Friday, August 10, 2018: 9:50 AM
335-336, New Orleans Ernest N. Morial Convention Center
Pablo E. Allen, Larissa Laforest and Adam G. Dale, Entomology and Nematology, University of Florida, Gainesville, FL
Background/Question/Methods Host-parasite interactions are pervasive in nature. Like predators, parasites are vital in maintaining ecological stability by controlling population size. Population explosions of invasive species are hypothesized to stem from a lack of these natural enemies. A documented consequence of escaping parasitic pressure is an increase in body size, which can enhance a species’ ability to disperse, reproduce, and survive, advantages that exacerbate its invasiveness. We hypothesized that the re-establishment of a host-parasite interaction would reduce the hosts’ body size. We used two invasive species of mole cricket, Southern (Neoscapetriscus borellii - SMC) and Tawny (N. vicinus - TMC), both introduced from South America (≈1904) free of natural enemies. The University of Florida has been involved in the control of these pest species, which have colonized the southeastern United States. In the 1980s, as part of its integrated pest management program, UF introduced several of the mole cricket’s natural enemies, including a parasitic nematode (Steinernema scapterisci) from Uruguay. Evidence suggests that these nematodes precipitated the decline of invasive mole crickets during subsequent decades. In this study, we compared body sizes of the two invasive mole cricket species from before parasitic nematode introduction and 30 years after introduction to the novel range.
Results/Conclusions
Our data suggests that SMC body size did not change since the re-establishment of interaction with their old enemy, but contrary to predictions, TMC body size has increased. Body size seems to be a very labile trait for SMC, which may explain why we found no differences. Furthermore, seasonality and food availability may heavily influence body size patterns in this species. In the case of the TMC, the increase in body size could be due to selection imposed by the parasitic nematode or other biological control agents introduced 30 years ago. Results may have implications for the range expansion of an important invasive insect in the southern U.S.
