Regulatory roles of biogenic amines and juvenile hormone in the reproductive behavior of the western tarnished plant bug (Lygus hesperus)
Mating induces behavioral and physiological changes in the plant bug Lygus hesperus Knight (Hemiptera: Miridae). After receiving seminal products, which include the systemic regulator juvenile hormone (JH), females enter a post-mating period lasting several days during which they enhance their oviposition rate and lose interest in remating. To elucidate the regulation of these behavioral changes in L. hesperus, biogenic amines were quantified in the heads of females at 5 min, 1 h and 24 h after copulation and compared to levels in virgins using high-performance liquid chromatography coupled with electrochemical detection. Mating significantly increased dopamine (DA) after 1 and 24 h, and decreased octopamine (OA) after 5 min and 1 h. Serotonin did not change with mating, but tyramine was significantly reduced after 5 min. While injection of amines into virgin females did not influence sexual receptivity, OA caused a decrease in oviposition during the 24 h following injection. Topical application of the JH analog methoprene to virgins caused an increase in DA, and a decline in mating propensity, but did not influence other amines or the oviposition rate. The results suggest the decline in OA observed immediately after mating may promote egg laying, and that male-derived JH may induce an increase in DA that could account for the post-mating loss of sexual receptivity.