The absence of concordant population genetic structure in the black‐tailed prairie dog and the flea,Oropsylla hirsuta,with implications for the spread of Yersinia pestis

The black‐tailed prairie dog (Cynomys ludovicianus) is a keystone species on the mid‐ and short‐grass prairies of North America. The species has suffered extensive colony extirpations and isolation as a result of human activity including the introduction of an exotic pathogen, Yersinia pestis, the causative agent of sylvatic plague. The prairie dog flea, Oropsylla hirsuta, is the most common flea on our study colonies in north‐central Montana and it has been shown to carry Y. pestis. We used microsatellite markers to estimate the level of population genetic concordance between black‐tailed prairie dogs and O. hirsuta in order to determine the extent to which prairie dogs are responsible for dispersing this potential plague vector among prairie dog colonies. We sampled fleas and prairie dogs from six prairie dog colonies in two regions separated by about 46 km. These colonies were extirpated by a plague epizootic that began months after our sampling was completed in 2005. Prairie dogs showed significant isolation‐by‐distance and a tendency toward genetic structure on the regional scale that the fleas did not. Fleas exhibited higher estimated rates of gene flow among prairie dog colonies than the prairie dogs sampled from the same colonies. While the findings suggested black‐tailed prairie dogs may have contributed to flea dispersal, we attributed the lack of concordance between the population genetic structures of host and ectoparasite to additional flea dispersal that was mediated by mammals other than prairie dogs that were present in the prairie system.     

Control of flea populations in a simulated home environment model using lufenuron, imidacloprid or fipronil

Control strategies were evaluated over a 6-month period in a home simulation model comprising a series of similar carpeted pens, housing matched groups of six cats, in which the life-cycle of the flea Ctenocephalides felis felis Bouche (Siphonaptera: Pulicidae) had been established. Additional adult fleas were placed on the cats at intervals to mimic acquisition of extraneous fleas from outside the home. Treatment strategies included a single subcutaneous deposition of injectable lufenuron supported by initial treatments with a short-acting insecticidal spray, or monthly topical applications of imidacloprid or fipronil. An untreated control group indicated that conditions were suitable for flea replication and development. Controls had to be combed on 18 occasions to remove excessive flea burdens and two developed allergic reactions. Lufenuron cats were combed once and required two insecticidal treatments in the first month to achieve control. Even so, small flea burdens were constantly present thereafter. Imidacloprid and fipronil treatments appeared to give virtually complete control throughout. Single fleas were found on imidacloprid cats on two occasions, whereas none were recovered from fipronil cats at any time after the first treatment. Tracer cats were used to monitor re-infestation rates at the end of the trial period. Small numbers of host-seeking fleas were demonstrated in all treatment pens, indicating that total eradication had not been accomplished. It is concluded that the home environment simulation model incorporating tracer animals could provide a powerful tool for studying flea population dynamics under controlled conditions but improved techniques are needed for quantifying other off-host life-cycle stages.     

Prevalence of Yersinia pestis in rodents and fleas associated with black-tailed prairie dogs (Cynomys ludovicianus) at Thunder Basin National Grassland, Wyoming

Rodents (and their fleas) that are associated with prairie dogs are considered important for the maintenance and transmission of the bacterium (Yersinia pestis) that causes plague. Our goal was to identify rodent and flea species that were potentially involved in a plague epizootic in black-tailed prairie dogs at Thunder Basin National Grassland. We collected blood samples and ectoparasites from rodents trapped at off- and on-colony grids at Thunder Basin National Grassland between 2002 and 2004. Blood samples were tested for antibodies to Y. pestis F-1 antigen by a passive hemagglutination assay, and fleas were tested by a multiplex polymerase chain reaction, for the presence of the plague bacterium. Only one of 1,421 fleas, an Oropsylla hirsuta collected in 2002 from a deer mouse, Peromyscus maniculatus, tested positive for Y. pestis. Blood samples collected in summer 2004 from two northern grasshopper mice, Onychomys leucogaster, tested positive for Y. pestis antibodies. All three positive samples were collected from on-colony grids shortly after a plague epizootic occurred. This study confirms that plague is difficult to detect in rodents and fleas associated with prairie dog colonies, unless samples are collected immediately after a prairie dog die-off.     

Palatability and toxicity of fipronil as a systemic insecticide in a bromadiolone rodenticide bait for rat and flea control

Vector control in plague-infested areas requires a simultaneous killing of rodents and their fleas. We investigated the efficacy of a combination of a systemic insecticide, fipronil, in a rodenticide bait formulation under laboratory conditions. Four different concentrations of fipronil (0.05%, 0.005%, 0.0005% with acetone as a solvent, and 0.05% with propylene glycol as a solvent) and two controls (solvents only) were combined with the rodenticide bait (crushed organically grown wheat with 0.005% bromadiolone). Each concentration was offered together with an untreated non-poisonous challenge bait to 10 singly caged Rattus rattus L., each with 100 rat fleas Xenopsylla cheopis Rothschild (Siphonaptera: Pulicidae) in the nest. Treated bait consumption was relatively low and an unsatisfactory rat mortality of around 50% only was obtained in all tests. The palatability of the bait, however, was not affected by the fipronil concentration. Even at the lowest fipronil concentration, average flea mortality was still above 95%, and doses of more than I mg fipronil per kg rat body weight gave a nearly complete kill of fleas. Fipronil can be highly effective as a systemic insecticide to for flea control, provided that a more attractive bait base for roof rats is used.     

Size and shape information serve as labels in the alarm calls of Gunnison's prairie dogs Cynomys gunnisoni

Some animals have the capacity to produce different alarm calls for terrestrial and aerial predators.However,it is not clear what cognitive processes are involved in generating these calls.One possibility is the position of the predator:Anything on the ground receives a terrestrial predator call,and anything in the air receives an aerial predator call.Another possibility is that animals are able to recognize the physical features of predators and incorporate those into their calls.As a way of elucidating which of these mechanisms plays a primary role in generating the structure of different calls,we performed two field experiments with Gunnison's prairie dogs.First,we presented the prairie dogs with a circle,a triangle,and a square,each moving across the colony at the same height and speed.Second,we presented the prairie dogs with two squares of differing sizes.DFA statistics showed that 82.6 percent of calls for the circle and 79.2 percent of the calls for the triangle were correctly classified,and 73.3 percent of the calls for the square were classified as either square or circle.Also,100 percent of the calls for the larger square and 90 percent of the calls for the smaller square were correctly classified.Because both squares and circles are features of terrestrial predators and triangles are features of aerial predators,our results suggest that prairie dogs might have a cognitive mechanism that labels the abstract shape and size of different predators,rather than the position of the predator.     

Characterization of seven polymorphic microsatellite loci in the Baja California endemic black‐tailed brush lizard Urosaurus nigricaudus

Seven microsatellite loci were developed for the Baja California endemic black‐tailed brush lizard Urosaurus nigricaudus, using an enriched genomic DNA library. All loci were polymorphic and overall presented high levels of variation. Number of alleles ranged from five to 16 (average 12.14), and observed heterozygosities from 0.535 to 0.923 (average 0.752). Cross‐species amplification was successful and polymorphism was detected for all the loci using the congeners Urosaurus lahtelai and Urosaurus ornatus. These markers will be useful to study fragmented populations of U. nigricaudus on agricultural landscape of the Baja California Peninsula.     

Impacts of simulated livestock grazing on Utah prairie dogs (Cynomys parvidens) in a low productivity ecosystem

Allometric foraging theory suggests that herbivores of greatly differing size should co-exist through niche segregation, but a few studies of large–small herbivore foraging relationships have reported competitive interactions. This study addresses the potential roles of habitat productivity and large herbivore grazing intensities on large–small herbivore foraging interactions. We examined effects of different intensity simulated grazing treatments on forage abundance and quality for Utah prairie dogs (Cynomys parvidens) in a low productivity ecosystem, and consequent effects on prairie dog individual growth rates, foraging preferences, and activity budgets. We hypothesized that simulated grazing would have predominantly facilitative impacts on Utah prairie dogs, as was found for black-tailed prairie dogs in higher productivity ecosystems. To test this hypothesis, we measured the effects of simulated grazing on forage nitrogen, digestibility, and biomass. Simulated grazing increased average forage nitrogen and digestibility while decreasing forage biomass. These effects were associated with reduced individual growth rates, increased juvenile foraging time, and reduced juvenile vigilance. Results suggest that the negative effects of reduced vegetation biomass greatly outweighed positive treatment effects in this study. However, prairie dogs in the moderate intensity defoliation treatment showed some preference for “grazed” plots over “ungrazed” plots, and this preference increased with time. Our study lends support to the idea that habitat productivity and herbivore densities may mediate shifts between facilitative and competitive interactions between different-sized herbivores.     

Establishment of the black-tailed prairie dog (Cynomys ludovicianus) as a novel animal model for comparing smallpox vaccines administered preexposure in both high- and low-dose monkeypox virus challenges

The 2003 monkeypox virus (MPXV) outbreak and subsequent laboratory studies demonstrated that the black-tailed prairie dog is susceptible to MPXV infection and that the ensuing rash illness is similar to human systemic orthopoxvirus (OPXV) infection, including a 7- to 9-day incubation period and, likely, in some cases a respiratory route of infection; these features distinguish this model from others. The need for safe and efficacious vaccines for OPVX in areas where it is endemic or epidemic is important to protect an increasingly OPXV-naïve population. In this study, we tested current and investigational smallpox vaccines for safety, induction of anti-OPXV antibodies, and protection against mortality and morbidity in two MPXV challenges. None of the smallpox vaccines caused illness in this model, and all vaccinated animals showed anti-OPXV antibody responses and neutralizing antibody. We tested vaccine efficacy by challenging the animals with 10⁵ or 10⁶ PFU Congo Basin MPXV 30 days postvaccination and evaluating morbidity and mortality. Our results demonstrated that vaccination with either Dryvax or Acambis2000 protected the animals from death with no rash illness. Vaccination with IMVAMUNE also protected the animals from death, albeit with (modified) rash illness. Based on the results of this study, we believe prairie dogs offer a novel and potentially useful small animal model for the safety and efficacy testing of smallpox vaccines in pre- and postexposure vaccine testing, which is important for public health planning.     

毒死蜱与噻嗪酮、吡虫啉混用防治稻飞虱和二化螟田间试验

20 0 2年在安徽省庐江县 4次田间试验结果表明 ,防治 3代和 4代稻飞虱 (Sogatellafurcifera(Horvath)和Nilaparvatalugens(St l) ) ,667m2 用 48%毒死蜱乳油 41 67mL +1 0 %吡虫啉可湿性粉剂 2 0g的处理 7d后防治效果分别为 93 0 3 %和 92 67% ,毒死蜱 5 2 0 8mL +2 5 %噻嗪酮可湿性粉剂 5 0g分别为92 79%和 95 2 2 %。防治 2代和 3代二化螟Chilosuppressalis(Walker) ,667m2 用毒死蜱 41 67mL +吡虫啉2 0g的处理 1 6d后防治效果分别为 73 2 2 %和 80 43 % ,毒死蜱 5 2 0 8mL +噻嗪酮 5 0g分别为 76 81 %和84 80 %。建议交替轮换使用以上混剂及剂量 ,并掌握在稻飞虱低龄若虫高峰期和二化螟卵孵高峰期施药 ,可有效防治稻飞虱和二化螟。     

Field evaluation of Tilapia zilli (Gervais) as a biological control agent for mosquito control

Tilapia zilli (Gervais), a larvivorous fish identified in the Mwea Rice Irrigation System (Kenya), was evaluated in the field to assess its potential for biological control of mosquito larvae. The study was conducted from October 1991 to April 1992 in experimental ponds constructed at Mbui-Njeru, which is one of the 36 villages in the irrigation scheme. T. zilli was found to be extremely effective in controlling mosquito breeding that persisted throughout the study period. However, the presence of vegetation and turbidity significantly reduced its efficiency in predation. The negative effects of vegetation could be averted by combining T. zilli with an herbivorous fish to control weeds. Similarly, breeding of other larvivorous organisms, including frogs, should be encouraged to enhance mosquito control efficiency. It is suggested that positive measures should be taken to deter colonization of catfish whose presence aggravates the turbidity problem and also depletes the fish population due to its substrate feeding and carnivorous behaviour.     

Characterization of 20 microsatellite loci in the long‐tailed tit Aegithalos caudatus (Aegithalidae,AVES)

We characterized 20 microsatellite loci in the long‐tailed tit, Aegithalos caudatus. Polymorphic loci were identified by testing 114 loci that had been originally isolated in other avian species. The loci were characterized in 23–163 unrelated long‐tailed tits from a British population and displayed between two and 42 alleles, with observed heterozygosity ranging between 0.09 and 0.97.     

Identification of a WT1 protein‐derived peptide,WT1187, as a HLA‐A*0206‐restricted,WT1‐specific CTL epitope

The Wilms' tumor gene WT1 is overexpressed in various kinds of hematopoietic malignancies as well as solid cancers, and this protein has been demonstrated to be an attractive target antigen for cancer immunotherapy. WT1‐specific CTL epitopes with a restriction of HLA‐A*2402 or HLA‐A*0201 have been already identified. In the present study it has been demonstrated that a 9‐mer WT1‐derived WT1₁₈₇ peptide, which had already been shown to elicit a WT1‐specific CTL response with a restriction of HLA‐A*0201, can also elicit a CTL response with a restriction of HLA‐A*0206. In all three different HLA‐A*0206⁺ healthy donors examined, WT1₁₈₇ peptide‐specific CTL could be generated from peripheral blood mononuclear cells, and the CTL showed cytotoxic activity that depended on dual expression of WT1 and HLA‐A*0206 molecules. The present study describes the first identification of a HLA‐A*0206‐restricted, WT1‐specific CTL epitope. The present results should help to broaden the application of WT1 peptide‐based immunotherapy from only HLA‐A*0201‐positive to HLA‐A*0206‐positive cancer patients as well.     

Lymphangioma of the pancreas: a multimodal approach to pre‐operative diagnosis

Background: Lymphangioma of the pancreas is an extremely rare benign tumour of lymphatic origin, with only four cases diagnosed by EUS‐FNA reported to date. Methods and materials: Five cases of either cytologically or histologically diagnosed pancreatic lymphangioma with pre‐operative cytological analysis by EUS‐FNAC were reviewed. Results: All patients were female, with a mean age of 56.4 years. By imaging, the cystic lesions ranged in size from 2 to 7 cm (mean 4.5 cm) and were mainly located in the head of the pancreas. All cysts had thin walls and no cyst demonstrated a mural nodule. Diagnosis based on imaging features was benign in all cases due to the absence of high‐risk features. Four samples were sent for biochemical analysis, which showed low CEA levels (range, <0.5–19.4 ng/ml; mean, 5.45 ng/ml) and CA 19.9 and CA 72.4 levels within normal range. All cyst fluids showed numerous small lymphocytes with no atypia; no epithelial cells were present, including no gastrointestinal contamination. Flow cytometry in two cases showed T lymphocytes with a mature phenotype. Surgical resection in two patients confirmed the cytological diagnosis. Benign clinical follow‐up was available in three patients at 2, 3 and 3.5 years. Conclusion: A multimodal approach to cytological diagnosis (combining clinical, radiological and cyst fluid gross, biochemical and cytological characteristics) can lead to the diagnosis of this cystic neoplasm and distinguish it from other more common cysts in the pancreas, potentially avoiding the need for unnecessary surgery.     

Transmembrane redox control and proteolysis of PdeC,a novel type of c‐di‐GMP phosphodiesterase

The nucleotide second messenger c‐di‐GMP nearly ubiquitously promotes bacterial biofilm formation, with enzymes that synthesize and degrade c‐di‐GMP being controlled by diverse N‐terminal sensor domains. Here, we describe a novel class of widely occurring c‐di‐GMP phosphodiesterases (PDE) that feature a periplasmic “CSS domain” with two highly conserved cysteines that is flanked by two transmembrane regions (TM1 and TM2) and followed by a cytoplasmic EAL domain with PDE activity. Using PdeC, one of the five CSS domain PDEs of Escherichia coli K‐12, we show that DsbA/DsbB‐promoted disulfide bond formation in the CSS domain reduces PDE activity. By contrast, the free thiol form is enzymatically highly active, with the TM2 region promoting dimerization. Moreover, this form is processed by periplasmic proteases DegP and DegQ, yielding a highly active TM2 + EAL fragment that is slowly removed by further proteolysis. Similar redox control and proteolysis was also observed for a second CSS domain PDE, PdeB. At the physiological level, CSS domain PDEs modulate production and supracellular architecture of extracellular matrix polymers in the deeper layers of mature E. coli biofilms.     

Field evaluation of a slow release pheromone formulation to control the American bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae) in Pakistan

Trials to control the American bollworm, Helicoverpa armigera (Hübner) by the technique of mating disruption were carried out in the Pakistan Province of Punjab during the 1996 cotton season. A slow release PVC resin formulation, Selibate(R) HA, containing a 97:3 mixture of the major (9Z-hexadecenal) and minor (11Z-hexadecenal) components of the female sex pheromone of H. armigera was applied at a rate of 40 g active ingredient ha-1 during August 1996. The formulation was applied around the terminal portion of the cotton plant by hand using local labour at a rate of c. 250 pieces per hectare. The efficacy of the formulation was compared to conventional insecticide regimes to control H. armigera on four farmer practice fields situated at least 1 km to the north, south, east and west of the pheromone treated area. A high degree of trap catch shutdown (indicating mating suppression) was observed throughout the pheromone treated area during the whole of the season compared to non-pheromone treated farmer practice fields. Night observations confirmed that mating disruption occurred in the pheromone treated area as a smaller percentage of mated females were collected from this area compared to farmer practice fields. A majority of mated females collected from the pheromone treated area mated only once, whereas females in farmer practice fields had undergone multiple matings. A greater percentage of tethered female H. armigera moths retrieved from farmer practice fields had successfully mated compared to tethered females retrieved from the pheromone treated area. Release rate data of H. armigera pheromone from the formulation show that c. 70% was released during the two month trial period. However, the highly dispersive pre-oviposition flight behaviour of females meant that the area treated was not sufficient to eliminate the problem of gravid females migrating in from surrounding areas, and ovipositing therein. The implications of using the technique of mating disruption to control large strong flying insects like H. armigera are discussed.