The commonly held theory that alien invasive plants do not taste good to indigenous animals, and spread rapidly due to lack of predation, is being challenged. Researchers from the Georgia Institute of Technology found that crayfish actually prefer alien vegetation to their natural food and published the findings in Ecology Letters. Surprised by their results, they looked at other scientific literature for similar studies.
Graduate student John Parker says, "We had essentially four separate studies with 11 herbivores and over 300 plants species collected from all around the continental United States all saying essentially the same thing: native herbivores prefer to consume exotic over native plants." Some scientists believe that this may hold new hope for combating the threat of alien invasive species.
However, Llewellyn Foxcroft, Kruger National Park's alien plant guru says that he has not seen this happening in Kruger. He adds that if it is, the animals are only eating those plants that are not abundant and therefore not a worry. "I have seen birds eating Lantana fruit, and hippos sometimes eat water lettuce or water hyacinth, but they are mostly nibbling, possibly to eat grass between the plants."
He adds that Addo's elephants sometimes eat one variety of the sweet prickly pear plants that occur there. Parker plans to test whether native herbivores can control exotic plants in field settings, which may lead to biological control of alien plants using indigenous animal species. "Hopefully our results will also lead to better hypotheses about why some exotic species fare so well in their new environments."
The Sweet Prickly Pear grows across South Africa, having spread over the centuries after been imported from Mexico....