Land-use intensity affects the potential for apparent competition within and between habitats

Area of Science:

• Ecology
• Agricultural Entomology
• Community Ecology

Background:

• Arthropod communities in adjacent habitats interact through shared natural enemies.
• Resource availability differences between crop and non-crop habitats create variations in insect herbivore densities.
• Landscape composition influences natural enemy attack rates by affecting arthropod community structure.

Purpose of the Study:

• To determine how resource availability impacts apparent competition between habitats.
• To examine the influence of landscape composition on these inter-habitat effects.
• To investigate the relationship between the potential for apparent competition and realized attack rates.

Main Methods:

• Utilized DNA metabarcoding to map host-parasitoid interactions in two habitat types with differing nutrient inputs.
• Analyzed 11 agroecosystem locations with variable landscape composition.
• Estimated potential apparent competition and compared expected versus realized attack rates using interaction networks.

Main Results:

• Shared natural enemies structure herbivore communities within and across habitats.
• High nutrient habitats exhibited a stronger effect of apparent competition.
• Apparent competition potential decreased with increased surrounding land-use intensity and impacted realized attack rates.

Conclusions:

• Habitat resource availability and landscape composition significantly mediate indirect ecological effects like apparent competition.
• Increasing perennial habitat in agroecosystems can amplify apparent competition among insect herbivores.
• Enhanced apparent competition may lead to improved population regulation through increased natural enemy attack rates.