Formigas infectadas por fungos parasitas: fenótipos estendidos e pressões ambientais na Amazônia central Brasileira

Abstract

Some parasites can go beyond taking advantage of their hosts' resources. They can modify the behavior of infected individuals for their own survival and reproductive fitness. Ophiocordyceps fungi can cause ants to die in strategic locations for parasite reproduction. Distant from the colony and foraging trails, the hosts may die biting their jaws in plant tissue, burying themselves in leaf litter and moss on tree trunks, or with their legs tangled in shrubs. These behaviors, examples of extended phenotypes, keep the hosts adhered to the plant tissue and can provide for the growth of the reproductive stage of the parasites. Therefore, this thesis aims to explore whether environmental pressures can affect the reproductive fitness of parasites. Specifically, the plant species in the understory where we found the ants, the height from the ground, the time spent by the corpses in the substrates, and the predation of infected ants relocated at the ground level. We found that ants that bite plants were most often found in palm leaves (Arecaceae) of the Attalea sp and Euterpe caatinga species and appear to avoid plant species that contain latex, potential antifungal compounds, and insect repellents. The ants found in higher places tend to remain longer on the substrate, not necessarily biting the plant tissue. Additionally, corpses with fruiting bodies at ground level were more preyed than the others. Thus, our results point to environmental pressures associated with ant death sites. We suggest that the niche selection influenced by predation pressure exerted by opportunistic invertebrates at ground level may select corpses to occupy higher levels in the forest.