No abstract

No abstract

The cabbage stem flea beetle, Psylliodes chrysocephala L. is a major pest of winter oilseed rape in several European countries. Traditionally, neonicotinoid and pyrethroid insecticides have been widely used for control of P. chrysocephala , but in recent years, following the withdrawal of neonicotinoid insecticide seed treatments, control failures have occurred due to an over reliance on pyrethroids. In line with previous surveys, UK populations of P. chrysocephala were found to exhibit high levels of resistance to the pyrethroid lambda-cyhalothrin. This resistance was suppressed by pre-treatment with the cytochrome P450 inhibitor PBO under laboratory conditions, suggesting that the resistance has a strong metabolic component. The L1014F (kdr) mutation in the voltage-gated sodium channel, which confers relatively low levels (10–20 fold) of resistance to pyrethroids, was also found to be widespread across the UK regions sampled, whereas the L925I (s-kdr) mutation was much less common. The current survey also suggests that higher levels of pyrethroid resistance have spread to the North and West of England, and that resistance levels continue to remain high in the South East.

No abstract

Sweet basil (Ocimum basilicum L.) plants at the three-leaf-pair growth stage were grown in controlled environment rooms at 15 and 25• C for 2 weeks. Analysis of volatiles from blended leaves by gas chromatography/mass spectrometry showed that the plants grown at 25• C contained significantly more volatile oils than those grown at 15• C. The total volatile oil content in fresh leaves was enhanced by 70%. Temperature also affected the composition of volatile oils. At 25• C there was an accumulation of eugenol, which contributes to the characteristic taste of basil. Although there was no effect on the relative contents of linalool and 1,8-cineole, the absolute contents in fresh leaves were significantly different. Sensory analysis showed that 18 out of 21 trained sensory panellists perceived different intensities of volatile oils in fresh basil leaves from the two sources of plants. In addition, a simple consumer preference test conducted with basil users showed a significant preference for the stronger intensity (41 out of 64 consumers).