A multi-scale, landscape approach to predicting insect populations in agroecosystems

Area of Science:

• Agricultural Entomology
• Landscape Ecology
• Ecosystem Services

Background:

• Agricultural pest management is influenced by landscape composition, but land use-insect relationships are complex and not fully understood.
• Investigating the impact of non-agricultural landscapes on agricultural pests and the effects of multiple spatial scales of land use is crucial.

Purpose of the Study:

• To determine if non-agricultural landscapes can suppress agricultural pests.
• To analyze how multiple spatial scales of land use affect insect populations (pests and predators).
• To examine the relationship between regional land use and insect populations in cornfields.

Main Methods:

• Tracking densities of three specialist corn pests (European corn borer, western corn rootworm, northern corn rootworm) and two generalist lady beetle predators.
• Analyzing relationships between insect densities and agricultural land use at field perimeter, 1-km, and 20-km radius scales.

Main Results:

• Pest densities (western corn rootworm, northern corn rootworm) were higher in landscapes with more corn; European corn borer densities were unchanged.
• Natural enemy densities (lady beetles) were lower or unchanged in more corn-dominated landscapes.
• Western corn rootworm and northern corn rootworm populations were suppressed by decreasing the area of corn in the landscape.
• Multiple land use scales influenced western corn rootworm and lady beetle populations; western corn rootworm showed strong links to regional (20-km) land use.

Conclusions:

• Decreasing crop uniformity in agricultural landscapes can directly suppress specialist insect pests.
• Farm planning and policies promoting landscape diversification can enhance biological control and pest suppression.