Identification of human-derived volatile chemicals that interfere with attraction of the Scottish biting midge and their potential use as repellents.
The Scottish biting midge, Culicoides impunctatus (Diptera: Ceratopogonidae), is a major pest in Scotland, causing a significant impact to the Scottish tourist and forestry industries. C. impunctatus is a generalist feeder, preferring to feed on large mammals, and is notorious for its attacks on humans. Until now, there was anecdotal evidence for differential attraction of female host-seeking C. impunctatus to individual human hosts, and the mechanism for this phenomenon was unknown. Using extracts of human odor collected by air entrainment, electroantennogram recordings to identify the physiologically active components, followed by behavioral assays, we show, for the first time, the differential attraction of female C. impunctatus to human odors and the chemical basis for this phenomenon. Certain chemicals, found in greater amounts in extracts that cause low attractiveness to midges, elicit a repellent effect in laboratory assays and repellency trials in the field. Differences in the production of these natural human-derived compounds could help to explain differential "attractiveness" between different human hosts. A mixture of two compounds in particular, 6-methyl-5-hepten-2-one and geranylacetone [(E)-6,10-dimethylundeca-5,9-dien-2-one], showed significant repellency (87, 77.4, 74.2, and 31.6% at hours 0, 1, 2, and 3, respectively) in the field and have the potential to be developed as novel repellents.
Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK. james.logan@bbsrc.ac.uk
James G
JG
Logan
Nicola J
NJ
Seal
James I
JI
Cook
Nina M
NM
Stanczyk
Michael A
MA
Birkett
Suzanne J
SJ
Clark
Salvador A
SA
Gezan
Lester J
LJ
Wadhams
John A
JA
Pickett
A Jennifer
AJ
Mordue
D000328:Adult; D000388:Air / Q000032:analysis; D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects*; D002519:Ceratopogonidae / Q000187:drug effects*; D004594:Electrophysiology; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007302:Insect Repellents / Q000032:analysis* / Q000494:pharmacology; D008297:Male; D008875:Middle Aged; D009812:Odorants / Q000032:analysis*; D012606:Scotland; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000494:pharmacology; D055815:Young Adult
D007302:Insect Repellents; D055549:Volatile Organic Compounds