Sex, light, and sound: location and combination of multiple attractants affect probability of cane toad (Rhinella marina) capture

Abstract

Invasive species management is a critical issue worldwide, but mitigation strategies are slow to develop, and invader populations often expand too rapidly for eradication to be feasible. Thus, reduction in numbers of individuals is the most heavily used management strategy for invasive pests. While long-term biocontrol agents may take years or decades to develop, simple trap modifications can increase capture of targeted demographic groups, such as ovigerous females. The present study identifies the effectiveness of trap modification and use of multiple attractants to capture the invasive cane toad (Rhinella marina). Cane toad traps typically use lights to attract insect prey. Studies suggest that adding a male cane toad advertisement call to attract toads by phonotaxis may be effective. The aims of this study were to determine whether (i) female capture efficiency was influenced by attractants in the same manner as male and juvenile captures, (ii) an acoustic attractant alone (without a light attractant) was sufficient to attract toads, and (iii) the location of an acoustic attractant (inside or on top of the trap) influenced trap success. Male toads were captured more frequently than females and juveniles; combining light and acoustic attractants increased toad capture; and placing the acoustic attractant inside the trap increased the capture of female cane toads. Removal of adult, ovigerous females is a promising strategy to slow population growth of invasive species. Our results suggest that using a sound attractant inside the trap with a UV light is most effective in targeting that particular cane toad cohort.