document nonuniform insecticide sensitivity across body regions, which has not been previously assessed in mosquitoes. Insecticide contact with appendages, such as the leg and the wing, returned much lower mortality from both insecticides than exposure to the primary body (i.e., head, thorax, and abdomen). No difference was observed in percent mortality 24 h after exposure to different insecticides to the same body region. Sublethal behaviors were also observed and discussed for both insecticides. Our findings provide valuable information for those performing topical bioassays, and may help explain insecticide effectiveness wherever droplets impinge upon the mosquito body during laboratory or field applications.

Aspirator Gun for High-Throughput Mosquito Bioassays

Abstract We describe an innovative aspirator gun designed to transfer individual anesthetized mosquitoes directly into glass bioassay tubes. The gun has been used for thousands of transfers with extremely low associated mortality and is the central component of a high-throughput bioassay system. The gun is constructed using readily obtainable materials and can be modified for a range of insects.

Application Site and Mosquito Age Influences Malathion- and Permethrin-Induced Mortality in Culex quinquefasciatus (Diptera: Culicidae)

Abstract Concentrations of malathion and permethrin typical in droplets generated from ultra-low-volume and low-volume applications used to control mosquito populations were evaluated for efficacy against multiple-aged Culex quinquefasciatus Say (Diptera: Culicidae), using a topical bioassay. Although insecticide droplets will impinge on many exoskeletal body regions and a range of ages of mosquitoes in a population, traditional mosquito topical bioassays focus pesticide application to the mesothoracic pleural or dorsal regions across an average mosquito age (e.g., 3–7 d). Our results document nonuniform insecticide sensitivity across body regions at ages not previously assessed in mosquitoes (teneral and 14-d old). We expect our findings to influence the topical bioassay process, illustrating the difference in mosquito body regions and ages that ultimately may explain insecticide effectiveness wherever droplets impinge upon the mosquito body during field control applications.

Comparison of Volatiles and Mosquito Capture Efficacy For Three Carbohydrate Sources In A Yeast-Fermentation CO2 Generator

Abstract Mosquito surveillance in remote areas with limited access to canisters of CO2 or dry ice will benefit from an effective alternative CO2 source, such as the natural production of CO2 from yeast fermentation. In this study, we investigate differences in mosquito capture rates from the Centers for Disease Control and Prevention (CDC) light traps baited with dry ice compared with traps baited with yeast fermentation of several carbohydrate sources over 23 trap-nights. Results demonstrated the ability of yeast-generated CO2 to effectively attract mosquitoes to a CDC trap, regardless of carbohydrate source. Total collections of mosquitoes using dry ice were significantly higher than collections from yeast-generated CO2 sources. However, mosquito community structure, i.e., the species and relative capture rate of each species, was represented comparably across collections regardless of CO2 source. Volatiles produced by yeast fermentation were analyzed by carbohydrate source, revealing a suite of compounds, possibly synergistic, enhancing effects with CO2 on mosquito collection capability compared with the amount of CO2 used to attract mosquitoes.

Passive Baited Sequential Filth Fly Trap

Abstract Filth fly control measures may be optimized with a better understanding of fly population dynamics measured throughout the day. We describe the modification of a commercial motorized sequential mosquito trap to accept liquid odorous bait and leverage a classic inverted-cone design to passively confine flies in 8 modified collection bottles corresponding to 8 intervals. Efficacy trials in a hot-arid desert environment indicate no significant difference (P  =  0.896) between the modified sequential trap and a Rid-Max® fly trap.

High-Throughput Mosquito and Fly Bioassay System for Natural and Artificial Substrates Treated with Residual Insecticides

A high-throughput bioassay system to evaluate the efficacy of residual pesticides against mosquitoes and muscid flies with minimal insect handling was developed. The system consisted of 4 components made of readily available materials: 1) a CO2 anaesthetizing chamber, 2) a specialized aspirator, 3) a cylindrical flat-bottomed glass bioassay chamber assembly, and 4) a customized rack.

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.

Residual Pesticide On Hesco® Blast Protection Wall In Temperate Florida Habitat Effective Against Mosquitoes, Stable Flies, and Sand Flies

United States military troops in the field are exposed to the environment and are thus at high risk for transmission of arboviruses, and degradation of mission from continual harassment from insects. Passive vector control, such as application of residual insecticides to US military materials common in the field such as tents and camouflage netting, has been shown to be effective and can contribute to a successful integrated vector management (IVM) plan in the field to reduce this risk. However, other common US military field materials have not been evaluated with residual pesticides. In this study we conducted the first known investigation of the efficacy and longevity of a residual pesticide containing λ-cyhalothrin applied to HESCO® blast protection wall geotextile. We exposed treated material to a temperate Florida environment and found that this treatment can be effective against sand flies, filth-breeding flies, and mosquitoes for at least 6 wk. This study provides evidence that residual treatment of this US military material may be leveraged as an IVM component to enhance the US Department of Defense pest management system.

Portable Battery Power and Small-Reservoir Modifications For Pesticide Misting Systems

United States military personnel deployed in austere hot-arid, temperate, and tropical conditions in remote locations worldwide rely on the Department of Defense (DoD) Pest Management System measures such as application of pesticide residual and ultra-low-volume or thermal fog treatments for protection from routine exposure to nuisance and disease-vector insects. Timed pesticide misting systems originally developed for residential outdoor use show promise as potential enhancements to standard DoD Pest Management System measures, in particular to protect perimeters surrounding US military field encampments. To investigate the capabilities of misting systems in remote locations in diverse environments, this technical engineering report describes the development of 2 key modifications to a commercial residential misting system to enable us to operate the system away from a standard power grid, and to safely operate the system with small volumes of a variety of pesticide misting formulations. The components needed to modify the commercial misting system include the following: 5,000-W inverter, 12-V 100 Ah battery, 24-gal tote, solar panel with charge controller, 18 in. (45.7 cm) 0-gauge wire with ½-in. (1.27-cm) eyebolt connectors, 5-gal container (wide mouthed), ½-in.-to-½-in. connector, ½-in. tubing, ⅜-in.-to-⅜-in. connector, ⅜-in. tubing, ¼-in.-to-¼-in. connector, ¼-in. flexible tubing, securable patio box (80 gal), 5-gal (18.9-liter) bucket (modified), and a canning funnel.