COS 96-6
Biological control of Dioscorea bulbifera, air potato, by Lilioceris cheni (Coleoptera: Chrysomelidae): the role of two biotypes
Air potato, Dioscorea bulbifera L., (Liliales: Dioscoreaceae) is an invasive herbaceous vine. It does not produce fertile flowers in the U.S. and instead reproduces via aerial bulbils, vegetative propagules that form in the leaf axils and dehisce as this deciduous plant senesces in the fall. Bulbils and persistent subterranean tubers produce new spring vines. Air potato vines can grow more than 20 m long and outcompete native vegetation. The range of D. bulbifera extends throughout Florida and into the southeastern U.S., plus Hawaii.
Lilioceris cheni Gressitt & Kimoto (Coleoptera: Chrysomelidae) is an Asian beetle that feeds voraciously on air potato leaves. The beetle is host-specific to D. bulbifera and was approved for release as a biological control agent in 2011. Two biotypes of the beetle are available for release, one from Nepal the other from China. Studies are underway in environmental chambers set to different temperatures and day lengths to evaluate potential differences in life history traits and diapause behavior of the two biotypes. The overwintering ability of the two biotypes is being assessed within field cages replicated in three plant hardiness zones across Florida.
Results/Conclusions
Eggs of the Chinese biotype of L. cheni did not eclose at 10 or 15°C. Females of the Chinese biotype entered diapause at 20°C and short days (10L:14D) but were reproductive at 20°C under long days (14L:10D) and at 25°C under both light regimes. Oviposition by both biotypes ceased in field cages by the end of November 2013. Fewer adults were present in field cages in Tallahassee compared to Fort Pierce or Homestead in December 2013, but beetles were active in the cages in all three sites in January 2014. The results of these studies will guide the design of the most effective release strategy for the two biotypes of L. cheni throughout the range of D. bulbifera.