Enhancing the Biological Control of the Diamondback Moth (Plutella xylostella) Through Habitat Management for Sustainable Brassica Production

View the project report

Commodities

• Vegetables: brassicas

Practices

• Pest Management: biological control, cultural control, integrated pest management

Diamondback moth (DBM), Plutella xylostella, is a ubiquitous pest of Brassicaceae crops that leads to a global economic burden of $ 4-5 billion annually from yield losses and control costs. Over the past few decades, it has gained importance as a key pest of brassica crops due to resistance development against over 98 active insecticide ingredients, including novel diamide insecticides. Several natural enemies of DBM attack its larval and pupal stages and alone can suppress DBM populations through high parasitism rates (>80%). However, grower reliance on insecticides eliminates beneficial natural enemies and drives the development of insecticide resistance. Sustainable biocontrol tactics, such as enhancing conservation biological control (through habitat management), could bring promising results if strategically introduced. This project will investigate the impact of sweet alyssum flowers (which attract and enhance the efficiency of natural enemies) in suppressing DBM populations. We will conduct trials on commercial and small brassica farms in the Southern United States to provide equal benefits to small and large-acreage growers. Preliminary results revealed increased DBM parasitism nearer to alyssum flowers; however, more trials are required to determine how to most effectively incorporate alyssum flowers and determine its effects across spatial scales. Project findings will be shared with stakeholders through broad Extension programs. This project addresses environmental, economic, and health sustainability by developing a total-system approach that relies on naturally occurring resources (natural enemies) that will reduce chemical use, thus increasing profitability, yield, and land use efficiency, ultimately improving the quality of life for farms and communities.

The objectives of this project are:

1. Develop a habitat management strategy that uses sweet alyssum flowers to improve biological control of DBM in the Brassica fields of the southern United States.

1a. Conduct small plot experiments to determine how incorporating alyssum flowers influences predation and parasitism of DBM (to benefit small growers).

1b. Conduct large on-farm trials to assess how alyssum flowers influence DBM parasitism and predation at different spatial scales realistic to intensive brassica production systems in order to optimally distribute insectary plants (to benefit large growers)

2. Evaluate seasonal parasitoid species and parasitism rates of DBM, which would serve as a valuable tool for understanding biological control potential and developing DBM management strategies based on the occurrence of DBM parasitoids during different brassica growing seasons throughout the year.