Recipient Organization
UNIVERSITY OF ARKANSAS
(N/A)
FAYETTEVILLE,AR 72703
Performing Department
Entomology
Non Technical Summary
Background: United States Military (USM) personnel, beneficiaries, and Department of Defense (DoD) civilians and contractors are affected by a wide range of biting and pestiferous insects both at home and abroad. When insect populations on a military installation are uncontrolled, force readiness suffers. The DoD maintains a list of approved insecticides for use in contingency operations. Despite the importance of controlling biting and nuisance fly populations on installations, only 5 products are available for mosquito larval control, and no products are available to target filth fly or biting midge larvae. Fluralaner, a recently approved ectoparasiticide, shows enormous promise as a broad-spectrum insecticide, and is highly active against a number of pestiferous fly species. We propose to assess the efficacy of a novel, microencapsulated fluralaner larvicide against multiple target species, and to determine whether fluralaner can provide enhanced vector control compared to commercial off-the-shelf (COTS) products currently in use by the DoD.Hypothesis: The proposed research will test the hypothesis that yeast microencapsulated fluralaner will provide significantly enhanced control (higher toxicity and/or lower dose) of larval mosquitoes, biting midges, and filth flies compared to currently available insecticides. Previous work has shown that larval mosquitoes and adult house flies are highly susceptible to fluralaner, with significantly lower LD50 values compared to the active ingredients in currently available insecticides, and that ingested formulations are likely to further enhance toxicity.Specific Aims: 1) conduct in vivo laboratory studies to assess product efficacy against medically important insect larvae, 2) conduct semi-field studies to assess product performance under natural conditions, and 3) pursue product commercialization.Study Design: In year 1, dose-response assays using larval mosquitoes, biting midges, and house flies will be conducted to determine product LD50/90 for each species. Microencapsulated fluralaner will also be compared to 3 COTS mosquito larvicides with national stock numbers (Vectobac, Abate, Altosid) using mosquito larval toxicity assays to determine whether the experimental product provides equivalent control as COTS products with less active ingredient. Due to the lack of technical data on biting midge susceptibility to fluralaner, modified WHO cone and contact toxicity assays will be used to determine the LD50 and KD50 dose for adult midges. In year 2, semi-field experiments will be conducted to determine appropriate reapplication intervals needed to maintain acceptable control, and to assess product performance under natural conditions. Because of key differences in the biology of the 3 study species, multiple application protocols will be tested in order to make best practices recommendations for achieving population control on installations.Relevance: The lack of effective larvicides for filth flies and biting midges represents a significant capability gap in the USM's vector control response. A more efficient mosquito larvicide, requiring less material to achieve acceptable control, helps the USM move towards the goal of becoming a more agile fighting force. Overall, novel compounds with new modes of action are critical for combating insecticide resistance in vector and pest populations globally.
Animal Health Component
50%
Research Effort Categories
Basic
0%
Applied
50%
Developmental
50%
Goals / Objectives
We will address three technical objectives related to the optimization and performance of the product. Achieving these objectives will allow us to compare microencapsulated fluralaner directly to available COTS products, as well as to develop precise application rates, intervals, and methods tailored to specific groups of pestiferous flies.Technical Objective 1. Determine the efficacy of yeast microencapsulated fluralaner against larval mosquitoes, biting midges, and house fliesSub-Objective 1.1. Optimize yeast microencapsulation of the active ingredientSub-Objective 1.2. Calculate the LD50 and LD90 dose for each species using dose-response assaysSub-Objective 1.3. Compare the levels of mosquito larval control achieved with microencapsulated fluralaner compared to currently available larvicidesTechnical Objective 2. Determine the topical and contact toxicity of fluralaner against adult biting midgesSub-Objective 2.1. Calculate the topical lethal dose (LD)50 and LD90 dose for C. sonorensis using modified WHO contact toxicity assaysSub-Objective 2.2. Calculate the contact knock-down dose (KD)/LD50 and KD/LD90 dose for C. sonorensis using modified WHO cone assaysTechnical Objective 3. Assess product performance under semi-field conditions and determine appropriate application intervals for target speciesSub-Objective 3.1. Determine how long a single application of microencapsulated fluralaner provides acceptable control (<90% emergence) of mosquito, midge, and house fly larvaeSub-Objective 3.2. Compare the efficacy of single vs. repeated applications of microencapsulated fluralaner to food waste for house fly control?
Project Methods
Insecticide formulationFluralaner will be microencapsulated into yeast using established methods. Product formulation will be validated using HLPC mass spectrometry. Dose-response experiments using larval Aedes albopictus, Culicoides sonorensis, and Musca domesticawill be conducted in the laboratory in order to calculate the LD50 for each species. 10-fold dilutions of the product will be applied to larval replicates, and mortality will be recorded at 24h.Comparison to COTS ProductsIn order to assess whether microencapsulated fluralaner is a more efficient insecticide than currently available commercial off-the-shelf products, the experimental product will be compared to the mosquito larvicides Abate, Vectobac, and Altosid at both their labeled rates and at equivalent concentrations. Products will be applied to replicates ofAe. albopictuslarval replicates, and mortality will be recorded at 24 h or 5d (Altosid experiments).Contact and topical toxicity of fluralaner on Culicoides biting midgesBecause fluralaner has never been assessed as a topical insecticide forCulicoides, we will conduct WHO contact and topical toxicity assays using adult femaleC. sonorensis. 10 fold dilutions of fluralaner formulated in acetone will be applied topically to midges at a rate of 20nL/midge and mortality will be recorded at 24h. Modified WHO cone assays will be used to assess contact toxicity. Filter papers will be treated with 10 fold dilutions of fluralaner, as above, and cones placed over filter papers. Midges will be introduced into the cones for 3min. Knock-down will be recorded after 60min and mortality will be recorded at 24h.Semi-fieldexposuresTo determine product efficacy under field conditions and to determine appropriate reapplication rates, semi-field exposure experiments will be conducted. Microencapsulated fluralaner will be applied to larval replicates ofAe. albopictus,C. sonorensis, andM. domesticaat the previously determined LD90 rate. Replicates will be held outdoors, exposed to natural conditions and sunlight. Mortality and emergence will be counted weekly, and new larvae will be added to replicates weekly, until emergence exceeds 90%. To simulate treatment of waste disposal sites for house fly population control, bucket traps will be baited with standardized food waste and treated with microencapsulated fluralaner. Traps will be open to colonization from wild flies. We will test the effect of single and repeated treatments of waste sites to determine the most effective application strategy.