Frugivorous mammals prefer citrus fruit infected by Penicillium: was Janzen wrong?

Abstract

Peris, J.E., Fedriani, J.M., Peña, L. 2015. Frugivorous mammals prefer citrus fruit infected by Penicillium digitatum: was Janzen wrong?. Ecosistemas 24(3): 5-13. Doi.: 10.7818/ECOS.2015.24-3.02

Janzen (1977) suggested that frugivorous vertebrates prefer healthy fruit against infected by fungi and bacteria because microbes produce toxic compounds and antibiotics, and also reduces the nutritional value of infected fruit. We evaluated this hypothesis by field experiments in which we offered three commercial varieties of Citrus fruits, both healthy and infected by Penicillium digitatum. Surprisingly, frugivores (mainly rabbits Oryctolagus cuniculus and rodents such as black rats Rattus rattus and mice, probably, Mus spretus and Apodemus sylvaticus) always preferred infected as compared with "control" uninfected fruits. In particular, the consumption of infected fruits of all three varieties studied was up to 32 times higher compared with healthy fruit consumption. We propose three non-mutually exclusive hypotheses that could explain the revealed strong preference of infected fruit by mammals and other frugivores.