Predation was often significantly higher in alfalfa compared to cotton. In an experiment station trial, mean predation in alfalfa was 78% compared to 48-58% in cotton. The primary predators were ladybug adults, nabids and various spiders. At very high predation rates, there was little difference in predation rates between adjacent alfalfa and cotton fields with 85-97% predation in alfalfa and up to 300 feet into cotton. However, there was significantly less predation 1000 feet into the cotton field with 67% predation on one date suggesting that close proximity may have the highest impact. After cutting and cooler weather, predation rates declined in the commercial field with a mean 65% predation in alfalfa but only 28% predation in the commercial cotton field. September also produced lower predation rates in the experiment station trial with 35% predation compared to 53-77% predation in July and August.
On the experiment farm, four transects from hay into cotton were placed on each border of a small cotton field. Each transect was replicated four times for each of the four borders of the field. Eggs were placed 10 feet into hay and 10, 30 and 80 feet into the cotton field. Predation of eggs was evaluated in the laboratory. Sweep net samples were collected to identify and quantify predators in each location. Results from that trial will be discussed.
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