The lily beetle (Lilioceris lilii, Coleoptera: Chrysomelidae) has a univoltine life cycle and
a limited host range (Lilium, Fritillaria and Cardiocrinum). A survey of 237 professional
growers indicates that L. lilii is a problem for many in the UK lily industry.
A three-year field trial using six different Lilium indicated that the species Lilium
regale is more resistant to L. lilii than the hybrids L. ‘Tiber’, L. ‘Brindisi’, L. ‘Conca d’Or’,
L. ‘Eliganzer’ and L. ‘Golden Joy’. Phenology observations between the trial and an
established population of the beetle have provided base-line data to which further
observations can be compared. Future host susceptibility trials should use a standard
lily such as L. regale against which others can be compared.
Behavioural bioassays using a linear-track olfactometer demonstrated that the
responses of L. lilii to hosts and conspecifics are at least in part odour-mediated.
Significantly more diapaused females moved into airstreams containing the odour of
intact hosts over clean air, to that of hosts and beetles combined over that of
undamaged or manually-damaged plants, and into airstreams from intact plants over
larval-infested plants. Pre-diapause males moved into the airstreams of intact hosts in
preference to L. lilii-infested plants.
Using air entrainment, gas chromatography (GC) and coupled gas
chromatography-mass spectrometry (GC-MS), headspace volatiles from beetleinfested
host plants have been collected and identified. From these compounds, methyl
salicylate, nonanal, cis-jasmone, linalool, 6-methyl-5-hepten-2-one and β-pinene
elicited electrophysiological responses from L. lilii using electroantennography (EAG)
and coupled GC-EAG. Bioassays indicate that diapaused female beetles move into the
airstream of clean air in preference to cis-jasmone.
Investigations from all areas of the project have progressed our understanding
of the ecology of L. lilii but further studies are needed before more effective control
strategies can be developed
