The role of cover crop diversity on key generalist predator attraction and pest suppression

Project Overview

Project Type: Graduate Student
Funds awarded in 2014: $14,996.00
Projected End Date: 12/31/2016
Grant Recipient: Penn State University
Region: Northeast
State: Pennsylvania
Graduate Student:
Faculty Advisor:
Mary Barbercheck
PSU Dept. of Entomology

Annual Reports

Information Products


  • Agronomic: corn


  • Crop Production: cover crops
  • Education and Training: extension
  • Natural Resources/Environment: biodiversity, habitat enhancement, hedgerows
  • Pest Management: biological control, cultural control, integrated pest management, trap crops
  • Production Systems: organic agriculture
  • Sustainable Communities: sustainability measures

    Proposal abstract:

    Insect natural enemies play a critical role in suppressing agricultural pests, but they also rely on plants for alternative food and shelter when prey is scarce. Many agricultural landscapes are simplified and lack alternative plant resources. Natural enemy survival in these landscapes may be reduced because the resources on which they depend are absent. Incorporation of resource-producing insectary plants in the landscape represents an effective tactic to promote natural enemies. Insects exhibit preferences toward particular plant species; therefore, plant mixtures can be deliberately designed to maximize the presence of specific natural enemies. My project will complement a larger field experiment designed to investigate agronomic, ecological and economic tradeoffs associated with cover crop mixtures. I will conduct field and greenhouse experiments to investigate the potential for two cover crops, buckwheat and cowpea, in monocultures and mixture to function as an early season resource for insect predators. Project objectives include characterizing the insect community associated with these species, documenting predation throughout the field, and to monitor insect dispersal from insectary strips into the cash crop. This research is novel because it aims to provide research-based information geared toward understanding the influences of plant resources on beneficial insects by considering the role of cover crop mixtures and their management to enhance beneficial insects in the field. Using cover crops to promote the presence of beneficial insects in the field represents a sustainable approach to pest management that can result in reduced reliance on pesticides which can safeguard grower health and the environment.

    Project objectives from proposal:

    OBJECTIVE 1: Evaluate the effects of resources from cover crops on the longevity and survival of two key generalist predators


    Predators rely on plant-provided resources when prey is scarce. Because these insects exhibit preferences toward plant species, it is important to evaluate how cover crops used as insectary plants benefit natural enemies or biological control of pests in enclosed settings before being used in the field.


    OBJECTIVE 2: Determine the effects of cover crop growth, development and floral density on plant resource quality for two key generalist predators.


    When incorporating cover crop species to support predators, it is vital that flowering times coincide with the springtime emergence of the predators. By monitoring plant growth and phenology, I will document windows where these cover crop species may be used as insectaries, as well as the amount of resource potentially available to natural enemies.


    OBJECTIVE 3: Assess the foliar insect community associated with buckwheat and cowpea monocultures, and a cowpea-buckwheat mixture compared to a fallow control.


    Insects are linked with their plant habitats and are differentially attracted to plants. Therefore, cover crops intended to function as insectary plant species should be “screened” to assess which are most effective at promoting natural enemies while minimizing the potential to attract pest insects.


    OBJECTIVE 4: Monitor predation on prey insects within the cover crop resource and an adjacent corn crop.


    When floral resources are present, natural enemy abundances are higher; however, there are often no
    corresponding increases in pest suppression. To understand the possible consequences of using cover crops as insectary plants, it is necessary to compare levels of predation in both the resource patch and the cash crop.


    OBJECTIVE 5: Investigate the ability of cover crops used as an early season insectary to attract and support natural enemies, and to serve as a source of natural enemies for an adjacent cash crop.


    Studies investigating the use of insectary plants as a biological control tactic must demonstrate movement from the insectary into the target cash crop. To demonstrate this, we can use mark-recapture methods, in which insects in the cover crop are marked with a protein, and then insect specimens collected from the cash crop can be assessed for the presence of the mark. The presence of the cover crop-associated mark confirms the origin and movement of the insect to the cash crop from the cover crop.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.