Effects of position within wheat field and adjacent habitats on the density and diversity of cereal aphids and their natural enemies
Date
2013
Authors
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Abstract
The spatial structure of agricultural land-
scapes can have a strong impact on the distribution and
diversity of insects. Here we studied the effects of
within-field position (edge or center) as well as adjacent
habitats on the community structure of the natural
enemies of cereal aphids. Twelve agricultural sites were
included in the study, with two spring wheat fields
selected for each site (one adjacent to an alfalfa field, the
other adjacent to a corn field). We sampled two rows per
field (1 and 20 m from the edge) using pitfall trapping
for ground-dwelling predators, sweep netting for leaf-
dwelling predators and hand collecting of aphid
mummies for parasitoids. Adjacent alfalfa areas, as
opposed to corn fields, can significantly increase the
abundance and diversity of leaf-dwelling predators and
parasitoids near the field edges. Abundance and diver-
sity were found significantly higher near the edges than
in the centers of fields adjacent to alfalfa areas. In
contrast, no significant differences were found between
edges and centers of fields adjacent to corn fields. Of the
fifteen most abundant species,
Aphidius avenae
(Hali-
day),
A. gifuensis
(Ashmead),
Hippodamia variegata
(Goeze) and
Chrysopa sinica
(Tjeder) were significantly
more abundant near the edge than in the center. Being
adjacent to alfalfa habitats could enhance parasitism and
predator/prey ratios of leaf-dwelling predators at the
edges, but has no effects on ground-dwelling predators.
In conclusion, the effect of within-field position and
adjacent habitats on natural enemies of agricultural pests
was species specific. This should be considered for
designing efficient plans of biological control.
Description
Keywords
Abundance, Alfalfa, Edge effects, Natural control, Parasitoids, Species diversity
Citation
Zhao, Z.H., Hui, C., He, D.H. & Ge, F. (2013) Effects of position within wheat field and adjacent habitats on the density and diversity of cereal aphids and their natural enemies. BioControl, 58: 765-776.