Additional advantage of endozoochory by mammals: disinfestation of parasitized seeds

VELEZ, SILVINA; ANTÚNEZ, ANA L.; LOMÁSCOLO, SILVIA B.; CHACOFF, NATACHA P.

Mendoza, Argentina

Congreso; 10th International Mammalogical Congress; 2009

Grupo de Investigaciones de la Biodiversidad (GIB), IADIZA; CCT-Mendoza; CONICET; Federación Internacional de Mastozoologos (IFM); y Sociedad Argentina para el Estudio de los Mamíferos (SAREM)

In some arid ecosystems, large mammalian herbivores disperse and facilitate germination of many Fabaceae species by scarifying the seeds. Additionally, herbivores may reduce bruchid infestation by the action of digestive fluids that penetrate through the larval entry hole. Lastly, they may prevent reinfestation of seeds by simply removing them from the parent plant. In the Monte DesertProsopis flexuosa is a key species; its pods are highly attractive to several insects and vertebrates. P. flexuosa depends on mammals for dispersal and germination of seeds. Before dispersion, seeds are attacked by bruchid beetles. The larva consumes a seed entirely if it completes the cycle, but scarified seeds containing early larval stages can germinate. We ask whether and to what extent different medium-size mammals in the Monte Desert disinfest parasitized P. flexuosa seeds. During secondary dispersal of P. flexuosa seeds, we collected recent feces of Patagonian hare (Dolichotis patagona), gray fox (Lycalopex griseus), and exotic European hare (Lepus europaeus) in Ñacuñan MaB Reserve. Every sample was analyzed separately to extract all the seeds and discard those that had already been depredated. Seeds were observed under the dissecting scope to determine non-infested and disinfested seeds (those with dead bruchids at different stages). We germinated disinfested seeds to determine their viability. The number and percentage of non-infested seeds per fecal sample was similar for fox (14 seeds, 69%) and Patagonian hare (12 seeds, 65%), but lower for the European hare (6 seeds, 68%). Seed damage by chewing was very low and similar for the three mammal species. Foxes disinfest 68% of bruchid-infested seeds, of which 13% germinate. Patagonian hares disinfest 64.4%, of which 11.3% germinate, and European hares disinfest 91.1%, of which 20% germinate. In conclusion, Patagonian hare and gray fox are highly effective in the dispersal and disinfestation of P. flexuosa seeds.