Attraction of Male Pine Sawflies, Diprion jingyuanensis, to Synthetic Pheromone Candidates: Synergism between Two Stereoisomers
Author:
Anderbrant Olle1, Zhang Qing-He23ORCID, Chen Guo-Fa2, Östrand Fredrik1, Bergström Gunnar4, Wassgren Ann-Britt4, Zhang Zhen5, Hedenström Erik6, Högberg Hans-Erik6
Affiliation:
1. Department of Biology, Lund University, Sölvegatan 37, SE-22362 Lund, Sweden 2. Biological Disaster Prevention and Control Center, National Forestry and Grassland Administration, No. 58 Northern Huanghe Street, Shenyang 110034, China 3. Sterling International, Inc., 3808 N. Sullivan Rd., Bldg 16, Spokane, WA 99216, USA 4. Chemical Ecology, Göteborg University, SE-40530 Göteborg, Sweden 5. Key Laboratory of Forest Protection of National Forestry and Grassland Administration, Research Institute of Forest Ecology, Environment and Nature Conservation, Chinese Academy of Forestry, No. 2 Dong Xiao Fu Street, Beijing 100091, China 6. EcoChemistry, Department of Natural Sciences, Design and Sustainable Development, Mid Sweden University, SE-85170 Sundsvall, Sweden
Abstract
The pine sawfly Diprion jingyuanensis Xiao and Zhang (Hymenoptera: Diprionidae) is a serious pest of Pinus tabulaeformis Carr. in the Shanxi, Gansu, and Inner Mongolia provinces in P. R. China. The sex pheromone of D. jingyuanensis was shown to be the propionate ester of 3,7-dimethyl-2-tridecanol. Virgin females contained an approximate 1:3 blend of the pheromone precursors erythro-(2S,3S,7R/S and 2R,3R,7R/S)-3,7-dimethyl-2-tridecanol and threo-(2S,3R,7R/S and 2R,3S,7R/S)-3,7-dimethyl-2-tridecanol, but the exact stereoisomers were not determined. Males responded the strongest to the propionate ester of the two threo-isomers, (2S,3R,7R) and (2S,3R,7S), in electroantennogram (EAG) recordings, followed by a significant EAG response to the (2S,3R,7R) propionate of diprionol (pheromone component of D. similis), whereas the remaining two isomers (2S,3S,7S and 2S,3S,7R) of the propionate ester of 3,7-dimethyl-2-tridecanol and the acetate of the (2S,3R,7R) isomer (one of the two pheromone components of D. pini) did not elicit any significant increase in antennal response. In the field, the strongly EAG-active (2S,3R,7R)-isomer alone was only weakly (but significantly) attractive to D. jingyuanensis males at 100 µg, while the equally EAG- active (2S,3R,7S)-isomer alone at the same loading was 8–14 times more attractive than was the (2S,3R,7R)-isomer alone. Traps baited with the same amounts of the two threo-isomers ((2S,3R,7R) and (2S,3R,7S), 100 µg + 100 µg) caught significantly more males than did traps baited with other isomers, either of the two isomers alone or other proportions of the two isomers. Thus, the (2S,3R,7S)-isomer is considered as a strong and essential sex-attractant component for D. jingyuanensis males, whereas the (2S,3R,7R)-isomer is a weak but synergistic sex-attractant. This is one of the few examples of a pine sawfly responding significantly stronger to a binary blend of stereoisomers in a synergistic fashion than to a single stereoisomer alone.
Funder
The Swedish Council for Forestry and Agricultural Research the Royal Society of Arts and Sciences in Göteborg the Carl Trygger Foundation
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