1a. Objectives (from AD-416):
1. Determine efficacy and residual activity of registered insecticides against chilli thrips, Bemisia tabaci, and other taxa of invasive pests. 2. Determine direct impact and residual activity of insecticides against key beneficial organisms used for biological control of thrips, Bemisia tabaci, mites, and other taxa of invasive pests. 3. Develop model pesticide rotation programs, based on residual activity, labeled restrictions on frequency of application, and impact on key beneficial arthropods.
1b. Approach (from AD-416):
The approach of this cooperative research project is to evaluate registered pesticides alone and in rotation on different floral and ornamental host plants such as knock-out roses and hawthorne for efficacy against chilli thrips (Scirtothrips dorsalis) and their impact on predatory mites, (Amblyseius swirskii and Neoseiulus californicus ) for development of BMPs. In order to minimize reliance on spinosad and the attendant problems that this poses for western flower thrips management, efficacy trails will be conducted to find additional materials for chilli thrips control and their impact on beneficials. We fully expect to find pesticides that have lost their efficacy on WFT but not to chilli thrips. Bioassays will be conducted to determine susceptibility baseline data for chilli thrips to the most important compounds. Data will be used to develop robust IPM programs and BMPs for thrips control in general and Scirtothrips dorsalis in particular.
3. Progress Report:
This project related to in-house objective 1b: Investigate biological control and ecological interactions of chilli thrips and whiteflies and their natural enemies in order to promote their environmentally sound control in vegetable and ornamental crops. Because poinsettia crops are the primary focus when it comes to the development and spread of pesticide resistant strains of Bemisia tabaci (B and Q biotypes) we conducted a banker-plant demonstration project within one of the nation’s largest poinsettia rooting stations. Rooting stations receive cuttings from around the world and they are known to have spread pesticide resistant strains of whiteflies to almost every agricultural commodity impacted by Bemisia. They are the vectors of resistant strains to greenhouse vegetable producers as well as field grown crops such as tomatoes, squash and cotton. The nursery is located in Winter Garden, FL. The extension experiment was performed from Oct-Dec, 2010 and 2011 in their lighted poinsettia greenhouses. Each season there were two treatments (Chemical vs. Biological control) that were arranged in two portions of the same greenhouse. The biological control agents on banker plants (papaya for E. sophia, ornamental pepper for A. swirskii) were randomly placed within the biologically managed crop. Pesticides were used in the Chemical-treatment as needed or on a weekly basis. All other practices were similar. In the biocontrol treatment, poinsettia plants received the same initial treatment as insecticide but none of the additional pesticide treatments that the control group received. The biological control plants were exposed to the parasitic wasp (E.sophia) from papaya plants by placing the papaya at the end of the benches taking care to prevent the contamination of the poinsettia for honeydew that drips from infested banker plants. Ornamental peppers infested with A. swirskii were randomly placed within the crop. Pepper fruit were removed bi-weekly to maintain the plants in bloom. The number of pepper plants per “run” was between 10-20 per 1,000 square feet of bench. We couldn’t reach some of the plants to remove fruit or examine them for predatory mites because they were inaccessible. Whitefly was a natural occurrence within this greenhouse and initial populations were high. Twenty tested plants were surveyed regularly after introducing the banker plants. The number of whitefly (B.tabaci) adults and nymphs on each tested plant was recorded a total of 5-8 times during each trial. The farm poinsettia experiment suggests that using two banker plant systems (papaya and ornamental pepper) in an IPM system can effectively maintain whitefly populations at very low densities. Both biological control (banker plants) and chemical (pesticides) were equal in quality and were sold. In addition, both E. sophia on all papaya plants and A. swirskii on all banker pepper were observed during each weekly survey. Studies continue using the ornamental pepper banker-plant system against multiple pests. More information about this banker plant system can be found in the related in-house project and at http://news.ufl.edu/2011/06/29/banker-plants/.