The effects of temperature and propagule pressure on the establishment success of Ceratitis capitata (Wiedemann)

Abstract

A number of biotic and abiotic factors may determine the successful establishment of new invasive populations. Moreover, the dynamics of the introduction can also play a crucial role especially in light off the number of propagules introduced and the number of introduction events. Here we experimentally assessed whether temperature dependence and founding population density interact to determine establishment success in Ceratitis capitata. Laboratory reared flies were used to initiate new colonies at five different starting densities (N= 2, 4, 8, 16, 20) at three controlled experimental temperatures (20 ̊C, 25 ̊C, 30 ̊C) and with a combination of artificially manipulated introduction events. To determine establishment success, the number of pupae and the number of emerging adults were counted in the F1 generation. Establishment was deemed successful if the population completely replaced itself (at start n+1) and survived >5 days. Establishment success was high under optimal conditions, but varied markedly at the extremes. Our results suggest that establishment probability varies as a function of both the environment and the propagule pressure. This information may be critical to understanding when and where newly introduced populations are more likely to establish in novel climatic conditions and what conditions promote population establishment and likely subsequent invasion.