ABSTRACT
Cultivated aloes are more susceptible to arthropod pests than those growing in their natural habitats. The main arthropod pests include mealy bugs, scales, beetles, mites and aphids. When grown under glass the dominant pests are mealy bugs, scales, aphids and thrips. A survey of aloes growing at the Royal Botanic Gardens, Kew, showed that the susceptibility of different species of Aloe to these pests varied. Aloe ferox and A. marlothii were the most susceptible species. The role of aloe-derived compounds in aloe-insect interactions is not known. Although
many compounds, especially phenolics, have been isolated from aloes their potential ecological role has not been studied. Extracts from aloes can stimulate Locusta migratoria and Spodoptera littoralis to feed. This suggests that the extracts contain compounds that could act as phagostimulants. One of the compounds, a dihydroisocoumarin glucoside isolated from A. hildebrandtii, did not significantly influence the feeding behaviour of Spodoptera littoralis, although it was a potent anti-feedant against Pieris brassicae. and Plutella xylostella. Some aloe extracts also deterred S. littoralis from feeding. A comparison of the compounds in the aloes that vary in their susceptibility to insect herbivory might provide an insight into the role these compounds have in the ecology of aloes.
