Land use intensification differentially benefits alien over native predators in agricultural landscape mosaics
Correspondence: Audrey A. Grez, Fac. Ciencias Veterinarias y Pecuarias, Universidad de Chile, Casilla 2 Correo 15, La Granja, Santiago, Chile.
Both anthropogenic habitat disturbance and the breadth of habitat use by alien species have been found to facilitate invasion into novel environments, and these factors have been hypothesized to be important within coccinellid communities specifically. In this study, we address two questions: (1) Do alien species benefit more than native species from human-disturbed habitats? (2) Are alien species more generalized in their habitat use than natives within the invaded range or can their abundance patterns be explained by specialization on the most common habitats?
We quantified the use of different habitat types by native and alien coccinellid beetles by sampling individuals in nine habitat types that spanned a gradient in disturbance intensity, and represented the dominant natural, semi-natural and agricultural habitats in the landscape.
Our results provide strong support for the hypotheses that more-disturbed habitats are differentially invaded. Both the proportion of alien individuals and the proportion of alien species increased significantly with increasing disturbance intensity. In contrast, we found no evidence that alien species were more generalized in their habitat use than native species; in fact, the trend was in the opposite direction. The abundance of specialized alien coccinellid species was not correlated with the area of the habitat types in the landscape.
The results suggest that successfully established alien coccinellid species may be ‘disturbance specialists’ that thrive within human-modified habitats. Therefore, less-disturbed agroecosystems are desirable to promote the regional conservation of native species within increasingly human-dominated landscapes.