A PHARMACOLOGICAL AND ENDOCRINOLOGIC STUDY OF FEMALE INSEMINATION IN PHORMIA-REGINA (DIPTERA, CALLIPHORIDAE)

Injections of octopamine, dopamine, and the octopaminergic agonists, c lonidine and naphazoline, into the thoracic hemocoel enhanced female i nsemination in sugar-fed (sexually unreceptive) Phormia regina. Topica l applications of the juvenile hormone (JH) analogue, methoprene, also enhanced female insemination in sugar-fed (sexually unreceptive) P. r egina. Since JH plays a role in receptivity in protein-fed females, it was originally hypothesized that one agonist, clonidine, enhanced fem ale insemination by acting on the corpus allatum (CA) to increase JH b iosynthesis. Two or three doses of the antiallatal agent, precocene II , prior to administration of clonidine, did not inhibit clonidine-enha nced female insemination. Removal of the corpus allatum also did not h ave a significant effect on clonidine-enhanced female insemination. Me asurement of juvenile hormone (JH) biosynthesis/release in corpora all ata, which were removed at 1, 3, 5, and 7 h postinjection, revealed th at clonidine does not affect JH biosynthesis/release. Our study reveal s a possible role for the biogenic amines in female insemination in in sects. We suggest that the octopaminergic agonist, clonidine, acts dow nstream from the corpus allatum on the regulatory mechanisms involved in female insemination.