Meat Ants and Cane Toads

March 24, 2010

Georgia Ward-Fear of the University of Sydney (Australia) and her colleagues have found that Cane Toads (bufo marinus) are in fact quite vulnerable to a native species of Australian ant. Although cane toads are poisonous to most of their predators, these ants are immune to the toxins secreted by the amphibians.

To measure the toad’s response to attack, they placed toads in a shallow plastic dish and tapped on it until it had completed five hops. They also measured the toads’ activity in the wild vs. the ants’ activity.

They concluded that because the toads have shorter, slower hops than other native frog species and share similar activity patterns with the ants, they are far more vulnerable to meat ant attack. As toads mature, they are active diurnally, which increases their encounters with meat ants. The experiment also showed that many toads failed to detect and evade approaching ants.

Functional Ecology Vol 23, Pages 559-568 (2009)

Opening a Second Front in the War on Cane Toads

March 24, 2010

Ben Berg

Gene Expression Patterns, July 2008

The fight against cane toads has been waged since shortly after their introduction to the Australian continent in 1935. Many different strategies have been tried to limit population growth, but none deterred the poisonous toads’ invasion. New research led by Damian Halliday et al., however, attempts to find a weakness in the toad’s life cycle by examining changes in toad gene expression during metamorphosis.

Funded by the Australian Government’s Department of Environment and Heritage, the study identified changes in gene expression that occur during the somewhat miraculous metamorphosis from tadpole to toad. Transformations such as changing hemoglobin structures and creation of different digestive enzymes are known to occur between the stages. Halliday et al. were able to isolate the specific genes used in these transitions through the use of microarray analysis of toad DNA. Pending further research, the authors hope to find a method of preventing these genes from being expressed, inhibiting metamorphosis and thus eliminating the toad problem.