title: Precocene-I inhibits juvenile hormone biosynthesis, ovarian activation, aggression and alters sterility signal production in bumble bee (Bombus terrestris) workers.
abstract: Juvenile hormone (JH) is an important regulator of development and physiology in insects. While in many insect species, including bumble bees, JH functions as gonadotropin in adults, in some highly eusocial insects its role has shifted to regulate social behavior including division of labor, dominance and aggression. Studying JH functions across social insect species is important for understanding the evolution of sociality; however, these studies have been limited because of the inability to reduce JH levels without surgically removing its glandular source, the corpora allata. Precocene is known to inhibit JH biosynthesis in several non-social insects, but has been poorly studied in social insects. Here, we tested whether precocene-I can effectively reduce JH levels in Bombus terrestris workers, and examined its effects on their physiology and behavior. Precocene-I treatment of three-worker groups decreased JH titer and ovarian activation, irrespective of the bees' dominance rank within the group, and was remedied by JH replacement therapy. Precocene-I also decreased aggressiveness and increased ester-sterility signal production; these changes were rank-dependent, and affected mainly the most reproductive and the least aggressive workers, respectively, and could not be remedied by JH replacement therapy. These results clearly confirm the role of JH as a gonadotropin and mediator of aggression in B. terrestris, and indicate that JH effects are associated with worker dominance rank. The ability to chemically reduce JH titer provides us with a non-intrusive method to probe the evolutionary changes associated with JH and the hormonal mechanisms that are associated with reproduction and behavior in social insects.
authors.affiliation: Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA eua6@psu.edu.
authors.forename: E
authors.initials: E
authors.lastname: Amsalem
authors.affiliation: Chemistry Research Unit, 1600-1700 SW, 23rd Drive, Gainesville, FL 32608, USA.
authors.forename: P
authors.initials: P
authors.lastname: Teal
authors.affiliation: Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, University Park, PA 16802, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Grozinger
authors.affiliation: Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
authors.forename: A
authors.initials: A
authors.lastname: Hefetz
mesh_terms: D000374:Aggression / Q000187:drug effects*; D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000502:physiology*; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001578:Benzopyrans / Q000494:pharmacology*; D005260:Female; D007247:Infertility, Female; D007605:Juvenile Hormones / Q000096:biosynthesis* / Q000502:physiology*; D010053:Ovary / Q000187:drug effects* / Q000502:physiology*; D012098:Reproduction / Q000187:drug effects; D012919:Social Behavior
chemical_list: D001578:Benzopyrans; D007605:Juvenile Hormones; C019539:precocene I
keywords: Aggressive behavior; Dominance; Hormones; Pheromones; Reproduction; Social insects