Development of semiochemical attractants for monitoring bean seed beetle, Bruchus rufimanus.

Background: Bruchus rufimanus is a serious pest of field beans. The objective here was to develop a semiochemical-baited trapping system to facilitate monitoring of the pest.

Results: Volatile compounds that were electrophysiologically active with the antennae of B. rufimanus females were identified from headspace samples of Vicia faba flowers and from male B. rufimanus. Selected headspace samples and synthetic compounds were tested in olfactometer bioassays. The semiochemicals were then formulated in lures for traps and evaluated in a field trapping experiment. Cone traps baited with a three-component blend of floral volatiles, releasing (R)-linalool (17.7 mg day(-1)), cinnamyl alcohol (0.4 mg day(-1)) and cinnamaldehyde (0.77 mg day(-1)), caught significantly more of both sexes of B. rufimanus than unbaited control traps. A male volatile, 1-undecene, was EAG active with female antennae. It was attractive to females in an olfactometer, indicating that it is a sex pheromone. However, in the field it only enhanced trap catches if it was released together with the floral volatiles.

Conclusion: The blends of semiochemicals identified were shown to be attractive in cone traps under field conditions. The prototype trapping system developed could be used as a monitoring tool to determine infestation levels of B. rufimanus in bean fields.