Trap Crops Are A Good Alternative Pest Management Strategy
April 12, 2013 
Editor’s Note: Majumdar is an Extension entomologist and state sustainable agriculture coordinator at Alabama Cooperative Extension System.
Trap crop studies conducted in Alabama for leaf-footed bug (LFB) management using sorghum varieties and Peredovik sunflower proved to be successful, keeping the pest out of the main crop, tomatoes. This marks the third year trap crops have been studied in an effort to lure LFBs away from a main crop.
In 2012, large tomato plots (300-by-50 feet) were surrounded on two sides by different layouts, such as perimeter and strip intercrop designs. The trap crops were separated by a distance of 6 to 10 feet from the closest tomato plants. Mixed plantings provide food continuity to the LFBs and prevent them from infesting the tomato crop.
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According to data from the 2012 summer research, trap crops planted two to three weeks ahead of the main crop worked best. Sorghum panicle and sunflower seeds were found to be strongly attractive to LFB adults. Predominant species of LFBs were Leptoglossus phyllopus (with a white band across the forewing), but a small number of L. gonagra (without the white band) have also been observed in sorghum trap crop (NK300).
LFBs are extremely mobile insects and will move in search of suitable host plants. At one site used in the research, LFBs appeared to migrate from a mature tomato field to the trap crops that arrested their further movement. Mixed stand of trap crops performed very well.
Sunflowers were more attractive to LFBs compared to NK300 sorghum when both were in reproductive stages. Once sunflower seeds were too mature, LFBs migrated to sorghum. LFBs will readily mate and reproduce in the trap crops. Nymphs were found on trap crops (NK300 sorghum and sunflower) but not in the tomato main crop.
At the commercial farm used in the study, LFBs remained in the NK300 rows that were planted more than 100 feet away from the main crop. As the trap crops withered and died, the LFBs migrated to the main crop.
At two locations in the study, no insecticides were used to control LFB on tomato plants. Typically, one to two applications of synthetic pyrethroids to the trap crop provided significant control of LFBs, with one application of insecticide to the main crop. Significant reduction in pesticide usage is a major benefit of trap cropping system. Overall, the trap crop and insecticide combination provided 70% to 90% control of LFBs, when the timing of insecticide usage matches peak insect activity.
Insecticide application to a sunflower trap crop is not recommended to prevent nontarget impact on pollinators.
In organic farming situations, staggered planting of sunflower trap crops away from the main crop can be used to keep LFBs away until the production season is over.
Overall, trap crops appear to be a good alternative pest management strategy on small to medium scale farms. However, a trap cropping system is management intensive and needs prior planning according to pest species, pest pressures, and farm layout. Good knowledge of insect life cycle and migration patterns may also be needed.
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