Venom apparatus of the endoparasitoid wasp Opius caricivorae Fischer (Hymenoptera: Braconidae): morphology and ultrastructure.

The morphology and ultrastructure of the venom apparatus of the endoparasitoid wasp, Opius caricivorae Fischer (Hymenoptera: Braconidae), were observed using light and electron microscopes. The venom apparatus consists of one venom reservoir and several gland filaments. The gland filaments join together at the end of the reservoir and consist of an outer single layer of secretory cells, a layer of degenerated epidermal cells, and an inner intima that encloses the lumen. The secretory cells are organelle rich, with abundant rough endoplasmic reticulum, mitochondria, and vacuole, in which vesicular organelles secrete the components of venom. The reservoir consists of a muscular sheath, secretory cells, and squamous cells. The intima has an unevenly thickened chitinous coat. The vesicular organelles of the reservoir secretory cells differ from those of the gland filament: the microvilli being much longer and radiating in all directions. The venom reservoir not only serves to store but also secretes the venom. Virus-like particles were discovered in the secretory cells of the gland filaments. The structural features of venom apparatus of this species are discussed in a biological context.