The potential of classical biological control against leucaena psylid, heteropsylla cubana crawford in eastern Tanzania

Tanzania Journal of Agricultural Sciences 2000, Vol 3(2): 113 -122The Leucaena psyllid HeteropsyHa cubana Crawford (Homoptera: Psyl/idae) has ~aused damaging ef fects to Leucaena leucocephala (Lam.) de Wit in Tanzania since its outbreak in 1992. Cultural, genetic and chemical controls havebel!n tried in some localised areas. In 1995, a hymenopterous parasitoids, Tamarixia leucaenae Boucek (Eupelmidae) was imported from Trinidad and Tobago for biological control of this pest in Tanga and Morogoro areas. Mummies of the parasitoid were recordedfrom the sixth week after release. The population declined to the lowest level between November 1995 and January 1996 before building-up again to about 10 and 11 mummies per shoot in July for Tanga and Morogogro respectively. Spread of the parasitoidwas fairly fast, and at about 16 months afterrelease it had covered over 300 Ian from the release sites. The spread and population build up indicates that this species has been established in Eastern Tanzania. In spite of declining shoot damage at about ten months after parasitoid release, it is probably too early to associate it with the parasitoid. Shoot damage was found to be more closely correlated to laboratory nymph count (r = 0.52) than to field nymph shoot numbers (r =\0.35). Several potential indigenous natural enemies were recorded in association with the psy/lid; however, their role as biological control agents needs further quantification