STUDIES ON THE ADULT REPRODUCTIVE DIAPAUSE OF THE MONARCH BUTTERFLY,DANAUS PLEXIPPUS

Abstract

Monarch butterflies obtained at monthly intervals during the annual adult cycle were held in summer conditions for 5, 10, and 20 days. Examination of these revealed in both sexes an adult reproductive diapause characterized by depressed growth of those reproductive organs sensitive to juvenile hormone. Diapause began for both sexes in late August or early September; female diapause ended in December while male diapause ended in November. Diapause intensity, maximal in September-October, appeared to be greatest in females. In summer conditions, reproductive tract growth in postdiapause females, but not males, was comparable to that observed in prediapause animals. Previously mated postdiapause, but not diapause, females showed a greater response to summer conditions than did virgins. Storing prediapause monarchs in winter conditions for up to 5 months did not induce diapause, indicating that diapause may be induced in a preadult stage. Diapause monarchs of both sexes responded to juvenile hormone with pronounced growth of the pertinent reproductive organs, suggesting that decreased production of juvenile hormone may be a characteristic of adult diapause. The possible advantages of diapause to the survival of the adult population are discussed.

Reply to Nylin, Wickman & Wiklund regarding sex ratios of California overwintering monarch butterflies

“…In contrast, we observed active spermatozoans from the male testes throughout the winter months, a condition also reported by Hill et al (1976). The difference in reproductive readiness (development) agrees with Herman's (1981) conclusion that female monarchs had more intense and longer duration diapause than the males. Our data suggest that overwintering males, because of the presence of spermatozoans within their testes, are capable of becoming sexually mature sooner than the females, even if both sexes were to resume repro ductive development at the same point in time.…”

Photoperiodic regulation of life-history traits before and after eclosion: Egg-to-adult development time, juvenile body mass and reproductive diapause in Drosophila montana

“…Studies on monarch butterflies (e.g. Herman, 1981;Goehring and Oberhauser, 2002) and several grasshopper (e.g. Geldiay, 1967;Broza and Pener, 1969) and Drosophila species (e.g.…”

Diapause in Stingless Bees (Hymenoptera: Apidae)

“…Among the major insect orders, including hemimetabolous and holometabolous ones, diapause behavior has been best observed in Orthoptera, Diptera, Coleoptera, Lepidoptera, Hemiptera and Hymenoptera (Tauber & Tauber, 1976;Herman, 1981;Denlinger, 1986;Lefevere et al, 1989;Kort, 1990;Greenfield & Pener, 1992;van Benthem et al, 1995;Kipyatkov et al, 1997;Pick & Blochtein, 2002b). Diapause behavior may be divided into at least three stages: (1) pre-diapause, (2) diapause, and (3) post-diapause, during which insects exhibit a series of behavioral, biochemical and morphological changes (Denlinger, 2002;Koštál, 2006).…”

“…Diapause behavior may be divided into at least three stages: (1) pre-diapause, (2) diapause, and (3) post-diapause, during which insects exhibit a series of behavioral, biochemical and morphological changes (Denlinger, 2002;Koštál, 2006). Furthermore, diapause behavior may occur at any stage of the insect life cycle: egg, larval, pupal (or nymph) or adult (Tauber & Tauber, 1976;Herman, 1981;Denlinger, 1986;Lefevere et al, 1989;Kort, 1990;Greenfield & Pener, 1992;van Benthem et al, 1995;Kipyatkov et al, 1997;Pick & Blochtein, 2002b). When diapause occurs in sexually active insects, breeding is usually compromised due to the interruption of certain physiological processes related to: (1) female oogenesis, (2) the activity of male accessory glands, or (3) the reproductive behavior of both sexes (Kimura, 1988;Tatar & Yin, 2001).…”