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

Megaplatypus mutatus (Chapuis) (Coleoptera: Platypodidae) is an ambrosia beetle native to South America that causes economic loss and was recently introduced to Italy, where it attacks and damages live poplar trees. Sulcatol and sulcatone are male-produced pheromone components involved in the mating process of M. mutatus. Their relative proportions are highly variable among insects, although the temporal pattern shows that initially only sulcatol is present, and sulcatone increases with time, until they are finally both depleted. Sulcatol and sulcatone may be produced de novo by the beetles, they may be produced by fungi, or both pathways may 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 transform the alcohol to the ketone before or during pheromone release. It is our hypothesis that fungi associated with M. mutatus are responsible for this process. In this work, we studied a possible contribution of associated microorganisms in the conversion of sulcatol into sulcatone and its consequent role in the temporal release pattern of these sex pheromone components observed in male insects. Moreover, we inhibited the postulated enzymes involved in this pheromone conversion process – 3-hydroxy-3-methyl-glutatyl-CoA reductase (HMGR) and P450 enzymes of 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 (Matsush.) Seifert & Okada (Microascales), as it is present in male but not in female exoskeletons and in insect gallery samples, suggesting a possible different role in pherome production, as the male is the pheromone-producing sex. Several isolated strains were able to convert sulcatol to sulcatone, whereas the fungus G. basitruncatum showed the highest production of this ketone. Additionally, inhibition of P450 enzymes and HMGR from G. basitruncatum on this alcohol-ketone conversion demonstrated that HMGR is involved in sulcatone generation using sulcatol as precursor, and that P450 enzymes are not. Finally, sulcatone production diminished significantly in homogenized tissues of male and female M. mutatus following addition of an antibiotic and a fungicide. The results suggest that fungi associated with M. mutatus are involved in pheromone production.Fil: Slodowicz, Mariel Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Ceriani Nakamurakare, Esteban Daniel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Carmaran, Cecilia Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Gonzalez Audino, Paola Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; Argentin

Sonochemical reduction of Cr(VI) in air in the presence of organic additives: What are the involved mechanistic pathways?

The sonochemical (850 kHz) reduction of Cr(VI) (0.3 mM, pH 2, reactor open to air) was analyzed in the presence of different additives. The effects on Cr(VI) reduction efficiency of added formic acid (FA, 10 mM), citric acid (Cit, 2 mM), ethylenediaminetetraacetic acid (EDTA, 1 mM), methanol (MeOH, 0.1 M), ethanol (EtOH, 0.1 M), 2-propanol (2-PrOH, 0.1 M), tert-butanol (t-BuOH, 0.1 M), phenol (PhOH, 2 mM) and sodium lauryl sulfate (SLS, 1 mM) have been evaluated in comparison with the system in the absence of additives. Complete Cr(VI) reduction was obtained only when using EDTA (at 120 min) and Cit (at 180 min). Cr(III) complexes with these compounds or with their degradation products were detected as final products. For EDTA, Cit, t-BuOH, FA and SLS, the Cr(VI) decay could be adjusted to a zero-order kinetics; in the cases of MeOH, EtOH and 2-PrOH, there was a deviation from the zero-order kinetics. The Cr(VI) conversion increased in the order SLS (very low) < no additive ≅ MeOH ≅ EtOH ≅ 2-PrOH < FA < t-BuOH < PhOH < Cit < EDTA. The role of EDTA and Cit in stabilizing intermediate Cr(V) peroxo compounds and enhancing their direct transformation into different Cr(III) species is considered a major factor in the acceleration of Cr(VI) reduction processes. Mechanistic pathways are proposed.Fil: Meichtry, Jorge Martin. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Slodowicz, Mariel Pamela. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cancelada, Lucia. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); ArgentinaFil: Destaillats, Hugo. Laboratorio Nacional Lawrence Berkeley; Estados UnidosFil: Litter, Marta Irene. Universidad Nacional de San Martín. Instituto de Investigación en Ingeniería Ambiental; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Seguridad Nuclear y Ambiente. Gerencia de Química (CAC); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Mycobiota associated with the ambrosia beetle Megaplatypus mutatus: Threat to poplar plantations

Megaplatypus mutatus (syn. Platypus sulcatus) is an ambrosia beetle native to South America, which represents the main forest pest in Argentina of Poplar plantations and is also an emerging pest in Europe, representing a potential risk to forest and fruit plantations globally due to its low specificity. Knowledge of the interactions this insect has with microbes will be important in understanding its impacts and management. In this study, we characterized the fungal diversity associated with M. mutatus in Populus trees in Argentina. The fungal community of 28 attacked trees was studied by evaluating 1104 gallery fragments and 110 fragments of insects. Fungal isolates were identified using morphology and phylogenetic analysis of the internal transcribed spacer region of nDNA. Nineteen taxa were identified, the most relevant Fusarium solani species complex, three species of Raffaelea and Graphium basitruncatum. Despite the lower frequency occurred by Raffaelea spp. and G. basitruncatum, we detected a specificity between male/female and location in the gallery. Additionally, the topology of the galleries is described based on analyses with computed tomography and nuclear magnetic resonance. Enhancing these techniques, an image combining both data was produced, suggesting that the water circulation across outer sections might be involved in the modulation of the gallery topology.Fil: Ceriani Nakamurakare, Esteban Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; ArgentinaFil: Slodowicz, Mariel Pamela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Gonzalez Audino, Paola Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones Científicas y Técnicas para la Defensa. Centro de Investigación de Plagas e Insecticidas; ArgentinaFil: Dolinko, Andrés Ezequiel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; ArgentinaFil: Carmaran, Cecilia Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria; Argentin