Search Results (133)

Acrobeloides nanus is a cosmopolitan, parthenogenetic soil nematode that is widely distributed across various terrestrial environments, including forests, sand dunes, and agricultural lands. In Korea, this nematode was first isolated from soil collected from a potato farm. It has been used as a biological indicator for monitoring contamination caused by divalent metals such as copper and zinc. In this study, A. nanus was isolated from the soil collected from a cucumber farm, and its identity was confirmed using both morphological and molecular markers. Spray-induced gene silencing using double-stranded RNA (dsRNA) represents a promising new strategy for pest control. Here, we tested a spraying dsRNA that would specifically suppress the target genes in A. nanus. Three genes (Pat-10, Unc-87, and vATPase-B) were targeted, and their expression levels were assessed following treatment with their corresponding dsRNAs. The dsRNAs were sprayed onto the nematode diet. As the concentration of dsRNA increased, the expression levels of the target genes were significantly reduced, leading to notable nematode mortality. However, nematicidal activity varied among the three different dsRNAs. To practically assess these dsRNAs under field conditions, the dsRNAs were applied to the soil containing the nematodes by a drenching application. Significant mortality was observed in treatments with dsRNAs targeting vATPase-B or Pat-10, but not with dsRNA targeting Unc-87. To enhance nematicidal activity in soil, the dsRNAs were formulated with chitosan. This formulation significantly improved the stability of dsRNAs under soil conditions and increased their control efficacy against A. nanus. This study suggests that the drenching technique offers an effective strategy to the control of soil-dwelling nematode pests affecting agricultural crops. Full article

The migratory locust (Locusta migratoria), is a destructive pest in agriculture and ecological conservation, characterized by its unique phase polyphenism (phase change). Parthenogenesis, defined as oviparous reproduction without fertilization, has been studied less extensively than fertilized reproduction, with particularly scarce research on parthenogenesis in migratory locust. This study investigates the relationship between parthenogenesis and the phase change in migratory locusts. Through comparative studies between two phases, we found that solitary locusts exhibit a higher parthenogenesis capacity compared to gregarious locusts, as evidenced by greater total oviposition quantity and higher hatching rates. However, parthenogenesis resulted in significantly lower hatching rates compared to sexually fertilized females, with distinct differences in oviposition dynamics and hatching patterns. Furthermore, we observed that gregarious locusts, when isolated after eclosion, exhibited increased parthenogenetic capacity, depending on their juvenile density. Together, this study provides insights into the understanding of insect parthenogenesis and lays basis for the potential underlying mechanism. Full article

Although previous studies have investigated the reproductive (performance and mode) and lifespan traits of parthenogenetic Artemia, ploidy level has not been considered. Four parthenogenetic Artemia lineages, i.e., diploid, triploid, tetraploid, and pentaploid, were examined to determine the role of ploidy level under osmotic stress conditions (50, 100, and 150 ppt). Although the reproductive mode of the pentaploid lineage is unaffected by changes in salinity, it is entirely switched to oviparity in the diploid lineage at 50 ppt and in the tetraploid lineage at 100 ppt. Moreover, tetraploid reproduction is completely inhibited at 50 ppt. Although oviparity has been proposed as an adaptive strategy enhancing Artemia fitness at high salinities, the exclusive oviparous reproduction observed in the diploid parthenogenetic lineage at 50 ppt suggests that low salinity may also act as an environmental stressor, driving oviparity to ensure the next generation. On the basis of lifespan data, the tetraploid lineage presents greater euryhalinity than other ploidy levels do, whereas the pentaploid lineage is more stenohaline. Additionally, discriminant function analysis revealed that diploid and tetraploid lineages display heterogeneous reproductive/lifespan patterns across salinities, whereas triploid and pentaploid lineages exhibit homogeneous patterns within their respective groups. Our findings challenge the prevailing view that the ploidy level of parthenogenetic Artemia is correlated with tolerance to critical hypersaline conditions. In conclusion, we propose that the life history of parthenogenetic Artemia is influenced not only by ploidy level but also by the multifactorial integration of environmental conditions (particularly salinity and temperature) and local intra-variation/adaptation within isolated habitats. Full article

The closely related Naupactini species Naupactus leucoloma, Naupactus peregrinus, and Naupactus minor—collectively known as “white-fringed weevils”—form a monophyletic group within the N. leucoloma species group. Mostly parthenogenetic, a few sexually reproducing populations of both N. leucoloma and N. peregrinus occur in their native ranges (Argentinian Mesopotamian region), where they overlap. In 2013, after several decades during which only females had been recorded, a few males potentially belonging to these species were discovered. To clarify their taxonomic identity and understand the group’s evolutionary dynamics, we analyzed their mitochondrial and nuclear genetic markers to assess their genetic variation distribution and infer their phylogenetic relationships. Molecular phylogenetic analyses revealed that these males constitute an independently evolving lineage, whereas morphological comparisons produced inconclusive results. Statistical tests confirmed introgression between these unidentified males and N. leucoloma. These findings uncover unexpected levels of genetic divergence within this group of Neotropical weevils. Full article

Oxidative stress poses a challenge to in vitro embryo culture. As a flavonoid, galangin (GAL) has been shown to have antioxidant effects, but the effect and antioxidant capacity of GAL in the in vitro development of porcine parthenogenetic embryos are still unknown. In this study, we demonstrated that 1 µM GAL significantly increased the blastocyst rate, decreased the accumulation of intracellular reactive oxygen species (ROS), increased the glutathione (GSH) level, and enhanced mitochondrial function in early porcine embryos. Nuclear factor erythroid-2-related factor 2 (Nrf2) was identified as the target gene of GAL via network pharmacology, and the transcript levels of related antioxidant enzymes (HO-1, NQO1, SOD2, and CAT) were found to be increased. Since Nrf2 has seven domains, we constructed Nrf2 mutants lacking different domains in vitro. We found that GAL specifically binds to the Neh1 domain of Nrf2. Subsequent embryonic experiments demonstrated that the antioxidant effect of GAL was abolished after Nrf2 deletion. These results suggest that GAL can directly bind to Nrf2 to regulate the level of oxidative stress and improve mitochondrial function in embryos. Full article

Protein kinase A (PKA), commonly referred to as cAMP-dependent protein kinase, exists as a heterotetramer composed of two catalytic (C) and regulatory subunits (R). This versatile kinase exhibits regulatory functions in various biological processes including growth, division, and differentiation. Although PKA is well established as a master regulator of oocyte maturation across species, its functional role in insect parthenogenesis has remained enigmatic. Here, we systematically investigated the regulatory effect of PKA in the induction of parthenogenesis in model lepidopteran Bombyx mori. Our findings demonstrated an inverse correlation between PKA activity and parthenogenetic induction efficiency in silkworms. Notably, PKA activation resulted in delayed embryonic development, whereas PKA-C1 knockdown disrupted normal cell cycle progression. These results indicated that maintaining appropriate PKA activity is essential for ensuring proper cell division process, especially in the successful induction of silkworm parthenogenesis. The evolutionary conservation of PKA across species, coupled with its critical regulatory role in parthenogenesis, positions this kinase as a promising molecular target for breeding design. Our findings establish a foundation for developing silkworm strains with enhanced parthenogenetic capacity through PKA modulation, thereby facilitating the preservation of elite production traits. These results provide novel mechanistic insights into parthenogenesis while demonstrating the potential application of PKA regulation in both genetic studies and breeding programs. Full article

Fourteen Ameletus species are recognized in the eastern Nearctic (south of the Artic zone), including six described as new. Keys to adult males and full-grown larvae are provided. Taxonomic decisions were based on morphologic and genetic evidence. Their justification is discussed in depth and four species groups are proposed. The vast majority of Ameletus encountered in the eastern Nearctic are members of one of three triploid, clonal parthenogenetic species, at least two of which are of hybrid origin. Bisexual progenitors of the parthenogens were inferred using a combination of mitochondrial and nuclear genetic markers. The parthenogens likely arose during the Late Pleistocene when glacial advances brought previously allopatric species/populations into contact, and as glaciers retreated the parthenogens rapidly expanded their range while the sexual lineages remained in presumed glacial refugia. Although parthenogenesis is relatively common in Ephemeroptera, these Ameletus represent the first known cases of polyploidy and hybrid origin. Full article

In many vertebrates, mature ovulated eggs are arrested at metaphase II prior to fertilization. The eggs exit meiotic arrest after fertilization-induced or parthenogenetic activation, followed by embryo development or egg degradation, respectively. Calcium-dependent activation of meiotically-arrested eggs has been thoroughly investigated in various species. In addition, several recent studies have detailed the excessive activation of ovulated frog eggs, so-called overactivation. This overview highlights the major events of overactivation observed in mature ovulated eggs of the African clawed frog Xenopus laevis with a focus on similarities and differences between spontaneous, oxidative stress-induced, and mechanical stress-induced overactivation. The dramatically different cell death scenarios that unfold in activated and overactivated eggs are also exposed in the article. Full article

Parasitic diseases constitute a significant challenge to global public health, with Strongyloides stercoralis ranking among the most prevalent and clinically significant parasites. The limitations of current nematocidal therapies highlight an urgent need for novel treatment strategies. In this study, the nematocidal activity of chalepensin and graveoline, two compounds isolated from Ruta chalepensis, was evaluated against larval and adult stages of Strongyloides venezuelensis (model for S. stercoralis). The in vitro efficacy of these compounds was assessed on third-stage infective larvae (L3) and adult parthenogenetic females at various time points, while cytotoxicity was determined using Vero cells to calculate selectivity indices (SI). Both compounds showed good antiparasitic activity, but chalepensin exhibited superior nematocidal activity compared to graveoline, with an LC₅₀ of 3.9 µg/mL and an SI of 990 for L3, and an LC₅₀ of 16.8 µg/mL and an SI of 200 for adult females at 72 h. Morphological analysis via scanning electron microscopy in adult females revealed that graveoline induced mostly cuticle detachment, while chalepensin caused protuberances across the parasite body. These findings suggest that both compounds possess promising antiparasitic potential, with chalepensin emerging as a particularly potent candidate for further exploration. Full article

Xiphinema israeliae has been reported in the rhizosphere of olives in Crete, Greece. Attempts were made to culture this nematode in pots planted with olive and fig seedlings, using Xiphinema index as a control. In these conditions, X. index showed a high reproduction rate on fig in a few months and none on olive. The experiments with X. israeliae indicated that olive and fig are suitable hosts for this dagger nematode, since juveniles of various life stages were found in plants inoculated exclusively with females, although the rate of nematode reproduction was low. Xiphinema israeliae was proved to have a parthenogenetic reproduction and a long life cycle, from female to female, taking more than nine months at a 24–26 °C temperature to complete. Therefore, a quite long period, even a few years, may be necessary to obtain a high number of nematodes in pots under experimental conditions. In contrast, Xiphinema italiae did not reproduce on olive and fig after a seven-month period. Accordingly, to our knowledge, this study increases the host range and knowledge about the culturing of these species, as only seven species of Xiphinema have been successfully cultured in pots till now. The potential of fig and olive for culturing X. israeliae gives an opportunity for further studies of its biology and host range. Full article

Cyclin-dependent protein kinase 2 (Cdk2), an important member of the serine/threonine-specific protein kinase family, plays a critical regulatory role in biological processes. Previous studies have demonstrated that Cdk2 is involved in the arrest and resumption of meiosis in mammalian oocytes. In this study, we explored the function of Cdk2 through parthenogenetic lines (PLs) and corresponding amphigonic lines (ALs) in a model lepidopteran insect silkworm, Bombyx mori L. Our findings revealed a positive correlation between Cdk2 activity and the parthenogenesis induction rate. The pharmacological inhibition of Cdk2 using the specific inhibitor AUZ454 not only significantly reduced the parthenogenesis induction rate but also caused developmental delays in embryos. These results demonstrate that Cdk2 is essential for parthenogenesis success and is a potential target gene for biological reproductive regulation. Full article

Both the livestock and biomedical fields require a large supply of high-quality mature oocytes. However, the in vitro maturation (IVM) process often leads to an accumulation of reactive oxygen species (ROS), which can cause defects in oocyte meiosis and embryo development, ultimately compromising oocyte quality. Urolithin A (UA), known for its antioxidant properties, has not been thoroughly investigated for its potential to mitigate the negative effects of oxidative stress during the in vitro culturing of oocytes, and its underlying mechanism is not well understood. In this study, an in vitro oxidative stress model was established using porcine oocytes treated with H₂O₂, followed by exposure to varying concentrations of UA. The results revealed that 30 μM UA significantly improved both the quality of oocyte culture and the developmental potential of the resulting embryos. UA was found to enhance oocyte autophagy, reduce oxidative stress-induced mitochondrial damage, and restore mitochondrial function. Additionally, it lowered ROS and DNA damage levels in the oocytes, maintained proper spindle/chromosome alignment and actin cytoskeleton structure, promoted nuclear maturation, prevented abnormal cortical granule distribution, and supported oocyte cytoplasmic maturation. As a result, UA alleviated oxidative stress-induced defects in oocyte maturation and cumulus cell expansion, thereby improving the developmental potential and quality of parthenogenetic embryos. After supplementation with UA, pig parthenogenetic embryo pluripotency-related genes (Nanog and Sox2) and antiapoptotic genes (Bcl2) were upregulated, while proapoptotic genes (Bax) were downregulated. In conclusion, this study suggests that adding UA during IVM can effectively mitigate the adverse effects of oxidative stress on porcine oocytes, presenting a promising strategy for enhancing their developmental potential in vitro. Full article

Maternally inherited endosymbionts are widespread in arthropods, with multiple symbionts commonly co-existing within a single host, potentially competing for or sharing limited host resources and space. Wolbachia and Rickettsia, two maternally-inherited symbionts in arthropods, can co-infect hosts, yet research on their combined impacts on host reproduction and interaction remains scarce. Tetranychus turkestani (Acari: Tetranychidae) is an important agricultural pest mite, characterized by rapid reproduction, a short life cycle, and being difficult to control. Wolbachia and Rickettsia are two major endosymbiotic bacteria present in T. turkestani. This study used diverse parthenogenetic backcross and antibiotic screening to explore the reproductive effects of these two symbionts on T. turkestani. The results show that single Rickettsia infection induced male killing in the amphigenesis of T. turkestani, leading to arrhenotokous embryo death and fewer offspring. Single Wolbachia infection induced strong cytoplasmic incompatibility (CI). During dual infection, CI intensity decreased because Rickettsia’s male-killing effect antagonized the Wolbachia-induced CI. Dual-infected mites had increased oviposition, lower mortality, a higher female-to-male ratio, and more offspring, thus enhancing T. turkestani’s fitness. These findings will be helpful for understanding the nature of host–endosymbiont interactions and the potential for evolutionary conflicts, offering insights into their co-evolutionary relationship. Full article

The bush cricket Saga pedo, listed as Vulnerable globally by the IUCN and included in Annex IV of the EU Habitats Directive, is a parthenogenetic species highly sensitive to environmental changes, facing threats from forest expansion and agricultural intensification. S. pedo prefers dry, open habitats with sparse vegetation, and its pronounced thermo-heliophily makes it an indicator of xerothermic habitats. In many areas of Italy, including the Northern Apennines (Piedmont), semi-natural grasslands are fragmented. Open habitats have been reduced to small, isolated patches surrounded by forests due to the abandonment of agropastoral activities. Consequently, the occurrence of open habitat species is related to the quality and availability of suitable areas and ecological connectivity. We developed a spatial Bayesian framework to identify areas of occurrence for S. pedo. Using the inverse probability of occurrence, we derived ecological corridors among suitable patches. Our findings indicate that the occurrence and connectivity of S. pedo are reduced by intensive cultivation but favored by open habitats with 10–50% woody tree cover, suggesting sustainable land management is crucial for supporting the species. Given the extinction risk S. pedo faces, we urge local administrations to maintain and improve suitable areas and guarantee the network of ecological corridors identified. Full article

Endosymbiotic bacteria play a significant role in the co-evolution of insects and plants. However, whether they induce or inhibit host plant defense responses remains unclear. In this study, non-targeted metabolomic sequencing was performed on cotton leaves fed with Wolbachia-infected and uninfected spider mites using parthenogenetic backcrossing and antibiotic treatment methods. A total of 55 differential metabolites were identified, which involved lipids, phenylpropanoids, and polyketides. KEGG pathway enrichment analysis revealed seven significantly enriched metabolic pathways. Among them, flavonoid and flavonol biosynthesis, glycerophospholipid metabolism, and ether lipid metabolism showed extremely significant differences. In Wolbachia-infected cotton leaves, the flavonoid biosynthesis pathway was significantly up-regulated, including quercetin and myricetin, suggesting that the plant produces more secondary metabolites to enhance its defense capability. Glycerophosphocholine (GPC) and sn-glycerol-3-phosphoethanolamine (PE) were significantly down-regulated, suggesting that Wolbachia may impair the integrity and function of plant cell membranes. The downregulation of lysine and the upregulation of L-malic acid indicated that Wolbachia infection may shorten the lifespan of spider mites. At various developmental stages of the spider mites, Wolbachia infection increased the expression of detoxification metabolism-related genes, including gene families such as cytochrome P450, glutathione S-transferase, carboxylesterase, and ABC transporters, thereby enhancing the detoxification capability of the host spider mites. This study provides a theoretical basis for further elucidating the mechanisms by which endosymbiotic bacteria induce plant defense responses and expands the theoretical framework of insect–plant co-evolution. Full article