DEVELOPMENT AND LIFE TABLE OF OLLA-V-NIGRUM [COL, COCCINELLIDAE], A NATURAL ENEMY OF HETEROPSYLLA-CUBANA [HOM, PSYLLIDAE] INTRODUCED IN NEW-CALEDONIA

The psyllid Heteropsylla cubana Crawford, a pest on Leucaena leucocephala (Lam.) de Wit (Leguminosae), invaded New Caledonia in October 1985. The lady-bird Olla nu-nigrum (Mulsant) was introduced from Tahiti in early 1987 to control the pest, and its biology was studied in control conditions. At 25,7-degrees-C (24,6/26,8) the median for the duration of the development from egg to adult is 16,5 days. At 25,8-degrees-C (25/26,6), using the hatching rate observed on wild female egg batches, the net reproductive rate R0 = 201,4, the innate capacity for increase r(m) = 0,165, the mean length of a generation T = 32,2 days. The observed rate of egg hatching decreased during the life of females in the cohort, resulting in lower values: R0 = 153,9, r(m) = 0,160, T = 31,4 days. When compared to other preys, these values indicate that H. cubana is highly suitable as a prey for O. nu-nigrum, though it is toxic for most polyphagous predators. By July 1989, O. nu-nigrum was present in most parts of New Caledonia.