Can sulfur fertilisation improve the effectiveness of trap crops for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae)?

BACKGROUND: The effect of sulfur fertilisation on chemical constituents of yellow rocket, Barbarea vulgaris (R. Br.), was studied with regard to its potential use as a trap crop for the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Two types of B. vulgaris var. arcuata were used: the G‐type, resistant to P. xylostella and proposed as a ‘dead‐end’ trap crop, and the P‐type, not resistant to P. xylostella and used as a control. RESULTS: In G‐type B. vulgaris , sulfur fertilisation increased the content of the dominant glucosinolate ( S )‐2‐hydroxy‐2‐phenylethylglucosinolate by 20%. Sulfur fertilisation did not significantly change levels of the saponins 3‐ 0 ‐β‐cellobiosylhederagenin and 3‐ 0 ‐β‐cellobiosyloleanolic acid, known to act as feeding deterrents for P. xylostella larvae. In P‐type B. vulgaris , the same levels of sulfur fertilisation did not change the glucosinolate content significantly. Two‐choice oviposition preference tests with B. vulgaris plants showed that P. xylostella laid 144% and 45% more eggs on G‐ and P‐type plants with sulfur fertilisation respectively. CONCLUSIONS: The studies suggest that sulfur fertilisation could increase the effectiveness of G‐type B. vulgaris as a trap crop for P. xylostella . The effect of plant sulfur fertilisation on P. xylostella oviposition preference is associated with a quantitative glucosinolate increase, but other compounds could also be involved. Copyright © 2010 Society of Chemical Industry