Ma l e - spe c i f i c compounds, previously identified from Phyllotreta
cruciferae and synthesized or isolated from natural sources, attracted both
sexes of the beetle in field trials and therefore function as components of a
male-produced aggregation pheromone. Six field experiments of 7 to 10 d
duration each were conducted over 2 yr using modified boll weevil traps and
two doses of pheromone. Treatments containing two doses of allyl
isothiocyanate (AITC), a breakdown product of glucosinolates in Brassica
napus L., a host plant of the beetles, were included in the study. A dose
response was observed for both the pheromone components and AlTC, and
combinations of the pheromone and AlTC generally attracted greater numbers
of flea beetles than did either component itself. This increased attraction to a
combination of beetle-produced compounds and host odors has not been
previously demonstrated in halticine beetles and could help explain patterns of
movement by P. cruciferae into field crops