Spray characterization of thermal fogging equipment typically used in vector control

Field efficacy of palm oil-based nanoemulsion insecticides against Aedes aegypti in Malaysia

This study evaluates the efficacy of palm oil-based nanoemulsion insecticides in thermal fogging applications against adult Ae. aegypti. The nanoemulsion formulations contained a palm oil methyl ester solvent, water, a non-ionic surfactant, and active ingredient deltamethrin, with nanoemulsion droplet diameters ranging from 362 to 382 nm. Knockdown and mortality rates of caged mosquitoes were measured at various distances up to 18 m from the spray nozzle. After 15 min of insecticide exposure, nanoemulsion insecticides achieved a knockdown rate of >97% at a spraying distance of 4 m, and the knockdown effect increased substantially with exposure time. At an 18 m spraying distance, the best nanoemulsion formulation, NanoEW8, achieved a high mosquito mortality rate of more than 80%, whereas the non-nanoemulsion and the commercial product reached only 14 and 8 m distances, respectively, for comparable mortality. The artificial neural network (ANN) was used to predict the mosquito knockdown distribution over the spraying distances and time intervals. The models predicted that NanoEW8 can still cause knockdown at a maximum distance of 61.5 m from the discharge point 60 min after spraying. The results established that Ae. aegypti was susceptible to the newly developed palm oil-based nanoemulsion insecticide, indicating a high potential for mosquito control.

Synthetic and Natural Insecticides: Gas, Liquid, Gel and Solid Formulations for Stored-Product and Food-Industry Pest Control

The selective application of insecticides is one of the cornerstones of integrated pest management (IPM) and management strategies for pest resistance to insecticides. The present work provides a comprehensive overview of the traditional and new methods for the application of gas, liquid, gel, and solid physical insecticide formulations to control stored-product and food industry urban pests from the taxa Acarina, Blattodea, Coleoptera, Diptera, Hymenoptera, Lepidoptera, Psocoptera, and Zygentoma. Various definitions and concepts historically and currently used for various pesticide application formulations and methods are also described. This review demonstrates that new technological advances have sparked renewed research interest in the optimization of conventional methods such as insecticide aerosols, sprays, fumigants, and inert gases. Insect growth regulators/disruptors (IGRs/IGDs) are increasingly employed in baits, aerosols, residual treatments, and as spray-residual protectants for long-term stored-grain protection. Insecticide-impregnated hypoxic multilayer bags have been proven to be one of the most promising low-cost and safe methods for hermetic grain storage in developing countries. Insecticide-impregnated netting and food baits were originally developed for the control of urban/medical pests and have been recognized as an innovative technology for the protection of stored commodities. New biodegradable acaricide gel coatings and nets have been suggested for the protection of ham meat. Tablets and satchels represent a new approach for the application of botanicals. Many emerging technologies can be found in the form of impregnated protective packaging (insect growth regulators/disruptors (IGRs/IGDs), natural repellents), pheromone-based attracticides, electrostatic dust or sprays, nanoparticles, edible artificial sweeteners, hydrogels, inert baits with synthetic attractants, biodegradable encapsulations of active ingredients, and cyanogenic protective grain coatings. Smart pest control technologies based on RNA-based gene silencing compounds incorporated into food baits stand at the forefront of current strategic research. Inert gases and dust (diatomaceous earth) are positive examples of alternatives to synthetic pesticide products, for which methods of application and their integration with other methods have been proposed and implemented in practice. Although many promising laboratory studies have been conducted on the biological activity of natural botanical insecticides, published studies demonstrating their effective industrial field usage in grain stores and food production facilities are scarce. This review shows that the current problems associated with the application of some natural botanical insecticides (e.g., sorption, stability, field efficacy, and smell) to some extent echo problems that were frequently encountered and addressed almost 100 years ago during the transition from ancient to modern classical chemical pest control methods.

Sanitization During and After COVID-19 Pandemic: A Short Review

Sanitization is a preventive and strategic method to contain the spread of SARS-CoV2. Since there is no foolproof method to tackle the present COVID-19 pandemic, sanitization has a central role to play. The present article briefly reviews various methods of sanitization for individuals, surfaces and ambience. The article reviews different approaches toward sanitization and examines the historicity of the methods employed.

Not in my backyard: effectiveness of outdoor residual spraying from hand-held sprayers against the mosquito Aedes albopictus in Rome, Italy

BACKGROUND

WHO guidelines state that adulticide interventions are recommended only in case of disease outbreak. However, peridomestic sprayings are carried out routinely to reduce Aedes albopictus (Skuse) nuisance, at least in Italy. Failing to keep low adult abundance over time triggers the need for further applications. The aim of the study was to investigate the effectiveness of a common control strategy routinely performed by citizens in highly infested urban sites inside the metropolitan city of Rome using a freely purchasable pyrethroid and a hand-held sprayer. Moreover, the effectiveness evaluated in three field experiments was compared with that achieved by blending the pyrethroid with a new carbon-based liquid additive.

RESULTS

An 86% post-treatment reduction in Ae. albopictus abundance was observed in gravid and host-seeking females, while the population recovery time was 10 days. Blending the insecticide with the additive lengthened mosquito recovery time to over 14 days.

CONCLUSION

Peridomestic sprayings largely reduce mosquito populations immediately after treatment but fail to keep low mosquito abundance for a longer period, partially explaining the uncontrolled repetitions of treatments. An optimal control application could benefit from research in the field of additives to improve mosquito abatement and the performance of pyrethroids over time. © 2016 Society of Chemical Industry.

Characteristics and Efficacy of Three Commercial Handheld Thermal Foggers with Pyrethroid Insecticides Against Three Species of Mosquitoes

The field study's objectives were to compare the physical characteristics as well as efficacy with multiple insecticides for Bonide(®) Fog Rx Insect Fogger, Black Flag(®) Propane Insect Fogger, and Burgess(®) Outdoor Propane Insect Fogger. Evaluations were conducted with 7 machine chemical combinations, 3 depths of spray, and 3 species of laboratory-reared mosquitoes, Anopheles quadrimaculatus, Culex quinquefasciatus, and Aedes aegypti. Combinations of these factors were analyzed in conjunction with environmental parameters. Data showed statistical significance between all machines. The Bonide machine maintained integrity and durability for the longest period of time compared with the other 2 machines. When evaluating the 3 machines with DUET™, mortality was highest with the Bonide and lowest with the Burgess machine.

Field evaluation of truck-mounted thermal fog of DUET and Aqualuer using different solvents against Aedes albopictus

DUET ultra-low volume (ULV) (1% parllethrin, 5% sumithrin) and Aqualuer ULV (20.6% permethrin), applied neat, diluted with mineral oil, and diluted with diesel oil by a truck-mounted thermal fogger (LongRay TS-95 model) was evaluated in the field against caged Aedes albopictus adults. The application of Aqualuer ULV was significantly more effective than DUET ULV (t = 12.1, df = 5, P < 0.001) without dilution. There were no significant differences between the applications of DUET ULV or Aqualuer ULV diluted 1:3 with mineral oil (t = 0.662, df = 5, P = 0.518) or with 1:3 of diesel oil (t = 1.19, df = 5, P = 0.251). The solvents (mineral oil and diesel oil) to dilute DUET and Aqualuer and sprayed by the truck-mounted thermal fogger did not result in significant differences in the mortalities of caged Ae. albopictus.

Field comparison of thermal and non-thermal ultra-low-volume applications using water and diesel as solvents for managing dengue vector, Aedes aegypti

OBJECTIVES

To compare the effectiveness on Aedes aegypti (Linneo) (Diptera: Culicidae) of a larvicide-adulticide ULV formulation applied by a thermal or a cold fogger using different solvents.

METHODS

We applied, in field conditions, a ULV formulation containing pyriproxyfen and permethrin, using a thermal and a cold fogger and water or diesel as solvent. We determined the effectiveness of these applications on Ae. aegypti adults and larvae by different bioassays and measuring Breteau, house and adult indices.

RESULTS

When water was used as solvent, the treatments applied with the cold or the thermal foggers were equally effective on adult mortality (close to 90%) and adult emergence inhibition (% EI) (close to 70%). When the thermal fogger was used with water as solvent, the adult mortality outside the houses (85%) was higher, but not significantly different, than with diesel (65%). The contrary happens inside (22%vs. 58%), while there were no differences in %EI. Adult and larval indices behaved similarly in all areas, with a slight tendency for the treatments applied using water as solvent to be more effective.

CONCLUSIONS

Water-based formulations are equally or more effective than the one applied with diesel as solvent. The use of water as solvent will not only improve the effectiveness of this formulation but also reduce the environmental impact and costs of spraying compared to the use of diesel.

Further evaluation of spray characterization of sprayers typically used in vector control

This work reports droplet-size data measured as part of a collaborative testing program between the US Department of Agriculture, Agricultural Research Service, and the US Navy, Navy Entomological Center for Excellence. This is an ongoing relationship that seeks to test new and revised spray technologies that may potentially be used by deployed personnel. As new equipment comes to market or when existing equipment is modified they are all integrated into this annual testing. During the 2011 equipment evaluations, 24 sprayers were operated across their range of available settings (pressure and flow rate), using both water and oil solutions. Droplet-size data as measured with laser diffraction ranged from 4 to 223 microm (volume median diameter). Generally, as the spray rate increased, droplet size increased, and as the pressure increased at a given same spray rate, droplet size decreased. This information allows users to set up and operate these sprayers in a manner such that a particular droplet size is applied optimizing efficiency and efficacy of applications.

Droplet size and efficacy of an adulticide-larvicide ultralow-volume formulation on Aedes aegypti using different solvents and spray application methods

BACKGROUND

When cases of dengue are reported or the density of adult Aedes aegypti (L.) becomes too high, ultralow-volume (ULV) application of insecticides is the recommended control method. The droplet size of an aerosol insecticide influences its efficiency in killing adult mosquitoes. Many studies have been carried out to determine the optimum droplet size that maximises vector control efforts, but only a few have determined droplet-size spectra for specific equipment using different solvents and comparing thermal and non-thermal aerosols.

RESULTS

The present study showed that the droplet size for a water-based adulticide-larvicide formulation was larger than for the same formulation diluted in gasoil or biodiesel. No significant differences in adult mortality were observed between sprayers and solvents, but efficacy decreased with distance from the sprayer nozzle. Adult emergence inhibition was more than 90% when using water as a solvent for both thermal and cold foggers, and the efficacy did not decrease with distance from the sprayer nozzle. On the other hand, oil-based solvents became less effective with distance.

CONCLUSION

The use of water as a solvent with both thermal and cold foggers improves the efficacy of the studied formulation containing permethrin as adulticide and pyriproxyfen as larvicide in scaled-up assays. Moreover, it reduces the environmental impact and costs of spraying by comparison with formulations using oil solvents.

Thermal fog efficacy tests against mosquitoes in storm drains in Harris County, Texas 2008-09

In 2008 and 2009, our current thermal fogging methods and materials were evaluated in underground systems against feral and laboratory strains of adult Culex quinquefasciatus. Culex quinquefasciatus adults collected from storm drain systems the night before treatment were tested concurrently with adults from a susceptible laboratory strain (Sebring) in 10 separate tests. During 2008, there were no significant differences in the low mean percent control obtained between any of the feral populations (29.39%) and susceptible (Sebring) populations (56.04%) tested, whereas in 2009, application of mineral oil alone yielded extremely low, but significantly different mean percent control at 0.99% for ferals and 0.01% for Sebrings. During 2009 mineral oil evaluations, 45,677 droplets were collected in storm drains at distances of 99.1, 50.6, 57.9, 67.7, and 109.7 m from the application site, with 99% of the droplets below 3 microm in diam; additionally, we found no significant differences between mean percent control of Sebring and feral mosquito populations using the higher (3.2x) 1:10 application rate of Pyrocide. However, mean percent control between the feral and susceptible strain (Sebring) during 2009 was lower than in 2008 at 16.55% for ferals and 24.43% in Sebrings. Results indicated that control methodologies and/or chemicals used were ineffective at controlling Cx. quinquefasciatus in storm drains using the chosen experimental design. Based upon this information, thermal fog operations were discontinued due to lack of effectiveness.

Evaluation of ULV and thermal fog mosquito control applications in temperate and desert environments

Ultra-low-volume (ULV) and thermal fog aerosol dispersals of pesticides have been used against mosquitoes and other insects for half a century. Although each spray technology has advantages and disadvantages, only 7 studies have been identified that directly compare their performance in the field. US military personnel currently operating in hot-arid environments are impacted by perpetual nuisance and disease vector insect problems, despite adulticide operations using modern pesticide-delivery equipment such as ULV. None of the identified comparative studies has looked at the relative feasibility and efficacy of ULV and thermal fog equipment against mosquitoes in hot-arid environments. In this study we examine the impact of ULV and thermal fog applications of malathion against caged sentinel mosquitoes in the field in a warm temperate area of Florida, followed by a similar test in a hot-dry desert area of southern California. Patterns of mortality throughout 150 m x 150 m grids of sentinel mosquitoes indicate greater efficacy from the thermal fog application in both environments under suboptimal ambient weather conditions. We discuss the implications of these findings for future military preventive medicine activities and encourage further investigations into the relative merits of the 2 technologies for force health protection.

Spray characterization of ultra-low-volume sprayers typically used in vector control

Numerous spray machines are used to apply pesticides for the control of human disease vectors, such as mosquitoes and flies, and the selection and setup of these machines significantly affects the level of control achieved during an application. The droplet spectra produced by 9 different ultra-low-volume sprayers with oil- and water-based spray solutions were evaluated along with 2 thermal foggers with the use of diesel-based spray solutions. The droplet spectra from the sprayers were measured with the use of laser diffraction droplet sizing equipment. The volume median diameter from the sprayers ranged from 14.8 to 61.9 microm for the oil-based spray solutions and 15.5 to 87.5 microm for the water-based spray solutions. The 2 thermal foggers generated sprays with a volume median diameter of 3.5 microm. The data presented will allow spray applicators to select the spray solution and sprayer that generate the droplet-size spectra that meet the desired specific spray application scenarios.