Will biological control agents of Lilioceris lilii, lily leaf beetle, parasitize congeneric weed biological control agents for air potato?

Authors: Lake, Ellen; TEWKSBURY, LISA - University Of Rhode Island; Smith, Melissa; Dray, F Allen; Rayamajhi, Min; CASAGRANDE, DICK - University Of Rhode Island

Submitted to: Entomological Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2018
Publication Date: N/A
Citation: N/A

Interpretive Summary: Biotic resistance in the form of attack by predators or parasitoids may prevent the establishment of a weed biological control agent or reduce its efficacy. We investigated the potential for biological control agents of the pest insect lily leaf beetle, Lilioceris lilii Scopoli (Coleoptera: Chrysomelidae), to impact closely related weed biological control agents. Lily leaf beetle was introduced to North America in 1945. This Eurasian insect is a pest of cultivated and native lilies and Fritillaria spp. Three parasitoid species have been released for control of L. lilii in the USA since 1998: Tetrastichus setifer Thomson (Hymenoptera: Eulophidae), and Lemophagus errabundus Gravenhorst and Diaparsis jucunda (Holmgren) (Hymenoptera: Ichneumonidae). Releases of L. cheni Gressitt & Kimoto, a biological control agent of the invasive weed air potato, Dioscorea bulbifera L. (Dioscoreaceae), began in Florida, USA in 2011. The L. lilii parasitoids can attack a few Lilioceris species in their native range. Although the ranges of these beetles and the parasitoids do not yet overlap in the U.S., all are undergoing range expansion. Our objectives were to determine if parasitoids of L. lilii could successfully parasitize L. cheni, and, if so, to design a strategy to decrease the impact of the parasitoids on L. cheni. We conducted no choice and choice tests with the three parasitoid species and larvae of the two Lilioceris species. In no choice tests, up to 17.5% of L. lilii larvae were parasitized, with successful attack by all three species, but no L. cheni larvae were parasitized by any of the parasitoid species. In choice tests, parasitoids attempted to oviposit in up to 53.3% of L. lilii larvae but no L. cheni larvae. These results suggest that the parasitoids for L. lilii will not pose a risk to the effective air potato biological control agent L. cheni if range overlap occurs in the future. Similar tests are underway with the parasitoids and L. egena (Weise), which is under consideration for release as an additional biological control agent of air potato.

Technical Abstract: Biotic resistance may prevent the establishment of a weed biological control agent or reduce its efficacy. We investigated the potential for biological control agents of Lilioceris lilii Scopoli (Coleoptera: Chrysomelidae) to impact congeneric weed biological control agents. The Eurasian insect L. lilii, lily leaf beetle, was introduced to North America in 1945, where it is a pest of cultivated and native lilies and Fritillaria spp. Three parasitoid species have been released for control of L. lilii in the USA since 1998: Tetrastichus setifer Thomson (Hymenoptera: Eulophidae), and Lemophagus errabundus Gravenhorst and Diaparsis jucunda (Holmgren) (Hymenoptera: Ichneumonidae). Releases of L. cheni Gressitt & Kimoto, a biological control agent of the invasive weed air potato, Dioscorea bulbifera L. (Dioscoreaceae), began in Florida, USA in 2011. Our objective was to determine if parasitoids of L. lilii could successfully parasitize L. cheni if their expanding ranges overlap in the future. In no choice tests, up to 17.5% of L. lilii larvae were parasitized, with successful attack by all three species, but no L. cheni larvae were parasitized by any parasitoid species. In choice tests, parasitoids attempted to oviposit in up to 53.3% of L. lilii larvae but no L. cheni larvae. These results suggest that L. lilii parasitoids will not pose a risk to the effective air potato biological control agent L. cheni should range overlap occur. Similar tests will be conducted with the parasitoids and L. egena (Weise), which is under consideration for release as an additional air potato biological control agent.