Frontiers in Sustainable Food Systems (Apr 2020)
Effects of Field and Landscape Scale Habitat on Insect and Bird Damage to Sunflowers
Abstract
Agriculture-dominated landscapes harbor significantly diminished biodiversity. Woody vegetation along field margins can provide farmers with ecosystem services and benefit biodiversity. However, when crops are damaged by the biodiversity harbored in such vegetation, farmers are reluctant to incorporate field margin habitat onto their land and may even actively remove such habitats. We investigated how damage by both insect pests (sunflower moth, Homoeosoma electellum) and avian pests to sunflower (Helianthus annuus) seed crops varied as a function of field-margin and landscape-scale habitat, as well as by bird abundance and diversity. Surveys for insect damage, avian abundance, and bird damage were carried out over 2 years in 30 different fields. The mean percentage of moth-damaged sunflowers sampled was nearly four times higher in fields that had bare or weedy margins (23.5%; $877/ha) compared to fields with woody vegetation (5.9%; $220/ha) and was positively associated with landscape-scale habitat complexity. Birds damaged significantly fewer sunflower seeds (2.7%) than insects, and bird damage was not affected by field margin habitat type, landscape-scale habitat variables, or avian abundance, but was significantly higher along field edges compared to ≥ 50 m from the field edge. Avian species richness nearly doubled in fields with woody margin habitat compared to fields with bare/weedy margins in both the breeding season and in fall. These results indicate that the benefits of planting or retaining woody vegetation along sunflower field margins could outweigh the ecosystem disservices related to bird damage, while simultaneously increasing the biodiversity value of intensively farmed agricultural landscapes.
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