Abstract

Fundamental and applied studies have been initiated in order to understand the role(s) of flower volatiles in host finding and recognition by adults of Byturus tomentosus. Behavioural assays using a linear track olfactometer showed that females clearly prefer host (raspberry (Rubus idaeus), hawthorn (Crataegus monogyna)) to non-host (oilseed rape (Brassica napus)) flower volatiles. They also preferred the flower volatiles of susceptible red raspberry cv. Glen Prosen to those emitted from flowers of the highly resistant related species, R. phoenicolasius. The phenological stage of the developing raspberry flower also influenced the characteristic volatile profile and appeared to convey additional information to the females when searching for feeding and oviposition sites. Chemical investigations of entrained flower volatiles or ether extracts indicated that >100 chemical compounds are emitted, with profiles characteristic of the plant species and its phenological stage. Electrophysiological techniques using electroantennogram and single cell recordings are being applied to 'shortlist' active chemicals from these complex profiles for behaviour testing. Recent results using olfactometers and a wind tunnel indicate that B. tomentosus uses several flower compounds, in specific ratios, to identify suitable hosts for feeding and oviposition. Several of the main flower volatile components involved in host recognition by B. tomentosus were identified and this information is being used to target breeding for the development of resistant Rubus genotypes and to design more effective field traps for monitoring beetle activity.