Land use intensification differentially benefits alien over native predators in agricultural landscape mosaics

Authors: GREZ, AUDREY - Universidad De Chile; Rand, Tatyana; ZAVIEZO, TANIA - University Of Catolica De Chile; CASTILLO-SEREY, FRANCISCA - Universidad De Chile

Submitted to: Diversity and Distributions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2012
Publication Date: 7/1/2013
Citation: Grez, A.A., Rand, T.A., Zaviezo, T., Castillo-Serey, F. 2013. Land use intensification differentially benefits alien over native predators in agricultural landscape mosaics. Diversity and Distributions. 19(7): 749-759; DOI: 10.1111/ddi.12027.

Interpretive Summary: Both human disturbance and the number of habitats used by non-native species can assist their invasion into new environments, and these factors have been predicted to be important within lady beetle communities specifically. This study addressed two questions: 1) Do non-native species benefit more than native species from human disturbed habitats? 2) Are non-native 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 measured the use of different habitat types by native and non-native lady 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 prediction that more disturbed habitats are more invaded by non-native lady beetles. Both the proportion of non-native individuals, and the proportion of non-native species increased significantly (4.8 fold and 1.3 fold respectively) with increasing disturbance intensity. In contrast, we found no evidence that non-native species were more generalized in their habitat use than native species, in fact the trend was in the opposite direction. The results suggest that successful non-native lady beetles may be “disturbance specialists” that thrive within human modified habitats. Therefore, to avoid the expansion of non-native species in agricultural landscapes, less disturbed agricultural production systems could be promoted.

Technical Abstract: Aim: 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? Location: Chile. Methods: 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. Results: 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. Main conclusion 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.