Evaluation of predation risk in the collectively foraging termite Macrotermes bellicosus
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Few studies have investigated foraging decisions in collectively foraging social insects with no studies in termites. In termites predation is assumed to be a key mortality factor. Therefore, we experimentally investigated the role of predation pressure in foraging decisions of the fungus cultivating, mound building termite Macrotermes bellicosus in two habitats of the Comoé National Park (Ivory Coast). We used the indirect approach of measuring the Giving up Density (GUD), which is the amount of food left when individuals stop foraging in a food patch, whilst experimentally varying predation pressure. Three different conditions were examined: (a) natural predation, (b) no predation, and (c) experimental predation through artificial removal of termites. In the shrub savanna, foraging termites responded to increasing predation with increasing GUDs. By contrast, in the gallery forest, there was no gradual response. Instead termites abandoned a food patch immediately after an attack by predators. Without predation GUDs were lower in the savanna than in the gallery forest indicating that food had a higher value in the former habitat. This, together with the differential behavioral responses to predation, was in accordance with high availability of food in the gallery forest and a limited supply of food in the savanna. Thus, according to our results termites traded off predation pressure differently, according to the availability of food in both habitats.
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