Adaptive strategies of overwintering adults: Reproductive diapause and mating behavior in a grasshopper, Stenocatantops splendens (Orthoptera: Catantopidae)

Abstract

To understand the adaptive strategies of the overwintering adults of Stenocatantops splendens, the mechanism of maintenance and termination of the reproductive diapause, the variation in mortality between overwintering females and males, and the mating strategy of the males were investigated. The results indicated that the adult reproductive diapause in natural conditions was mainly regulated by photoperiod in the fall - long photoperiods promoted reproductive development and short photoperiods maintained reproductive diapause, and the sensitivity of the overwintering adults to photoperiod was over before the end of the winter. When transferred from natural conditions to controlled laboratory conditions on dates from September through February, pre-oviposition became increasingly shorter with increasingly deferred transfer dates regardless of photoperiod conditions. The adults treated with low temperature for 30 days in September through November had significantly shorter pre-oviposition, suggesting that low temperatures in winter had an important role in the termination of reproductive diapause. The female had a significantly lower supercooling point than the male, which was related to their lower mortality after winter. In addition, observations of wild populations of the species indicated that mating behavior prior to winter and the duration of pre-mating period were not affected by photoperiod; mating and sperm transfer were mostly completed by November. Compared with females only mating before winter, females mating in the spring had shorter life span, longer pre-oviposition, lower hatching rate and laid fewer egg pods while showing no significant difference with regard to ovipositional interval, per pod number of eggs and nymph dry weight.

Characterization of Reproductive Dormancy in Male Drosophila melanogaster

“…In D. melanogaster females the fecundity of the recovered flies remained low (Figure 3B). A similar effect was seen in the post-diapausing grasshopper S. splendens (Zhu et al, 2013). Even after 3 weeks of recovery (R3) from diapause, when the male reproductive organs were fully mature, the number of copulation attempts was low between R3 and the control (C1) partners (Figure 3A), as well as between R3 flies of the two sexes (Figure S1A).…”

“…Depending on species and habitat the duration of adult diapause can vary from several weeks to many months or even years, and reproduction can, thus, be postponed substantially (Tauber et al, 1986; Pener, 1992; Denlinger, 2002), a life history pattern which has been particularly well studied in butterflies (Karlsson et al, 2008; McElderry, 2016). Although male diapause has been described in some species (see Pener, 1992; Tatar and Yin, 2001; Lehmann et al, 2012, 2015; Zhu et al, 2013; Ojima et al, 2015; Hand et al, 2016), surprisingly little is known about its physiology and molecular mechanisms. In fact, it is not clear to what extent mechanisms of male and female diapause are similar.…”

“…Thus, there are two main mating strategies to allow for successful reproduction in insects that diapause as adults (Denlinger, 1981; Kimura, 1988; Pener, 1992). The first is that mating occurs before diapause induction and sperm are stored in the spermatheca of the females throughout dormancy, as seen in the grasshopper, Stenocatantops splendens (Zhu et al, 2013) and firebug, Pyrrhocoris apterus (Socha, 2010). In this scenario the males become redundant and die after mating, like in some wasps (Lehmann et al, 2015) and mosquitos (Ceprani et al, 2008), or spend only a short time in dormancy as in S .…”

“…In this scenario the males become redundant and die after mating, like in some wasps (Lehmann et al, 2015) and mosquitos (Ceprani et al, 2008), or spend only a short time in dormancy as in S . splendens (Zhu et al, 2013). The other strategy is that male insects also enter diapause and recover in time to join their future unfertilized mates, as seen in e.g., Colorado potato beetles, monarch butterflies, and grasshoppers (Tatar and Yin, 2001).…”

Environmental conditions terminate reproductive diapause and influence pheromone perception in the long‐lived moth Caloptilia fraxinella

“…In other insects with facultative reproductive diapause, short-day conditions induce adult diapause and long-day conditions either terminate diapause or prevent individuals from entering diapause. This phenomenon is widespread among species in several orders of insects that overwinter as adults, including the Coleoptera (Berkvens et al, 2008), Hymenoptera (Kipyatkov & Lopatina, 2009), Orthoptera (Zhu et al, 2013), Hemiptera (Numata, 1992;Morita & Numata, 1997;Nakamura & Numata, 2000;Kostal et al, 2008;Musolin & Ito, 2008) and Lepidoptera (Barker & Herman, 1976;Pullin, 1986;Pieloor & Seymour, 2001;Fujita et al, 2009). Most C. fraxinella males eclose in reproductive diapause, which is maintained when males are held under suboptimal short-day or cool conditions.…”