The effect of flower colour and glucosinolates on the interaction between oilseed rape and pollen beetles

Abstract

Pollen beetles (Meligethes aeneus) are important pests on Brassica oilseed crops and herbivores of wild crucifer populations. The adults feed on flowers and unopened buds in which they oviposit. The larvae feed mainly on pollen, but all parts of the flower may be destroyed. Adult pollen beetles will also feed on non-cruciferous taxa, in contrast to the majority of herbivorous insects on Brassica, which are specialist feeders on crucifers. Many of the specialist insects have been shown to be attracted by glucosinolates and their hydrolytic products. These metabolites also act as ovipositioning and feeding stimulants. Polyphagous non-insect herbivores such as molluscs and pigeons are deterred by glucosinolates (Giamoustaris & Mithen, 1995). Flower colour has been shown to be important in attracting pollinators to crucifers (Kay, 1976). It is not known whether variation in flower colour may also affect plant attractiveness to herbivorous insects.