Effect of superparasitism of Microplitis rufiventris parasitoid on the total and differential haemocyte counts of its host, Spodoptera littoralis

摘要

Superparasitism of Spodoptera littoralis by the braconid Microplitis rufiventris resulted in a reduction in the total haemocyte count (THC) and was attributed to the incorporation of some haemocytes within the cellular capsule formed around supernumerary larvae involved in physical attack (losers) in addition to feeding by parasitoid larvae (winner) on haemocytes. In either singly (control) or superparasitized host larvae, the THCs on the last day of parasitoid development or after parasitoid egression were substantially reduced and were significantly lower compared to those which had been parasitized earlier. From changes in differential haemocyte counts of superparasitized host larvae, the abnormal increase in granular cells (GRs) was due to thetransformation of prohaemocytes into GRs. The degree of superparasitism seemed to have had no effect on the plasmatocyte population. Changes in GRs in either singly or superparasitized host larvae seemed to be due to some factors released from parasitoid eggs.