Phenological synchrony between a weed (Dioscorea bulbifera) and a biocontrol agent (Lilioceris cheni) in the introduced range, Florida: implications for biological control

ABSTRACT

Dioscorea bulbifera has invaded, smothered, and disrupted ecological functions of native plant communities in Florida. Vines senesce in late fall, then overwinter as tubers and aerial bulbils which sprout in spring and repeat the growth cycle. A foliage-feeding beetle Lilioceris cheni, introduced from Asia as a biocontrol agent has established throughout D. bulbifera's range in Florida. Synchronies among the growth phenology of the weed, life stages of biocontrol agents and weather conditions, are considered essential for the successful suppression of an introduced weed. We conducted a common garden study that encompassed pre-biocontrol release attributes of D. bulbifera followed by a 5-yr post-L. cheni release impacts study on its natural infestations in four sites. We gathered monthly data on D. bulbifera and L. cheni and assessed possible synchronies between their life stages and with local weather variables. Air and soil temperatures and total rainfall showed positive correlation with timing of D. bulbifera vine emergence/senescence, vine coverage, adult beetle emergence from diapause, and their life stages (egg clutches, larvae, and adults). Vine sprouting and beetle emergence in two southern sites began in February and April, and in the remaining two northern sites in March and May, respectively. Vine sprouting and beetle emergence was initiated at 15 and 20°C, respectively. All sites achieved maximum vine coverage in July. Bulbil development, oviposition by overwintering adults, and vine damage by adult and larval feeding began in June. These sequences of events indicated phenological synchrony of the beetle and air potato life stages in Florida.

KEYWORDS:

• Air potato
• weed phenology
• herbivore life-stages
• weed biocontrol
• weed-herbivore synchrony
• weed-insect-abiotic environment

Acknowledgements

Authors thank county parks (Alachua, Broward, and Miami Dade), Terra Ciea Preserve State Park (Manatee County), for providing research sites. Also, thanks are extended to Reynaldo Moscat, Jorge Cedeno, Ryan Poffenberger, Molly Clark, Ken Hibbard, Beth Curry and many interns from Broward College for technical assistance in the laboratory and field. Mention of the trade names or commercial products in this article is solely for the purpose of providing information and does not imply any recommendation or endorsement by the U.S. Depart of Agriculture. USDA Department of Agriculture is an equal opportunity employer.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded by the United States Department of Agriculture. Partial support for this research was provided by the Comprehensive Everglades Restoration Project (CERP).