Homotypic assortative mating is consistent across temporal scales in the spider Mecynogea lemniscata (Araneidae)

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Homotypic assortative mating is consistent across temporal scales in the spider Mecynogea lemniscata (Araneidae) Abstract Identifying patterns of size-assortative mating (SAM) indicates the direction of genetic changes in a population. A reliable method for estimating it in a population is to measure mate assortments within and between breeding seasons¸ as well as describing size variation of males and females between temporal scales to avoid Simpson’s paradox. We assessed sexual size dimorphism, the effects of ontogeny, size differences within each sex, the consistency of SAM within and between seasons, and male mate choice in the spider  Mecynogea lemniscata . We collected mating pairs in a  Eucalyptus  plantation across two breeding seasons and in four periods of the second season. We measured body mass and carapace width of spiders. Males matured earlier than females and guarded subadult partners. Although adults were larger and heavier than subadults, ontogeny did no...

Sublethal effects of matrine and azadirachtin on the wolf spider Pardosa laura: no impairment of growth but marked suppression of reproduction

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Sublethal effects of matrine and azadirachtin on the wolf spider Pardosa laura: no impairment of growth but marked suppression of reproduction

BACKGROUND

Plant-derived pesticides (PDPs) are increasingly promoted as ‘eco-friendly’ alternatives to agrochemicals because of their low vertebrate toxicity, yet their safety for non-target arthropod natural enemies is rarely tested, especially the enrichment effect via trophic transfer.

RESULTS

We cultured fruit flies using media supplemented with two widely applied Chinese PDPs in tea plantations, matrine or azadirachtin, under commercial concentration, which were fed to newly emerged spiderlings of wolf spider Pardosa laura (Araneae: Lycosidae) throughout their entire life cycle. We examined the effect of these two PDPs on their survival, developmental parameters and reproduction. The results showed that developmental traits remained unaffected, but both PDPs markedly suppressed male mating success and female fecundity. Histological examination of paraffin sections revealed markedly impaired ovarian maturation. Microbiome profiling indicated that pesticide exposure disrupted ovarian microbial communities, with azadirachtin exerting the strongest effect, whereas gut and testicular communities remained largely unchanged. Transcriptomic analysis of ovaries showed significant enrichment of pathways related to ovarian development. Ten representative differentially expressed genes (DEGs) within these pathways were selected and validated by RT-qPCR.

CONCLUSION

PDPs may not compromise the development of spiders in the first generation, yet they can severely affect reproduction of the spiders, thereby precipitating substantial declines in population size of future generations. This result challenges the conventional wisdom of botanical pesticides, inspiring re-consideration of their rational use in integrated pest management. © 2025 Society of Chemical Industry.


Ma, Y., Yan, H., Abukhader, O. S., Li, D., & Zhang, S. Sublethal effects of matrine and azadirachtin on the wolf spider Pardosa laura: No impairment of growth but marked suppression of reproduction. Pest Management Science. https://doi.org/10.1002/ps.70347