Size and protein content of accessory glands in adult male Caloptilia fraxinella in different physiological states

Abstract

Reproductive diapause is a strategy employed by some insects to coordinate reproduction with the appropriate environmental conditions for mate location and offspring development. Male Caloptilia fraxinella Ely (Lepidoptera: Gracillariidae) eclose in July in reproductive diapause, and remain unmated until May of the next year, when they emerge from overwintering sites in a reproductively active state. The present study assesses characteristics of male sex accessory glands (SAG) throughout the adult life stage when males are reproductively active and in early and late reproductive diapause. Male SAG are longer and positively correlate with moth body size when males are reproductively active in the spring compared with males in reproductive diapause in the summer and autumn. Male SAG also contain significantly more protein during the period of reproductive activity than during reproductive diapause. Access to a carbohydrate nutrition source does not impact male SAG length or protein concentration when males are reproductively active in the spring. Treatment with a Juvenile Hormone analogue in the autumn, but not the summer, tends to increase the total protein concentration compared with that of untreated control moths.

Juvenile hormone regulates photoperiod‐mediated male reproductive diapause via the methoprene‐tolerant gene in the ladybeetle Harmonia axyridis

“…Several studies have shown that treatment of diapause-destined insects with JH analog (JHA) can promote ovarian development. Conversely, reducing JH signaling by knocking down the JH receptor gene methoprene-tolerant (Met) can suppress ovarian development in reproductive insects (Smykal et al, 2014;Liu et al, 2016;Gujar & Palli, 2016;Roy et al, 2018). However, most research on reproductive diapause has been conducted on female insects, and regulation of male reproductive diapause is less well understood (Pener, 1992;Lemmen et al, 2016;Ala-Honkola et al, 2020).…”

“…Male reproductive diapause is characterized by arrested development of the male internal reproductive system (IRS), which consists of the testis, vas deferens (VD), ejaculatory duct (ED), and male accessory glands (MAGs), and by the cessation of mating activity (Pener, 1992;Ikeno et al, 2011;Kubrak et al, 2016;Lemmen et al, 2016). In several hemipteran and lepidopteran species, including Pyrrhocoris apterus and Polygonia c-aureum, photoperiod was determined to regulate diapause through JH signaling, which affected MAG development (Urbanova et al, 2016;Hiroyoshi et al, 2017).…”

Sexual selection shapes development and maturation rates inDrosophila

“…; Lemmen et al. ). It is not clear what selective forces and trade‐offs shape the maturation process after final size is attained, and in particular whether sexual selection plays a major role.…”

“…These arguments on the evolution of age at maturity neglect the fact that processes of maturation often continue after the animal has reached its final size (Roff 1992;Stearns 1992;Baker et al 2003;Jones et al 2007;Lemmen et al 2016). It is not clear what selective forces and trade-offs shape the maturation process after final size is attained, and in particular whether sexual selection plays a major role.…”

The insect HR38 nuclear receptor, a member of the NR4A subfamily, is a synchronizer of reproductive activity in a moth

“…In most mammals, females perceive the male‐emitted pheromones exclusively during oestrus and adopt a receptive posture for allowing sexual intercourse . In insects, especially in the fruit flies and the long‐lived moths, the males are more sensitive to the female sex pheromone and display the highest degree of mating activity when they reach the full sexual maturity a few days after emergence . To date, the molecular basis of such coordination between sexual activity and fertility remain largely unknown.…”