Evaluation of several novel alkynols, alkenols, and selected host odor blends as attractants to female Aedes albopictus and Culex quinquefasciatus.

The compound 1-octen-3-ol is a strong attractant for some mosquito species. Based on chemical structure, this may be due to a terminal site of unsaturation or high electron density, a structural capability for hydrogen bonding, e.g., -OH, -NH2, NHR, NR2, etc., a saturated hydrocarbon chain of a certain minimum length, and a certain relative distance between the region of high electron density and the alcohol (or other hydrogen-bonding) functional group. Based on this hypothesis, 4 novel alkynol (triple-bonded) analogs were synthesized and evaluated alone or in combination with acetone and dimethyl disulfide, and with and without carbon dioxide in Mosquito Magnet-X suction traps. Attraction of laboratory-reared adult Aedes albopictus and Culex quinquefasciatus to these analogs and combinations was compared to 1-octen-3-ol as a standard in semi-field trials. For both species none of the alkynols, with and without carbon dioxide or acetone and dimethyl disulfide, were significantly different from 1-octen-3-ol. The compounds 2-octyn-4-ol and 2-nonyn-4-ol alone and with carbon dioxide suppressed Cx. quinquefasciatus collections. An additional 6 alkenol (double-bonded) analogs were tested in mixtures with 3-n-propylphenol and 4-methylphenol in a ratio of 4:1:8, respectively. Using the same trapping methods, Cx. quinquefasciatus catches containing 3-decen-1-ol were increased nearly 3-fold when combined with carbon dioxide. Aedes albopictus collections in traps with the 3-decen-1-ol/phenol mixture and carbon dioxide were significantly greater than similar traps with 1-octen-3-ol. Traps baited with the phenol blends that incorporated (Z)-3-nonen-1-ol, (Z)-8-nonen-3-ol, or 1-octen-3-ol were considerably suppressed in the presence of carbon dioxide.

Semi-field evaluation of several novel alkenol analogs of 1-octen-3-ol as attractants to adult Aedes albopictus and Culex quinquefasciatus.

The compound 1-octen-3-ol is a known attractant of some mosquito species, which has led to the hypothesis that olfactory stimulation by this alkenol may be associated with the following structural elements: a terminal site of unsaturation or high electron density; a structural capability for hydrogen bonding, e.g., -OH, -NH2, NHR, NR2, etc.; a saturated hydrocarbon chain of a certain minimum length; and a certain relative distance between the region of high electron density and the alcohol (or other hydrogen-bonding) functional group. Using this logic, we synthesized 20 alkenol analogs based on the octenol double-bonded carbon skeleton. The attraction of female Aedes albopictus and Culex quinquefasciatus to these analogs was compared with 1-octen-3-ol as a standard in semi-field trials. For both species, collections from Mosquito Magnet-X (MMX) suction traps baited with the alkenol analogs in the absence of carbon dioxide were not significantly different from octenol-only baited traps, with the exception of (Z)-3-hepten-1-ol which collected significantly more Ae. albopictus. In the presence of CO2, most of the collections from traps baited with an alkenol were considerably increased for both species but not different from octenol plus CO2, with the exception of Ae. albopictus where (Z)-3-decen-1-ol, (Z)-4-hexen-1-ol, 7-octen-2-ol, and 8-nonen-3-ol significantly depressed trap catches. Although no clearly identifiable structure-activity relationship could be determined from our collected data, we did find that MMX traps baited with carbon dioxide and 4-penten-2-ol or (E)-2-decen-4-ol significantly enhanced Cx. quinquefasciatus collections up to nearly 3-fold compared with octenol plus carbon dioxide.