The Use of Alfalfa Trap Crops to Monitor and and Control Early Season Build-up of Lygus Bug, the Key Economic Pest in Strawberries
2011 Annual Report
1a.Objectives (from AD-416)
To quantify Lygus and their natural enemy dipersal patterns between trap crops (strategically placed alfalfa weeds) and an organically grown strawberry cropping system. This research will lead to more efficient(less costly and less environmental impact)pest management of Lygus in strawberry.
1b.Approach (from AD-416)
Will assist with marking the trap crops and strawberry fields with various markers and assaying all the captured insects for the presence of the markers using a suite of enzyme-linked immunosorbent assays. These data will quantify Lygus movement between the various cropping systems.
The final year of a three year mark-capture type study was completed that examined Lygus (the key strawberry pest) and natural enemy dispersal patterns between strips of alfalfa (i.e., a Lygus trap crop) strategically planted within an organic strawberry field located near Watsonville, CA. A 162 X 1-m strip of alfalfa located in the center of the large strawberry field was sprayed with a 1:1 mixture of bovine milk and chicken egg whites. The crops were then spatially and temporally sampled for insects after marking and the insects were assayed for the presence of the marks. Data yielded from the first two years of study indicate that the vast majority Lygus remained in the marked alfalfa and very few ventured more than 5.0-m into the surrounding strawberries. Strips of alfalfa planted intermittently within organic strawberry fields serves as a trap crop for Lygus and a refuge for their predators and parasitoids. This method has enormous potential as an environmentally friendly cultural pest management tactic for organic strawberry growers. A second year of a two year field study is underway to quantify Lygus and natural enemy dispersal patterns between the natural weed flora (Lygus overwintering sites) surrounding an organic strawberry field. Patches of weeds of various sizes surrounding the strawberry field were sprayed with protein markers. The weeds and the strawberry plots within the vicinity were then spatially and temporally sampled for Lygus, predators and parasitoids after marking and then the insects were assayed for the presence of the marks. All insect samples from the first year of the study have been assayed and data are being compiled for analysis. The field research for the second year of the study is underway. These data will be used to quantify Lygus, predator, and parasitoid dispersal patterns from their overwintering host plants (weeds) into the strawberry crop. Results will benefit pest control advisors and producers by allowing more efficient pest monitoring activities.