1887

Abstract

Leaf-cutting ants (genera and ) cultivate a specialized fungus for food in underground chambers employing cut plant material as substrate. Parasitism occurs in this agricultural system and plays an important role in colony fitness. The microfungi , a specialized mycoparasite of the fungal cultivar, is highly prevalent among colonies. In this study, we tested the antagonistic activity of several strains from different geographical areas in Costa Rica. We employed a combination of laboratory tests to evaluate virulence, including pure culture challenges, toxicity to fungus garden pieces and subcolony bioassays. We also performed a phylogenetic analysis of these strains in order to correlate their virulence with the genetic structure of this population. The bioassays yielded results consistent between each other and showed significant differences in antagonistic activity among the parasites evaluated. However, no significant differences were found when comparing the results of the bioassays according to the source of the ants’ fungal cultivar. The phylogenetic analyses were consistent with these results: whilst the fungal cultivar phylogeny showed a single clade with limited molecular variation, the phylogeny yielded several clades with the most virulent isolates grouping in the same well-supported clade. These results indicate that there are strains better suited to establish their antagonistic effect, whilst the genetic homogeneity of the fungal cultivars limits their ability to modulate antagonism. These findings should be taken into consideration when evaluating the potential of isolates as biocontrol agents for this important agricultural pest in the Neotropics.

Funding
This study was supported by the:
  • Vicerrectoría de Investigación, Universidad de Costa Ric (Award VI 810-B0-501)
  • Fondo de Reinserción del Ministerio de Ciencia y Tecnología (MICIT)
  • Premio Aportes a la Creatividad y la Excelencia de Florida Ice and Farm Company
  • National Science Foundation (Award MCB-0702025)
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2014-08-01
2024-04-25
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