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United States Department of Agriculture

Agricultural Research Service

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Location: Subtropical Insects and Horticulture Research

2011 Annual Report

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

project related to inhouse 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.

Banker plants were explored as a means of dispersing biological control agents for control of multiple pests (whitefly, thrips, two spotted spider mite) found in vegetable and ornamental commercial greenhouses. The first study was conducted to evaluate and compare the potential role of three commercially available predators: predatory gall midge (PGM) and two predacious mite species, Amblyseius swirskii, and Neoseiulus californicus, as biological control agents of two spotted spider mites (TSSM). The functional responses at prey densities and prey-stage preferences (when offered TSSM eggs and nymphs) of these predators were investigated under laboratory conditions. The PGM was highly effective and the two species of predacious mites were modestly effective in regulating TSSM egg densities. Our results on prey-stage preferences showed that all three predator species exhibited no-prey stage preference to prey eggs or nymphs. Among the three predators, the PGM had the highest predation potential, in particular at high prey densities and was chosen for further investigation. The second project was conducted under laboratory and greenhouse conditions to evaluate whether corn plants could be potential non-crop banker plants for the PGM. Multi-choice and no-choice experiments were conducted to determine the host plant specificity of an alternative non-pest prey (Oligonychus pratensis) to potential cash crops of green bean and tomato plants. Results revealed that the corn plants were a non-target crop banker plant for supporting the non-target pest prey, O. pratensis for feeding and reproduction, whose larvae also showed strong host specificity to corn plants in both multi-choice and no-choice tests. The PGM was able to disperse by flight at least 7.0 m away from corn banker plants and the number of PGM found on green bean after 5-14 d dispersal ranged from 8-176 larvae per leaf. PGM proved to be an excellent predator on TSSM. In closed caged greenhouse studies, TSSM was suppressed by 81% compared to the control treatment. These studies suggest that corn plants (banker plants), O. pratensis (alternative prey), and PGM (predator) constitute an excellent potential banker plant system that should provide a new approach to control TSSM for greenhouse vegetable growers. The third banker plant project employed papaya as the non-crop banker plant for supporting the papaya whitefly as the alternative prey. Papaya whitefly is host specific to papaya and not a pest on other host plants and can support the development of the parasitoid wasp, Encarsia sophia which is also a very effective biological control agent for the devastating whitefly pest, Bemisia tabaci. This banker plant system has broad application in protected horticultural crops and pilot studies have been successful in commercial tomato, herb, cucumber, eggplant, lettuce and poinsettia greenhouses in Florida.

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Last Modified: 4/21/2014
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