Effect of Rhabdias pseudosphaerocephala on prey consumption of free-ranging cane toads (Rhinella marina) during Australian tropical wet seasons

Abstract

The development of biological control measures to reduce the impact of invasive species is a desired goal. Rhabdias species have recently been advocated as biological control agents for invasive anurans. This study describes a field-based approach to support laboratory results on the potential impact of the lung nematode Rhabdias pseudosphaerocephala on the prey consumption of its host, the invasive cane toad (Rhinella marina, Bufonidae). Toads were sampled from various populations in the Wet Tropics of Australia during the wet seasons of 2010 and 2012. Consumed prey items were counted in 212 cane toads and identified to class and order levels and the number of lung nematodes was counted for each toad. The number of R. pseudosphaerocephala in free-ranging cane toads affected negatively the diversity of prey items consumed, but was not related to the number of prey items or the number of ants consumed. The results suggest that infection of free-ranging cane toads by the lung nematode reduces their range of prey items. Possible reasons could be a reduced locomotor activity resulting in changes of foraging modes of infected toads which was reported from some laboratory trials. Infection of cane toads by R. pseudosphaerocephala may therefore have the potential to alter the impact of cane toads on invertebrate communities and their competition for food resources with native Australian anurans.