2001 Annual Report for FS01-140
Using companion plants to increase biological control for thrips in pepper crops
Summary
Thrips are a pest on peppers. They are difficult to control using insecticides because of resistance problems and difficulty in reaching them with sprays. When they feed in the flower and then on the developing fruit it is almost impossible to get sprays to reach them. The problem is compounded when we try to control pepper weevil. To kill this pest, I often have to use especially harsh chemicals, which increases the thrips problem. I try to use “softer” chemical sprays, things like B.t., Confirm, and spinosad, for my worm problems, but thrips control is difficult to get with just chemicals. I spray many more harsh chemicals then I would like. This is not a good situation for the crop, my workers or me.
I would like to investigate the use of beneficial insect habitat to keep thrips predators around and in my pepper field by using companion plantings. With the help of Glades Crop Care, Inc. I have been looking at multi-headed sunflowers (variety Santa Fe), grown along my ditch banks in blocks of my peppers. This companion plant, with its small flower heads (3″ dia.), does not interfere with my field operations.
The minute pirate bug (MPB) Orius insidiosus , a very good thrips predator, builds up on the sunflowers just as thrips are starting to enter the field. I want to determine if these predators are moving into the field to feed on the thrips or are they just staying in the sunflower heads. I also intend to find how far they move into the field. Do they move only a couple of rows into the field or do they move farther than that? I have seen a consistent build-up of minute pirate bugs on the sunflowers over the season. If they move into the field in a significant number, I should get almost season-long control of thrips.
I will grow sunflowers (Santa Fe) along my irrigation banks to build populations of the minute pirate bugs. Sunflowers will be planted a week or two after pepper transplants are put in the field. I have found that the sunflowers flower at about the same time as the peppers when planted at this time. I will plant the sunflowers about one foot apart along the banks in most of my blocks (blocks are 2-2.5 acres in size) but will leave some blocks with no sunflowers. I will measure the number of minute pirate bugs that are in the sunflowers and those in the peppers in the blocks with sunflowers and the blocks without sunflowers. I will also measure the number of predators found in each row of peppers with increasing distance from the sunflowers. Then, I will compare the numbers of predators and thrips found in blocks with and without sunflowers and the numbers in each pepper and sunflower row. I will also determine thrips damage in each row of peppers. If the thrips predator, the minute pirate bug, is working, there should be more marketable peppers to pack out in the blocks with sunflowers than ones without sunflowers.