Biosynthetic precursors, temporal emission and localization site of pheromones in Ambrosia beetle Megaplatypus mutatus

PABLO E. GATTI; EDUARDO N.ZERBA; PAOLA A. GONZÁLEZ AUDINO

Colonia,

Congreso; Primer Congreso latinoamericano de Ecología Quimica; 2010

Sociedad Latinoamericane de Ecologia Quimica

Megaplatypus mutatus, an Ambrosia beetle (Platypodidae) native to South America, is a main forest pest that attacks live standing trees, affecting commercial poplar and broadleaf plantations. Attack is initiated by pioneer males selecting a host tree to build a short nuptial gallery, from which they attract females using a sexual pheromone. In previous work we identified volatile emission as composed by (+) 6-methyl-5-hepten-2-ol ((+)-sulcatol), 6-methyl-5-hepten-2-one (sulcatone) and 3-pentanol. Behavioral bioassays in olfactometer and electroantennogram recordings confirmed an attractive response for the three chemicals specifically attracting females. In the present study, we determined the sites of production of the pheromones within males, the temporal pattern of pheromone emission during gallery initiation and establishment and the possible biosynthetic precursors for sulcatol and sulcatone. (+)- Sulcatol, sulcatone and 3-pentanol were found only in proctodeum. Production of sulcatol is independent of its interaction with the host, although the amount produced significantly increases after 48hs of tunnel excavating. Exposition of living males to synthetic vapors of sulcatol, sulcatone, geraniol and citral showed that sulcatone and citral increase sulcatol production and consequently can be used as a precursors for sulcatol biosynthesis. We collected male volatile emissions daily during the hours of peak flight by using a specific polar microextraction phase and the extract was analyzed by GC-MS. Sulcatol and 3-pentanol production was detected 1-2 days after gallery initiation with maximal production between 5-12 days. Sulcatone production was noted during the same period although only in trace quantities. Both pheromones were present in male emissions from three different host species between days 2-12 after gallery initiation, but sulcatone was always present in very low concentrations. The temporal patterns of sulcatol and sulcatone production or storage in male M. mutatus corresponded to the temporal patterns of emission.