Female reproductive system morphology and the development of a physiological age-grading system for bagrada hilaris (Hemiptera: Pentatomidae)

Abstract

In this paper, we describe the morphology of the female Bagrada hilaris (Burmeister) reproductive system and develop a physiological age-grading system related to egg production. The female reproductive system is composed of two meroistic and telotrophic ovaries each containing 5-6 tubular ovarioles. The ovarioles unite into the lateral oviduct which combine to form the common oviduct. The ovarioles are composed of two regions; the distal germarium and the tubular vitellarium which contains maturing follicles. Each follicle is surrounded by a layer of cells; the follicular epithelium. As the follicle passes from the ovariole to the lateral oviducts the follicular epithelial cells slough off and accumulate in the base of the ovarioles and are known as follicular relics. The continuum of ovarian development is divided into two categories: nulliparous ('nonreproducing') and parous ('reproducing'). The nulliparous category is characterized by the absence of follicular relics or eggs in the oviducts as opposed to the parous category where follicular relics and, in many cases, eggs occurred in the oviducts. The nulliparous category is divided further into two stages; N1 and N2 based on ovariole differentiation. The parous category is divided into three stages; P1, P2, and P3, based on the quantity and appearance of follicular relics. Females characterized as P3 produced three times more eggs (79.2 eggs ± 5.7) than females characterized as P1 (27.1 eggs ± 6.0).