START: 01 AUG 2001 TERM: 31 JUL 2004 FY: 2003 GRANT YR: 2001
GRANT AMT: $38,232
INVESTIGATOR: Van Driesche, R.
PERFORMING INSTITUTION:
ENTOMOLOGY
UNIV OF MASSACHUSETTS
AMHERST, MASSACHUSETTS 01003
PHYTOSEIIDS AND SPINOSAD FOR THRIPS: IPM IN GREENHOUSE EFFICACY AND COMPATIBILITY
NON-TECHNICAL SUMMARY: Bedding plants (transplants for garden use) are a major crop. In the NE U.S., they generate $343,000,000 in annual sales. This "hidden" crop is composed of diverse plant material, but is unified by production methods and timing and is a major contributor to the incomes of many small producers. In surveys, growers of bedding plants have identified western flower thrips (Frankliniella occidentalis) as their most important pest, as judged by pesticide application number. Work in MA showed the predatory mite Neoseiulus cucumeris can control WFT in spring bedding plants. However, there is not enough information from realistic field trials to rely on this control method at this time. We need more knowledge on thrips control by predatory mites in bedding plants. We will compare efficacy of two mites and study their potentials to be integrated with spinosad, the insecticide used against WFT in greenhouses. We propose to test N. cucumeris and a new phytoseiid from Australia known as Ozzie 1. We will run laboratory tests to determine the compatibility of spinosad with both species. Finally, we will compare the control provided by the better mite when used alone versus its efficacy when combined with spinosad. These trials will help integrate biological control into western flower thrips control programs in flower production.
OBJECTIVES: Obj. 1. Comparison of WFT control by N. cucumeris and Ozzie #1 in bedding plant crops. The goal of this objective is to determine how well the major commercially available predatory mite (N. cucumeris) sold for thrips control works in bedding crops in commercial greenhouses under northeastern U.S. conditions and to compare its efficacy with what may well be the next important predator mite commercialized for thrips control (Ozzie 1, being brought into mass production in 2001 by Novartis). We believe, based on preliminary trials in MA and NY in 2000 that N. cucumeris will provide adequate control, but it may not do so in all cases. We don't know how well Ozzie 1 will work and we need to find out as this product will soon be marketed. Obj. 2. Determination of compatibility of spinosad with N. cucumeris and Ozzie #1. Spinosad (Conserve) is the major insecticide used for WFT control. Some evidence suggests that it may be compatible with phytoseiid mites, but there are no data on this. Growers who use predatory mites for biological thrips control may need to supplement these mites with chemical applications if control is insufficient or begins to fail before harvest. If there is a compatible chemical that could be used without persistent damage to the predatory mites, it would be beneficial. If spinosad, the compound most growers are now using for thrips control were compatible, it would be especially good as growers would be very comfortable with that as their back up product. We don't have this information and need to run some rather straight forward laboratory tests to get it.Obj. 3. Assessment of integration of spinosad and phytoseiids in commercial greenhouses. Given the laboratory measurements of compatibility of these phytoseiids and spinosad, we next want to assess what happens to both thrips control and phytoseiid numbers when a spinosad application is added to a thrips biological control program in mid-crop. We will compare this to the use of mite releases alone to see if laboratory estimates of spinosad's compatibility are borne out in real crops. We will also include comparison to spinosad used alone to determine the contribution of the addition of mites to the IPM package.
APPROACH: Obj. 1. Comparison of WFT control by N. cucumeris and Ozzie #1 in bedding plant crops. This trial will be run at three commercial greenhouse businesses in MA. At each site there will be three test greenhouses. Two will be phytoseiid mite release greenhouses, one for N. cucumeris and one for Ozzie 1. The third greenhouse will be a chemical control greenhouse in which the grower will apply insecticides for thrips suppression as he or she sees fit based on counts of thrips on sticky cards, which we will provide. The grower, however, will make any decisions about whether or not to spray and which products to use. The release rate and frequency for N. cucumeris will be the same as we employed in our spring 2000 trial (10,000 mites per 1000 sq. ft.) repeated in weeks 1, 2, 3, 5, and 7 of the 10 week crop) because we have confidence that this rate can work. The application rate for Ozzie 1 will be the same, unless the insectary has a different, specific recommended rate. Obj. 2.Determination of compatibility of spinosad with N. cucumeris and Ozzie #1. To determine the relative compatibility of spinosad with these mites, we will run tests on (1) direct toxicity, (2) effect on egg laying, and (3) repellency. For comparison, the direct toxicity test will also include first instar larvae and adult females of western flower thrips and both thrips and mites will be tested at both the maximum labeled rate and half maximum labeled rate. Obj. 3. Assessment of integration of spinosad and phytoseiids in commercial greenhouses. Based on the results of work for the first two objectives, by the second year of the project (2003), we should have information to suggest if one mite gives better control than the other and whether or not Conserve is compatible with either species of mite in laboratory assays. We will then conduct a second grower trial. As in the first year's trial, it will be run at three locations and at each location there will be two biological control greenhouses and one chemical control greenhouse. In one biological control greenhouse, we will release the better of the two mite species but make no application of Conserve. In the second biological control greenhouse, we will combine releases of the same mite with one mid crop application of Conserve at the high label rate. In the chemical control greenhouse, one high rate application of Conserve will be made on the same date on which Conserve is applied in the mites plus spinosad greenhouse.
PROGRESS: 2001/08 TO 2004/07
Objectives for this project were to run greenhouse trials to determine if releases
of the phytoseiid mite Neoseiulus cucumeris could effectively suppress population
growth of western flower thrips (Frankliniella occidentalis), either alone or
in combination with the insecticide spinosad. We ran three trials. Trial one
was done in six commercial greenhouses filled with spring bedding plants. There
were two replicates of each of three treatments (mites at the commercial rate,
spinosad at label rate, or both). As the measure of outcome, we trapped adult
thrips with yellow sticky cards. Under commercial greenhouse conditions there
was too much variability in plant species in the greenhouse and too much between-greenhouse
movement of plants by growers to see clear treatment effects. In one block,
spinosad alone was highly effective, but in the other it was not. Mites were
not highly effective in either block. Trial two was run in University greenhouses
in pure impatiens monocultures, with two replications (over time) of the same
three treatments as in Trial 1. Using thrips per flower as the measure of outcome,
mite releases caused ca 50% reduction in both larvae and adults of western flower
thrips. To see if a higher mite release rate might increase the level of control,
Trial 3 was run in the same university greenhouses, with three replications
(over time) of two rates of mite release (the commercially recommended rate
and 3.8X that rate) plus an untreated control. In two replicates, the higher
mite release rate was better than the commercially recommended rate, providing
ca 80% control of larvae in flowers, but having no obvious effect on adults
per flower. A manuscript has been prepared covering these trials and has been
submitted to the journal Biological Control and is in review. The other objective
of this grant was to assess the compatibility of spinosad with N. cucumeris.
This was done by measuring mortality and oviposition of mites exposed to spinosad
residues. This compound was found to have only minimal effects on this mite.
The results of this study are being prepared for publication.
IMPACT: 2001/08 TO 2004/07
This study provides evidence that releases of N. cucumeris are only partially
effective in suppressing WFT within a ten week impatiens crop, even at 3.8X
the commercially recommended rate. Spinosad was found to be highly effective
and to have no impact on N. cucumeris, so the two approaches can be used together
without conflict, and the combination should be useful in slowing the development
of resistance by thrips to spinosad. One impact of this work is to advise growers
that this particular biological control method is not highly effective.
PUBLICATIONS: 2001/08 TO 2004/07
No publications reported this period
PROJECT CONTACT:
Name: Cromack, P.
Phone: 413-545-2771
Fax: 413-545-5910
Email: pcromack@fnr.umass.edu