Insect juvenile hormone: from "status quo" to high society

Abstract

Juvenile hormone (JH) exerts pleiotropic functions during insect life cycles. The regulation of JH biosynthesis by neuropeptides and biogenic amines, as well as the transport of JH by specific binding proteins is now well understood. In contrast, comprehending its mode of action on target organs is still hampered by the difficulties in isolating specific receptors. In concert with ecdysteroids, JH orchestrates molting and metamorphosis, and its modulatory function in molting processes has gained it the attribute status quo hormone. Whereas the metamorphic role of JH appears to have been widely conserved, its role in reproduction has been subject to many modifications. In many species, JH stimulates vitellogenin synthesis and uptake. In mosquitoes, however, this function has been transferred to ecdysteroids, and JH primes the ecdysteroid response of developing follicles. As reproduction includes a variety of specific behaviors, including migration and diapause, JH has come to function as a master regulator in insect reproduction. The peak of pleiotropy was definitely reached in insects exhibiting facultative polymorphisms. In wingdimorphic crickets, differential activation of JH esterase determines wing length. The evolution of sociality in Isoptera and Hymenoptera has also extensively relied on JH. In primitively social wasps and bumble bees, JH integrates dominance position with reproductive status. In highly social insects, such as the honey bee, JH has lost its gonadotropic role and now regulates division of labor in the worker caste. Its metamorphic role has been extensively explored in the morphological differentiation of queens and workers, and in the generation of worker polymorphism, such as observed in ants.

Lay Eggs, Live Longer: Division of Labor and Life Span in a Clonal Ant Species

“…In most insect species, including annual social Hymenoptera, an increased juvenile hormone titer is essential for ovarian development and vitellogenesis (Rö seler 1991; Bloch et al 2000;Hartfelder 2000). This original gonadotropic function of juvenile hormone appears to have been lost in some highly social insects, such as honeybees and ants, in which it instead plays an important role in the regulation of division of labor in workers.…”

Effects of Soldier-Derived Terpenes on Soldier Caste Differentiation in the Termite Reticulitermes flavipes

“…Juvenile hormone is a morphogenetic hormone produced by a neurosecretory gland (the corpus allatum) that has a broad range of developmental and physiological effects (Wigglesworth, 1935;Schal et al, 1997;Truman and Riddiford, 1999;Gilbert et al, 2000;Truman et al, 2006). For example, in insects juvenile hormone plays a role in the control of larval/ nymphal development and metamorphosis, diapause, migratory behavior, wing length, seasonal development, reproduction, and caste determination (Hartfelder, 2000).…”

Beekeeping practice: effects of Apis mellifera virgin queen management on ovary development

“…Given the conditions for colony organization, three types of controls can influence queen ovarian function: an intrinsic control due to genetics and physiology; a colony environment control derived from interactions between castes and colony conditions, such as colony age demography, the number of cells available for egg laying and available food; and the beekeeper's management practice, such as fumigation that exposes bees to CO 2 that has an effect on the ovary of workers and queens (Berger and Cruz-Landim 2012;Berger et al 2015;Butler and Simpson 1965;CruzLandim et al 2006;Hamilton 1964;Hartfelder 2000;Page and Ericksons 1988;Patrício and Cruz-Landim 2003). Although Cobey (2007) found that the colony environment is indispensable for the start of oogenesis in the ovaries, the results herein showed that even in queens maintained outside of the colony environment, follicle differentiation can advance until separation of the oocyte and pre-nurse cells, which is just one step short of the ovarian development seen in queens maintained inside a colony.…”