- The current trend toward simplification of agricultural landscapes, as well as the associated loss of perennial cover types, can decrease landscape heterogeneity and also natural enemy abundance and diversity, favouring exotic species.
- We evaluated the effects of agricultural landscape composition and heterogeneity at two different spatial scales (radii of 250 and 1000 m), on the diversity and abundance of native and exotic coccinellids, associated with alfalfa fields located in two regions of Central Chile. Data were analyzed using partial least square regressions, considering the whole coccinellid assemblage and the three most abundant species.
- In both regions, coccinellid diversity and the abundance and proportion of native coccinellids in alfalfa responded differentially from total abundance and the abundance of exotic coccinellids. The diversity and abundance of coccinellids in alfalfa increased with the compositional and configurational heterogeneity of the landscape. The abundance of both native and exotic coccinellids in alfalfa fields decreased as the area covered by cultivated lands, such as annual crops and orchards, increased. Nevertheless, the responses of native and exotic coccinellids were not consistent among regions, which may be explained by responses of the dominant species in each region.
- The results of the present study suggest that variables related to a higher intensification of agricultural landscapes (lower compositional and configurational heterogeneity, as well as more annual crops) reduce coccinellid diversity and abundance in alfalfa fields. To maintain a higher abundance and diversity of these natural enemies in alfalfa, more heterogeneous landscapes with less annual crops should be promoted.
|afe12068-sup-0001-FigureS1.docWord document, 11 MB||Fig. S1. Distribution of the 23 alfalfa fields (10 in Pirque and 13 in Calera de Tango) and the surrounding landscapes at the three spatial scales.|
|afe12068-sup-0002-TableS1.docWord document, 80 KB||Table S1. Correlation matrices between landscape and coccinellid variables with the first three partial least square regression t-components.|
|afe12068-sup-0003-TableS2.docWord document, 25.5 KB||Table S2. Partial least square regression model quality parameters for the three first components (latent factors), for Pirque and Calera de Tango, and for the three most abundant exotic and native coccinellid species.|
|afe12068-sup-0004-TableS3.docWord document, 77 KB||Table S3. Correlation matrices between landscape variables and the three most abundant exotic and native coccinellid species with the first three partial least square regression t-components.|
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