Abstract: Six cultivars (two F1 hybrids, two open-pollinated and two landrace) of Brussels Sprout were grown in pots in four different types of compost containing different levels of fertilisers. The plants were infested with known numbers of the immature stages of pest insects in three separate experiments (Brevicoryne brassicae, Plutella xylostella, Delia radicum respectively) to determine their suitability as host plants. The results indicated that the landrace cultivars were the least suitable hosts for Brevicoryne brassicae and Delia radicum but fertiliser treatment appeared to have little effect on these species. In contrast, numbers of Plutella xylostella were associated with fertiliser treatment but there was no differential effect of cultivar. Most Plutella xylostella were recovered from plants grown in the compost with no added fertiliser. There were no statistically-significant cultivar x fertiliser interactions.