Comparative evaluation of development and reproductive capacity of two biotypes of Lilioceris cheni (Coleoptera: Chrysomelidae), biological control agents of air potato (Dioscorea bulbifera) in Florida.
A Chinese biotype of Lilioceris cheni Gressitt and Kimoto (Coleoptera: Chrysomelidae) is being mass reared and released in Florida for biological control of the invasive air potato vine, Dioscorea bulbifera L. (Dioscoreales). Another biotype from Nepal is under investigation for determining whether its release would benefit the ongoing biological control program. We compared temperature-dependent development, fecundity, life table parameters, and consumption of the two biotypes in the laboratory. Both biotypes completed development at 20-30°C, although survival of Chinese beetles was higher at 20°C and 27.5°C, and survival of Nepalese beetles was higher at 30°C. In addition, Nepalese beetles developed at a faster rate at 20°C, and consumed air potato foliage at a higher rate at 25°C. The most important difference between the biotypes, with regard to biological control purposes, was the shorter generation time of Nepalese beetles, which resulted in a higher intrinsic rate of population increase, despite much higher fecundity of Chinese beetles. The higher intrinsic rate of increase of the Nepalese beetles may allow a more rapid population increase in the field, and thus, greater damage to air potato plants. However, differences in other life history traits, such as overwintering ability, diapause, and cold tolerance, will also influence field performance.