The Science of Nature最新文献

Urban green spaces play a crucial role in protecting insect biodiversity against habitat loss. However, chemical pollution poses a potential threat to these ecosystems, making ecological risk assessment essential. In the city of San Luis Potosí, a former copper smelter operated for several decades, releasing arsenic into the environment. Despite this, its ecological impact has received no attention, which is important given the presence of nearby green spaces that provide habitat for urban insects. This study assessed arsenic levels in soil, plants, and insects near this former copper smelter to determine whether this pollutant poses risks to local insects. The study sites included green spaces near the smelter (smelter-impacted zone) and reference green spaces (reference zone), both ubicated within the same city. The study sites harbor more than 50 insect families with different ecological roles. Arsenic levels in soil, plants, and insects in the smelter-impacted zone were 4, 2, and 20 times higher compared to the reference zone, respectively. The analysis of exposure routes indicates that soil is a direct route for plants and insects, plants transfer the arsenic to several herbivores, decomposers reincorporate arsenic into the trophic chain, and predators are also exposed. Moreover, Cotinis mutabilis (Coleoptera: Scarabaeidae: Cetoniinae) was identified as a bioindicator of arsenic pollution, showing a positive correlation between its tissue concentrations and arsenic levels in soil. In conclusion, this study demonstrates that arsenic pollution threatens insects in the smelter-impacted zone, highlighting the need for further research to assess the potential ecological risks.

The house fly, Musca domestica L., plays a crucial role as a mechanical vector for a variety of pathogens that impact both humans and animals, highlighting the need for effective control measures. Conventional approaches, including sanitation and waste management, exhibit certain constraints, resulting in a dependence on synthetic insecticides that carry potential risks of toxicity and the development of resistance. This research examined the lethal and behavioral effects of Cinnamomum verum (cinnamon) extracts on house flies, employing an age-stage two-sex life table methodology to evaluate life table parameters. The analysis utilizing gas chromatography-mass spectrometry (GC–MS) revealed significant phytochemicals present in cinnamon bark, such as cinnamaldehyde and eugenol, which are recognized for their insecticidal and behavioral effects in insects. Acute toxicity assessments demonstrated lethal concentrations (LC₅, LC₂₅, and control) of cinnamon extracts, significantly affecting developmental and reproductive parameters. Interestingly, lower concentrations (LC₅) promoted fecundity and intrinsic growth rates compared to higher concentrations (LC₂₅), suggesting a biphasic response that aligns with the concept of pesticide-induced hormesis. Furthermore, oviposition preference trials confirmed a concentration-dependent deterrent effect of cinnamon extracts, with higher doses significantly reducing egg-laying behavior in gravid females. This research has included traditional GC–MS-based phytochemical screening by incorporating comprehensive biological and molecular assessments, offering a more integrated approach for biopesticide identification. The identification of phytochemicals like cinnamaldehyde and α-muurolene establishes a robust basis for the screening of additional bioactive compounds and exploring novel insecticidal agents.

Cecropia obtusa is a Neotropical myrmecophyte (i.e., plant sheltering ant colonies in hollow structures in exchange for protection against different enemies) that, in French Guiana, is associated with the dolichoderine ants Azteca alfari or A. ovaticeps that nest in this tree’s internodes and are provided food, mostly food bodies called Müllerian bodies. We show that the workers of the ectatommine ant Ectatomma tuberculatum are able to select small C. obtusa individuals (i.e., they were never noted on trees more than 3 m tall) to ambush the Azteca workers exiting the entrance holes to the internodes on these trees. Their presence is more frequent diurnally when the Azteca must leave their nest to harvest Müllerian bodies, whose production requires sunlight, than at night. We witnessed 36 E. tuberculatum foragers ambushing Azteca workers, then seizing and stinging them. Exceptionally, they captured three Azteca workers successively. In all cases, they retrieved them by carrying them between their mandibles. These results confirm that E. tuberculatum foragers, which nest at the base of different tree species, are well adapted to ambushing insect prey, including social insects exiting their nests.

Reproductive strategies often reflect species-specific adaptations to ecological pressures. However, identifying such strategies within cryptic species complexes remains challenging. We addressed this gap in two cryptic species of the European earwig complex (Forficula dentata and Forficula auricularia), both known for their agricultural importance, invasive potential, and maternal care. Using a common garden experiment with adults from seven populations, including sympatric ones, we quantified four forms of maternal egg care (egg gathering, egg defence, egg retrieval, and frequency of mother-egg contacts) and 20 additional life-history traits across the female life cycle. Species identity was then determined using COI analyses. Our results revealed that nine traits were species-specific, indicating distinct reproductive strategies. Both species produced a similar number of eggs. However, F. dentata females prioritized pre-ovipositional investment by delaying oviposition, a strategy that enhanced egg provisioning and offspring quality but shortened post-ovipositional egg development and reduced hatching success. Conversely, F. auricularia females invested more post-ovipositionally by laying earlier, which limited pre-ovipositional egg provisioning and resulted in lower-quality juveniles, but prolonged egg development, thereby increasing hatching success. These strategies did not alter three of the four maternal care behaviours, although F. dentata mothers showed stronger egg defence. Overall, these strategies may confer species-specific advantages in colonizing and competing for new environments, potentially contributing to the global invasive success of the European earwig complex.

Our previous research demonstrated that curcumin suppresses mouse colorectal cancer (CRC) cell CT26 migration and invasion by inhibiting heparanase (HPSE) mRNA expression. To further elucidate the mechanism of curcumin in human CRC treatment, we hypothesized that HPSE plays a pivotal role in human CRC metastasis and that curcumin inhibits this process by downregulating HPSE expression through epigenetic regulation mediated by non-coding RNAs. For further research, human CRC cells were infected with lentivirus to establish overexpression of HPSE cell lines and corresponding negative control cell lines. In vitro and in vivo experiments showed that curcumin inhibited the proliferation, migration, and metastasis of CRC cancer by inhibiting HPSE expression. In the tumor microenvironment, HPSE played an important role in activating the IL-6/STAT5 axis signaling pathway by destructing the extracellular matrix and releasing large number of cytokines, while changing the tumor microenvironment and EMT process, thus promoting tumor metastasis. RNA-seq analysis combined with qRT-PCR results showed that curcumin’s inhibition of HPSE expression involved the regulation of non-coding RNAs. Taken together, our results suggested that HPSE promotes CRC metastasis by activating the IL-6/STAT5 signaling axis, disrupting the ECM, releasing cytokines, and altering the tumor microenvironment to facilitate EMT. Curcumin significantly inhibits CRC cell proliferation, migration, and metastasis by downregulating HPSE expression via non-coding RNAs, which related to IL-6/STAT5 axis signal pathways. This research provides a comprehensive understanding of the molecular mechanisms underlying curcumin’s anti-CRC effects, emphasizing the role of HPSE and non-coding RNAs in tumor metastasis. These findings pave the way for the development of novel therapeutic strategies targeting HPSE and its regulatory pathways in CRC.

The invasive hemlock woolly adelgid, Adelges tsugae (HWA, Hemiptera: Adelgidae), is a detrimental pest to native eastern and Carolina hemlocks. In the last 2 decades, biological control utilizing two species of Laricobius beetles (Coleoptera: Derodontidae) has been of focus in the widespread effort to control HWA. Recently, two species of silver flies, native to the Pacific Northwest, Leucotaraxis argenticollis Zetterstedt and Leucotaraxis piniperda Malloch (Diptera: Chamaemyiidae), are being investigated as additional biological control agents. Releasing these two silver fly species in the eastern United States has yet to result in the establishment of these predators. During laboratory studies, Leucotaraxis larvae excreted a black substance in response to being disturbed, which contained anthraquinones previously detected in HWA. Previous research on Laricobius spp. found that the beetles likely sequestered these compounds from HWA. These compounds are feeding deterrents in other insect species. Leucotaraxis argenticollis life stages, their excrement, and honeydew produced by HWA were collected and analyzed by gas chromatography–mass spectrometry. Results showed that these anthraquinones were detected in various life stages of Le. argenticollis immatures and adults that fed on HWA. They were not detected in Le. argenticollis adults that were only fed artificial diet and water, indicating that Le. argenticollis sequesters the anthraquinones from HWA and may transmit the compounds to their eggs.

Learning and memory impairment is one of the main manifestations of cognitive impairment. Gut flora can affect cognitive function and behavior through the gut–brain axis. Ganoderma lucidum polysaccharide (GLP) is one of the main effective components of G. lucidum, with antioxidant and anti-aging effects. In this study, the learning and memory impairment model of aging mice was established by injecting D-galactose (D-gal). The learning and memory ability of mice was tested by a water maze experiment. Also, the biochemical indexes of mouse serum and brain tissue were determined. In addition, 16S rRNA sequencing was performed on mouse feces. The results showed that GLP significantly shortened the latency of mice to find a safe platform. Also, they enhanced superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities, increased glutamate (Glu) and acetylcholine (ACh) contents, and decreased malondialdehyde (MDA) and gamma-aminobutyric acid (GABA) contents in mice to improve antioxidant capacity, remove free radicals, and reduce lipid peroxidation and oxidative stress, thereby improving learning and memory disorders in mice. The analysis of the microflora after the intervention of GLP to improve learning and memory disorders in mice revealed changes in Lactobacillus abundance. In conclusion, D-gal causes learning memory impairment and reduced intestinal microbial diversity in aging mice, whereas GLP may ameliorate learning memory impairment by altering the distribution of Lactobacillus in the intestinal tract of mice and regulating the biosynthesis of peptidoglycan and secondary bile acids.

Miniaturisation can influence the foraging behaviour of flower visitors by shaping their sensory systems, flight capabilities, and their compatibility with floral shapes and structures. For bees, vision is a primary sensory modality, and a reduction in eye size compromises the resolution and sensitivity of vision. In Tetragonula iridipennis, a diminutive tropical stingless bee common in South Asia, we addressed the following questions: (a) Since flight capabilities are correlated with body size, does it largely utilise resources from understorey plants? (b) Does their small body size permit the utilisation of flowers with diverse morphologies? Further, we explored floral colour in relation to bee colour vision by examining if: (c) the distribution of marker points of the community floral spectra (n = 182 species) corresponds with bee photoreceptor sensitivities and (d) the colours of flowers visited or not visited by T. iridipennis form separate clusters in the bee colour space. We found a high degree of resource generalisation, with T. iridipennis visiting ~ 46% of flowering plant species (n = 215). However, three plant species accounted for the highest visitation rates (90%). There was no correlation between plant functional groups and foraging preferences. Floral shape and the interaction between floral area and shape significantly predicted visitation by T. iridipennis. Further studies on other bee species that are sympatric, closely related, and varying in body size will help understand the role of miniaturisation in foraging ecology of pollinators.

Wind, rain, and the activities of vertebrates frequently dislodge arthropods from tree surfaces, resulting in arthropod "rain" beneath trees. The probability of falling likely differs among taxa based on their adhesive capacities and ability to anticipate disturbance. We quantified the motion of red oak (Quercus rubra Linnaeus [Fagales: Fagaceae]) leaves, and the composition of arthropods dislodged from woody vegetation, following disturbance mimicking branch landings by eastern gray squirrels (Sciurus carolinensis Gmelin [Rodentia: Sciuridae]). Simulated squirrel landings caused terminal leaves on red oak branches to move rapidly (up to 100 cm s⁻¹) upward and inward toward the tree trunk during the first 50 ms, and dislodged 30% of the arthropods present on a branch. The composition of fallen arthropods was similar to those that remained on the branches, but the proportion dislodged differed among taxa. We used a small catapult to test the effect of leaf movement on the adhesive capabilities of workers of the carpenter ant Camponotus pennsylvanicus DeGeer (Hymenoptera: Formicidae). Arboreal ants presumably anticipate disturbance; thus, they were either "warned" or "unwarned" before each launch. Most ants (98%) were dislodged by the catapult. Warning did not affect the average (± SE) initial velocity (126.0 ± 72.0 cm s⁻¹) or maximum height (22.8 ± 9.3 cm) of launched ants. However, both variables were positively associated with ant mass. The results illustrate the limited ability of many arboreal arthropods to avoid the consequences of a common natural hazard and improve our understanding of the challenges imposed by an arboreal lifestyle.