Predation of Lepidoptera eggs in a cotton, pecan, alfalfa cropping system

Cotton and pecan in New Mexico often benefit from close proximity to alfalfa hay. Alfalfa is known for producing a source of beneficial arthropods for other crops. Field trials were conducted on an experiment station and on commercial farms to evaluate the impact of hay on predation on using cotton bollworm eggs from an insectary. Eggs were removed after 48 hours and examined for evidence of predation.

Predation in pecans was influenced by proximity to hay. Predation was also higher in large versus small trees.

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. At very high predation rates, there was little difference in predation rates in the commercial alfalfa and cotton fields, with 85-97% predation up to 300 feet into cotton. However, there was significantly less predation 1000 feet into the cotton field with 67% predation on one date. 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.