Comparative feeding and development of Pseudoplusia includens (Lepidoptera: Noctuidae) on kudzu and soybean foliage

Kudzu, Pueraria montana (Lour.) Merr. variety lobata (Willd.) Maesen & Alme ida, a close relative of soybean, Glycine max (L.) Merr., is an adventive a nd widely distributed weed in the southeastern United States. Conventional wisdom says that native arthropods do not feed heavily on kudzu, but recent evidence has indicated this is not the case. To better understand the inte raction of kudzu and native insects, the biology of the soybean looper, Pse udoplusia includens (Walker), was compared on kudzu and soybean. Insects fe d. on kudzu had higher mortality, longer development times with supernumera ry molts, and lower pupal weights than those fed on soybean. Rearing for up to three generations on either plant host had an effect on length of devel opment time but did not affect other measured parameters. Foliage consumpti on did not differ between treatments, and nutritional quality of soybean an d kudzu did not differ. The instar at which insects were transferred from a rtificial diet to either kudzu or soybean significantly influenced developm ent time, number of instars, foliage consumption, and pupal weights, with i nstar 4 being the optimum stage for transfer. In an oviposition test, femal es readily oviposited on kudzu in a no choice test, but when both kudzu and . soybean were provided, more eggs were deposited on soybean than on kudzu. Our studies show that although kudzu is an acceptable host, soybean is a p referred and better quality host.