COMUNIDADES BACTERIANAS ASOCIADAS AL CANAL ALIMENTARIO DE Dendroctonus spp.

Abstract

The beetles of the genus Dendroctonus feed on phloem of pine trees which is a poor nitrogen source. As a consequence, they need an additional intake of nitrogen and an efficient way to use it. It could be related to their associations with gut bacteria. The characterization of the bacterial community in the gut is the first step to understand the relationships among the bacteria and the host beetles. One of the aims of this work was to characterize the bacterial communities associated with the gut of D. valens and D. rhizophagus. Moreover, we tried to assign and evaluate some metabolic activities in vitro of the bacteria that could be beneficial to their insect host. The gut bacterial communities of D. valens and D. rhizophagus were integrated by 17 and 9 bacterial species, respectively as was revealed by culture-dependent and –independent methods. Both communities were scarce compared with the gut microbiota of others insects. Rahnella and Stenotrophomonas were the most abundant bacteria in the gut of both insect species. On the other hand, some of the gut bacteria of two Dendroctonus species were capable of fix nitrogen, use the uric acid as sole nitrogen source and utilize the carboxymethylcellulose in vitro. All these metabolic activities could be involved in depletion of C:N ratio in phloem, elevation of nitrogen-use efficiency and supplementation of nitrogen. As a consequence, the metabolic capabilities of gut bacteria could be have a huge impact in the fitness, development, reproduction and survival of Dendroctonus beetles.