Field and Laboratory Studies on the Ecology, Reproduction, and Adult Diapause of the Asian Comma Butterfly, Polygonia c-aureum L. (Lepidoptera: Nymphalidae)

Abstract

Adult diapause and reproduction of a nymphalid butterfly, Polygonia c-aureum L., were investigated in field and laboratory examinations. Laboratory studies showed that old virgin male butterflies of non-diapausing generations had heavy accessory glands and simplex, which were suppressed in diapausing generations. The number of eupyrene sperm bundles in the duplex increased with adult age, whereas testis size decreased with age. Field examinations indicated that reproductive development of both sexes of diapausing generations in autumn was suppressed, and developed in spring. We attempted to estimate the physiological age of wild-caught males, as adult male age can be estimated from the testis size. We also attempted to determine whether or not wild male butterflies had mated from the development of the accessory glands and simplex, as well as the number of eupyrene sperm bundles in the duplex, by comparing unmated males with mated males. Field examinations suggest that almost all females in a population of non-diapausing generations mated and showed a tendency toward polyandry, while in the diapausing generation, in spring, monoandry rather than polyandry predominated. This suggests a different mating strategy between non-diapausing and diapausing generations.

Temporal shift between daily sperm movement and mating (sperm reflux) in the Asian comma butterfly, Polygonia c‐aureum

“…5AE 0.6b (28) 3.4 AE 0.7b (22) 3.0 AE 0.7b (12) ≥103.7 AE 0.5b (18) 3.9 AE 0.3b 12 (Drummond, 1984), or continues to the adult stage (Shen & Berryman, 1967;Lai-Fook. 1982), and relatively many apyrene sperm are found in the testis in the initial adult stage of P. c-aureum (Hiroyoshi & Reddy, 2018). As the presence of eupyrene and/or apyrene sperm in the spermatheca can delay remating of females (Cook & Wedell, 1999;Wedell, 2005;Thorburn et al, 2018), males would try to produce as many offspring as possible, by producing more sperm and inseminating more females.…”

“…During mating, males of P. c-aureum transfer the component of simplex as a spermatophore upon females, and then eject the seminal fluids including the sperm in the duplex followed by the contents of the accessory glands quickly during the last phase of mating (Hiroyoshi, 1995). Both sexes of this butterfly copulate multiply (Hiroyoshi & Reddy, 2018). Females retain spermatophores in the bursa copulatorix during and after mating, and then commence egg deposition (Hiroyoshi & Reddy, 2018).…”

“…Both sexes of this butterfly copulate multiply (Hiroyoshi & Reddy, 2018). Females retain spermatophores in the bursa copulatorix during and after mating, and then commence egg deposition (Hiroyoshi & Reddy, 2018). Females store the sperm in the seminal receptacle (spermatheca) after which the sperm leave the bursa copulatorix after mating (S Hiroyoshi, unpubl.…”

“…In the swallowtail butterfly Papilio xuthus L., it is suggested that the sperm in the spermatheca transferred from a male at a second mating expel those from a first mating (Watanabe & Sasaki, 2010). As the summer-form females of P. c-aureum also mate multiply (Hiroyoshi & Reddy, 2018), sperm competition could occur.…”

Size‐dependent investment in tusk length, testis size and sperm length in a biparental geotrupid beetle

“…The less intense decrease in absolute testis size in case of small individuals suggests that they may be able to gain fertilization advantage during the later periods. It is also possible that the observed decrease in testis size is caused by differences in the average age of the active beetles early and late in the breeding season as testis shrinkage over age was shown in Lepidoptera (Hiroyoshi & Reddy, ) and older individuals may be more eager to exploit every last mating opportunity and hence start preparing for the inactive period later than 1‐year old ones. It is important to note, however, that more small individuals were excluded due to abnormal testis structure and a lack of sperm late in the season than large one (six and one, respectively), which might have contributed to these results.…”