Landscape Complexity has Mixed Effects on an Invasive Aphid and Its Natural Enemies in Sorghum Agroecosystems

Area of Science:

• Agricultural Entomology
• Landscape Ecology
• Pest Management

Background:

• Agroecosystem complexity influences natural enemy populations and pest suppression.
• The invasive sorghum aphid, Melanaphis sorghi, poses a significant threat to sorghum production.

Purpose of the Study:

• To evaluate the impact of landscape complexity on sorghum aphid and natural enemy abundance.
• To determine the relationship between landscape composition/configuration and insect populations at various spatial scales.

Main Methods:

• Conducted two-year field sampling of aphids and natural enemies in sorghum fields.
• Utilized correlation and multivariate regression to analyze landscape composition and configuration effects.
• Assessed insect responses at different spatial scales within a southern U.S. coastal region.

Main Results:

• Increased landscape complexity, particularly habitat edges, correlated with higher aphid and natural enemy abundance.
• Noncrop habitat composition had an inverse relationship with insect abundance.
• Natural enemy response varied by taxa: parasitism decreased with complexity, while predator response remained unaffected.

Conclusions:

• Landscape complexity can amplify both pest and natural enemy populations, but may reduce parasitism rates.
• Habitat configuration, especially edges, is crucial for understanding pest-natural enemy dynamics in cereal agroecosystems.
• Environmental suitability for aphid increase influences the observed landscape-insect relationships.