Effect of seasonal augmentation of Leptomastix dactylopii How. on Planococcus citri (Risso) population.
Releases of Leptomastix dactylopii were made in 1991 and 1992 in a coffee plantation in Karnataka, India, following infestations by Planococcus citri. A total of about 9750 adults of the parasitoid were released in 6 batches in January-March,1991, and March-April, 1992. Parasitized pests were recorded about 30 days after the first release. In 1991, parasitism increased to a maximum of 52.03% by June and in 1992, to a maximum of 22.22% by July. Before the releases, in January 1991, the population of P. citri was 4.44 healthy individuals/node. This decreased to 0.59 healthy and 0.64 parasitized individuals/node by June. In March 1992, 3.78% of pests were parasitised, indicating that a small population of the parasitoid had persisted. The numbers of healthy and parasitised P. citri fell from 13.22 and 2.17 individuals/node, resp., in April 1992 to 0.25 and 0.07 individuals/node, resp. in July 1992. It is concluded that L. dactylopii can reduce a population of P. citri if it is released when the pest population is small and if augmentative releases are subsequently used.