Repellency of synthetic and plant‐derived preparations for Culicoides imicola

Abstract

The study was conducted to find a safer and longer lasting repellent for C.imicola than di-ethyl toluamide (DEET), to validate whether the current recommendations in Israel for application of repellents during an outbreak of disease caused by pathogens borne by Culicoides imicola are justified, and to test plant-derived preparations as potential replacements for the synthetic repellents. Seven repellents were compared by a method using treated netting across the entrance of a suction light trap. Those inferior to DEET were: oregano and Herbipet which showed a slight non-significant repellency for 2 h, Tri-Tec 14TM which showed significant (P < 0.05) repellency with respect to controls for 2 h and Stomoxin which showed significant (P < 0.05) repellency for 1 h. As the active ingredient of Stomoxin is permethrin, this indicates that recommendations to spray animals with this insecticide to prevent the spread of C.imicola-borne pathogens will not be useful. The repellents superior to DEET were: the plant-derived material Ag 1000 that repelled significantly (P < 0.05) with respect to controls for up to 4 h following a similar pattern to but somewhat more strongly than DEET, and pyrethroid-T which exerted significant (P < 0.05) repellency for 9 h. Pyrethroid-T proved to be the best repellent tested, and if sprayed nightly it might provide protection from C.imicola-borne pathogens.

African horse sickness

“…However, none are completely effective and the deterrent effect, even of the best, rarely persists for more than a few hours [18,115]. Di-ethyl toluamide (DEET) seems to be the only commercially available repellent that has been shown to have a significant deterrent effect against Culicoides for periods of up to four hours [18]. Since C. imicola attacks apparently peak during the first four hours of the night, if applied nightly to susceptible animals, DEET may have a significant but temporary effect in reducing the biting rate of this species.…”

Duration of repellency of N,N-diethyl-3-methylbenzamide, citronella oil and cypermethrin against Culicoides species when applied to polyester mesh

“…Assessment of efficacy of repellents applied to horses against Culicoides species and especially C. imicola is hampered by their relatively small size and their nocturnal activity which make direct observation difficult. A novel method for preliminary field screening of potential repellents to protect animals against Culicoides has been reported (Braverman and Chizov-Ginzburg, 1997). Studies using this method, which utilizes light traps and repellent-impregnated polyester mesh, have provided an indication of the duration of repellency of the various compounds tested (Braverman and Chizov-Ginzburg, 1998, Braverman et al, 1999and Braverman et al, 2000.…”

Suppression of Mosquito (Diptera: Culicidae) and Black Fly (Diptera: Simuliidae) Blood Feeding from Hereford Cattle and Ponies Treated with Permethrin

“…Reductions in blood-feeding levels of 40 Ð70% from permethrintreated cattle have been reported for mosquitoes (Shemanchuk et al 1991, Loftin et al 1996, up to 70% or greater for black ßies (Shemanchuk and Taylor 1984) and up to 80% for biting midges (Mullens et al 2000). Bioassays documenting permethrin-induced mortality or interference with mosquito and biting midge feeding are reported by Holbrook (1986), McLaughlin et al (1989), Mullens (1993) , Braverman and Chizov-Ginzburg (1997), and Mullens et al (2000).…”