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vol.37 issue2An analysis of factors affecting the adoption of economic and productive data recording methods of Chilean farmersComparison of relative abundance and diversity of coccinellids (Coleoptera: Coccinellidae) in blueberries (Vaccinium corymbosum L.), under two production systems in the La Araucanía Region, Chile author indexsubject indexarticles search
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Ciencia e investigación agraria

On-line version ISSN 0718-1620

Abstract

GREZ, Audrey A et al. Migration of coccinellids to alfalfa fields with varying adjacent vegetation in Central Chile. Cienc. Inv. Agr. [online]. 2010, vol.37, n.2, pp.111-121. ISSN 0718-1620.  http://dx.doi.org/10.4067/S0718-16202010000200011.

Permanent and permeable edges, where natural enemies can feed, overwinter or easily cross over, should enhance the early arrival of these predators to crops. We evaluated the abundance and species richness of coccinellids migrating to alfalfa fields adjacent to Eucalyptus, a mix of false acacia, blackberries and poplar (F-B-P), vineyards, corn and annual vegetables. From September 2007 to May 2008, we captured coccinellids in three sticky traps (2.64 m2) placed at the borders between alfalfa fields and adjacent vegetation. We also estimated the abundance of aphid populations in the alfalfa fields, by counting the number of individuals per alfalfa stem in spring, summer and autumn. We collected 90,396 coccinellids from 14 species. Neither total abundance nor species richness of coccinellids was significantly affected by adjacent vegetation, but Adalia deficiens, Psyllobora picta and Cycloneda sanguínea were more abundant in alfalfa adjacent to Eucalyptus and F-B-P, meanwhile Olla v-nigrum next to annual crops and Hyperaspis sphaeridioides next to vineyards. Edge height and orientation explained 94% of the variance in species abundance. Particularly, P. picta and O. v-nigrum were positively and negatively influenced by border height, respectively. Hyperaspis sphaeridioides was negatively affected by northern exposure and none of the species was affected by edge permeability. Aphids were less abundant in alfalfa fields adjacent to F-B-P, especially in spring. These results show that most species of coccinellids were not affected by the composition of crop edges, although tall permanent edges may enhance the arrival of particular coccinellid species to alfalfa fields.

Keywords : agroecosystems; conservation biological control; edge effects; ladybeetles; migration; natural enemies.

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