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Lily beetle, Lilioceris lilii, host range, Lilium, lilies, risk assessment, chemical ecology, odour-mediated, behaviour.
Red lily beetle has become the lily growers’ nemesis; the adults and larvae can devour a lily (Lilium and Cardiocrinum spp.) or fritillary (Fritillaria spp.) plant in a matter of days. The lily beetle is not native to the UK; it was first noticed at the end of the 19th century, with a handful of short-lived infestations. It was not until 1939 that an established colony was discovered in Surrey. By the late 1950s the beetle had become widespread in Surrey and was also found in Berkshire. By 1990 it was found in Hampshire, Middlesex, Wiltshire, Dorset, Hertfordshire and Oxfordshire and by the end of 2005 had been found in almost every English county. In 2002 the beetle was reported from Glasgow and Belfast. Continued reports to the RHS indicate that the beetle is established and spreading in Scotland and Northern Ireland. During the past decade it has been consistently one of the top ten pest problems reported to the RHS Members’ Advisory Service.
The lily beetle was the subject of a three-year PhD research degree project, which was jointly funded by the RHS and the Horticultural Development Council (now Company). The PhD was successfully completed in January 2008. The risk that the beetle poses to the lily growing industry was assessed by surveys of end users (professional and amateur gardeners) and companies supplying lilies. Host range was assessed using a field trial assessing six different lilies (one species and five hybrids). Investigations into the beetle’s odour-mediated behaviour were carried out using a linear track olfactometer in a laboratory.
This PhD research project has provided valuable insights into the lily beetle’s ecology and host range. The project made some progress towards developing improved control measures against the beetle.
The risk assessment surveys found that a quarter of those people who had experienced a problem with the beetle, would reduce or stop growing lilies. It was also established that lilies grown under any regime, including under glass can be susceptible to damage. The primary conclusions were that the lily beetle problem is likely to get worse as it continues to spread throughout Britain. This is likely to result in increased insecticide use. However, despite many end-users of lilies stating they would stop growing lilies, lily suppliers indicated that sales have increased. A summary of the risk assessment was produced in 2007 (Salisbury, 2007). The field trial indicated that the species lily, Lilium regale, was less susceptible than the hybrids. The results of this trial were published in 2010 (Salisbury et al. 2010). Results from the olfactometer experiments indicate that in the spring female beetles are able to locate lilies by odour alone, and that the beetles preferentially move towards the odour of plants already infested with other beetles. Results are due for publication in 2012 (Salisbury et al. 2012).
Salisbury A. 2007. Risk Assessment (258kB pdf): The effect of the Red Lily Beetle, Lilioceris lilii (Scop.) on horticulture in the UK: Results of two surveys of professional horticulturists in the UK. Summary Report, HDC, RHS, Imperial College London and Rothamsted Research. Salisbury A. 2008. Impact, host range and chemical ecology of the lily beetle, Lilioceris lilii. PhD thesis, Imperial College, London. Salisbury A, Clark S J, Powell W, and Hardie, J. 2010. Susceptibility of six Lilium to damage by the lily beetle, Lilioceris lilii (Coleoptera; Chrysomelidae) Annals of Applied Biology 156: 103–110. Salisbury A, Cook, S M, Powell W and Hardie J. 2012. Odour-mediated orientation behaviour of the lily beetle, Lilioceris lilii. Physiological Entomology 37: 97-102 Lily beetle survey and further information on the beetle Read the literature review (520kB pdf) Rothamsted Research Imperial College, London Horticultural Development Company
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