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

SLODOWICZ, MARIEL; CERIANI-NAKAMURAKARE, ESTEBAN; CARMARAN, CECILIA; GONZALEZ AUDINO, PAOLA

ENTOMOLOGIA EXPERIMENTALIS ET APPLICATA

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019

0013-8703

Megaplatypus mutatus (Chapuis, 1865) (Coleoptera: Platypodinae) is an ambrosiabeetle native to South America that causes economic loss and was recently introduced to Italy,where it attacks and damages living poplar trees. Sulcatol and sulcatone are male-producedpheromone components involved in the mating process of M. mutatus. Their relativeproportions are highly variable among insects, although the temporal pattern shows that initiallyonly sulcatol is present, and sulcatone increases with time, until they are finally both depleted.Sulcatol and sulcatone might be produced de novo by the beetles, they might be produced byfungi, or both pathways might contribute to their production. Sulcatol is stored in the males?hindgut but sulcatone is only present in emissions, so there is an oxidation process to transformthe alcohol to the ketone before/during pheromone release. It is our hypothesis that fungiassociated with M. mutatus are responsible for this process.In this work, we studied a possible contribution of associated microorganisms in theconversion of sulcatol into sulcatone and its consequent role in the temporal release pattern ofthese sex pheromone components observed in male insects. Moreover, we inhibited thepostulated enzymes involved in this pheromone conversion process, HMGR and P450 enzymesof a fungal strain, and added an antibiotic and a fungicide to the homogenate during sulcatol/sulcatone conversion.Among the fungal species, particular interest was given to Graphium basitruncatum, as it ispresent in male but not female exoskeletons and in insect gallery samples, suggesting a possibledifferent role in pherome production, as the male is the pheromone producing sex.Several isolated strains were able to convert sulcatol to sulcatone, while the fungi Graphiumbasitruncatum showed the highest production of this ketone. Additionally, inhibition of P450enzymes and HMGR from G. basitruncatum on this alcohol/ ketone conversion demonstratedthat HMGR is involved in sulcatone generation using sulcatol as precursor, and that P450enzymes are not. Finally, sulcatone production diminished significantly in homogenised tissuesof male and female M. mutatus following addition of an antibiotic and a fungicide. The resultssuggest that fungi associated with M. mutatus are involved in pheromone production.