Zhang Keshi, Cao Junlin, Li Xintong, Zhang Zhi-Qiang
School of Biological Sciences, University of Auckland, Auckland, 1072, New Zealand.
Manaaki Whenua- Landcare Research, 231 Morrin Road, Auckland, 1072, New Zealand.
Exp Appl Acarol. 2025 Jun 3;95(1):8. doi: 10.1007/s10493-025-01034-6.
Asexual reproduction can be advantageous in the short term but is generally considered an evolutionary dead end due to the lack of genetic diversity and the accumulation of deleterious mutations. The thelytokous predatory mite Amblyseius herbicolus (Chant) (Acari: Mesostigmata) shows potential for biological pest control, but its reproductive mechanism remains poorly understood. This study examined whether A. herbicolus females have retained mating ability by exposing them to morphologically similar heterospecific males from three sexually reproducing phytoseiid species: Amblydromalus limonicus (Garman & McGregor), Amblyseius lentiginosus Denmark & Schicha, and Neoseiulus cucumeris (Oudemans). No mating or insemination occurred between A. herbicolus females and heterospecific males within 24 h. In contrast, nearly all males successfully inseminated conspecific females in a follow-up observation. Mating behaviours varied across species, with A. lentiginosus showing the longest pre-mating duration and lowest insemination rate, indicating higher mate selectivity. Most Ad. limonicus males inseminated a single spermatophore, while A. lentiginosus and N. cucumeris deposited two spermatophores, suggesting differences in sperm allocation and competition. No correlation was found between male body size, mating duration, and endospermatophore volume, possibly due to the small sample size. This study does not establish whether A. herbicolus reproduces strictly through thelytoky, nor does it exclude the possibility of sexually reproducing populations elsewhere. Further research, including interspecific mating trials with the more morphologically similar Amblyseius largoensis and an investigation into the role of endosymbionts such as Wolbachia, is needed to reveal the mechanisms underlying asexuality in A. herbicolus.
无性繁殖在短期内可能具有优势，但由于缺乏遗传多样性以及有害突变的积累，通常被认为是进化的死胡同。产雌孤雌生殖的捕食螨赫氏钝绥螨（Amblyseius herbicolus (Chant)）（蜱螨亚纲：中气门目）显示出生物防治害虫的潜力，但其生殖机制仍知之甚少。本研究通过将赫氏钝绥螨雌螨暴露于来自三种有性生殖的植绥螨物种（形态相似的异种雄螨）：柠檬钝绥螨（Amblydromalus limonicus (Garman & McGregor)）、斑点钝绥螨（Amblyseius lentiginosus Denmark & Schicha）和胡瓜新小绥螨（Neoseiulus cucumeris (Oudemans)），来检验赫氏钝绥螨雌螨是否保留了交配能力。在24小时内，赫氏钝绥螨雌螨与异种雄螨之间未发生交配或受精。相比之下，在后续观察中，几乎所有雄螨都成功地使同种雌螨受精。不同物种的交配行为各不相同，斑点钝绥螨的交配前持续时间最长，受精率最低，表明其配偶选择度更高。大多数柠檬钝绥螨雄螨只排出一个精包，而斑点钝绥螨和胡瓜新小绥螨则排出两个精包，这表明在精子分配和竞争方面存在差异。未发现雄螨体型、交配持续时间和内精包体积之间存在相关性，这可能是由于样本量较小所致。本研究既未确定赫氏钝绥螨是否严格通过产雌孤雌生殖进行繁殖，也未排除其他地方存在有性生殖种群的可能性。需要进一步开展研究，包括与形态更相似的拉哥钝绥螨（Amblyseius largoensis）进行种间交配试验，以及调查诸如沃尔巴克氏体等内共生菌的作用，以揭示赫氏钝绥螨无性繁殖的潜在机制。
