Sex pheromone component produced by microbial associates of the forest pest Megaplatypus mutatus

SLODOWICZ M; CERIANI-NAKAMURAKARE, ESTEBAN; CARMARÁN, CECILIA C.; GONZÁLEZ-AUDINO, P.

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019

0013-8703

Megaplatypus mutatus (Chapuis) (Coleoptera: Platypodidae)is an ambrosia beetle native to South America that causes economic loss and wasrecently introduced to Italy, where it attacks and damages live poplar trees.Sulcatol and sulcatone are male-produced pheromone components involved in themating process of M. mutatus. Their relative proportions arehighly variable among insects, although the temporal pattern shows thatinitially only sulcatol is present, and sulcatone increases with time, untilthey are finally both depleted. Sulcatol and sulcatone might be produced denovo by the beetles, they might be produced by fungi, or both pathways mightcontribute to their production. Sulcatol is stored in the males? hindgut butsulcatone is only present in emissions, so there is an oxidation process totransform the alcohol to the ketone before or during pheromone release. It isour hypothesis that fungi associated with M. mutatus are responsible for this process. In this work, we studied a possiblecontribution of associated microorganisms in the conversion of sulcatol intosulcatone and its consequent role in the temporal release pattern of these sexpheromone components observed in male insects. Moreover, we inhibited thepostulated enzymes involved in this pheromone conversion process ?3-hydroxy-3-methyl-glutatyl-CoA reductase (HMGR) and P450 enzymes of a fungalstrain ? and added an antibiotic and a fungicide to the homogenate duringsulcatol-sulcatone conversion. Among the fungalspecies, particular interest was given to Graphium basitruncatum (Matsush.) Seifert & Okada(Microascales), as it is present in male but not female exoskeletons and ininsect gallery samples, suggesting a possibledifferent role in pherome production, as the male is the pheromone-producingsex. Several isolated strains were able to convert sulcatol tosulcatone, whereas the fungus G. basitruncatum showed the highest production ofthis ketone. Additionally, inhibition of P450 enzymes and HMGR from G. basitruncatum on this alcohol-ketone conversiondemonstrated that HMGR is involved in sulcatone generation using sulcatol asprecursor, and that P450 enzymes are not. Finally, sulcatone productiondiminished significantly in homogenized tissues of male and female M. mutatus following addition of an antibiotic and a fungicide. The resultssuggest that fungi associated with M.mutatus areinvolved in pheromone production.