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    Resource allocations of Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) in response to socio-sexual environment during immature and adult stages : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Entomology at Massey University, Palmerston North, New Zealand
    (Massey University, 2023) Liu, Junyan
    Animals adjust their investment in different life history traits according to their surroundings to maximise their fitness. Using a polygamous insect, the Mediterranean flour moth Ephestia kuehniella Zeller, which produces fertile eupyrene and infertile apyrene sperm, I investigated resource allocation strategies employed by males in response to socio-sexual cues during the adult and juvenile stages. I demonstrate that adult males raised their lifetime production and ejaculation of both eupyrenes and apyrenes after detecting either acoustic or chemical cues from adult rivals with combined cues strengthening such response, and that rival-experienced males could remember the sperm competition risk for most of their reproductive life. I manipulated juvenile socio-sexual settings and then examined their sperm production and ejaculation as well as survival, body and testis size, and mating behaviour. I provided the first evidence that juvenile social cues from conspecific larvae, pupae or adults had lasting impacts on lifetime sperm production and allocation. Adults from group-reared larvae, regardless of sex ratio, had smaller testes but produced more eupyrenes at emergence than from singly reared ones, and that body size and apyrene numbers remained the same across treatments. Male pupae had similar testis size but increased production of both eupyrenes and apyrenes at emergence in response to cues from conspecific pupae irrespective of sex. Late instar male larvae were able to detect cues from adult rivals and subsequently produced more sperm of both types at emergence, but adult cues had no effect on body and testis size. Juvenile socio-sexual environment had significant effects on sperm production and ejaculation during adult stage. My study indicates that after their late instar larvae were exposed to juvenile or adult rivals, adults produced and ejaculated more eupyrenes and apyrenes in their lifetime and had shorter mating latency. However, rival exposure had no effect on males’ mating frequency and longevity. Knowledge generated here enhances our understanding of how males of a polygamous insect calibrate their resource investment in response to dynamic social environment.
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    A study of the transport of spermatozoa in the reproductive tract of the ewe after artificial insemination : a thesis presented in partial fulfilment of the requirements for the degree of Master of Agricultural Science at Massey University
    (Massey University, 1975) Giles, Kerin Harle
    Two preliminary experiments were conducted with artificially inseminated ewes to examine the considerable variation in counts of spermatozoa recovered in flushings from the reproductive tract. In the second trial, road transport stress immediately after insemination caused a reduction in the number of spermatozoa reaching the Fallopian tubes. In the third trial, sperm transport after insemination with fresh, undiluted semen at two sites in the tract at predetermined times relative to synchronised ovulation (progestagen-HCG treatment) was investigated. Deposition of semen at the uterine end of the cervix or within the uterus using a specially adapted inseminating pippette, resulted in the recovery of higher numbers of spermatozoa from the uterus and Fallopian tubes 4 hours after insemination, than did insemination at the external cervical os. Twenty-four hours after insemination similar numbers of spermatozoa were found in all segments for both sites of insemination. Deposition of semen before or after the expected time of ovulation, or at both times, had little effect on the numbers of spermatozoa recovered. More ova with accessory spermatozoa were recovered from oviducts containing high numbers of sperm. The transport of spermatozoa after deposition of fresh or frozen semen into the uterus by surgical and non-surgical methods, was studied in a fourth experiment. The number of spermatozoa recovered from the uterus and isthmus was similar for both types of semen, but only 'fresh' spermatozoa deposited at surgery, reached the ampulla in significant numbers. 'Frozen' sperm deposited by both methods, and fresh sperm deposited non-surgically, did not reach the ampulla within 4 hours of insemination. Impaired transport of 'frozen' spermatozoa to the site of fertilization appeared to be a result of reduced longevity of these cells within the female tract, and nay involve factors such as breakage of spermatozoa in the uterus, and delayed transport in the oviducts. The improvement of sperm transport in the ewe through the development of non-surgical, intrauterine inseminations and using either freshly extended or frozen semen, are discussed.
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    Juvenile socio-sexual experience determines lifetime sperm expenditure and adult survival in a polygamous moth, Ephestia kuehniella
    (Wiley, 8/02/2023) Liu J; He XZ; Zheng X-L; Zhang Y; Wang Q
    Male animals often adjust their sperm investment in response to sperm competition environment. To date, only a few studies have investigated how juvenile socio-sexual settings affect sperm production before adulthood and sperm allocation during the first mating. Yet, it is unclear whether juvenile socio-sexual experience (1) determines lifetime sperm production and allocation in any animal species; (2) alters the eupyrene:apyrene sperm ratio in lifetime ejaculates of any lepidopteran insects, and (3) influences lifetime ejaculation patterns, number of matings and adult longevity. Here we used a polygamous moth, Ephestia kuehniella, to address these questions. Upon male adult emergence from juveniles reared at different density and sex ratio, we paired each male with a virgin female daily until his death. We dissected each mated female to count the sperm transferred and recorded male longevity and lifetime number of matings. We demonstrate for the first time that males ejaculated significantly more eupyrenes and apyrenes in their lifetime after their young were exposed to juvenile rivals. Adult moths continued to produce eupyrene sperm, contradicting the previous predictions for lepidopterans. The eupyrene:apyrene ratio in the lifetime ejaculates remained unchanged in all treatments, suggesting that the sperm ratio is critical for reproductive success. Male juvenile exposure to other juveniles regardless of sex ratio caused significantly shorter adult longevity and faster decline in sperm ejaculation over successive matings. However, males from all treatments achieved similar number of matings in their lifetime. This study provides insight into adaptive resource allocation by males in response to juvenile social-sexual environment.