Visual assessment of morphological changes in female reproductive system of Bactrocera dorsalis (Hendel) (Diptera: Tephritidae)

Abstract

Reliable methods are needed to ascertain sexual maturity of field captured tephritid fruit flies. To provide such a tool for female Oriental fruit flies, this study documented the changes in ovarian development at different age intervals (1, 3, 6, 11, 15, 18, 20, 21, 23, 26, 30, 35, 40, 45, 52, 55 and 78 day old) of Bactrocera dorsalis (Hendel). As fly ages, the differences in morphological characters of female reproductive system were assessed visually and the ovarian maturation process was broadly classified into various developmental stages namely previtellogenesis (stage 1 and 2); vitellogenesis (stage 3 and 4), appearance of mature egg (stage 5) and post-oviposition (stage 6). Based on visual assessment of ovarian characters, from the day 1-6, the flies were in previtellogenic stage; from the day 7-11, the flies were in vitellogenic stage, and from the day 12-15, the flies were in late vitellogenic stage. From the day 15 onwards matured follicles were observed on the terminal end of the fly ovary. At the day 18, presence of opaque mature terminal oocyte (matured egg) was noticed in the flies confirming sexual maturity. This classification based on visual assessment of morphological changes in the ovary would help us determine the age of field collected female B. dorsalis.