Distiphallus Morphology and its Role in Copulation Dynamics in Anastrepha Suspensa (Loew)

Abstract

Anastrepha suspensa (Diptera; Tephritidae) is an agricultural pest species causing severe economic damage and is controlled, in part, by applying knowledge of this species' reproduction (e.g., disrupting fertile copulations by SIT). During copulation, males transfer sperm as well as protein rich fluids through an aedeagus and distiphallus, which females then store in three spermathecae and one ventral receptacle. Within the female reproductive tract, the ventral receptacle and the three spermathecae are strategically separated from each other. I hypothesized males' ability to direct sperm transfer within the female reproductive tract is through the structures found in the distiphallus. Utilizing scanning electron microscopy, fluorescent light microscopy and light microscopy, coupled pairs were dissected and their genitalic positions relative to each other's structures,specifically the position of the distiphallus during copulation, was deduced. Bifurcation of the sperm ducts within the distiphallus were observed, suggesting males possess the ability to direct sperm toward the sperm storing structures. Changes in female intergenitalic distances was found to correspond to findings on female sperm storage previously reported. However, through analysis of the distiphallus position during copulation, the ability for females to control the length of their reproductive tract was discovered, which suggests that a thorough and detailed understanding of the morphology of the male genitalia in relation to the morphology of the female reproductive tract may illuminate the important role of co-evolution between the sexes.

Date of Award	2018
Original language	American English
Awarding Institution	Eastern Illinois University
Supervisor	Ann H. Fritz (Supervisor)