The potential of classical biological control against Leucaena Psyllid, Heteropsylla cubana Crawford in eastern Tanzania

Abstract

The Leucaena psyllid Heteropsylla cubana Crawford (Homoptera: Psyllidae) has caused damaging effects to Leucaena leucocephala (Lam.) de Wit in Tanzania since its outbreak in 1992. Cultural, genetic and chemical controls have been 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 recorded from 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 parasitoid was fairly fast, and at about 16 months after release it had covered over 300 km 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 psyllid; however, their role as biological control agents needs further quantification.

Keywords: Leucaena leucocephala, Tamarixia Leucaenae, Biological Control

Tanzania J. Agric. Sc. (2000) Vol 3. No. 2, 113 -122