Prothoracicotropic hormone
Prothoracicotropic hormone (PTTH) was the first insect hormone to be discovered. It was originally described simply as "brain hormone" by early workers such as Stefan Kopeć (1922) and Vincent Wigglesworth (1934), who realized that ligation of the head of immature insects could prevent molting or pupation of the body region excluded from the head if the ligation was performed before a critical age in the lifestage was reached. After a certain point the ligation had no effect and both sections of the insect would molt or pupate. However, implantation of a conspecific brain to a sessile ligated abdomen or an abdomen under diapause would induce molting or pupation. Thus, the brain was originally thought to be the source of the hormone that induces molting in insects.
Josephine Ball
Ball’s research on the role of hormones and behavior was some of the earliest in the field, contemporaneous with work of Willam Caldwell (W.C) Young and preceding the work of Frank A. Beach, both of whom were considered founders of the field of behavioral neuroendocrinology. Ball's first paper in 1926 represented the earliest work on the role of steroid hormones on non-sexual behaviors, in this case learning and memory in rats. Her work on the role of hormones and reproductive behavior in both rats and macaques throughout the 1930's and early 1940's constituted fundamental contributions to the field. Beach once commented at a meeting that if a conference on reproductive behavior had been held in the 1930’s, it would have three participants: W.C. Young, Josephine Ball, and himself. Beach also considered Ball a friend.