GENETIC ESTIMATES OF DISPERSAL ABILITY IN THE LEUCAENA PSYLLID PREDATOR CURINUS-COERULEUS (COLEOPTERA, COCCINELLIDAE) - IMPLICATIONS FOR BIOLOGICAL-CONTROL

The leucaena psyllid, Heteropsylla cubana Crawford, can devastate plan tings of Leucaena leucocephala (Leguminosae), an economically importan t tree species in the Pacific Islands, Southeast Asia, Australia, Indi a, Africa, and elsewhere. The predatory beetle, Curinus coeruleus Muls ant (Coleoptera: Coccinellidae), has been introduced into many of thes e areas from Hawaii for biological control of the psyllid. In this stu dy, collections of C. coeruleus were made from II populations on four islands in the Hawaiian archipelago to determine population structure and estimate levels of gene flow. Over all populations, a measure of p opulation subdivision, theta, was 0.095, and the estimate of N(e)m, th e average migration rate, was 2.4 theta values for the individual isla nds were 0.02, 0.12, 0.24 and 0.05 for Kauai, Hawaii, Maul, and Oahu, respectively. Estimated levels of gene flow between populations were n ot correlated with geographic distance, therefore isolation by distanc e does not appear to be an important process structuring C. coeruleus populations. Gene flow estimates can be used to characterize dispersal capabilities in insects or other organisms released for biological co ntrol. In this case, the inferior dispersal ability of C. coeruleus li kely limits its rapid widespread establishment during release programm es.