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. Pesticides are often effective against the prey used by the predatory mites we are interested in evaluating the side effects of pesticides on. One pesticide we are interested in using for ornamental IPM programs is called Sultan (cyflumetofen). The material is active on the two-spotted spider mite but not against whiteflies and thrips. The toxicity of cyflumetofen against Phytoseiulus persimilis and Amblyseius swirskii, two of the most commonly used biological control agents, was unknown. The acute toxicity of cyflumetofen against P. persimilis has been studied in the laboratory but not against A. swirskii. The residual toxicity of cyflumetofen against both predatory mite species is also unknown. This lack of information will hinder the practical integration of cyflumetofen with biological control programs in floricultural production. Does cyflumetofen have acute or residual effect on the survival of A. swirskiii and can it be safely integrated with existing whitefly and thrips biological control programs? Since cyflumetofen does not have translaminar or systemic activity, thorough coverage of the infested plants is required for effective spider mite management. If a grower does not achieve good coverage, can P. persimilis be used to ‘clean up’ the remaining or hidden colonies of spider mites? Can cyflumetofen be applied when biological control program is on-going (acute toxicity)? How many days after treatment with cyflumetofen can P. persimilis and A. swirskii be released (residual toxicity)? One issue we discovered when trying to evaluate the impact of pesticides on A. swirskii is that the pesticides had an impact on the whiteflies we were using to feed this predatory mite. We have developed two systems that will allow us to evaluate the impact of various pesticides in the future. The system being currently evaluated uses what we have learned concerning pepper banker plants. These plants, when in flower, are suitable for the maintenance/ development of significant populations of A. swirskii even if no prey are present on the plant. We expose flowering Red Missile pepper plants to a source of the predatory mite. Once adequate numbers of the predators can be found on the test plants we count the numbers of individuals on a subsample of leaves, treat with the pesticide of interest. Populations are then monitored over time on the test plants. We utilize the maximum labeled rate of each pesticide being evaluated and compare to a water treated set of control plants in each experiment. To date we have run preliminary trials with Floramite, Avid and Sultan. We have observed significant reductions in the predatory mite populations but the populations are not eradicated. We will continue these studies over time to determine if the mites are able to rebound and develop populations large enough to manage thrips and whiteflies on the peppers and on other target crops if these treated peppers are used as banker plants.