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Lethal and behavioural effects of three synthetic repellents (DEET, IR3535 and KBR 3023) on Aedes aegypti mosquitoes in laboratory assays
Author(s) -
LICCIARDI S.,
HERVE J. P.,
DARRIET F.,
HOUGARD J.M.,
CORBEL V.
Publication year - 2006
Publication title -
medical and veterinary entomology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 82
eISSN - 1365-2915
pISSN - 0269-283X
DOI - 10.1111/j.1365-2915.2006.00630.x
Subject(s) - deet , aedes aegypti , toxicology , biology , chemistry , larva , ecology
Abstract The knock‐down, mortality and ‘irritancy’ effects of three synthetic repellents (DEET, IR3535 and KBR 3023) on Aedes aegypti (L) (Diptera: Culicidae) were evaluated in the laboratory in the absence of animal bait. Filter paper tests were carried out to assess the knock‐down effect (KDt 50 and KDt 95 ) and mortality (LC 50 and LC 95 ) induced by each repellent. ‘Irritancy’ tests were carried out to compare the flight response (time to first take‐off, or FT) to increasing concentrations of repellents (2–7%) and at five distances from the treated surface (0–40 mm). DEET had an insecticidal effect (KDt 50 = 9.7 min at 7%; CL 50 = 1165 mg/m 2 ), whereas IR3535 and KBR 3023 did not. Relative to an untreated control, IR3535 was an irritant (relative irritancy or RI > 1) at doses of 5% and 7% (RI = 17.7 and 9.9, respectively), whereas DEET was an irritant at lower concentrations (RI = 12.3 at 2% DEET). KBR 3023 was the weakest irritant over the same range of concentrations (RI max = 3.6 at 6%). DEET was more of an irritant (RI 20 = 9.4) than IR3535 (RI 20 = 2.9) over a range of distances (0–20 mm), and KBR 3023 was not an irritant unless mosquitoes made contact with the treated surface. All three repellents had a significant effect on mosquitoes, but DEET exhibited a more complex mode of action than the others due to its insecticidal properties. The repellents do not behave as a single class of compounds with a common mode of action, but most probably affect different physiological systems in insects. The physiological and molecular mechanisms of repellents, especially DEET, should be investigated to ensure a better use of these molecules for skin applications and/or for treating materials against mosquitoes.