Evaluation of trap cropping and biological control against southern corn rootworm (Coleoptera: Chrysomelidae) in peanuts

Field trials to test the efficacy of trap cropping and biological control for the management of Diabrotica undecimpunctata howardi Barber (Chrysomelidae: Luperini) in peanuts were conducted in 1992, 1993, and 1994. Cucurbita maxima Duchesne cv. 'Blue Hubbard' was used as a trap crop for adult beetles and the entomopathogenic nematodes, Steinernema carpocapse Weiser and Steinernema riobravis Cabanillas, Poinar and Raulston, were used as biological control agents against soil-inhabiting larvae. In 1992, peanut yields were highest in treatments that included a trap crop. Trap crop did not affect yield in 1993 or 1994. In 2 out of the 3 years, distribution of pod damage relative to the trap crop suggested that beetles oviposited more frequently in peanuts growing in the row next to the trap crop than in peanuts 3 rows from the trap crop. Although entomopathogenic nematodes persisted for a sufficient period to overlap with the presence of rootworms, they did not affect yield or pod damage in peanuts.