Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/6/2009
Publication Date: 1/20/2009
Citation: Arthurs, S., McKenzie, C.L., Chen, J., Dogramaci, M., Brennan, M., Houben, K., Osborne, L.S. 2009. Evaluation of Neoseiulus cucumeris and Amblyseius swirskii (Acari: Phytoseiidae) as biological control agents of Chilli thrips, Scirtothrips dorsalis (Thysanoptera: Thripidae) on pepper. Biological Control. 49(1):91-96. Interpretive Summary: The invasive chilli thrips, Scirtothrips dorsalis, is a polyphagous species known to attack more than 100 recorded hosts from about 40 different families. As of August 23, 2007, S. dorsalis has been detected in Florida from Duval County (on the northern border with Georgia) to Monroe County (the Florida Keys) and in South Texas retail garden centers. Biological control is a viable alternative to chemicals in several perennial crops, strawberries, vegetable and ornamental crops grown in greenhouses. Therefore, we evaluated two species of phytoseiid mites as predators of S. dorsalis. Neoseiulus cucumeris and Amblyseius swirskii both fed on S. dorsalis at statistically similar rates and established and reduced thrips numbers significantly over 28 days following a single mite release. A. swirskii was the more effective predator and was able to control the thrips for up to 63 days post release in the landscape.
Technical Abstract: The invasive chilli thrips, Scirtothrips dorsalis Hood poses a significant risk to many food and ornamental crops in the Caribbean, Florida and Texas. We evaluated two species of phytoseiid mite as predators of S. dorsalis. In leaf disc assays, gravid females of Neoseiulus cucumeris and Amblyseius swirskii both fed on S. dorsalis at statistically similar rates. Larvae were the preferred host by both species, consuming on average 2.7/day, compared with 1.1- 1.7 adults/day in no choice tests. Adult thrips were rarely consumed in subsequent choice tests when larvae were also present. Mite fecundity was statistically similar for both species feeding on thrips larvae (˜ 1.3 eggs/day) but significantly less for A. swirskii restricted to a diet of adult thrips (0.5 eggs/day). In greenhouse tests with infested pepper plants, both mite species established and reduced thrips numbers significantly over 28 days following a single release (30 mites/plant). However, A. swirskii was the more effective predator, consistently maintaining thrips below 1 per terminal leaf, compared with up to 36 for N. cucumeris and 70 in control treatments. Similar results were obtained for plants maintained outside in the landscape, where A. swirskii continued to reproduce and control thrips up to 63 days post release.