A collagen-based layered chronic wound biofilm model for testing antimicrobial wound products.

A new in vitro chronic wound biofilm model was recently published, which provided a layered scaffold simulating mammalian tissue composition on which topical wound care products could be tested. In this paper, we updated the model even further to mimic the dynamic influx of nutrients from below as is the case in a chronic wound. The modified in vitro model was created using collagen instead of agar as the main matrix component and contained both Staphylococcus aureus and Pseudomonas aeruginosa. The model was cast in transwell inserts and then placed in wound simulating media, which allowed for an exchange of nutrients and waste products across a filter. Three potential wound care products and chlorhexidine digluconate 2% solution as a positive control were used to evaluate the model. The tested products were composed of hydrogels made from completely biodegradable starch microspheres carrying different active compounds. The compounds were applied topically and left for 2-4 days. Profiles of oxygen concentration and pH were measured to assess the effect of treatments on bacterial activity. Confocal microscope images were obtained of the models to visualise the existence of microcolonies. Results showed that the modified in vitro model maintained a stable number of the two bacterial species over 6 days. In untreated models, steep oxygen gradients developed and pH increased to >8.0. Hydrogels containing active compounds alleviated the high oxygen consumption and decreased pH drastically. Moreover, all three hydrogels reduced the colony forming units significantly and to a larger extent than the chlorhexidine control treatment. Overall, the modified model expressed several characteristics similar to in vivo chronic wounds.

Endophytic insect pathogenic fungi-host plant-herbivore mutualism: elucidating the mechanisms involved in the tripartite interactions.

Various techniques used by crop plants to evade insect pests and pathogen attacks have been documented. Among these, plant defense strategies induced by endophytic insect pathogenic fungi are arguably one of the most discussed. Endophytic fungi frequently colonize plants and inhabit their internal tissues for a portion of their lifespan without producing visible symptoms of the disease. This phenomenon is widespread and diverse in both natural and agricultural ecosystems, and is present in almost all plant organs. Many fungi can obtain nutrients by infecting and killing insects, and this ability has been developed numerous times in different fungal lineages. These species mainly consist of those in the order Hypocreales (Ascomycota), where the generalist insect pathogens, Beauveria sp. (Cordycipitaceae) and Metarhizium sp. (Clavicipitaceae) are two of the most studied endophytic entomopathogenic fungal genera. However, most fungi that kill insects do not survive in the tissues of living plants. The data published thus far show a high degree of variability and do not provide consistent explanations for the underlying mechanisms that may be responsible for these effects. This implies that available knowledge regarding the colonization of plant tissues by endophytic insect pathogenic fungi, the effects of colonization on plant metabolism, and how this contributes to a decrease in herbivore and pathogens damage is limited. To adequately utilize fungal-based products as biological control agents, these products must be effective and the reduction of pests and infection must be consistent and similar to that of chemical insecticides after application. This article discusses this possibility and highlights the benefits and the specific techniques utilized by endophytically challenged plants in invading insect pests and disease pathogens.

Exotic Ants of the Asia-Pacific: Invasion, National Response, and Ongoing Needs.

Human activity has facilitated the introduction of many exotic species via global trade. Asia-Pacific countries comprise one of the most economically and trade-active regions in the world, which makes it an area that is highly vulnerable to invasive species, including ants. There are currently over 60 exotic ant species in the Asia-Pacific, with the red imported fire ant, Solenopsis invicta, among the most destructive. Exotic ants pose many economic and ecological problems for the region. Countries in the Asia-Pacific have dealt with the problem of exotic ants in very different ways, and there has been an overall lack of preparedness. To improve the management of risks associated with invasive ants, we recommend that countries take action across the biosecurity spectrum, spanning prevention, containment, and quarantine. The creation of an Asia-Pacific network for management of invasive ants should help prevent their introduction and mitigate their impacts.

The Intestinal Immune Defense System in Insects.

Over a long period of evolution, insects have developed unique intestinal defenses against invasion by foreign microorganisms, including physical defenses and immune responses. The physical defenses of the insect gut consist mainly of the peritrophic matrix (PM) and mucus layer, which are the first barriers to pathogens. Gut microbes also prevent the colonization of pathogens. Importantly, the immune-deficiency (Imd) pathways produce antimicrobial peptides to eliminate pathogens; mechanisms related to reactive oxygen species are another important pathway for insect intestinal immunity. The janus kinase/STAT signaling pathway is involved in intestinal immunity by producing bactericidal substances and regulating tissue repair. Melanization can produce many bactericidal active substances into the intestine; meanwhile, there are multiple responses in the intestine to fight against viral and parasitic infections. Furthermore, intestinal stem cells (ISCs) are also indispensable in intestinal immunity. Only the coordinated combination of the intestinal immune defense system and intestinal tissue renewal can effectively defend against pathogenic microorganisms.

Comprehensive Detoxification Mechanism Assessment of Red Imported Fire Ant (Solenopsis invicta) against Indoxacarb.

The red imported fire ant (Solenopsis invicta) is one of the deadliest invasive ant species that threatens the world by disrupting biodiversity, important functions within a natural ecosystem, and community structure. They are responsible for huge economic losses in the infested countries every year. Synthetic insecticides, especially indoxacarb, have been broadly used to control S. invicta for many years. However, the biochemical response of S. invicta to indoxacarb remains largely undiscovered. Here, we used the sublethal doses of indoxacarb on the S. invicta collected from the eight different cities of Southern China. The alteration in the transcriptome profile of S. invicta following sublethal dosages of indoxacarb was characterized using high-throughput RNA-seq technology. We created 2 libraries, with 50.93 million and 47.44 million clean reads for indoxacarb treatment and control, respectively. A total of 2018 unigenes were regulated after insecticide treatment. Results indicated that a total of 158 differentially expressed genes (DEGs) were identified in the indoxacarb-treated group, of which 100 were significantly upregulated and 58 were downregulated, mostly belonging to the detoxification enzymes, such as AChE, CarE, and GSTs. Furthermore, results showed that most of these DEGs were found in several KEGG pathways, including steroid biosynthesis, other drug metabolizing enzymes, glycerolipid metabolism, chemical carcinogenesis, drug-metabolizing cytochrome P450, glutathione metabolism, glycerophospholipid metabolism, glycolysis/gluconeogenesis, and metabolism of xenobiotics. Together, these findings indicated that indoxacarb causes significant alteration in the transcriptome profile and signaling pathways of S. invicta, providing a foundation for further molecular inquiry.

Symbiotic microbiota may reflect host adaptation by resident to invasive ant species.

Exotic invasive species can influence the behavior and ecology of native and resident species, but these changes are often overlooked. Here we hypothesize that the ghost ant, Tapinoma melanocephalum, living in areas that have been invaded by the red imported fire ant, Solenopsis invicta, displays behavioral differences to interspecific competition that are reflected in both its trophic position and symbiotic microbiota. We demonstrate that T. melanocephalum workers from S. invicta invaded areas are less aggressive towards workers of S. invicta than those inhabiting non-invaded areas. Nitrogen isotope analyses reveal that colonies of T. melanocephalum have protein-rich diets in S. invicta invaded areas compared with the carbohydrate-rich diets of colonies living in non-invaded areas. Analysis of microbiota isolated from gut tissue shows that T. melanocephalum workers from S. invicta invaded areas also have different bacterial communities, including a higher abundance of Wolbachia that may play a role in vitamin B provisioning. In contrast, the microbiota of workers of T. melanocephalum from S. invicta-free areas are dominated by bacteria from the orders Bacillales, Lactobacillales and Enterobacteriales that may be involved in sugar metabolism. We further demonstrate experimentally that the composition and structure of the bacterial symbiont communities as well as the prevalence of vitamin B in T. melanocephalum workers from S. invicta invaded and non-invaded areas can be altered if T. melanocephalum workers are supplied with either protein-rich or carbohydrate-rich food. Our results support the hypothesis that bacterial symbiont communities can help hosts by buffering behavioral changes caused by interspecies competition as a consequence of biological invasions.

A novel chronic wound biofilm model sustaining coexistence of Pseudomonas aeruginosa and Staphylococcus aureus suitable for testing of antibiofilm effect of antimicrobial solutions and wound dressings.

Chronic wounds are a large burden to patients and healthcare systems. Biofilm infections in chronic wounds are crucial factors leading to non-healing of wounds. It is important to study biofilm in wounds and to develop effective interventions against wound biofilm. This study presents a novel in vitro biofilm model mimicking infected chronic wounds. The novel layered chronic wound biofilm model uses woundlike media and includes both Pseudomonas aeruginosa and Staphylococcus aureus, which have been identified as the most important pathogens in wounds. The model sustains their coexistence for at least 96 h. Microscopy of the model revealed microbial growth in non-surface attached microcolonies as previously observed in vivo. The model was used to determine log10 -reduction for the use of an antimicrobial solution and antimicrobial dressings (containing silver or honey) showing moderate-to-low antibiofilm effect, which indicates better concordance with the observed clinical performance of this type of treatment than other widely used standard tests.

Influence of biofilm growth age, media, antibiotic concentration and exposure time on Staphylococcus aureus and Pseudomonas aeruginosa biofilm removal in vitro.

BACKGROUND: Biofilm is known to be tolerant towards antibiotics and difficult to eradicate. Numerous studies have reported minimum biofilm eradication concentration (MBEC) values of antibiotics for many known biofilm pathogens. However, the experimental parameters applied in these studies differ considerably, and often the rationale behind the experimental design are not well described. This makes it difficult to compare the findings. To demonstrate the importance of experimental parameters, we investigated the influence of biofilm growth age, antibiotic concentration and treatment duration, and growth media on biofilm eradication. Additionally, OSTEOmycin™, a clinically used antibiotic containing allograft bone product, was tested for antibiofilm efficacy. RESULTS: The commonly used Calgary biofilm device was used to grow 24 h and 72 h biofilms of Staphylococcus aureus and Pseudomonas aeruginosa, which were treated with time-dependent vancomycin (up to 3000 mg L- 1) and concentration-dependent tobramycin (up to 80 mg L- 1), respectively. Two common bacteriological growth media, tryptic soy broth (TSB) and cation-adjusted Mueller Hinton broth (CaMHB), were tested. We found for both species that biofilms were more difficult to kill in TSB than in CaMHB. Furthermore, young biofilms (24 h) were easier to eradicate than old biofilms (72 h). In agreement with vancomycin being time-dependent, extension of the vancomycin exposure increased killing of S. aureus biofilms. Tobramycin treatment of 24 h P. aeruginosa biofilms was found concentration-dependent and time-independent, however, increasing killing was indicated for 72 h P. aeruginosa biofilms. Treatment with tobramycin containing OSTEOmycin T™ removed 72 h and 168 h P. aeruginosa biofilms after 1 day treatment, while few 72 h S. aureus biofilms survived after 2 days treatment with vancomycin containing OSTEOmycin V™. CONCLUSIONS: This study demonstrated biofilm removal efficacy was influenced by media, biofilm age and antibiotic concentration and treatment duration. It is therefore necessary to taking these parameters into consideration when designing experiments. The results of OSTEOmycin™ products indicated that simple in vitro biofilm test could be used for initial screening of antibiofilm products. For clinical application, a more clinically relevant biofilm model for the specific biofilm infection in question should be developed to guide the amount of antibiotics used for local antibiofilm treatment.

Differential Contributions of Specimen Types, Culturing, and 16S rRNA Sequencing in Diagnosis of Prosthetic Joint Infections.

Prosthetic joint failure is mainly caused by infection, aseptic failure (AF), and mechanical problems. Infection detection has been improved with modified culture methods and molecular diagnostics. However, comparisons between modified and conventional microbiology methods are difficult due to variations in specimen sampling. In this prospective, multidisciplinary study of hip or knee prosthetic failures, we assessed the contributions of different specimen types, extended culture incubations, and 16S rRNA sequencing for diagnosing prosthetic joint infections (PJI). Project specimens included joint fluid (JF), bone biopsy specimens (BB), soft-tissue biopsy specimens (STB), and swabs (SW) from the prosthesis, collected in situ, and sonication fluid collected from prosthetic components (PC). Specimens were cultured for 6 (conventional) or 14 days, and 16S rRNA sequencing was performed at study completion. Of the 156 patients enrolled, 111 underwent 114 surgical revisions (cases) due to indications of either PJI (n = 43) or AF (n = 71). Conventional tissue biopsy cultures confirmed PJI in 28/43 (65%) cases and refuted AF in 3/71 (4%) cases; one case was not evaluable. Based on these results, minor diagnostic adjustments were made. Fourteen-day cultures of JF, STB, and PC specimens confirmed PJI in 39/42 (93%) cases, and 16S rRNA sequencing confirmed PJI in 33/42 (83%) cases. One PJI case was confirmed with 16S rRNA sequencing alone and five with cultures of project specimens alone. These findings indicated that JF, STB, and PC specimen cultures qualified as an optimal diagnostic set. The contribution of sequencing to diagnosis of PJI may depend on patient selection; this hypothesis requires further investigation.

Toxicity of flavor enhancers to the oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae).

The objective of this study was to evaluate the toxicity of flavor enhancers to the oriental fruit fly Bactrocera dorsalis (Hendel). The flavor enhancers glycine, disodium guanylate, succinic acid disodium salt, monosodium glutamate (MSG), disodium inosinate, and L-alanine significantly increased the mortality of B. dorsalis flies. The mortality of flies that fed on glycine, disodium guanylate, succinic acid disodium salt, and MSG was greater than 90%. Additionally, fruit fly mortality increased with increases in both time and concentration. Glycine not only reduced the climbing ability of B. dorsalis but also affected the duration and frequency of its behavioral patterns (flight, walking, grooming and inactivity). Compared with adult flies in the control group, adult B. dorsalis flies that fed on glycine exhibited a significantly increased duration and frequency of inactivity and a decreased duration and frequency of both flight and walking. However, the effect of glycine on grooming activity was not significant. These findings demonstrate the toxic effects of flavor enhancers on B. dorsalis. Glycine also affected the behavior of adult flies at a low dose. Therefore, glycine has potentially toxic to insects and also likely to have a negative impact at sublethal concentrations.

Transmission modes of a pesticide-degrading symbiont of the oriental fruit fly Bactrocera dorsalis (Hendel).

Symbionts are associated with many insects and play several multifunctional roles in insect-microorganism mutualistic relationships. The trichlorphon-degrading symbiont Citrobacter freundii (CF-BD) of the oriental fruit fly Bactrocera dorsalis was recently discovered; however, its intraspecies transmission pathway among flies remains unknown. Here, we use fluorescence in situ hybridization (FISH), PCR detection, and a series of ingenious experiments to reveal that CF-BD was aggregated in rectal pads associated with the female ovipositor, and the CF-BD symbiont was vertically transmitted via egg surface contamination. Although CF-BD was not detected in ovaries, it was found in deposited eggs. In addition, CF-BD was readily acquired horizontally between larvae or adults via oral uptake, although it was not transferred via mating behavior. Surface sterilization of eggs had a negative effect on the insects, which exhibited a lower body weight and a sharp decrease in fecundity, suggesting important biological roles of CF-BD in the fitness of the host insects. Our findings may also help to explain the high pesticide resistance levels of B. dorsalis. Furthermore, identifying a clear transmission pathway of this organophosphorus-degrading symbiont will be useful for pesticide resistance management and future pest control technologies.

[In vivo study of Chuankezhi metabolism in rat].

To study the metabolic products of main compounds of Chuankezhi injection in rat, 12 Sprague Dawley rats were classed into 2 groups, a blank control group and an intermuscular administration group, respectively. Rat feces and urine samples were collected from 0−24 h and 24−48 h after administration. All the samples were ultrasonically treated with methanol and then analyzed using LC-LTQ Orbitrap MSn. By comparison with the total ion chromatogram of samples from the blank control group, the metabolites in the samples of drug-treated group were screened. These metabolites were further analyzed by multistage product ion scanning and comparison of retention time with reference substances. As a result, a total of 12 flavonoid metabolites were tentatively identified from the rat feces and no metabolite was discovered in the rat urine. Epimedin C and icariin were detected in the rat blood samples after 30 min of administration, but their metabolites and other original flavones were not detected. Furthermore, no original flavones and their metabolites were detected in rat blood samples after 2 and 4 h of administration. The potential metabolism paths were further characterized and the principal in vivo transformation of flavones from Chuankezhi injection were deglycosylation, dehydration, methylation, oxidation and isomerization in rats.

In vivo gene expression in a Staphylococcus aureus prosthetic joint infection characterized by RNA sequencing and metabolomics: a pilot study.

BACKGROUND: Staphylococcus aureus gene expression has been sparsely studied in deep-sited infections in humans. Here, we characterized the staphylococcal transcriptome in vivo and the joint fluid metabolome in a prosthetic joint infection with an acute presentation using deep RNA sequencing and nuclear magnetic resonance spectroscopy, respectively. We compared our findings with the genome, transcriptome and metabolome of the S. aureus joint fluid isolate grown in vitro. RESULT: From the transcriptome analysis we found increased expression of siderophore synthesis genes and multiple known virulence genes. The regulatory pattern of catabolic pathway genes indicated that the bacterial infection was sustained on amino acids, glycans and nucleosides. Upregulation of fermentation genes and the presence of ethanol in joint fluid indicated severe oxygen limitation in vivo. CONCLUSION: This single case study highlights the capacity of combined transcriptome and metabolome analyses for elucidating the pathogenesis of prosthetic infections of major clinical importance.

Comparing culture and molecular methods for the identification of microorganisms involved in necrotizing soft tissue infections.

BACKGROUND: Necrotizing soft tissue infections (NSTIs) are a group of infections affecting all soft tissues. NSTI involves necrosis of the afflicted tissue and is potentially life threatening due to major and rapid destruction of tissue, which often leads to septic shock and organ failure. The gold standard for identification of pathogens is culture; however molecular methods for identification of microorganisms may provide a more rapid result and may be able to identify additional microorganisms that are not detected by culture. METHODS: In this study, tissue samples (n = 20) obtained after debridement of 10 patients with NSTI were analyzed by standard culture, fluorescence in situ hybridization (FISH) and multiple molecular methods. The molecular methods included analysis of microbial diversity by 1) direct 16S and D2LSU rRNA gene Microseq 2) construction of near full-length 16S rRNA gene clone libraries with subsequent Sanger sequencing for most samples, 3) the Ibis T5000 biosensor and 4) 454-based pyrosequencing. Furthermore, quantitative PCR (qPCR) was used to verify and determine the relative abundance of Streptococcus pyogenes in samples. RESULTS: For 70 % of the surgical samples it was possible to identify microorganisms by culture. Some samples did not result in growth (presumably due to administration of antimicrobial therapy prior to sampling). The molecular methods identified microorganisms in 90 % of the samples, and frequently detected additional microorganisms when compared to culture. Although the molecular methods generally gave concordant results, our results indicate that Microseq may misidentify or overlook microorganisms that can be detected by other molecular methods. Half of the patients were found to be infected with S. pyogenes, but several atypical findings were also made including infection by a) Acinetobacter baumannii, b) Streptococcus pneumoniae, and c) fungi, mycoplasma and Fusobacterium necrophorum. CONCLUSION: The study emphasizes that many pathogens can be involved in NSTIs, and that no specific "NSTI causing" combination of species exists. This means that clinicians should be prepared to diagnose and treat any combination of microbial pathogens. Some of the tested molecular methods offer a faster turnaround time combined with a high specificity, which makes supplemental use of such methods attractive for identification of microorganisms, especially for fulminant life-threatening infections such as NSTI.

High genetic diversity in the offshore island populations of the tephritid fruit fly Bactrocera dorsalis.

BACKGROUND: Geographic isolation is an important factor that limit species dispersal and thereby affects genetic diversity. Because islands are often small and surrounded by a natural water barrier to dispersal, they generally form discrete isolated habitats. Therefore, islands may play a key role in the distribution of the genetic diversity of insects, including flies. RESULTS: To characterize the genetic structure of island populations of Bactrocera dorsalis, we analyzed a dataset containing both microsatellite and mtDNA loci of B. dorsalis samples collected from six offshore islands in Southern China. The microsatellite data revealed a high level of genetic diversity among these six island populations based on observed heterozygosity (Ho), expected heterozygosity (HE), Nei's standard genetic distance (D), genetic identity (I) and the percentage of polymorphic loci (PIC). These island populations had low F ST values (F ST = 0.04161), and only 4.16 % of the total genetic variation in the species was found on these islands, as determined by an analysis of molecular variance. Based on the mtDNA COI data, high nucleotide diversity (0.9655) and haplotype diversity (0.00680) were observed in all six island populations. F-statistics showed that the six island populations exhibited low or medium levels of genetic differentiation among some island populations. To investigate the population differentiation between the sampled locations, a factorial correspondence analysis and both the unweighted pair-group method with arithmetic mean and Bayesian clustering methods were used to analyze the microsatellite data. The results showed that Hebao Island, Weizhou Island and Dong'ao Island were grouped together in one clade. Another clade consisted of Shangchuan Island and Naozhou Island, and a final, separate clade contained only the Wailingding Island population. Phylogenetic analysis of the mtDNA COI sequences revealed that the populations on each of these six islands were closely related to different populations on mainland China. CONCLUSIONS: Our study suggests that these island populations have high genetic diversity, experience frequent gene flow and exhibit low or medium levels of genetic differentiation among some island populations. Therefore, the geographic isolation of the six islands does not appear to be a major dispersal barrier to B. dorsalis. Such knowledge is helpful for a better understanding of evolutionary processes of the species of island populations.

[Simultaneous determination of 4 prenylflavonoids of Chuankezhi injection in rat plasma by LC-MS/MS].

A quantitative method for epimedin A, B, C and icariin in rat plasma was established using LC-MS/MS after intermuscular administration of Chuankezhi injection to rat. Chromatographic separation was performed on an Agilent Eclipse XDB-C(18) column (150 mm × 2.1 mm, 5.0 µm) at 40 ℃. Mobile phase consisted of acetonitrile-0.1% formic acid in water（35∶65）, and the flow rate was 0.22 m L·min(-1). The LC effluent was detected and analyzed using an ESI-triple quadrupole tandem mass spectrometer under the multiple reaction monitoring (MRM) in the negative ion mode. The plasma samples were treated with solid phase extraction prior to LC-MS/MS analysis. As a result, all of the four analytes displayed a good linearity over the concentration of 1-1 000 ng·mL(-1). The RSDs of intra-day and inter-day assays were less than 5.99% and 10.16%, respectively. The relative recovery of each analyte was between 88.1%-101.1% with RSD < 7.9% and the absolute recovery was between 72.0%-86.6%（RSD < 6.3%）. In conclusion, the established method shows good specificity, sensitivity and efficiency for quantifying the four flavonoid glycosides contained in rat plasma.

[Pharmacokinetics of epimedin A, B, C and icariin of Chuankezhi injection in rat].

To study pharmacokinetic characteristics of epimedin A, B, C and icariin after intermuscular administration of Chuankezhi injection to rat. The established RRLC-MS/MS method was applied for simultaneous determination of four analytes in rat plasma and calculating their pharmacokinetic parameters. As a result, each analyte showed a good linear relationship in the concentration range of 1-1 000 µg•L⁻¹.The intra-day precise was 96.9%-107.5% with RSD<5.99%, inter-day precise was 92.3%-105.0% with RSD<10.16%. The relative recovery of four analytes was 88.1%-101.1% with RSD<7.9% and their absolute recovery was 72.0%-86.6% with RSD<6.3%. After intermuscular administration of Chuankezhi injection, the plasma concentration of four flavonoid glycosides rapidly arose to peaks at about 10 min, and then quickly declined in rat. Tmax of epimedin A, B, C and icariin was 0.21, 0.19, 0.16 and 0.49 h, respectively, and their mean elimination half-life(t1/2z) was 0.60, 0.62, 0.47 and 0.49 h. The established method was validated to be sensitive, rapid and specific for determination of the four analytes. Serum concentration of 4 species of epimedium flavonoids in Chuankezhi injection was low, and their absorption and elimination seem quickly, displaying similar pharmacokinetic characteristics in this study.

Status of Urban Bed Bug Infestations in Southern China: An Analysis of Pest Control Service Records in Shenzhen in 2012 and Dongguan in 2013.

The recent resurgence of bed bugs (Cimex spp.) in many developed countries has drawn increasing attention worldwide. The status of urban bed bug infestations were investigated in Shenzhen and Dongguan, two major cities in southern Guangdong Province of southern China, based on pest control service records from two different companies (one during 2012 and another during 2013). The results showed that Shenzhen and Dongguan have a severe problem with bed bug infestations: the control of bed bugs is a constant concern, except during the winter. In Shenzhen, a similar number of premises were treated for bed bugs in central business districts and suburban districts. However, in Dongguan, more premises were treated for bed bugs in suburban districts than in central business districts. The treatment rate for worker sleeping quarters, apartments, hotel, and private houses in Shenzhen was 53.8, 43.0, 1.9, and 1.3%, respectively. The percentage of treated rooms was 56.1% for worker sleeping quarters and 91.1% for apartments. In Dongguan, the treatment rate for worker sleeping quarters, apartments, hotel, and private houses was 90.0, 10.0, 0.0, and 0.0%, respectively.

Mutualism Between Fire Ants and Mealybugs Reduces Lady Beetle Predation.

Solenopsis invicta Buren is an important invasive pest that has a negative impact on biodiversity. However, current knowledge regarding the ecological effects of its interaction with honeydew-producing hemipteran insects is inadequate. To partially address this problem, we assessed whether the interaction between the two invasive species S. invicta and Phenacoccus solenopsis Tinsley mediated predation of P. solenopsis by Propylaea japonica Thunbery lady beetles using field investigations and indoor experiments. S. invicta tending significantly reduced predation by the Pr. japonica lady beetle, and this response was more pronounced for lady beetle larvae than for adults. A field investigation showed that the species richness and quantity of lady beetle species in plots with fire ants were much lower than in those without fire ants. In an olfaction bioassay, lady beetles preferred to move toward untended rather than tended mealybugs. Overall, these results suggest that mutualism between S. invicta and P. solenopsis may have a serious impact on predation of P. solenopsis by lady beetles, which could promote growth of P. solenopsis populations.

Effects of Solenopsis invicta (Hymenoptera: Formicidae) and Its Interaction With Aphids on the Seed Productions of Mungbean and Rapeseed Plants.

Although many reports suggested the economic importance of the red imported fire ant, Solenopsis invicta Buren, few attempts to test the hypothesis that the red imported fire ant-aphid mutualism enhances the occurrence of red imported fire ant on crops, thereby interfering with their flowering and fruiting and affecting their output. To address this problem, we compare the effects of red imported fire ant on the flowering and fruiting of self-pollinating and cross-pollinating crops by field investigations and indoor experiments. In the field, our results revealed that regardless of the aphid interaction, red imported fire ant preferred flowering mungbean plants, and their activities decreased the yields of single plants, total pod number, kernel number, and kernel weight. The interaction of red imported fire ant and aphids generated unfavorable effects on rapeseed yields per plant, total pod number, grain number, grain weight, and thousand-kernel weight and stimulated an elevated proportion of malformed seeds. However, the differences were not significant if only red imported fire ant was present. In the laboratory, although red imported fire ant display no apparent preference toward the seedlings of mungbean or rapeseed, the ants clearly favor the flowering plants of mungbeans. Therefore, this study indicated that one of the main mechanisms whereby red imported fire ants affect the crop yield is by compromising the reproduction processes.