RESUMEN
Most beetle-fungus symbioses do not represent a threat to agricultural and natural ecosystems; however, a few beetles are able to inoculate healthy hosts with disease-causing fungal symbionts. Here, we report the putative nutritional symbionts associated with five native species of ambrosia beetles colonizing commercial avocado trees in four locations in Michoacán. Knowing which beetles are present in the commercial orchards and the surrounding areas, as well as their fungal associates, is imperative for developing a realistic risk assessment and an effective monitoring system that allows for timely management actions. Phylogenetic analysis revealed five potentially new, previously undescribed species of Raffaelea, and three known species (R. arxi, R. brunnea, R. fusca). The genus Raffaelea was recovered from all the beetle species and across the different locations. Raffaelea lauricola (RL), which causes a deadly vascular fungal disease known as laurel wilt (LW) in Lauraceae species, including avocado, was not recovered. This study points to the imminent danger of native ambrosia beetles spreading RL if the pathogen is introduced to Mexico's avocado orchards or natural areas given that these beetles are associated with Raffaelea species and that lateral transfer of RL among ambrosia beetles in Florida suggests that the likelihood of this phenomenon increases when partners are phylogenetically close. Therefore, this study provides important information about the potential vectors of RL in Mexico and other avocado producing regions. Confirming beetle-fungal identities in these areas is especially important given the serious threat laurel wilt disease represents to the avocado industry in Mexico.
Asunto(s)
Escarabajos , Ophiostomatales , Persea , Gorgojos , Ambrosia , Animales , Escarabajos/microbiología , Ecosistema , México , Filogenia , Simbiosis , Gorgojos/microbiologíaRESUMEN
Currently, the reclassification of the genus Persea is under discussion with molecular techniques for DNA analysis representing an alternative for inter- and intra-specific differentiation. In the present study, the traditional random-amplified polymorphic DNA (RAPD) and the inter simple sequence repeat (ISSR) markers were used to determine the genomic relationship of different species and hybrids representative of the subgenera Eriodaphne and Persea in a population conserved in a germplasm bank. The data were analyzed statistically using multivariate methods. In the RAPD analysis, a total of 190 polymorphic bands were produced, with an average of 23.7 bands per primer, the percentage contribution of each primer was from 7.66 to 19.63; the polymorphic information content (PIC) ranged from 0.23 to 0.45, with an average of 0.35. In the ISSR analysis, a total of 111 polymorphic bands were considered, with an average of 18.5 bands per primer, the percentage contribution of each was from 11.83 to 19.57; the PIC ranged from 0.35 to 0.48, with an average of 0.42. The phenograms obtained in each technique showed the relationship among the accessions through the clusters formed. In general, both the techniques grouped representatives of the Persea americana races (P. americana var. drymifolia, P. americana var. guatemalensis, and P. americana var. americana). However, it was not possible to separate the species of Persea used as reference into independent clades. In addition, they tended to separate the representatives of subgenera Eriodaphne and Persea.