THE EFFECT OF SOME INVERTEBRATE SPECIES ON THE GROWTH OF WHITE CLOVER (TRIFOLIUM-REPENS L) IN THE LABORATORY

In laboratory experiments to clarify earlier field observations, Sitona lepidus larvae caused significant damage to established clover plants at infestations of approximately 1.2 per plant. When eggs were placed on the soil, cultivars of differing cyanogenic capacity were damaged equally. The plants did not recover when larval feeding ended. Leatherjackets, slugs and ''lucerne flea'' [Sminthurus viridis] fed most on the least cyanogenic cultivars, even where no choice was offered. Plants ultimately recovered from damage by leatherjackets. Deroceras reticulatum caused more damage than did Arion fasciatus. The proportion of leaves damaged by lucerne flea was highest in the least cyanogenic cultivar but also tended to increase in the most cyanogenic cultivar, confirming a field observation, At high population densities lucerne flea was capable of killing some seedlings but was not tested against established plants.