Cane toad chemical ecology: controlling an invasive pest

The cane toad (Bufo marinus) is a very successful invasive species native to central and South America. In 1935, 101 individuals of B. marinus were introduced into Australia in an attempt to control a beetle pest of sugar cane fields [1]. The cane toad did not control the beetles, and itself became a pest species. Since its initial release, the toads have spread rapidly and widely across the northern landscape of Australia. Cane toads have been implicated in the population declines of native frog species (although recent evidence suggests these impacts may have been overstated [2]) and also in population declines of mammalian and reptilian predators. These effects are primarily through the toad's toxic secretions that impact on toad predators. Our study uses HPLC, LC-MS and NMR to examine variability in the chemical composition of cane toads, across life-history stages (eggs, tadpoles, metamorphs, adults) and throughout the population.

• Chronic exposure throughout larval development to an alarm signal alters the chemical profile of juvenile toads; this has implications for lifetime reproductive fitness, and potentials for control of the species.

• The chemical profile, and thus toxicity, of the various ontogenetic stages of the toad changes through time.

• Throughout the toad's Australian range there is no difference in the toxin profile of adult toads, although this is different to what has previously been reported for toads from other places.

Beyond this, the toad's chemical ecology, including probable pheromonal communication, may offer opportunities for control of the pest.

References: 1. Mungomery, RW. (1935) Cane Grow. Q. Bull. 3:21–27.

2. Grigg, GC. et al. (2006) Science of Cane Toad Invasion and Control. Invasive Animals CRC, Canberra pp 47–54.