Biological control of the lily leaf beetle, Lilioceris lilii in North America
The lily leaf beetle, Lilioceris lilii (Scopoli), first officially reported in the U.S. in 1992, has become a serious pest of native and cultivated lilies throughout its North American distribution. With no effective North American natural enemies, this exotic insect poses a potential economic threat to horticulturists and an environmental threat to native lilies. This study presents the results of an ongoing classical biological control program initiated against L. lilii in North America. Based on its Eurasian geographic distribution, L. lilii seems capable of spreading throughout much of North America. In Europe, the lily leaf beetle is well known but is not considered a problem. We traveled to Europe where we discovered L. lilii to be under good natural control by six species of parasitoids: five wasps and a fly. Of these, four larval parasitoids were identified as potential candidates for introduction to the United States: Tetrastichus setifer Thomson (Hym: Eulophidae), Lemophagus pulcher Szepligeti (Hym: Ichneumonidae), L. errabundus Gravenhorst, and Diaparsis jucunda (Holmgren) (Hym: Ichneumonidae). We collected parasitized larvae throughout Europe from 1998–2002. The larvae were shipped to the University of Rhode Island quarantine facility for use in laboratory studies to evaluate host range and host preferences. Lemophagus errabundus, D. jucunda and T. setifer were found to have the requisite degree of host specificity needed for release in North America. We selected T. setifer as the first parasitoid to release, based its effectiveness in Europe, where it demonstrates high parasitism rates and wide climatic range. Three release and two control sites were established and T. setifer was released from 1999–2002. We sampled all plots to detect parasitism and overwintering and to evaluate phenology. Tetrastichus setifer was recovered in the weeks immediately following release, but overwinter survival was not detected until 2002. Tetrastichus setifer is established in two sites and showed high rates of parasitism in these plots in 2003.
Marion Secrest Gold,
"Biological control of the lily leaf beetle, Lilioceris lilii in North America"
Dissertations and Master's Theses (Campus Access).