Knocking on heaven's door : are novel invaders necessarily facing naive native species on islands ?

The impact of alien predator species on insular native biota has often been attributed to island prey naivete (i.e. lack of, or inefficient, anti-predator behavior). Only rarely, however, has the concept of island prey naivete been tested, and then only a posteriori (i.e. hundreds or thousands of years after alien species introduction). The presence of native or anciently introduced predators or competitors may be crucial for the recognition and development of adaptive behavior toward unknown predators or competitors of the same archetype (i.e. a set of species that occupy a similar ecological niche and show similar morphological and behavioral traits when interacting with other species). Here, we tested whether two squamates endemic to New Caledonia, a skink, Caledoniscincus austrocaledonicus, and a gecko, Bavayia septuiclavis, recognized and responded to the odor of two major invaders introduced into the Pacific islands, but not yet into New Caledonia. We chose one predator, the small Indian mongoose Herpestes javanicus and one competitor, the cane toad Rhinella marina, which belong respectively to the same archetype as the following two species already introduced into New Caledonia in the nineteenth century: the feral cat Felis catus and the golden bell frog Litoria aurea. Our experiment reveals that geckos are naive with respect to the odors of both an unknown predator and an unknown competitor, as well as to the odors of a predator and a competitor they have lived with for centuries. In contrast, skinks seem to have lost some naivete regarding the odor of a predator they have lived with for centuries and seem "predisposed" to avoid the odor of an unknown potential competitor. These results indicate that insular species living in contact with invasive alien species for centuries may be, although not systematically, predisposed toward developing adaptive behavior with respect to species belonging to the same archetype and introduced into their native range

Continental comparisons of the interaction between climate and the herbivorous mite, Floracarus perrepae (Acari : Eriophyidae)

The Old World climbing fern, Lygodium microphyllum, is an invasive weed in the Florida Everglades and the leaf roll galling mite, Floracarus perrepae, is a proposed biological control agent. Field studies were conducted for one to two years at sites in its native range in Australia, New Caledonia, and India to evaluate the effect of climate on F perrepae. Monthly counts of the proportion of L. microphyllum subpinnae (leaflets) with leaf roll galls were used to measure the incidence of damage caused by F perrepae. Between sites the most significant weather variable was rainfall 14 to 28 days prior to sampling, with higher levels having a depressive effect on the incidence of leaf rolls. Within sites the mean maximum temperature was the only significant weather variable, showing a decrease in the incidence of leaf rolls above 27 degrees C, and it was predicted that no leaf rolls would form above 35 degrees C. The weather parameters in Homestead, Florida for 2002 were within the range of those evaluated in the eight native range field sites. Thus, we do not predict that climate will prevent the establishment of this biological control agent for L. microphyllum in southern Florida