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Effects of agricultural intensification on ability of natural enemies to control aphids.

Zhao ZH, Hui C, He DH, Li BL - Sci Rep (2015)

Bottom Line: It is however extremely difficult to disentangle the effects of agricultural intensification on arthropod communities at multiple spatial scales.As such, agricultural intensification (increasing nitrogen fertilizer and cropland expansion) can destabilize the interspecific relationship and lead to biodiversity loss.To this end, sustainable pest management needs to balance the benefit and cost of agricultural intensification and restore biocontrol service through proliferating the role of natural enemies at multiple scales.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University. Beijing 100193, P. R. China.

ABSTRACT
Agricultural intensification through increasing fertilization input and cropland expansion has caused rapid loss of semi-natural habitats and the subsequent loss of natural enemies of agricultural pests. It is however extremely difficult to disentangle the effects of agricultural intensification on arthropod communities at multiple spatial scales. Based on a two-year study of seventeen 1500 m-radius sites, we analyzed the relative importance of nitrogen input and cropland expansion on cereal aphids and their natural enemies. Both the input of nitrogen fertilizer and cropland expansion benefited cereal aphids more than primary parasitoids and leaf-dwelling predators, while suppressing ground-dwelling predators, leading to an disturbance of the interspecific relationship. The responses of natural enemies to cropland expansion were asymmetric and species-specific, with an increase of primary parasitism but a decline of predator/pest ratio with the increasing nitrogen input. As such, agricultural intensification (increasing nitrogen fertilizer and cropland expansion) can destabilize the interspecific relationship and lead to biodiversity loss. To this end, sustainable pest management needs to balance the benefit and cost of agricultural intensification and restore biocontrol service through proliferating the role of natural enemies at multiple scales.

No MeSH data available.


Related in: MedlinePlus

Effect of spatial scales on the Pearson correlation between the proportion of cropland and the abundance of cereal aphids and their natural enemy in agricultural landscapes (cereal aphids (individuals/100 straws): solid circular indicates S. avenae, hollow circular indicates S. graminum; primary parasitoids (individuals/100 straws): solid triangle indicates A. avenae, hollow triangle indicates A. gifuensis; leaf-ground predators (individuals/100 nets): solid square indicates H. variegata, hollow square indictes S. nitens; ground-dwelling predators (individuals/traps): solid rhomb indicates P. astrigena, hollow rhomb indicates C. spallipes).
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f2: Effect of spatial scales on the Pearson correlation between the proportion of cropland and the abundance of cereal aphids and their natural enemy in agricultural landscapes (cereal aphids (individuals/100 straws): solid circular indicates S. avenae, hollow circular indicates S. graminum; primary parasitoids (individuals/100 straws): solid triangle indicates A. avenae, hollow triangle indicates A. gifuensis; leaf-ground predators (individuals/100 nets): solid square indicates H. variegata, hollow square indictes S. nitens; ground-dwelling predators (individuals/traps): solid rhomb indicates P. astrigena, hollow rhomb indicates C. spallipes).

Mentions: At the population level, agricultural intensification (AI) caused by increasing proportion of cropland has a positive effect on the abundance of cereal aphids at all spatial scales except when measured at the broadest scale (1500 m; Figure 2, see supplementary Table S3). The correlation coefficients between the proportion of cropland and the population densities of the two aphid species (Sitobion avenae and Schizaphis graminum) peaked at the scales of 800 m and 200 m, respectively. Furthermore, the correlation coefficients for primary parasitoids and leaf-dwelling predators were positive, which peaked at the scales of 200 m and 500 m. In contrast, the correlation coefficients became negative for ground-dwelling predators (see supplementary Table S3). Overall, at broad scales increasing proportion of cropland had a positive effect on cereal aphids, leaf-dwelling predators and primary parasitoids but had a negative effect on ground-dwelling predators (Figure 2, see supplementary Table S3). Moreover, the response of cereal aphids and their natural enemies to cropland expansion was species specific. The parasitic wasps were more sensitive than cereal aphids to cropland expansion across multiple scales, while even species within the same module (e.g. the two leaf-dwelling predators, H. variegata and S. nitens) responded differently (Figure 2, see supplementary Table S3).


Effects of agricultural intensification on ability of natural enemies to control aphids.

Zhao ZH, Hui C, He DH, Li BL - Sci Rep (2015)

Effect of spatial scales on the Pearson correlation between the proportion of cropland and the abundance of cereal aphids and their natural enemy in agricultural landscapes (cereal aphids (individuals/100 straws): solid circular indicates S. avenae, hollow circular indicates S. graminum; primary parasitoids (individuals/100 straws): solid triangle indicates A. avenae, hollow triangle indicates A. gifuensis; leaf-ground predators (individuals/100 nets): solid square indicates H. variegata, hollow square indictes S. nitens; ground-dwelling predators (individuals/traps): solid rhomb indicates P. astrigena, hollow rhomb indicates C. spallipes).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306106&req=5

f2: Effect of spatial scales on the Pearson correlation between the proportion of cropland and the abundance of cereal aphids and their natural enemy in agricultural landscapes (cereal aphids (individuals/100 straws): solid circular indicates S. avenae, hollow circular indicates S. graminum; primary parasitoids (individuals/100 straws): solid triangle indicates A. avenae, hollow triangle indicates A. gifuensis; leaf-ground predators (individuals/100 nets): solid square indicates H. variegata, hollow square indictes S. nitens; ground-dwelling predators (individuals/traps): solid rhomb indicates P. astrigena, hollow rhomb indicates C. spallipes).
Mentions: At the population level, agricultural intensification (AI) caused by increasing proportion of cropland has a positive effect on the abundance of cereal aphids at all spatial scales except when measured at the broadest scale (1500 m; Figure 2, see supplementary Table S3). The correlation coefficients between the proportion of cropland and the population densities of the two aphid species (Sitobion avenae and Schizaphis graminum) peaked at the scales of 800 m and 200 m, respectively. Furthermore, the correlation coefficients for primary parasitoids and leaf-dwelling predators were positive, which peaked at the scales of 200 m and 500 m. In contrast, the correlation coefficients became negative for ground-dwelling predators (see supplementary Table S3). Overall, at broad scales increasing proportion of cropland had a positive effect on cereal aphids, leaf-dwelling predators and primary parasitoids but had a negative effect on ground-dwelling predators (Figure 2, see supplementary Table S3). Moreover, the response of cereal aphids and their natural enemies to cropland expansion was species specific. The parasitic wasps were more sensitive than cereal aphids to cropland expansion across multiple scales, while even species within the same module (e.g. the two leaf-dwelling predators, H. variegata and S. nitens) responded differently (Figure 2, see supplementary Table S3).

Bottom Line: It is however extremely difficult to disentangle the effects of agricultural intensification on arthropod communities at multiple spatial scales.As such, agricultural intensification (increasing nitrogen fertilizer and cropland expansion) can destabilize the interspecific relationship and lead to biodiversity loss.To this end, sustainable pest management needs to balance the benefit and cost of agricultural intensification and restore biocontrol service through proliferating the role of natural enemies at multiple scales.

View Article: PubMed Central - PubMed

Affiliation: Department of Entomology, College of Agriculture and Biotechnology, China Agricultural University. Beijing 100193, P. R. China.

ABSTRACT
Agricultural intensification through increasing fertilization input and cropland expansion has caused rapid loss of semi-natural habitats and the subsequent loss of natural enemies of agricultural pests. It is however extremely difficult to disentangle the effects of agricultural intensification on arthropod communities at multiple spatial scales. Based on a two-year study of seventeen 1500 m-radius sites, we analyzed the relative importance of nitrogen input and cropland expansion on cereal aphids and their natural enemies. Both the input of nitrogen fertilizer and cropland expansion benefited cereal aphids more than primary parasitoids and leaf-dwelling predators, while suppressing ground-dwelling predators, leading to an disturbance of the interspecific relationship. The responses of natural enemies to cropland expansion were asymmetric and species-specific, with an increase of primary parasitism but a decline of predator/pest ratio with the increasing nitrogen input. As such, agricultural intensification (increasing nitrogen fertilizer and cropland expansion) can destabilize the interspecific relationship and lead to biodiversity loss. To this end, sustainable pest management needs to balance the benefit and cost of agricultural intensification and restore biocontrol service through proliferating the role of natural enemies at multiple scales.

No MeSH data available.


Related in: MedlinePlus