Enhancing insect pest management in organic systems using genotypically diverse cultivar mixtures


Coordinator: John Tooker, Pennsylvania State University
Project location: Russel Larson Agricultural Research Center, Rock Springs, PA

Organic growers rely on natural processes to help manage their crops. For pest management, growers rely in part on naturally occurring arthropod predators and parasitoids to control populations of plant-feeding insect pests. This tactic is feasible on organic farms because, unlike conventional farms, they tend to harbor a diversity of crop and non-crop plant species, which support diverse natural enemy communities. Nevertheless, despite weed populations, in-field plant diversity is often relatively low and pest control could be more efficient if growers had an integrated strategy for increasing in-field diversity without relying on tactics that have negative influences on yield, (e.g. tolerating higher than ideal populations of weeds, or establishing insectary plantings within crop fields).  

In this project, I propose to use genotypically diverse cultivar mixtures to diversify fields, enhance natural enemy populations, and limit damage from herbivorous insect pests.

Recent research with native plant species has demonstrated that genotypic diversity is nearly as valuable as plant species diversity for structuring insect communities and driving ecological interactions. Field crop growers in Europe and Asia are aware of the utility of genotypically diverse cultivar mixtures and routinely use them to manage plant diseases. Surprisingly, this previous research has not been translated for use in organic agriculture. By simply planting numerous agronomically similar, yet genetically distinct cultivars in a field, organic growers would be able to diversify arthropod populations in the crop fields and reduce the incidence of outbreaks of insect pests. I propose to evaluate the utility of using diverse cultivar mixtures to manage insect pests in two organic field crops: soybean and wheat. These two crops are vital for organic production in the Northeast because of increasing demand from organic dairies.

The proposed research will be conducted on a 1.7 acre field in certified organic ground at Penn State's Russell Larson Agricultural Research Center.

The main objectives of the project are to assess the potential of using genotypic diversity cultivar mixtures to:

    1. Increase natural enemy diversity and abundance in crop fields;
    2. Decrease abundance of herbivorous insect pests in crop fields;
    3. Improve crop yield