Assessment of different methodologies for evaluating the virulence of biological agents against fire ants (Solenopsis spp.) under laboratory conditions

A number of phorid flies are known to parasitize various life stages of bees and wasps, including reproductives (Kistner 1982). Several genera of phorids are known or assumed to be parasitic on worker ants but not on reproductives (Borgmeier 1963; Borgmeier and Prado 1975). Williams (1980) summarized the known data on phorids attacking and parasitizing fire ants sens. str., Solenopsis (Solenopsis) spp., in South America. To date, only one species is definitely known to parasitize fire ant workers, although other species are assumed to be parasitic on fire ants (Williams 1980). None of these species are present in the United States (Borgmeier 1963). Fire ant colonies collected as part of our continuing survey for biological control agents of fire ants were processed by the methods given in Jouvenaz et al. (in press). One colony of Solenopsis invicta Buren, collected 5-Feb-85 on the road shoulder of BR-070, km 616, ca. 1/2 way between Caceres and Cuiaba, Mato Grosso, Brasil, in disturbed cerrado (arid tropical savanna), was found to contain an unidentified nematode (Jouvenaz et al. in press). During studies of the nematode, 200 adult workers, 200 worker pupae, 200 adult males, and 65 alate females (all that were present in the collection) were dissected, yielding one puparium of a phorid fly (identified by D. H. Habeck, Dept. Entomology and Nematology, University of Florida, Gainesville, FL) from one alate female (virgin queen). The first two body segments of the puparium were darkened and heavily sclerotized. Two large conspicuous horn-like structures were noted on the prothoracic segment, probably the prothoracic spiracles. The remainder of the puparium was white and unmelanized. No gross morphological alterations were noticed in the alate ant before dissection. After several months preservation in 70% ethanol, the unmelanized portion of the puparium cleared, revealing the partially developed pupa inside. The pupa had developed to the point of eye facet coloration but no other parts were melanized. Since fire ants are not routinely dissected as part of our survey in Brazil, a special effort was made to collect alate females from fire ant nests on a subsequent trip (February to March 1986). Alate females were found in 93 colonies. These were preserved in alcohol and dissected in the United States. Up to 20 alate females were dissected from each colony (total of 1,561). No fly puparia were found although an unidentified microsporidian disease and nematodes were found. This is the first report of a phorid fly parasitizing alate female ants of any species. This find raises the possibility that a species of phorid exists that may be good biological control agents for queens and alate females of fire ants, not just workers. The success of a biological control program for fire ants using parasitoids which affect only worker ants would not seem to hold much promise, because of the large numbers of workers in fire ant colonies (Markin et al. 1973). The possibility exists that this is an instance of mistaken parasitism by the fly. During mating flights, activity on the surface of fire ant mounds becomes very hectic and a phorid could attack an alate by mistake. All reported cases of attack on worker ants describe the ant as stunned (Williams 1980; Kistner 1982). An alate female which

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Chapter 99 - Fire Ants

In the uropathogenic Escherichia coli strain F11, in silico genome analysis revealed the dicistronic iron uptake operon fetMP, which is under iron-regulated control mediated by the Fur regulator. The expression of fetMP in a mutant strain lacking known iron uptake systems improved growth under iron depletion and increased cellular iron accumulation. FetM is a member of the iron/lead transporter superfamily and is essential for iron uptake by the Fet system. FetP is a periplasmic protein that enhanced iron uptake by FetM. Recombinant FetP bound Cu(II) and the iron analog Mn(II) at distinct sites. The crystal structure of the FetP dimer reveals a copper site in each FetP subunit that adopts two conformations: CuA with a tetrahedral geometry composed of His(44), Met(90), His(97), and His(127), and CuB, a second degenerate octahedral geometry with the addition of Glu(46). The copper ions of each site occupy distinct positions and are separated by ∼1.3 Å. Nearby, a putative additional Cu(I) binding site is proposed as an electron source that may function with CuA/CuB displacement to reduce Fe(III) for transport by FetM. Together, these data indicate that FetMP is an additional iron uptake system composed of a putative iron permease and an iron-scavenging and potentially iron-reducing periplasmic protein.

STINGING INSECT HYPERSENSITIVITY: A PRACTICE PARAMETER

Urban agroforestry and its potential integration into city planning efforts

The red imported fire ant, Solenopsis invicta Buren, was first discovered in Japan in 2017. As this ant remains at the early invasion stage, efforts in establishing a rapid-response framework, such as evaluating available control methods, are urgently needed. Despite the presence of numerous household insecticides against invasive/household pest ants in Japan, the effects of these products on fire ants remain poorly understood. This study assessed the efficacy of two bait products designed to target common household ant pests in Japan on S. invicta through under laboratory and field conditions in Taiwan. The two baits are Arino-su-korori (AK), a granule-formulated bait product with hydramethylnon as an active ingredient (A.I.), and Hyper Arino-su-korori (HAK), a paste-formulated bait with fipronil as A.I., respectively. We showed that both AK and HAK resulted in more than 99% mortalities of fire ant within 8 wk under laboratory conditions and significantly reduce fire ants' foraging activities in the field. AK generally performed slightly better than HAK in terms of the time required to achieve total laboratory colony elimination and also long-term suppression of field fire ants. Such differences most likely are attributable to the active ingredient's mode of action and/or formulation and their interactions with fire ant biology. This study demonstrates the feasibility of the two bait products in effectively controlling laboratory and field fire ants, thus representing a promising candidate pest management tool to cope with ongoing/future fire ant invasions in Japan.

Host Specificity and Risk Assessment of Releasing the Decapitating Fly Pseudacteon curvatus as a Classical Biocontrol Agent for Imported Fire Ants

Biotic interactions are often important in the establishment and spread of invasive species. In particular, competition between introduced and native species can strongly influence the distribution and spread of exotic species and in some cases competition among introduced species can be important. The Caribbean crazy ant, Nylanderia fulva, was recently introduced to the Gulf Coast of Texas, and appears to be spreading inland. It has been hypothesized that competition with the red imported fire ant, Solenopsis invicta, may be an important factor in the spread of crazy ants. We investigated the potential of interspecific competition among these two introduced ants by measuring interspecific aggression between Caribbean crazy ant workers and workers of Solenopsis invicta. Specifically, we examined the effect of body size and diet on individual-level aggressive interactions among crazy ant workers and fire ants. We found that differences in diet did not alter interactions between crazy ant workers from different nests, but carbohydrate level did play an important role in antagonistic interactions with fire ants: crazy ants on low sugar diets were more aggressive and less likely to be killed in aggressive encounters with fire ants. We found that large fire ants engaged in fewer fights with crazy ants than small fire ants, but fire ant size affected neither fire ant nor crazy ant mortality. Overall, crazy ants experienced higher mortality than fire ants after aggressive encounters. Our findings suggest that fire ant workers might outcompete crazy ant workers on an individual level, providing some biotic resistance to crazy ant range expansion. However, this resistance may be overcome by crazy ants that have a restricted sugar intake, which may occur when crazy ants are excluded from resources by fire ants.

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Urban agriculture is often associated with sustainable agricultural practices. However, the variety of systems qualifying as urban agriculture and the limited information available about their sustainability question this direct relationship. To better understand differences in intra-urban agriculture systems and their sustainability, this paper proposed an holistic classification of urban agricultural systems and collected knowledge about the environmental, social, and economic sustainability of these systems. Such a classification is important to evaluate sustainability claims on urban agricultural systems, anticipate potential sustainability trade-offs between urban agricultural systems and propose preventive measures to address these, and ultimately guide the sustainable deployment of these systems. Compared with existing classifications, the novel classification scheme proposed here accounts for technological, social and economic characteristics of urban agriculture systems to better distinguish between all systems. It was built on 91 scientific papers. The economic intensity of production was, for example, an important characteristic to coherently group urban agriculture systems. The intensity of cooperation between all actors was another characteristic emphasized for certain urban agriculture systems. One end of the classification scheme describes ground-based open, socially motivated urban agriculture systems with high cooperation intensity and low production intensity. The other end of the classification scheme describes building-integrated quasi-closed systems with high production intensity. In between, we find: building-integrated conditioned systems, ground-based conditioned systems, and building-integrated open systems. Mapping sustainability claims from literature in the classification scheme supported its definition along the three characteristics. For example, urban farming was associated with job creation, food safety, water savings, and higher yields while urban gardening with educational potentials, biodiversity improvements, and lower yields. Their display in the classification scheme was therefore supported. To further support the use of the proposed scheme, additional quantitative research to better understand and quantify the sustainability of urban agriculture systems is required.

Open AccessCCS ChemistryRESEARCH ARTICLE3 Oct 2022Supramolecular Polymerization Powered by Escherichia coli: Fabricating a Near-Infrared Photothermal Antibacterial Agent in Situ Zihe Yin, Yuchong Yang, Jinpeng Yang, Guobin Song, Hao Hu, Peng Zheng and Jiang-Fei Xu Zihe Yin Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 Google Scholar More articles by this author , Yuchong Yang Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 Google Scholar More articles by this author , Jinpeng Yang Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 Google Scholar More articles by this author , Guobin Song State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023 Google Scholar More articles by this author , Hao Hu Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 Google Scholar More articles by this author , Peng Zheng State Key Laboratory of Coordination Chemistry, Chemistry and Biomedicine Innovation Center (ChemBIC), School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023 Google Scholar More articles by this author and Jiang-Fei Xu *Corresponding author: E-mail Address: [email protected] Key Lab of Organic Optoelectronics and Molecular Engineering, Department of Chemistry, Tsinghua University, Beijing 100084 Google Scholar More articles by this author https://doi.org/10.31635/ccschem.021.202101490 SectionsSupplemental MaterialAboutAbstractPDF ToolsAdd to favoritesDownload CitationsTrack Citations ShareFacebookTwitterLinked InEmail An Escherichia coli reduction-powered supramolecular polymerization is reported, leading to the fabrication of a near-infrared (NIR) photothermal antibacterial agent in situ. To this end, a bifunctional monomer containing two viologen moieties was designed. When incubating E. coli with the bifunctional monomer and cucurbit[8]uril, viologen moieties were reduced to viologen cation radicals by E. coli, and a supramolecular polymer with supramolecular dimers of viologen cation radicals integrated into the main chain was fabricated on the surface of E. coli. The NIR photothermal conversion property of the supramolecular dimer of viologencation radicals endowed the supramolecular polymer with photothermal antibacterial ability, and this performance was further improved by the local enrichment effect of supramolecular polymers and their enhanced adsorption onto the bacteria surface. Moreover, only certain bacteria, such as E. coli, possess the reducing ability to power supramolecular polymerization, whereas many other bacteria, such as Bacillus subtilis, Pseudomonas aeruginosa, and Staphylococcus aureus, do not possess this ability. Therefore, the supramolecular polymer exhibits outstanding bacterial inhibition efficiency (>99.9%) with high specificity toward E. coli under 1064 nm NIR irradiation. It is anticipated that this biologically powered in situ supramolecular polymerization strategy presents great potential in fabricating smart biomedical supramolecular materials with adaptivity and programmability. Download figure Download PowerPoint Introduction In an out-of-equilibrium biological system, many metabolic activities and physiological functions are energy-consuming processes. For bacteria, a transmembrane redox potential generated by procaryote respiration not only supports biological functions,1,2 but also can be employed as an energy source for various artificial applications, such as bioelectrosynthesis, initiation of polymerization, and microbial fuel cells.3–10 Notably, the reducing ability of bacteria originating from this redox potential has been applied to the in situ fabrication of biomedical materials at the places where they function.7,8,11 Compared with conventional biomedical materials, which are generally readily constructed and then transported to the working area, in an in situ fabrication strategy, the targeting ability could be realized, and then the transporting process could be omitted, thus improving the specificity and adaptivity of biomedical materials.12–17 As an integration of polymer science and supramolecular chemistry, supramolecular polymers exhibit superiority in various biomedical applications18–25 such as drug delivery,26–30 bioimaging and diagnosis,31,32 phototherapy,33–35 and tissue engineering.36–38 If supramolecular polymerization could be implemented in biological environments, biodegradability and stimuli-responsiveness originating from the dynamic and reversible noncovalent interactions may be imparted to the supramolecular biomedical materials that are fabricated in situ. Therefore, we wondered whether the reducing ability of bacteria could be utilized to power a supramolecular polymerization process. Our design idea arises from the fact that some electron-deficient dyes with large π-conjugated structures can be reduced to organic free radicals in a local reducing environment produced by some facultative anaerobic bacteria such as Escherichia coli.11,39,40 On the one hand, the self-assembly of these organic free radicals into supramolecular free radicals may serve as the driving force for supramolecular polymerization.41–50 On the other hand, supramolecular free radicals are expected to possess remarkable near-infrared (NIR) absorption,51–54 which may endow the supramolecular polymers with an outstanding photothermal conversion property and photothermal antibacterial performance. Therefore, by integrating the formation of NIR photothermal conversion motifs into a bacteria-powered supramolecular polymerization process, NIR photothermal antibacterial supramolecular polymers are hopeful to be constructed. Such an antibacterial agent would be selectively activated by the reduction with E. coli, whereas it could exactly kill thebacteria that induced the activation before. Such a “suicide” process of the bacteria may impart high antibacterial specificity to the agent. To this end, we designed and synthesized a bifunctional monomer named isviologen-diazabicyclo[2.2.2]octane-viologen (VDV), which contained two viologen moieties as end groups linked by a rigid and positively charged 1,4-diazabicyclo[2.2.2]octane unit. It was discovered that E. coli possessed the ability for reducing viologen into viologen cation radical under anaerobic conditions. As shown in Schemes 1a and 1b, when incubating E. coli with equimolar amounts of VDV and cucurbit[8]uril (CB[8]), the viologen moieties could be reduced to viologen cation radicals, and an in situ supramolecular polymerization could occur driven by the 2:1 host–guest complexation between viologen cation radicals and CB[8], generating a supramolecular polymer (VR-SP) with supramolecular dimers of viologen cation radicals integrated into the main chain. Moreover, the supramolecular dimer of viologen cation radicals exhibited absorption at the NIR biowindow, which might endow the VR-SP with photothermal antibacterial activity. By forming such an NIR photothermal antibacterial agent, E. coli could be killed by the local increase in temperature under NIR irradiation. This photothermal therapy is a powerful antimicrobial method with high penetration depth, few side effects, and low risk in generating drug resistance.55–71 Furthermore, the photothermal antibacterial efficiency could be enhanced significantly by the local enrichment effect of supramolecular polymers and their enhanced adsorption onto the surface of bacteria, since the positively charged VR-SP would exhibit strong interactions with the negatively charged surface of the bacteria. In addition, after completely inhibiting E. coli, VR-SP would be spontaneously degraded, as the viologen cation radicals are easily oxidized (commonly by oxygen) without the continuous reduction powered by living bacteria, thus turning off the antibacterial activity automatically. We therefore envisioned that, based on the supramolecular polymerization powered by E. coli, an NIR photothermal antibacterial agent with high antibacterial efficiency, specificity, and degradability could be fabricated in situ. Scheme 1 | (a) Chemical structures of the bifunctional monomer VDV, CB[8], and the supramolecular dimer of viologen cation radicals, and a graphic representation of the photothermal antibacterial supramolecular polymer VR-SP. (b) A schematic representation for the photothermal therapy using an NIR photothermal antibacterial agent fabricated through in situ supramolecular polymerization powered by E. coli. Download figure Download PowerPoint Experimental Method Unless otherwise noted, materials were obtained from commercial suppliers and were used without further purification. All types of bacteria were grown in Luria–Bertani (LB) culture medium at 37 °C for 8 h before further application. The detailed synthetic routes of VDV and 1-methyl-1′-(3-(trimethylammonio)propyl)-viologen tribromide (VMA), as well as detailed experimental methods are shown in Supporting Information. UV–vis spectra were measured using a HITACHI UH4150 spectrophotometer (Hitachi, Ltd., Tokyo, Japan) or a GE Ultrospec9000 spectrophotometer (General Electric Company, Boston, Massachusetts, United States). VDV (0.20 mM), or VDV (0.20 mM) and CB[8] (0.20 mM) were dissolved in LB medium. Then, 3.5 mL LB medium with dissolved agent was transferred into a quartz cuvette (1.00 cm). Then 100 μL of the suspension of bacteria (E. coli, Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, or Pseudomonas aeruginosa) was added. The samples were sealed and incubated at 37 °C for 20 h, and then the UV–vis spectra were recorded. Electron paramagnetic resonance (EPR) spectra were obtained using a JEOL JES-FA200 spectrometer. VDV (0.20 mM), or VDV (0.20 mM) and CB[8] (0.20 mM) were dissolved in LB medium. Then 100 μL of the suspension of bacteria (E. coli or B. subtilis) was added into 3.5 mL LB medium with dissolved agent. The medium was blown by a pipette and transferred into a capillary tube (Φ = 0.5 mm). After being filled with the medium, the capillary tube was sealed by melted paraffin. The samples were incubated at 37 °C for 40 h and then measured with the EPR spectrometer. The redox potential of VDV and VDV-CB[8] was measured by differential pulse voltammetry. The differential pulse voltammetry measurements were carried out with the three-electrode system using a CHI660E electrochemical workstation (CH Instruments, Inc., Austin, Texas, United States). A glass carbon disk (0.07 cm2) was applied as the working electrode with a Pt counter electrode and a saturated Ag/AgCl electrode (KCl saturated) reference electrode. The working electrode was polished with 0.3 and 0.05 μm alumina (Al2O3) successively and washed with deionized water before use. NaCl solution (50 mM) was used as supporting electrolyte. After degassing by passing N2 through the solution for at least 30 min, differential pulse voltammetry measurements were conducted on VDV (0.20 mM), or VDV (0.20 mM) and CB[8] (0.20 mM) solution. The redox potential of the bacterial cultural medium was measured using a hand-held ORP probe (Shanghai Sanxin SX712). The E. coli suspension (15 μL) was added into a cuvette containing LB medium (2 mL). The composite electrode of the ORP probe (using saturated Ag/AgCl electrode as reference electrode) was also immersed in the medium to monitor redox potential changes. The cuvette was sealed to prevent interference from air, and the bacteria were then incubated at 37 °C for 12 h. After that, the redox potential of the medium of E. coli was detected. For E. faecalis, S. aureus, B. subtilis, and P. aeruginosa, the redox potential was measured with the same method. A Nanowizard 4 atomic force microscopy (AFM; JPK, Berlin, Germany) coupled to an inverted microscope (Olympus IX73, Olympus Corporation, Tokyo, Japan) was used to perform the AFM imaging on live E. coli. The AFM was equipped with a cell-culture chamber to keep the temperature appropriate for E. coli (37 ± 1 °C). And a poly-d-lysine-coated mica disc was used as the substrate for E. coli immobilization and subsequent imaging. A PFQMN-Lc-A-CAL AFM cantilever (Bruker Corporation, Billerica, Massachusetts, United States) with a nominal spring constant of 0.1 N/m was used. For detailed scanning parameters and sample preparation procedures, please refer to Supporting Information. An FC-1064-3000-MM Laser Light Source (Wavicle Laser) was applied to produce a 1064 nm NIR laser in the photothermal therapy under NIR irradiation, and the NIR laser-induced heat experimental phenomenon was recorded by a Fluke Ti450 Infrared Camera. VDV (0.20 mM), or VDV (0.20 mM) and CB[8] (0.20 mM), or VMA (0.40 mM) and CB[8] (0.20 mM) were dissolved in LB medium, and 3.5 mL LB medium with dissolved agents was transferred into a quartz cuvette (for control group, LB medium without dissolved agent was applied). Then 30 μL of the suspension of bacteria (E. coli or B. subtilis) was added. The samples were sealed and incubated at 37 °C for 20 h. After incubation, the samples were irradiated by a 1064 nm NIR laser (2.0 W/cm2) for 12.5 min at 37 °C, and the temperature of the cuvette was recorded by Fluke Ti450 Infrared Camera every 2.5 min. The inhibition ratio was determined by calculating the number of colony-forming units (CFUs). The cell viability of both BEAS-2B and NCM460 cells was measured in vitro by the Cell Counting Kit-8 (CCK-8) assay. The cells were planted in 96-well plates with a density of about 5 × 103–8 × 103 cells per well for 24 h. Then the cells were treated with the medium containing equimolar amounts of VDV and CB[8] or VDV alone ranging from 0.10 to 0.40 mM for 24 h. After that, the cells were treated with fresh medium containing CCK-8 for 1 h to replace the previous medium. A microplate reader (EnVision, PerkinElmer, Inc., Waltham, Massachusetts, United States) was used for the measurement of absorbance at 450 nm, which was applied to calculate the cell viability. For detailed cell culture conditions, please refer to Supporting Information. Results and Discussion The formation of viologen cation radicals from VDV by E. coli reduction was characterized by UV–vis spectroscopy. As shown in Figure 1a, when incubating E. coli with VDV or equimolar amounts of VDV and CB[8] for 12–20 h, the color of the solution changed from light yellow to blue or dark violet, which are the characteristic colors of viologen cation radical monomer or supramolecular dimer of viologen cation radicals, respectively. With the existence of CB[8], absorption bands ranging from the UV to the NIR regionpeaking at 366, 542, and 872 nm were observed, which were attributed to the characteristic absorption of the supramolecular dimer of viologen cation radicals. In contrast, the characteristic absorption peaks of viologen cation radical monomer at 396 and 601 nm were observed in the absence of CB[8]. These results suggest the formation of viologen cation radicals. Figure 1 | (a) UV–vis spectra and images of the solution of VDV with or without CB[8] after incubating with E. coli at 37 °C for 20 h. (b) EPR spectra of VDV with or without CB[8] after incubating with E. coli at 37 °C for 40 h. (c and d) UV–vis spectra and images of the solution of VDV and CB[8] after incubating with E. coli, E. faecalis, B. subtilis, P. aeruginosa, or S. aureus at 37 °C for 20 h (VDV: 0.20 mM, CB[8]: 0.20 mM, medium: LB medium). Download figure Download PowerPoint The generation of viologen cation radicals by E. coli reduction was further confirmed by EPR. As shown in Figure 1b, an EPR signal with g factor of 2.0034 was observed after incubating E. coli with VDV. When incubating E. coli with equimolar amounts of VDV and CB[8], an EPR signal with the same g factor but significantly lower intensity was observed. Given that no EPR signal was observed when incubating E. coli without any additives, the observed signals were ascribed to viologen cation radical monomer; the lower signal intensity observed in the presence of CB[8] indicated that most of the generated viologen cation radicals self-assembled with CB[8] to form the supramolecular dimer of viologen cation radicals.48,72 In contrast, no EPR signal was observed when incubating VDV or VDV-CB[8] with aerobic bacteria B. subtilis, indicating the negligible reducing ability of B. subtilis to viologen ( Supporting Information Figure S10). To understand whether E. coli was the only bacteria possessing the reducing ability, five types of bacteria including E. coli, E. faecalis, B. subtilis, S. aureus, and P. aeruginosa were incubated with VDV-CB[8], and UV–vis spectra were recorded after 20 h incubation. As shown in Figure 1c, only E. coli presented remarkable reducing ability to generate viologen cation radicals. E. faecalis showed a much weaker reducing capacity than E. coli. For the other three types of bacteria, no absorption of viologen cation radicals was observed (Figure 1d), indicating their low reducing ability. To study the reducing ability of different types of bacteria quantitatively, the redox potential of the medium of different types of bacteria after incubation was measured. As shown in Table 1, the redox potential of E. coli culture medium reached as low as −551 mV. As for E. faecalis, the redox potential of the medium was −429 mV. The other bacteria media exhibited higher redox potential (Table 1). Compared with the first one-electron reduction potential of VDV (−558 mV) and VDV-CB[8] (−481 mV) measured by differential pulse voltammetry ( Supporting Information Figure S12), we judged that E. coli could reduce VDV to generate viologen cation radicals with or without CB[8]. E. faecalis could only reduce a small proportion of VDV with the existence of CB[8], whereas the other three types of bacteria could not reduce VDV. All the above results reveal that only E. coli possesses the remarkable reducing ability to generate viologen cation radicals, and the viologen cation radicals self-assemble into supramolecular dimer of viologen cation radicals in the presence of CB[8]. Table 1 | The Redox Potential of the Medium of Different Types of Bacteria after Incubationa Bacteria Redox Potential (mV) E. coli −551 E. faecalis −429 B. subtilis −171 P. aeruginosa −289 S. aureus −300 aAll redox potential values were measured related to saturated Ag/AgCl electrode. The formation of supramolecular polymers in solution driven by the host–guest complexation between viologen cation radicals and CB[8] was investigated by diffusion-ordered NMR spectroscopy (DOSY). Equimolar amounts of VDV and CB[8] were dissolved in D2O and then VDV was reduced via a photoinduced electron transfer process under 254 nm UV irradiation. After the complete reduction of viologen moieties, the diffusion coefficient of the species in solution measured by DOSY decreased significantly from 1.80 × 10−10 to 6.35 × 10−11 m2·s−1, indicating the formation of supramolecular polymers. According to the Stokes–Einstein equation, the degree of polymerization (DP) was approximately 23 (see Supporting Information). This result indicates that VR-SP is formed in aqueous solution successfully. To investigate whether VR-SP could be fabricated and adsorbed on the surface of E. coli, AFM imaging was employed. E. coli was incubated with equimolar amounts of VDV and CB[8] for 20 h to prepare VR-SP on the surface. After the color of the medium changed from light yellow to dark violet, E. coli was transferred into the petri dish, and fixed onto a poly-d-lysine coated mica disc. After that, E. coli was imaged directly by AFM. Compared with the untreated E. coli shown in Figure 2a, the edge of the E. coli incubated with VDV-CB[8] was uneven, as shown in Figures 2b, 2c, and 2e, suggesting the formation and adsorption of supramolecular polymers on the surface of E. coli. To further support that the adsorbed supramolecular polymers were responsible for the observed uneven edge of E. coli, the buffer in culture dish with the imaged bacteria in Figure 2c was carefully replaced by phosphate-buffered saline (PBS) without disturbing the bacteria. As shown in Figures 2d and 2f, the E. coli again exhibited the smooth edge, which could be explained as the oxidation of VR-SP by air; therefore, the adsorbed supramolecular polymers were degraded. Considering that VDV alone could not lead to the uneven edges of bacteria ( Supporting Information Figure S17), AFM observations suggest that VR-SP is formed and adsorbed on the surface of bacteria. Figure 2 | AFM images of (a) untreated E. coli and (b and c) E. coli incubated with 0.20 mM VDV and 0.20 mM CB[8]. (d) AFM image of the E. coli in image (c) after replacing the solution in the petri dish with PBS buffer. (e) Magnified image of the labeled area in (c). (f) Magnified image of the labeled area in (d). Download figure Download PowerPoint The DP of VR-SP generated on the surface of E. coli was further estimated by end-group analysis measured by EPR. Viologen cation radical monomer, which is the end group of VR-SP, can be characterized by EPR, whereas the supramolecular dimer of viologen cation radicals exhibits no EPR signal. Combining the EPR measurements of E. coli with VR-SP adsorption and viologen cation radical monomer, the DP of VR-SP was estimated to be approximately 17 (see Supporting Information). In comparison, the DP of the supramolecular polymer formed in aqueous solution at the same concentration was also measured by the end-group analysis using EPR, which was estimated to be approximately 21. This result indicated that VR-SP could be formed on the surface of E. coli though the bacteria surface might disturb the host–guest complexation between viologen cation radical and CB[8] a little. Therefore, by combining the AFM imaging and end-group analysis, we conclude that supramolecular polymers can be fabricated on the surface of bacteria through in situ supramolecular polymerization powered by E. coli. Based on the E. coli-powered supramolecular polymerization in situ, and the NIR absorption of the supramolecular dimer of viologen cation radicals, we further explored the bacterial inhibition activity of VR-SP by photothermal therapy. The photothermal conversion property of VR-SP prepared by chemical reduction was first studied. As shown in Supporting Information Figure S19, a significant temperature increase of VR-SP solutionwas observed under 1064 nm irradiation at the second NIR (NIR-II) window, indicating the effective photothermal conversion of VR-SP. The photothermal conversion efficiency was 22.0% (see Supporting Information). Next, the photothermal antibacterial experiments were conducted. As shown in Figures 3a and 3b, under NIR irradiation at 1064 nm, the temperature of the medium with VR-SP adsorbed E. coli increased significantly. It rose from to °C after 12.5 min irradiation, indicating that VR-SP energy into When E. coli was incubated with VDV the increase of temperature was lower than the VR-SP group after irradiation for the same When E. coli was treated with viologen VMA (Figure and CB[8], which could be reduced to generate supramolecular dimer of viologen cation radicals but not supramolecular the temperature increase was to that of the control group without any agent under the same irradiation The significantly higher temperature increase of the VR-SP group could be ascribed to the local enrichment and enhanced adsorption of VR-SP onto the surface of E. coli. As shown in Supporting Information Table the potential of E. coli significantly increased from of untreated E. coli to when incubated with equimolar amounts of VDV and CB[8]. As a comparison, when incubated with only VDV, the potential increased to mV. These results that the adsorption of VR-SP onto the surface of E. coli is higher than that of VDV of the of of supramolecular polymers. As for bacteria with low reducing ability, B. subtilis for since no viologen cation radicals were generated and no supramolecular polymers could be the increase of temperature was after irradiation in the presence or absence of VDV-CB[8] °C or °C with or without VDV-CB[8], The results of these groups that the of VR-SP is to a higher temperature in photothermal therapy. Figure | (a) of the medium with E. coli or B. subtilis, or with E. coli or B. subtilis treated with different agents under irradiation. (b) images of the medium with E. coli or B. subtilis, or with E. coli or B. subtilis treated with different agents after 12.5 min irradiation. (c) The chemical of VMA (VDV: 0.20 mM, CB[8]: 0.20 mM, 0.40 mM, medium: LB medium). Download figure Download PowerPoint The antibacterial activity was by of As shown in Figure the inhibition efficiency of VR-SP to E. coli was after 12.5 min of 1064 nm irradiation, which was significantly higher than that of VDV and In contrast, equimolar amounts of VDV and CB[8] exhibited no inhibition of B. subtilis after irradiation under the same since no supramolecular polymers were It is that after 12.5 min irradiation under air, the absorption peaks of supramolecular dimer of viologen cation radicals in the UV–vis ( Supporting Information Figure and the EPR signal of viologen cation radicals ( Supporting Information Figure both of which the of VR-SP after the inhibition of E. coli. This is since E. coli reduce viologen to prevent the Therefore, these results that VR-SP is an NIR photothermal antibacterial agent with outstanding bacterial inhibition efficiency, high specificity E. coli, and Figure 4 | ratio of E. coli or B. subtilis incubated with or without different agents after 12.5 min irradiation figure of the ratio of VR-SP adsorbed E. coli group shown are ± from = = by the with the E. coli or B. subtilis group without any or Download figure Download PowerPoint To the of VR-SP as biological materials, the of equimolar amounts of VDV and CB[8] on cells was To this end, cell BEAS-2B and cell NCM460 were as As shown in Figures and when treated with equimolar amounts of VDV and CB[8] ranging from 0.10 to 0.40 mM, the cell viability of both BEAS-2B cell and NCM460 cell measured by CCK-8 was A was also observed on the cells treated with VDV alone ( Supporting Information Figure Therefore, VDV-CB[8] VDV alone exhibited at a high concentration (0.40 mM), which was the concentration used in antibacterial Therefore, VR-SP may be a potential agent for photothermal therapy. Figure 5 | of equimolar amounts of VDV and CB[8] to (a) BEAS-2B cell and (b) NCM460 Download figure Download PowerPoint We fabricated an NIR photothermal antibacterial agent through E. coli

Cities and agriculture are fundamentally linked, yet often coevolve in a contradicting manner. On the one hand, many scholars in science and urban planning argue in favor of satisfying urban food demands through local and regional agricultural production. On the other hand, as the process of urbanization occurs, competition between agricultural and non-agricultural land use is intensifying, more often than not to the disadvantage of agriculture in urban and peri-urban areas. In order to be part of sustainable land use in an urbanizing society, studies suggest that agriculture needs to become increasingly multifunctional. However, the interplay of multifunctional agriculture (MFA), food supply systems, and urban areas is not fully understood and requires more attention. Against this background, this chapter explores the potential of MFA within short food supply chains in peri-urban areas. In particular, MFA is seen as a resource for strengthening urban agriculture and city region food systems as a sustainable development. Based on a local case study in Berlin (CSA SpeiseGut), this chapter examines innovative practices and strategies at farm level that foster multifunctionality in community-supported agriculture (CSA). The case study illustrates how multiple functions such as producing local food (production goal), delivering amenities for urban lifestyles (consumption goal), and protecting ecosystem benefits (protection goal) emerged and how they contribute to a city region food system. The chapter reveals that peri-urban farming can indeed become an integrative land-use option when developing synergies between MFA and short food supply chains. In particular, MFA can stimulate the creation of new food networks, which strengthen urban agriculture and city region food systems.

This chapter describes an ARS headquarters-funded Areawide Pest Management (AWPM) project (the areawide Suppression of Imported Fire Ants Project), which aims to maintain low fire ant (Solenopsis invicta and S. richteri) populations with reduced need for bait toxicants by using available self-sustaining fire ant biological control agents in conjunction with bait toxicants. The project has entered the last 2 years of its expected duration. A new protocol has been developed to expand the project from the initial demonstration sites to other, smaller, sites in areas under different land use. Current sites were all established on improved, grazed pastures under cattle production. New demonstration sites were established on 'high value' properties where fire ant control is highly desirable and represents a high economic, environmental and/or aesthetic value (e.g. parks, poultry farms, hunting clubs, natural areas, military facilities, and urban horticulture). The objective is to expand the AWPM concept to other customers besides cattle farmers and to demonstrate that the concept of using biological controls in combination with toxic bait applications can be used in many different situations. This will apply what has been learned from the large-scale AWPM programme on pastures to properties and owners that have a high probability of continuing the fire ant IPM programme after project funding expires. It is expected that these properties will serve as examples for neighbouring property owners, and thus create a knowledge base on fire ant management and biological control that will provide for continuing expansion of interest in fire ant IPM in different regions in the USA.

Enhanced Rock Weathering (ERW) has emerged as a promising climate mitigation strategy, with many studies recommending annual application rates of 40–50 tonnes per hectare to maintain high, observable weathering rates. However, our analysis of 23 ERW field deployments reveals that such substantial application volumes may not significantly improve net carbon dioxide removal efficiency and could pose potential ecological risks to farmland and aquatic ecosystems1,2. As an alternative, we propose integrating ERW into urban farming systems as a sustainable carbon dioxide removal (CDR) technology.Urban farming systems, such as hydroponic and vertical farms, increasingly considered in future food production, offer unique opportunities for ERW deployment3. With 68% of the global population projected to live in urban areas by 20504, these systems are positioned to stabilise food security while supporting climate mitigation efforts. Incorporating ERW into these controlled environments offers several advantages. Unlike conventional field applications, the closed-loop cycling of carbon dioxide and water within urban farming systems enables precise monitoring and adjustment of key variables, including weathering products such as alkalinity and dissolved inorganic carbon (DIC) levels. These parameters can be efficiently tracked using cost-effective Monitoring, Reporting, and Verification (MRV) methods, potentially outperforming traditional field-based MRV methodologies in terms of accuracy and affordability.This approach not only enhances the carbon dioxide removal efficiency of ERW but also aligns with the sustainable intensification of food production. By integrating ERW into urban farming systems, we propose a novel pathway for simultaneously mitigating climate change and addressing food security challenges.