Location: Mosquito and Fly ResearchTitle: Spatial repellency screening in a high-throughput apparatus with Aedes aegypti and Anopheles gambiae Author
|Jiang, S - University Of Florida|
|Yang, L - University Of Florida|
|Tsikolia, Maia - University Of Florida|
|Bernier, Ulrich - Uli|
|Linthicum, Kenneth - Ken|
|Bloomquist, Jeffrey - University Of Florida|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/2/2018
Publication Date: 2/15/2018
Citation: Jiang, S., Yang, L., Tsikolia, M., Bernier, U.R., Linthicum, K., Bloomquist, J.R. 2018. Spatial repellency screening in a high-throughput apparatus with Aedes aegypti and Anopheles gambiae. Meeting Abstract. pg. 1.
Technical Abstract: Spatial repellents are essential for personal protection against mosquitoes, such as Aedes aegypti and Anopheles gambiae, to reduce annoyance biting and transmission of mosquito-borne diseases. The number of safe and effective repellents, including DEET, picaridin, and IR3535, is limited and continuous usage could lead to resistance. Thus, searching for new spatially-active compounds is necessary to reduce the risk of mosquito-transmitted diseases. Most current repellent screening methods, such as olfactometers and alternative choice test systems, require complex setup or use of a large quantity of compound (mg). The purpose of this study was to evaluate the efficacy of a high-throughput spatial repellent screening apparatus that occupies relatively little space and uses small amounts of compounds (typically µg levels). In this setup, compound-treated filter papers were held in caps on both ends of a 5” glass tube, and groups of mosquitoes (n = 16) were prevented from contacting filter paper by nettings. Spatial repellency was quantified by the ratio of mosquitoes on the treated side of the test tube, in which case a value of zero equaled to full repellency. Trifluromethylphenylamides (TFMPAs), anthranilates and other experimental compounds were tested in this apparatus, and their potency was compared to DEET, a standard spatial repellent. DEET had EC50 (half effective repellent concentration on the filter paper) values of 31 (25-39) µg/cm2 and 79 (51-120) µg/cm2 against Ae. aegypti wild-type (OR) and Puerto Rico (PR) resistant strains, respectively, and 39 (29-51) µg/cm2 against the An. gambiae G3 susceptible strain. Screening of TFMPAs identified several compounds (EC50 values in parentheses) that had activity comparable to DEET; 1-4A (25 µg/cm2), 4-2B (15 µg/cm2), 4-3D (17 µg/cm2), and 4-5A (17 µg/cm2) were the most active compounds. Interestingly, 4-3D had an EC50 of 16 (9-26) µg/cm2 against PR strain, ca. 5-fold lower than DEET. Three anthranilate compounds showed strong spatial repellency; ethyl anthranilate was most active, with an EC50 of 6.9 (4-10) µg/cm2 on OR strain, ca. 4-fold lower than DEET. This bioassay system was useful for quantifying both spatial repellency and vapor toxicity; compound CA-12 had knockdown activity at 100 µg/cm2, while all active mosquitoes accumulated in the untreated half. To conclude, this high-throughput screening setup is useful for fast-acting candidate spatial repellents against mosquitoes, other flying insect vectors like sand flies, and potentially mites and ticks, with slight modifications to the size of nettings. Further experiments include testing insecticide-resistant An. gambiae, and quantifying repellent potency of combination treatments.