Juvenile hormone regulation of longevity in the migratory monarch butterfly

Abstract

Monarch butter£ies (Danaus plexippus) of eastern North America are well known for their long-range migration to overwintering roosts in south-central Mexico. An essential feature of this migration involves the exceptional longevity of the migrant adults; individuals persist from August/September to March while their summer counterparts are likely to live less than two months as adults. Migrant adults persist during a state of reproductive diapause in which both male and female reproductive development is arrested as a consequence of suppressed synthesis of juvenile hormone. Here, we describe survival in monarch butter£ies as a function of the migrant syndrome. We show that migrant adults are longer lived than summer adults when each are maintained under standard laboratory conditions, that the longevity of migrant adults is curtailed by treatment with juvenile hormone and that the longevity of summer adults is increased by 100% when juvenile hormone synthesis is prevented by surgical removal of its source, the corpora allatum. Thus, monarch butter£y persistence through a long winter season is ensured in part by reduced ageing that is under endocrine regulation, as well as by the unique environmental properties of their winter roost sites. Phenotypic plasticity for ageing is an integral component of the monarch butter£ies' migration^diapause syndrome.

Copulation corrupts immunity: A mechanism for a cost of mating in insects

“…First, the mechanism we have identified may contribute to the expression of the longevity cost associated with mating in insects. Examination of monarch butterflies (13) has shown that high juvenile hormone titers reduce longevity: all insects produce juvenile hormone (11) and utilize PO in humoral immunity (17,18). Mating induced juvenile hormone secretion functions to switch on physiological processes associated with gametogenesis and spermatophore production (19), processes vital for female and male fitness.…”

“…These reductions did not seem to be the consequence of the energetic requirements of reproductive behavior (7), and a previous study (9) suggested they may not be the consequence of the energetic demands of gamete production either. It is generally assumed that physiological (and evolutionary) trade-offs are mediated by hormones (10), and there is good, but scarce, evidence in insects that the conserved insect hormone ''juvenile hormone'' (11) is involved in such trade-offs (12,13). We examined whether juvenile hormone was responsible for mating-induced down-regulation in immune function in T. molitor.…”

Overwintering strategies in the red mason solitary bee—physiological correlates of midgut metabolic activity and turnover of nutrient reserves in females of Osmia bicornis

“…In insects, an adult diapause is one of the most common types of quiescence observed which involves the arrest of reproductive development. The shortening of the day length in autumn or the change from long-to short-day photoperiod coupled with the lowering of temperature is sufficient to induce adult diapause in many insects (De Wilde et al 1968;Krafsur et al 1999;Herman and Tatar 2001), including some Osmia species Sgolastra et al 2010).…”

Dynamic mechanical oscillations during metamorphosis of the monarch butterfly

“…These late-season monarchs are larger and of the cohort migrating to the transverse Neovolcanic belt range in Mexico where they roost through the winter and in spring to reinitiate the northern cohorts. Tentatively, anatomical and physiological differences (Herman & Tatar 2001) in these late-season monarchs may be responsible for the peculiar mechanical oscillations detected. However, it is also possible that the atypical mechanical oscillations may result from inbreeding within the colony as it was observed that many of the butterflies were diseased and did not emerge from their pupae (approx.…”

“…In this study, we used an optical beam deflection (OBD) setup (figure 1c) similar to an atomic force microscope (AFM; Binnig et al 1986;Meyer & Amer 1988) to measure the surface motion of the pupa during metamorphosis. Although the AFM has been extensively employed to study the mechanics of single molecules and cells (Hinterdorfer & Dufrene 2006), it has rarely been employed to study whole organisms (McConney et al 2007).…”