Ultrastructure of the haemocytes of tobacco armyworm Spodoptera litura Fab. (Lepidoptera : Noctuidae)

Ultrastructural and histochemical studies revealed the presence of five typ es of haemocytes in the last instar larvae of Spodoptera litura Fab., namel y the prohaemocytes (PRs), plasmatocytes(PLs), granular haemocytes(GRs), sp herulocytes(SPs), and oenocytoids(OEs). The prohaemocytes were found to be the smallest of all the haemocyte types, having a high nucleo-cytoplasmic r atio. The plasmatocytes were polymorphic in shape and their nucleus was eit her lobed or oval. The granular haemocytes were characterized by two types of electron dense granules i.e, structureless, uniformly dense bodies and m embrane-bound structured granules having compactly arranged microtubules. T he spherulocytes were characterized by the presence of large-sized cytoplas mic spherules, generally obscuring the nucleus. The oenocytoids revealed ce rtain alternating and parallel hyaline and dark areas in their cytoplasm an d only this haemocyte type reacted positive to dihydroxy phenyl alanine (DO PA).