Egg morphology and hatching in Mormidea pictiventris (Hemiptera: Pentatomidae)

Abstract

Egg morphology and hatching in the stink bug Mormidea pictiventris (Hemiptera: Pentatomidae) are described with the aid of scanning electron microscopy. In addition, the eggshell is analyzed using transmission electron microscopy and the distribution of follicle cells at the surface of ovarian eggs is studied by epifluorescence microscopy using a DNA-specific fluorescent dye. The surface of the barrel-shaped eggs carries numerous slender processes. Binucleate follicle cells, in most cases arranged in a hexagonal pattern, are responsible for the synthesis of this portion of the eggshell. The rim at the anterior pole of the egg is studded at irregular intervals with short columnar processes, the aero-micropylar processes. Hatching occurs at this pole. The prolarva is wrapped in an embryonic cuticle. Its head portion carries a Y-shaped element, the egg-burster. The major features of the inner face of the eggshell are subtle, radially oriented grooves at the anterior plate and a hexagonal pattern to the surface ornamentation throughout the remainder of the eggshell. Transmission electron microscopy revealed that the processes extending from the surface of the eggshell have a coarse texture, while the eggshell proper is composed of amorphous material. The innermost layer, however, has a trabecular organization. The findings in M. pictiventris are compared with morphological observations on the eggshell in other families of Hemiptera and suggestions are made concerning the meaning of the diverse structures.