Jonathan Kolby and colleagues call for swift eradication of the invasive Asian common toad Duttaphrynus melanostictus from Madagascar (Nature 509, 563; 2014). We caution against disproportionate countermeasures that are not founded on proper data and assessment. These could have detrimental effects on local ecosystems that are comparable to the threat posed by the toads themselves.
Draining potential breeding ponds, for example (see Nature http://doi.org/ts3; 2014), could have an impact on local fauna or even on entire ecosystems. This approach would probably fail anyway because larvae of D. melanostictus can survive in streams, puddles and brackish waters. Also, efforts by amateur conservationists and locals to destroy toad spawn and larvae could jeopardize native frog species if people do not identify tadpoles or juveniles correctly (see, for instance, R. Somaweera et al. Biol. Conserv. 143, 1477–1484; 2010).
We consider the parallels drawn by Kolby and colleagues between D. melanostictus and the invasive cane toad (Rhinella marina) to be inappropriate. Invasion potential and the effects of alien species are hard to predict without sufficient data. To confirm a genuine biological invasion, information first needs to be collected on the toads' range extension and the impact on local flora and fauna.
Before implementing countermeasures, any negative effects should be evaluated. This calls for rapid assessment of the practical difficulties, risks and prospects of success.