Development of Push-pull System for Ambrosia Beetles, Vectors of Laurel Wilt Disease in Florida Avocado

View the project final report

Commodities

• Fruits: avocados

Practices

• Pest Management: chemical control, cultural control, integrated pest management, traps

The Redbay ambrosia beetle, Xyleborus glabratus, is a major ecological pest of laurel trees causing widespread tree death by vectoring laurel wilt caused by the fungal pathogen Raffaelea lauricola. Laurel wilt also leads to considerable tree loss in avocado groves in South Florida by secondary vectors. Growers are facing increasing challenges in controlling ambrosia beetle populations in the southeastern region as they have become increasingly unpredictable, and it is difficult to prevent visitation and attack in host trees. To develop a more effective and sustainable integrated pest management program, alternative methods for ambrosia beetle control are being explored.
Chemical and visual stimuli play a dominant role in host searching behavior, and the implementation of visual traps that display attractive wavelengths shows great potential in reducing X. glabratus infestations. In addition, many natural repellents including verbenone can reduce ambrosia beetle visitation and mask attractive stress-related volatiles produced by laurel trees. Preliminary studies have shown that verbenone acts as a successful repellent of ambrosia beetles. However, until this project, little research has been done to investigate the efficacy of verbenone in combination with attractive visual and chemical lures as part of a complete IPM system.
This study we investigated the implementation of a “push/pull” system utilizing a combination of verbenone as a repellent (“push”) with attractive visual and chemical lures (“pull”) to reduce ambrosia beetle visitation in susceptible trees. We found that ambrosia beetle traps cosnisting a cylindrical cardboard covered with reflective mulch were particularly attractive to ambrosia beetles. When positioned outside the citrus grove (10 m away from the border) and in combination with verbenone, the number of ambrosia beetles captured was significantly reduced. Interestingly, avocado trees in the push-pull plots but not directly treated with verbenone also had their population of ambrosia beetle reduced. In summary, this study indicated that verbenone can reduce significantly the number of ambrosia beetles that vector the laurel wilt pathogen in avocado. The addition of an attractive lure outside the grove increased the efficacy of the system. 

1. Determine effects of trap placement on efficacy of attractive visual and chemical traps.
2. Determine effects of complete “push-pull” strategy by combining the natural repellent verbenone (“push”) with the attractive visual and chemical traps (“pull”) compared to the traps alone.