Xian-Fu Liu1,2, Hong-Hao Chen3, Jun-Kai Li2, Rong Zhang3, Ted Cj Turlings4, Li Chen1. 1. State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, the Chinese Academy of Sciences, Beijing, China. 2. School of Agriculture, Yangtze University, Jingzhou, China. 3. Institute of Plant Protection, Ningxia Academy of Agriculture and Forestry Sciences, Yinchuan, China. 4. Laboratory for Fundamental and Applied Research in Chemical Ecology (FARCE), University of Neuchâtel, Neuchâtel, Switzerland.
Abstract
BACKGROUND: The cochineal scale, Porphyrophora sophorae (Hemiptera: Coccoidea, Margarodidae), is one of the most serious arthropod pests of Chinese liquorice, Glycyrrhiza uralensis (Fabaceae), an important medicinal herb. The adult females tend to deposit the ovisacs in soil relatively far away from liquorice plants. After hatching, neonates move out of the soil and may use chemical cues to search for new hosts. RESULTS: We collected and analysed the volatiles from soils with and without liquorice roots, and chromatographic profiles revealed hexanal, β-pinene and hexanol as potential host-finding cues for P. sphorae. The attractiveness of these compounds to neonates was studied in the laboratory using four-arm olfactometer bioassays. The larvae showed a clear preference for β-pinene over hexanal and hexanol, as well as all possible combinations of the three compounds. In addition, a field experiment confirmed that β-pinene was significantly more attractive than hexanal and hexanol. CONCLUSION: Newly eclosed larvae of P. sphorae exploit root volatiles as chemical cues to locate their host plant. β-Pinene proved to be the major chemical cue used by P. sphorae neonates searching for roots of their host plant.
BACKGROUND: The cochineal scale, Porphyrophora sophorae (Hemiptera: Coccoidea, Margarodidae), is one of the most serious arthropod pests of Chinese liquorice, Glycyrrhiza uralensis (Fabaceae), an important medicinal herb. The adult females tend to deposit the ovisacs in soil relatively far away from liquorice plants. After hatching, neonates move out of the soil and may use chemical cues to search for new hosts. RESULTS: We collected and analysed the volatiles from soils with and without liquorice roots, and chromatographic profiles revealed hexanal, β-pinene and hexanol as potential host-finding cues for P. sphorae. The attractiveness of these compounds to neonates was studied in the laboratory using four-arm olfactometer bioassays. The larvae showed a clear preference for β-pinene over hexanal and hexanol, as well as all possible combinations of the three compounds. In addition, a field experiment confirmed that β-pinene was significantly more attractive than hexanal and hexanol. CONCLUSION: Newly eclosed larvae of P. sphorae exploit root volatiles as chemical cues to locate their host plant. β-Pinene proved to be the major chemical cue used by P. sphorae neonates searching for roots of their host plant.