Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Author: search.filters.author.Wang QSubject: search.filters.subject.Animals

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    Reproductive plasticity in response to the changing cluster size during the breeding period: a case study in a spider mite
    (Springer Nature, 2023-10) Weerawansha N; Wang Q; He XZ
    Animals living in clusters should adjust their reproductive strategies to adapt to the social environment. Theories predict that the benefits of cluster living would outweigh the costs of competition. Yet, it is largely unknown how animals optimize their reproductive fitness in response to the changing social environment during their breeding period. We used Tetranychus ludeni Zacher, a haplodiploid spider mite, to investigate how the ovipositing females modified their life-history traits in response to the change of cluster size (i.e., aggregation and dispersal) with a consistent population density (1 ♀/cm2). We demonstrate that (1) after females were shifted from a large cluster (16 ♀♀) to small ones (1 ♀, 5 and 10 ♀♀), they laid fewer and larger eggs with a higher female-biased sex ratio; (2) after females were shifted from small clusters to a large one, they laid fewer and smaller eggs, also with a higher female-biased sex ratio, and (3) increasing egg size significantly increased offspring sex ratio (% daughters), but did not increase immature survival. The results suggest that (1) females fertilize more larger eggs laid in a small population but lower the fertilization threshold and fertilize smaller eggs in a larger population, and (2) the reproductive adjustments in terms of egg number and size may contribute more to minimize the mate competition among sons but not to increase the number of inhabitants in the next generation. The current study provides evidence that spider mites can manipulate their reproductive output and adjust offspring sex ratio in response to dynamic social environments.
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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.
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    Predator- and killed prey-induced fears bear significant cost to an invasive spider mite: implications in pest management
    (Wiley, 5/09/2022) Ristyadi D; He XZ; Wang Q
    BACKGROUND: The success of biological control using predators is normally assumed to be achieved through direct predation. Yet it is largely unknown how the predator- and killed prey-induced stress to prey may contribute to biological control effectiveness. Here, we investigate variations in life-history traits and offspring fitness of the spider mite Tetranychus ludeni in response to cues from the predatory mite Phytoseiulus persimilis and killed T. ludeni, providing knowledge for evaluation of the nonconsumptive contribution to the biological control of T. ludeni and for future development of novel spider mite control measures using these cues. RESULTS: Cues from predators and killed prey shortened longevity by 23-25% and oviposition period by 35-40%, and reduced fecundity by 31-37% in T. ludeni females. These cues significantly reduced the intrinsic rate of increase (rm ) and net population growth rate (R0 ), and extended time to double the population size (Dt ). Predator cues significantly delayed lifetime production of daughters. Mothers exposed to predator cues laid significantly smaller eggs and their offspring developed significantly more slowly but these eggs had significantly higher hatch rate. CONCLUSION: Predator- and killed prey-induced fears significantly lower the fitness of T. ludeni, suggesting that these nonconsumptive effects can contribute to the effectiveness of biological control to a great extent. Our study provides critical information for evaluation of biological control effectiveness using predators and paves the way for identification of chemical odors from the predator and killed prey, and development of new materials and methods for the control of spider mite pests. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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    A haplodiploid mite adjusts fecundity and sex ratio in response to density changes during the reproductive period
    (15/10/2022) Weerawansha N; Wang Q; He XZ
    Population density is one of the main socio-environmental factors that have critical impacts on reproduction of animals. Consequently, they need to adjust their reproductive strategies in response to changes of local population density. In this study we used a haplodiploid spider mite, Tetranychus ludeni Zacher (Acari: Tetranychidae), to test how population density dynamics during the reproductive period altered female reproductive performance. We demonstrate that females produced fewer eggs with a significantly higher female-biased sex ratio in dense populations. Reducing fecundity and increasing daughter production in a dense environment could be an advantageous strategy to minimise the intensity of local food competition. However, females also reduced their fecundity after arrival in a new site of larger area from a dense population, which may be associated with higher web production costs because females need to produce more webs to cover the larger area. There was no trade-off between egg number and size, and egg size had little impact on reproductive fitness. Therefore, T. ludeni females could adapt to the shift of population density during their reproductive period by manipulating the fecundity and offspring sex ratio but not the egg size.