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

CERIANI-NAKAMURAKARE, ESTEBAN; SLODOWICZ, MARIEL; GONZALES AUDINO, PAOLA; C.C. CARMARAN

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 p. 1 - 10

0013-8703

Megaplatypusmutatus(Chapuis) (Coleoptera: Platypodidae) is an ambrosia beetle native toSouth America that causes economic loss and was recently introduced to Italy,where it attacks and damages live poplar trees. Sulcatol and sulcatone aremale-produced pheromone components involved in the mating process ofM. mutatus.Their relative proportions are highly variable among insects, although thetemporal pattern shows that initially only sulcatol is present, and sulcatoneincreases with time, until they are finally both depleted. Sulcatol andsulcatone may be produced de novo by the beetles, they may be produced byfungi, or both pathways may contribute to their production. Sulcatol is storedin the males? hindgut but sulcatone is only present in emissions, so there isan oxidation process to transform the alcohol to the ketone before or duringpheromone release. It is our hypothesis that fungi associated with M. mutatus areresponsible for this process. In this work, we studied a possible contributionof associated microorganisms in the conversion of sulcatol into sulcatone andits consequent role in the temporal release pattern of these sex pheromonecomponents observed in male insects. Moreover, we inhibited the postulatedenzymes involved in this pheromone conversion process?3-hydroxy-3-methyl-glutatyl-CoAreductase (HMGR) and P450 enzymes of a fungal strain ?and added an antibioticand a fungicide to the homogenate during sulcatol-sulcatone conversion. Amongthe fungal species, particular interest was given toGraphium basitruncatum (Matsush.)Seifert & Okada (Microascales), as it is present in male but not in femaleexoskeletons and in insect gallery samples, suggesting a possible differentrole in pherome production, as the male is the pheromone-producing sex. Severalisolated strains were able to convert sulcatol to sulcatone, whereas thefungusG. basitruncatumshowed the highest production of this ketone.Additionally, inhibition of P450 enzymes and HMGR fromG. basitruncatumon thisalcohol-ketone conversion demonstrated that HMGR is involved in sulcatonegeneration using sulcatol as precursor, and that P450 enzymes are not. Finally,sulcatone production diminished significantly in homogenized tissues of maleand femaleM. mutatusfollowing addition of an antibiotic and a fungicide. Theresults suggest that fungi associated withM. mutatusare involved in pheromoneproduction.