BACKGROUND: The psocids Liposcelis bostrychophila Badonnel and L. entomophila (Enderlein) (Liposcelididae) are emerging pests of stored products. Although their behavior, particularly their high mobility, may contribute to the reported relatively low efficacy of insecticides against them, studies to investigate this have not been conducted. The present study aimed to assess the label rate efficacy of three commercial insecticides (β‐cyfluthrin, chlorfenapyr and pyrethrins) applied on concrete surfaces against L. bostrychophila and L. entomophila, and also their sublethal effect on the mobility of these species. RESULTS: The synthetic insecticides β‐cyfluthrin and chlorfenapyr showed high short‐term efficacy (LT95≤15 h) against both psocid species, unlike the natural pyrethrins (LT95 ≥ 4 days). Liposcelis bostrychophila was slightly more tolerant (≥1.2×) than L. entomophila to all three insecticides. Behavioral assays with fully sprayed and half‐sprayed concrete arenas indicated that the insecticides reduced the mobility of both species. Pyrethrins seem to elicit weak repellence in L. bostrychophila. CONCLUSION: β‐Cyfluthrin and chlorfenapyr were effective against both psocid species, but not pyrethrins. The mobility of both species does not seem to play a major role in the differential selectivity observed, but the lower mobility of L. bostrychophila may be a contributing factor to its higher insecticide tolerance. Published in 2008 by John Wiley & Sons, Ltd. 相似文献
The residual water from intensive aquaculture production systems can be utilized in integrated multitrophic cultivations. In this work, Artemia franciscana received daily feedings of 10 mg L?1 of Tetraselmis chuii, Nannochloropsis oculata and Chaetoceros muelleri, which were grown using residual water from an intensive biofloc Litopenaeus vannamei cultivation system. The goal of this study was to verify which species provide the best zootechnical performance and best crustacean biomass production efficiency. After 12 days of cultivation, A. franciscana wet biomass was 815.64 ± 18.74, 650.81 ± 83.98 and 40.76 ± 4.08 mg L?1 with C. muelleri, T. chuii and N. oculata (P < 0.05), with significant differences in dried biomass as well. As for the microalgae cultivation in the alternative culture medium, T. chuii had higher dry biomass gain, requiring less culture volume to achieve 10 mg L?1 and become ready to feed Artemia. Thus, T. chuii was the most efficient in Artemia biomass production with 0.83 L compared to 1.54 L g art?1 in C. muelleri. C. muelleri is recommended for feeding A. franciscana for biomass production purposes. However, due to its better efficiency, T. chuii can be selected to be part of a multitrophic system. 相似文献
Brain cholinesterases from four fish (Arapaimagigas, Colossoma macropomum, Rachycentron canadum and Oreochromis niloticus) were characterized using specific substrates and selective inhibitors. Parameters of catalytic efficiency such as activation energy (AE), kcat and kcat/km as well as rate enhancements produced by these enzymes were estimated by a method using crude extracts described here. Despite the BChE-like activity, specific substrate kinetic analysis pointed to the existence of only acetylcholinesterase (AChE) in brain of the species studied. Selective inhibition suggests that C. macropomum brain AChE presents atypical activity regarding its behavior in the presence of selective inhibitors. AE data showed that the enzymes increased the rate of reactions up to 1012 in relation to the uncatalyzed reactions. Zymograms showed the presence of AChE isoforms with molecular weights ranging from 202 to 299 kDa. Values of kcat and kcat/km were similar to those found in the literature. 相似文献
An experiment was conducted to determine if dietary inclusion of distillers dried grains with solubles (DDGS), soybean hulls, or soybean hulls sprayed with an egg-based, polyclonal antibody product would reduce the incidence or severity of infection, or both, in growing pigs after a Lawsonia intracellularis challenge. One hundred 17-d-old weaned pigs were blocked by sex, ancestry, and BW, and randomly allotted to 1 of 5 treatment groups: negative control, unchallenged, corn-soy diet; positive control, challenged, corn-soy diet; 20% DDGS diet (D), challenged; 5% soybean hulls diet (SH), challenged; and SH sprayed with a polyclonal antibody product diet, challenged. Challenged pigs were orally inoculated with 6.4 x 10(8) L. intracellularis organisms after a 4-wk prechallenge feeding period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Challenging pigs with L. intracellularis reduced growth rate, feed intake, and efficiency of gain (P < 0.02) and increased the proportion of internal organ weights relative to BW (P < 0.01). Dietary treatment did not affect growth performance pre- or postchallenge (P > 0.10). Heart, empty stomach, and liver weights were similar among dietary treatments (P > 0.10). Weight of the large intestine as a percentage of BW was increased in D and SH pigs compared with positive control pigs (P < 0.05). Lesion length, prevalence, and severity, and fecal shedding of L. intracellularis were primarily unaffected by dietary treatment (P > 0.10), although ileal lesion length and severity observed tended to be greater in the SH sprayed with polyclonal antibody product diet vs. the D pigs (P < 0.10). Results from a previous study indicated that diet composition may affect length, severity, and prevalence of lesions caused by L. intracellularis in growing pigs subjected to a moderate challenge. However, beneficial results were not observed by feeding the dietary treatments used in this study. 相似文献
An experiment was conducted to determine if including distillers dried grains with solubles (DDGS) in the diet of growing pigs reduces the incidence or severity of infection after a Lawsonia intracellularis challenge. Eighty 17-d-old weaned pigs were blocked by sex, ancestry, and BW and randomly allotted to 1 of 4 treatment groups: negative control (NC), unchallenged, corn-soy diet; positive control (PC), challenged, corn-soy diet; 10% DDGS diet (10D), challenged; and 20% DDGS diet (20D), challenged. Challenged pigs were orally inoculated with 1.5 x 10(9) L. intracellularis organisms after a 4-wk prechallenge feeding period. On d 21 postchallenge, pigs were euthanized, lesions of intestinal mucosa were evaluated, and ileal tissue samples were analyzed by immunohistochemistry to determine the presence and proliferation rate of L. intracellularis. Compared with unchallenged pigs, challenging pigs with L. intracellularis reduced growth rate, feed intake, and efficiency of gain (P < 0.01) and increased gauntness (P < 0.05) and diarrhea (P < 0.01). Diet did not affect growth performance postchallenge (P > 0.40). Feeding 10 or 20% DDGS diets did not reduce lesion length, prevalence, proliferation of L. intracellularis, or severity of lesions (P > 0.10). Thus, dietary inclusion of DDGS did not reduce the incidence or severity of lesions under the conditions of a severe L. intracellularis challenge used in this study. 相似文献
The aims of the present study were to determine (i) the profiles of phylogroup and (ii) the antimicrobial susceptibility of pathogenic Escherichia coli strains isolated from calves, and of Salmonella spp. strains isolated from calves and pigs in Minas Gerais State, Brazil. Sixty-one pathogenic E. coli strains and Salmonella spp. (n?=?24) strains isolated from fecal samples of calves and Salmonella spp. (n?=?39) strains previously isolated from fecal samples of growing/finishing pigs were tested. The minimum inhibitory concentration (MIC) using the agar dilution method was determined for nalidixic acid, amikacin, amoxicillin, ampicillin, cefoxitin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. All E. coli isolates were susceptible to amikacin. Tetracycline was the antimicrobial that presented the higher frequency of resistance among E. coli strains, followed by ampicillin, trimethoprim-sulfamethoxazole, amoxicillin, nalidixic acid, norfloxacin, gentamicin, and cefoxitin. E. coli (n?=?61) strains isolated from calves belonged to different phylogroup namely, phylogroup A (n?=?26), phylogroup B1 (n?=?31), phylogroup E (n?=?3), and phylogroup F (n?=?1). Phylogroups B2, C, and D were not identified among the E. coli in the present study. All Salmonella spp. (n?=?24) strains isolated from fecal samples of calves were susceptible to amikacin, amoxicillin, ampicillin, norfloxacin, gentamicin, tetracycline, and trimethoprim-sulfamethoxazole. Resistance to nalidixic acid and cefoxitin was detected in 16.66 and 8.33 % of the Salmonella spp. strains, respectively. Among the Salmonella spp. (n?=?39) strains isolated from fecal samples of pigs, the higher frequency of resistance was observed to tetracycline, followed by amoxicillin, gentamicin, ampicillin, trimethoprim-sulfamethoxazole, nalidixic acid, cefoxitin, and norfloxacin. All strains were susceptible to amikacin. Forty-eight (78.68 %) of the E. coli strains were classified as multidrug-resistant, whereas among Salmonella spp. strains, the percentage of multidrug resistance was 57.14 %, being all multidrug-resistant strains isolated from pigs (92.30 %). The results from the present study indicate a high frequency of antimicrobial resistance among pathogenic E. coli strains isolated from calves and Salmonella spp. strains isolated from pigs and a high rate of susceptibility to most antimicrobials tested among Salmonella spp. strains isolated from calves. Our study highlights the presence of multidrug-resistant strains of E. coli and Salmonella spp. isolated from food-producing animals in Minas Gerais, Brazil. 相似文献
The cover image, by Eugênio E. Oliveira et al., is based on the Research Article Pyrethroid resistance is associated with a kdr‐type mutation (L1014F) in the potato tuber moth Tecia solanivora, DOI: 10.1002/ps.4414 . Photo Credit: Edison Torrado‐Leon.
This article studies the dependence of spatial linear models using a slash distribution with a finite second moment. The parameters of the model are estimated with maximum likelihood by using the EM algorithm. To avoid identifiability problems, the cross-validation, the Trace and the maximum log-likelihood value are used to choose the parameter for adjusting the kurtosis of the slash distribution and the selection of the model to explain the spatial dependence. We present diagnostic techniques of global and local influences for exploring the sensibility of estimators and the presence of possible influential observations. A simulation study is developed to determine the performance of the methodology. The results showed the effectiveness of the choice criteria of the parameter for adjusting the kurtosis and for the selection of the spatial dependence model. It has also showed that the slash distribution provides an increased robustness to the presence of influential observations. As an illustration, the proposed model and its diagnostics are used to analyze an aquifer data. The spatial prediction with and without the influential observations were compared. The results show that the contours of the interpolation maps and prediction standard error maps showed low changes when we removed the influential observations. Thus, this model is a robust alternative in the spatial linear modeling for dependent random variables. Supplementary materials accompanying this paper appear online. 相似文献
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