Optimizing biological control of greenhouse pests with banker plant systems

Optimizing biological control of greenhouse pests with banker plant systems

Summary

Controlled experiments found that black pearl pepper plants increase survival and abundance of the biological control agent Orius insidiosus. In commercial greenhouses, a comparison of thrips biological control by augmentation and by banker plants found that both successfully reduce thrips abundance to levels tolerable by growers. These treatments also reduced spider mite abundance compared to untreated crops. However, banker plants in this system did not improve biological control compared to augmentation alone. We investigated intraguild predation by spiders as a potential mechanism.

Objectives/Performance Targets

1) Determine optimal ‘Black Pearl’ banker plant density by examining Orius dispersal and efficacy at different distances.

2) Determine if biological control by Orius is more effective and economical with ‘Black Pearl’ banker plants than with augmentative releases.

3) Determine the compatibility of biological control with insecticide using augmentative release or banker plants to maintain Orius populations

Accomplishments/Milestones

We have conducted experiments to fulfill Objective 1 and Objective 2 in large commercial greenhouses at Hoffman Nursery. Results of these Objectives indicated that, contrary to laboratory results, banker plants were not supporting Orius in the field. Thus instead of Objective 3 which was contingent upon banker plants actually harboring Orius populations, we conducted research to determine why banker plants were not improving biological control in this system. We found that in this outdoor nursery banker plants were colonized by spiders. Subsequent experiments found that spiders were both scaring Orius off of banker plants and eating Orius that were on banker plants. This information will contribute greatly to our knowledge of when banker plants are appropriate. We also held a field day at the farm on which our research is conducted.

Impacts and Contributions/Outcomes

This project is relevant to sustainable agriculture because its overall goal is to optimize the ‘Black Pearl’ banker plant system which will make biological control more effective, economical, and compatible as a pest management strategy. By eliminating drawbacks of augmentative biological control, banker plant systems will increase adoption and implementation of biological control as a pest management strategy. This will reduce reliance on chemical insecticides and their associated risks to non-target organisms and the environment. This work has been presented at the Entomological Society of America National and Southeast Branch meetings in 2010 and 2011. In addition, it was presented at the field day held by our grower cooperator and at an extension meeting of nursery and greenhouse growers in Johnston Co. NC. The work was also presented at national grower meetings in San Diego, CA and Baltimore, MD. This work contributed to the Masters thesis of a graduate student and 2 peer-reviewed publications have been submitted.

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