Predators of Mesoplatys ochroptera in sesbania planted-fallows in eastern Zambia

Mesoplatys ochroptera Stal (Coleoptera: Chrysomelidae) is a serious pest of the tropical legume sesbania (Sesbania sesban (L.) Merrill) widely used fo r soil fertility improvement in southern Africa. Surveys were conducted bet ween October 1997 and June 1999 in order to identify the predators of M. oc hroptera in sesbania fallows in eastern Zambia. The Heteroptera Afrius yolo fa (Guerin-Meneville), Glypsus conspicuus (Westwood), Macrorhaphis acuta Da llas, Mecosoma mensor (Germar), Rhinocoris segmentarius (Germar), and Derae ocoris ostentans (Stal), the carabid beetle Cyaneodinodes fasciger (Chaudoi r), the ants Tetramorium sericeiventre Emery and Pheidole sp., and the lace wing Mallada sp. were recorded as predators of M. ochroptera for the first time. The pentatomid bugs G. conspicuus, M. acuta and M. mensor were the mo st common predators in sesbania fallows. Adults and the different nymphal s tages of the three species preyed on larvae, adults and occasionally on egg s of the beetle. In the insectary, the adults of G. conspicuus, M. acuta an d M. mensor consumed a significantly higher number of larvae (p < 0.001) co mpared to adults of M. ochroptera under both free-choice and no-choice cond itions. The voracity of the three species showed a positive response to pre y density. The fifth instar nymphs showed variation in daily consumption of larvae, the highest number of prey being consumed two to three days after the fourth molt. These predators also attacked other pests associated with sesbania and crop plants. The potential role of the predators in the natura l control of pests in agroforestry systems is discussed, with a review of t heir prey species.