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The red imported fire ants (RIFA, Solenopsis invicta) have become a well-known invasive species that poses significant ecological and economic threats globally. As of recent times, the geographic scope of its invasion in China is rapidly expanding, thereby aggravating the extent and severity of its detrimental effects. The importance of soil microorganisms for maintaining soil health and ecosystem function has been widely acknowledged. However, the negative impact of RIFAs on soil microbial communities and their functions has not yet been fully understood. In this study, we sequenced the V3-V4 variable region of the bacterial 16S rRNA gene in soil samples collected from three types of RIFA nests to investigate the impact of RIFA invasion on soil microbial diversity and composition. The results of alpha diversity analysis showed that the normal soil without nests of RIFAs exhibited the highest level of diversity, followed by the soil samples from RIFA-invaded nests and abandoned nests. Taxonomy and biological function annotation analyses revealed significant differences in microbial community structure and function among the different samples. Our findings demonstrate that RIFA invasion can significantly alter soil microbial community composition, which could ultimately affect ecosystem function. Therefore, effective management strategies are urgently needed to mitigate the negative impact of invasive species on native ecosystems. [ABSTRACT FROM AUTHOR]

Ipomoea batatas (L.) Lam has been recognized as a very competitive crop against certain farming weeds, but more information is required to support its potential field application. The current study utilized a de Wit replacement series incorporating five ratios of I. batatas and Ageratina adenophora (Spreng.) R. M. King and H. Rob plants in 9 m2 plots in 2018. In monoculture, the main stem length, leafstalk length, leaf area, and biomass of I. batatas were significantly higher than those of A. adenophora. In mixed culture, the plant height, branch, leaf, and biomass of A. adenophora were significantly suppressed (P < 0.05) by I. batatas. The relative yield (RY) of I. batatas was significantly higher than 1.0, and the RY of A. adenophora was significantly less than 1.0 (P < 0.05) in mixed culture, indicating that the intraspecific competition was higher than interspecific competition for I. batatas, but the intraspecific competition was less than interspecific competition for A. adenophora. The competitive balance index of I. batatas demonstrated a higher competitive ability than A. adenophora. The net photosynthetic rate (Pn) of I. batatas and A. adenophora increased gradually from July to September, and then decreased from September to November in all treatments. The Pn of I. batatas was higher than that of A. adenophora in July and August, less than that of A. adenophora from September to November in monoculture, and the Pn of A. adenophora was significantly suppressed (P < 0.05) with increasing proportions of I. batatas in mixed culture after August. The activities of antioxidant enzymes superoxide dismutase, peroxidase and catalase for A. adenophora were significantly reduced (P < 0.05) with increasing proportions of I. batatas in mixed culture. Our results showed that plant growth of A. adenophora was significantly suppressed by I. batatas competition due to certain morphological and physiological advantages of I. batatas. Therefore, I. batatas is a promising replacement control candidate for managing the infestations of A. adenophora, reducing the soil seed bank and seedlings of A. adenophora. [ABSTRACT FROM AUTHOR]

Background: As a means of biologically controlling Mikania micrantha H.B.K. in Yunnan, China, the influence of sweet potato [Ipomoea batatas (L.) Lam.] on its reproductive characteristics was studied. The trial utilized a de Wit replacement series incorporating six ratios of sweet potato and M. micrantha plants in 25 m2 plots over 2 years. Results: Budding of M. micrantha occurred at the end of September; flowering and fruiting occurred from October to February. Flowering phenology of M. micrantha was delayed (P < 0.05), duration of flowering and fruiting was reduced (P < 0.05) and duration of bud formation was increased (P < 0.05) with increasing proportions of sweet potato. Reproductive allocation, reproductive investment and reproductive index of M. micrantha were significantly reduced (P < 0.05) with increasing sweet potato densities. Apidae bees, and Calliphoridae or Syrphidae flies were the most abundant visitors to M. micrantha flowers. Overall flower visits decreased (P < 0.05) as sweet potato increased. Thus the mechanism by which sweet potato suppressed sexual reproduction in M. micrantha was essentially two-fold: causing a delay in flowering phenology and reducing pollinator visits. The number, biomass, length, set rate, germination rate, and 1000-grain dry weight of M. micrantha seeds were suppressed (P < 0.05) by sweet potato competition. With proportional increases in sweet potato, sexual and asexual seedling populations of M. micrantha were significantly reduced (P < 0.05). The mortality of both seedling types increased (P < 0.05) with proportional increases in sweet potato. Conclusions: These results suggest that sweet potato significantly suppresses the reproductive ability of the invasive species M. micrantha, and is a promising alternative to traditional biological control and other methods of control. Planting sweet potato in conjunction with other control methods could provide a comprehensive strategy for managing M. micrantha. The scenario of controlling M. micrantha by utilizing a crop with a similar growth form may provide a useful model for similar management strategies in other systems. [ABSTRACT FROM AUTHOR]