These bugs are tolerant of most insecticides and difficult to manage effectively. Stink/leaffooted bugs are extremely polyphagous, but they prefer to feed on specific parts of plants in specific maturity stages, primarily seeds in the milk stage, and certain other succulent areas that are present on individual plants for only a limited time during the season. Use of trap crops is based on the assumption that stink bugs can be attracted away from the main cash crop into smaller areas where they can be more efficiently managed. Trap crops must continuously provide food plants in the preferred stage that are more attractive than the cash crop. As a result, pesticide use is eliminated, targeted in spot treatments or minimized, biological control is augmented, and crop damage is greatly reduced. Our ultimate objective is to develop trap cropping technology for each growing season of the year that is neutral relative to farmer philosophy and farm scale.
Small plantings of species such as triticale, sunflower, sorghum, millet, buckwheat, soybean, field peas and okra, provide superior food plants for the bugs while also attracting their natural enemies. Sorghum, millet, triticale and buckwheat are amenable to ratooning, i.e., mowing, to change crop phenology. This characteristic can be exploited to better manage and extend the timing of the trap crop attraction versus the cash crop, hence prolonging the efficacy of the trap crops and reducing the cost of trap crop reestablishment.
Previous trap crop research has tested a number of plant species. Buckwheat is planted because it is easy to obtain and culture, grows quickly and is highly attractive to stink/leaffooted bugs when in seed. The flowers also provide pollen and nectar to bees and wasps as well as tachinid fly parasitoids of stink bugs. Okra, field peas and sunflowers also provide nectar and pollen or alternate hosts (aphids, whiteflies, mites) for beneficial insects, as well as vegetative structures and large seeds attractive to stink/leaffooted bugs. Millet and sorghum provide highly attractive seeds.
Each of the plant species offer different attributes during the course of their growth from planting to senescence. They mature at different times offering the preferred food source - the seeds- to stink bugs at different times over the course of the 60 to 90 day maturation period. Buckwheat attracts all of the main pest species during the late flowering and seed formation stage three to five weeks after planting. Sorghum and millet are most attractive to the bugs when the seeds are in the milk stage. Following destruction of the seed heads by the bugs and seed maturation, the sorghum, millet and buckwheat can be ratooned to about 0.25 to 0.50 m in height. The millet and sorghum respond well to this technique and reform seed heads in about three to four weeks.
Ratooning greatly extends the life of the trap crop as individual millet and sorghum plants head out after different lengths of time following ratooning. Successful ratooning enables fewer planting dates and lowers costs due to the extended life of the trap crop in the seed stage when it is most attractive to the bugs.
Summary: Trap crops targeted to stink/leaffooted bug management have been shown to be very effective in some crops at certain times of the year such as in pecan during fall. However, a generic, economical approach to trap cropping for stink/leaffooted bugs remains to be developed. The present research indicates that such a system appears possible by ratooning sorghum and millet to reduce the number of plantings and maximize the attractancy and competitiveness of the trap crop vs the cash crop. The addition of other plants can fill in gaps inherent to sorghum/millet management, such as triticale and sunflowers for cooler weather in spring, and buckwheat as a relay crop to fill in until sorghum/millet mature. Field peas, okra, etc., provide additional bug attraction as well as providing a nutritional and attractive food source for beneficial insects. Incorporation of semiochemicals attractants and traps may further enhance the trap crop's efficacy and this is the focus of research. Note that triticale and other small grains as well as crimson clover and hairy vetch, plants that are also very good for attracting beneficial insects in spring, must be planted in the fall.
Recommendations: The planting dates, ratooning times and other details of the system must be tailored to the time of year. The cool soil temperatures of spring limit the growth of sorghum and millet but both triticale and sunflowers do better under cooler conditions. Effective management of the stink bugs within the plots and the effective spatial relationships among the trap and main crops remain to be determined. At this time producers may want to plant small plots of these trap crops and remove the bugs in the plots by hand or with insecticides. Sorghum and millet are available in a wide range of cultivars that provide plants of different heights, head and seed types, disease resistance and length of times to maturity; all of which may be important to develop a customized functioning trap crop system. Planting three to four cultivars will exploit this resource extending the effective duration of the trap crop.
Smaller growers or homeowners may wish to grow these trap crops in combinations in large containers that can be moved strategically around the garden to protect specific plantings. The most effective way to protect a crop in larger fields using trap crops is to surround the main crop with a 2-3 meter border of the trap crops. Smaller areas can be protected using parallel or edge-planted plots. Stink/leaffooted bugs display a definite edge response to and buildup populations in border rows of crops before moving into the crop interior. This behavior can be exploited in other crops as it often is in cotton by repeatedly spraying only the border rows.
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Mizell III RF, Riddle TC, Blount A. (May 2008). Trap Cropping for Stink Bugs. Traps and Sampling. http://ufinsect.ifas.ufl.edu/stink_bugs/StkBg-TpCrop-Poster.pdf (21 May 2008).
Roland G. (October 2008). Catering to stink bugs: A trap crop experiment success. Mother Earth News. http://www.motherearthnews.com/Grow-It/Catering-to-Stink-Bugs-Trap-Crop-Experiment.aspx?blogid=1502 (25 November 2008).
Mizell, R. F., T. C. Riddle and A. S. Blount. 2008. Trap cropping for management of stink and leaffooted bugs. Proc. Fla.. St. Hort. Soc. 121: 377-382.