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Implementation of an Insecticide Resistance Management Strategy for Onion Thrips on Onions 2003

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Project Leaders: A. M. Shelton, B. A. Nault, J. Plate and J. Zhao, Dept. of Entomology, NYSAES, Cornell Univ., Geneva, NY 14456



Rich Wildman, Agricultural Consulting Services, Inc.

Datthyn Farms, Sodus

Carol MacNeil, CCE

Franjo Farms, Potter

Christy Hoepting, CCE

DeLyser Farms, Newark


Torrey Farms, Potter


Karas Farms, Orleans


Kasmer Farms, Genesse Co.


Vigniri Farms, Genesse Co.

Type of Grant: Monitoring

Project Locations: Research was conducted in most of the major onion growing regions in NY. The survey information is applicable only to NY onion growers, but the technique is applicable worldwide.


Funds from the NYS IPM program were used to supplement funds from the NYS Onion Research and Development Program for a pest management program for thrips on onions. The primary goals of the overall project were to monitor thrips susceptibility to Warrior, Lannate and Penncap-M in commercial onion fields in upstate NY using TIBS (Thrips Insecticide Bioassay System) and work with extension educators and one private sector company to educate their personnel to use TIBS.

TIBS has proven to be an essential tool to monitor for resistance to Warrior, the most widely used insecticide against thrips (Shelton et al. 2003). Using TIBS, growers can have knowledge about the susceptibility of their thrips populations to Warrior prior to treatment, and thus only use this insecticide when appropriate. However, we needed to develop similar information about the other two major insecticide classes used against thrips in onions- organophosphates and carbamates. We used methyl parathion and methomyl as representatives of each respective class in eight commercial fields.Using the TIBS assay at the field concentration of each insecticide (3200 ppm for methomyl and 2000 ppm for methyl parathion), we had >90% mortality for both insecticides in seven of the eight populations examined (in the last field, mortality using methomyl was 73%). Based on our previous work with TIBS using Warrior, we can infer that field control would still be acceptable with both insecticides. However, our data also indicate potential problems in the future. At 100 ppm of methomyl, half of the 8 populations tested had < 50% mortality while the other half had mortality > 85. At 100 ppm of methyl parathion, one-quarter of the populations had < 60% mortality while half the population had >90% mortality. These larger differences between populations indicate the potential for resistance to develop if an insecticide resistance management program is not utilized.

We believe that the information on susceptibility to each of these classes of insecticides in individual fields can be provided in a timely fashion, and thereby allow growers to make more informed decisions on thrips management. From our outreach efforts (goal #2), we realize that TIBS is probably not going to be done by extension educators because they do not have the time or capacity to conduct these assays themselves. A good functioning private consultant group could implement TIBS but a different model is needed since they too may not have the capacity to do the actual tests. However, TIBS has proven to be an essential tool for thrips management so an alternative implementation strategy is needed. One model we are exploring is to have the private sector charge growers for the service and then bring infested onion plants to our lab so that we can run TIBS. The private sector would charge the grower for the service and then provide some payment to us for running the tests.

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