Larval competition within and between insecticide resistant and susceptible individuals in the oriental fruit fly,Bactrocera dorsalis

Insecticide resistance is a serious issue in agriculture. Ecological interactions may be used to manage the spread of resistance, but little information is currently available. In particular, virtually none is known about interactions between resistant and susceptible individuals. This study investigated competition between resistant and susceptible oriental fruit fly larvae (Bactrocera dorsalis). Competition in the larval stage was examined with an explicit consideration of individual identity (resistant or susceptible). Guava fruits were inoculated with eggs of susceptible and/or resistant flies, and their development and survival were monitored. Egg density influenced the time that larvae stayed in fruits as well as their survival. In addition, susceptible flies survived better when interacting with resistant flies than with other susceptible flies, indicating that susceptible flies are competitively superior to resistant flies. The results suggest that artificially creating environments that induce competition between susceptible and resistant flies can be useful for the management of insecticide resistance.     

Effects of herbivore stress by Aphis medicaginis Koch on the Malondialdehyde contents and the activities of protective enzymes in different alfalfa varieties

The study focused on the dynamics of Malondialdehyde (MDA) contents and the activities of protective enzymes in the leaves of alfalfa varieties with various resistances to Aphis medicaginis Koch. The results showed that susceptible varieties always had higher MDA contents than resistant varieties, and the MDA contents tended to rise in both susceptible and resistant varieties in period of the varieties were pierced and sucked by aphids. Superoxide dismutase (SOD), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities in susceptible varieties were lower than those in resistant varieties, and in both susceptible and resistant varieties the SOD and POD activities tended to rise at first and then decline, and the PAL activities rose to their peaks and then tended to remain stable. In the susceptible and resistant varieties the catalase (CAT) activities appeared to rise and decline alternatively; the PPO activities in resistant varieties were lower than those in susceptible varieties in early growth, but higher than those in susceptible varieties in later growth. It follows that infested by aphids, susceptible and resistant varieties had the MDA contents, variations of SOD, POD, PAL and PPO activities were closely correlated with their aphid resistances, hence these indexes could be used as physiological indexes for testing aphid resistance of alfalfa, whereas the relations of their CAT activities to their resistances needed to be further studied.     

Effects of herbivore stress by Aphis medicaginis Koch on the Malondialdehyde contents and the activities of protective enzymes in different alfalfa varieties

The study focused on the dynamics of Malondialdehyde (MDA) contents and the activities of protective enzymes in the leaves of alfalfa varieties with various resistances to Aphis medicaginis Koch. The results showed that susceptible varieties always had higher MDA contents than resistant varieties, and the MDA contents tended to rise in both susceptible and resistant varieties in period of the varieties were pierced and sucked by aphids. Superoxide dismutase (SOD), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities in susceptible varieties were lower than those in resistant varieties, and in both susceptible and resistant varieties the SOD and POD activities tended to rise at first and then decline, and the PAL activities rose to their peaks and then tended to remain stable. In the susceptible and resistant varieties the catalase (CAT) activities appeared to rise and decline alternatively; the PPO activities in resistant varieties were lower than those in susceptible varieties in early growth, but higher than those in susceptible varieties in later growth. It follows that infested by aphids, susceptible and resistant varieties had the MDA contents, variations of SOD, POD, PAL and PPO activities were closely correlated with their aphid resistances, hence these indexes could be used as physiological indexes for testing aphid resistance of alfalfa, whereas the relations of their CAT activities to their resistances needed to be further studied.     

树[鼠句]正常肠道细菌的培养分离鉴定及其药敏试验研究

目的了解人工饲养树[鼠句]肠道菌群感染情况及其各种细菌对药物的敏感性。方法通过肠道细菌采样、培养、分离和菌落生长特性观察,并经革兰氏染色、氧化酶试验、触酶试验、生化编码鉴定管试验和9种药敏试验分析,初步鉴定了107例人工饲养树[鼠句]肠道感染细菌的种类和这些细菌对药物的敏感程度。结果本次细菌培养共从树[鼠句]肠道中培养分离出5株细菌,其中革兰氏阳性菌2株,革兰氏阴性菌3株,以大肠杆菌和葡萄球菌最为多见。同时确定了菌株的药敏情况为：（1）大肠杆菌对头孢类药头孢哌酮最为敏感,对药物磺胺甲嚼唑／甲氧苄定、氧氟沙星、左氧氟沙星、呋喃妥因、诺氟沙星、氨苄西林高敏;（2）沙门氏菌对阿米卡星最为敏感,对药物头孢哌酮青霉素G高敏;（3）链球菌对试验药物氨苄西林、头孢哌酮、呋喃妥因显示为中敏;（4）葡萄球菌对头孢类药头孢哌酮、磺胺类磺胺甲晤唑／甲氧苄定、沙星类诺氟沙星、左氧氟沙星、氧氟沙星、呋喃妥因和氨苄西林最为敏感,对其它药物均为中敏;（5）假单胞菌对药物左氧氟沙星最为敏感,对大多数药物都显示高敏。结论大肠杆菌和葡萄球菌可能是树鼢肠道中正常寄生的主要菌群,同时其它菌群也有寄生。用药敏实验筛选出的药物可为临床用药和动物的生物净化提供指导依据。     

Antimicrobial susceptibility of cerebrospinal isolates from patients with meningitis

Str. pneumoniae isolates were susceptible to penicillin, all to also ofloxacin and chloramphenicol and cefotaxim and 39 (100%) to cotrimoxazol. Concerning S. aureus, all isolates 22 were susceptible to oxacillin and chloramphenicol, and 21 also to cotrimoxazol. All N. meningitidis isolates but one-10 of all were susceptible to penicillin, all to cefotaxim, chloramphenicol and cotrimoxazol. All H.influenzae isolates were susceptible to ampicillin and chloramphenicol, as well as to ofloxacin and cotrimoxazol. Those surprisingly high susceptibilities to rather "old" antibiotics may be explained by low antibiotic consumption, accessibility and therefore low usage which is a key promoter of resistance both in community and hospital.     

Oxydemeton-methyl resistance, mechanisms, and associated fitness cost in green peach aphids (Hemiptera: Aphididae)

Susceptibility to oxydemeton-methyl and imidacloprid, and the inhibitory effects of oxydemeton-methyl and some organophosphate compounds on acetylcholinesterase (AChE) and carboxylesterase activity were studied in two populations (Karaj and Rasht) of green peach aphids, Myzus persicae (Sulzer). Results show that the Karaj population was resistant to oxydemeton-methyl but susceptible to imidacloprid. The esterase activity of the resistant and susceptible populations suggests that one of the resistance mechanisms to oxydemeton-methyl was esterase-based. The inhibition assay shows that the AChE of the Karaj population is less sensitive to oxydemeton-methyl and paraoxon derivatives. Regarding the paraoxon derivatives, the smaller paraoxon side chain is more potent against the modified AChE than against the AChE from the susceptible strain. Fertility life table parameters of green peach aphid populations resistant and susceptible to oxydemeton-methyl also were studied under laboratory conditions. The standard errors of the population growth parameters were calculated using the Jackknife method. Results showed that susceptible strain exhibits a significantly higher r(m) than the resistant strain, probably because the resistant strain had a higher generation time than the susceptible strain. These results suggested that the resistant Karaj strain may be less fit than the susceptible strain.     

Modern antifungals in therapy of nosocomial mycosis in oncologic patients

Rational position of voriconazole in the treatment of oncologic inpatients was shown and the criteria of its use in the algorithms of the therapy and prophylaxis of nosocomial fungal infections were developed. The clinical trial enrolled 50 patients with oncologic pathologies. The patients were divided into two groups of possible invasive candidiasis risk. The patients of one group were treated with fluconazole (Diflucan) and those of the other group were treated with voriconazole (Vifend). The spectrum of the hospital fungal flora was determined and susceptibility of 310 clinically important opportunistic fungi was investigated. All the isolates of Candida albicans and C.tropicalis were susceptible to amphotericin B, fluconazole and voriconazole and 79 and 50% of the isolates were susceptible to intraconazole respectively. As for the C.krusei isolates, 67% was susceptible to amphotericin B, 50% was susceptible to fluconazole, 100% was susceptible to voriconazole and none of the strains was susceptible to intraconazole. By the clinical efficacy voriconazole was superior to fluconazole and comparable with amphotericin B, while superior to it by the number of the side effects and by the cost of the treatment course. It was concluded that voriconazole should be considered as the main agent in the antifungal therapy of oncologic patients.     

The effects of rootstock and scion on tobacco mosaic virus infection in susceptible, tolerant and immune cultivars of tomato

Reciprocal grafts were made between tomato cultivars Potentate, susceptible, and Virocross, tolerant (heterozygous for resistance gene Tm-i) to tobacco mosaic virus (TMV) isolates of Pelham type o and between isogenic lines of cv. Craigella, susceptible and homozygous for gene Tm-i. The grafted plants were inoculated with a type o isolate; both scion and stock inoculation were studied in the former, scion inoculation only, in the latter. With scion inoculation the virus content of a tolerant scion was greater on a susceptible stock than on a tolerant one, but that of a susceptible scion was unaffected by the type of stock: in contrast, the virus content of a tolerant stock was unaffected by the type of scion but that of a susceptible stock was less with a tolerant than with a susceptible scion. With root inoculation the virus contents of both tolerant and susceptible scions were greater on a susceptible than on a tolerant stock. With cv. Craigella the genotype Tm-1/Tm-1 was found to be immune to the type o isolate used, but in grafts the leaves of Tm-1/Tm-1 scions became tolerant to leaf inoculation when on susceptible stocks and the virus entered the stock. Tm-1/Tm-1 stocks became infected when attached to infected, susceptible scions and did not affect the virus content of those scions. The results indicate that a susceptible healthy stock may change the reaction of a tolerant or immune scion to infection by a strain of TMV.     

The effects of age, sex and breed of chicken on susceptibility to Clinostomum complanatum (Digenea: Clinostomatidae)

Susceptibility and development of Clinostomum complanatum in the chicken (Gallus gallus domesticus) have been studied. The progenetic metacercariae of C. complanatum developed into ovigerous worms in 3 days in the buccal cavity of the chicken and survived only 6-7 days in this experimental host. The susceptibility is influenced by the age, sex and breed/type of the host. Both percent susceptibility and recovery of the worms decreased with increase in the age of the host. The egg laying chickens were found to be least susceptible to the infection. Mature male chickens were more susceptible than the females. The single comb white Leghorn (SCWL) was found to be susceptible while the local type (LT) and the cross breed (SCWLxLT) were not susceptible to C. complanatum. The possible reasons for these variations have been discussed.     

Susceptibility to purple blotch (Alternaria porri) in garlic (Allium sativum)

Experiments were conducted to study the progress of purple blotch disease of garlic caused by Alternuria porri in the field, to determine the relationship between garlic leaf age and susceptibility to Alternaria porri, and also to assess loss in bulb characters due to purple blotch of garlic. Per cent disease severity and number of purple blotch lesions on four garlic genotypes of known susceptibility, Sel-10 (highly susceptible), G-41 (highly susceptible), IC-49382 (moderately susceptible) and IC-49373 (moderate to less susceptible) were monitored from bulb formation to bulb maturity at weekly intervals. Lesions appeared early on highly susceptible cultivars, Sel-10 and G-41. Rapid progress of disease development was noticed during the last 3 wk before bulb maturity. Peak severity at the maturity of the crop was significantly higher on highly susceptible genotypes. No definite correlation could be established between number of lesions and disease severity. A logistic curve was fitted to predict the disease progress on different weeks before bulb maturity. Levels of leaf tissue found damaged by A. porri at weekly intervals from bulb initiation to bulb maturity were significantly lower on younger leaves than on older leaves. Leaves that emerged 7 wk before bulb maturity required more than a 5 wk period to reach 50% leaf damage, whereas leaves emerging 2, 3 and 4 wk before bulb maturity exceeded 50% leaf damage within a 2–3 wk period. Individual garlic leaves became more susceptible to purple blotch as they aged and emerging leaves were more susceptible the closer they emerged to bulb maturity. Per cent loss in bulb weight and bulb volume was found to be significantly higher on highly susceptible genotypes. No significant reduction in number of cloves/bulb was observed. We propose 4 wk before bulb maturity as the action threshold for initiation of fungicidal application to prevent damaging levels of disease.     

Antibiotic sensitivity of pneumonia pathogens in newborns and problems of antibacterial therapy of the pathologic process]

The results of the bacteriological investigation of the secretion from the trachea, large bronchi and fauces of 36 newborns (including 27 preterms) with severe pneumonia were analyzed. 20 of them were born of women with complicating somatic, obstetric and gynecologic histories: candidiasis, herpes genitalis, chronic endometritis, adnexitis or chronic pyelonephritis that could be the risk of the fetus intranatal infection. During the acute period of pneumonia in the newborns within the first 4-8 days of life mainly Pseudomonas aeruginosa was isolated (51.3 per cent), Staphylococcus epidermidis, S. haemolyticus and Enterococcus faecalis were less frequent (18.9, 8.1 and 5.4 per cent, respectively). Klebsiella pneumoniae, Streptococcus anhaemolyticus and other organisms were extremely rare. On the whole the gramnegative microflora predominated. The study of the antibiotic susceptibility showed that the majority of the P. aeruginosa isolates were susceptible to amikacin and polymyxin B, the isolates susceptible to ceftazidime were less frequent, 20-25 per cent of the isolates were susceptible to ciprofloxacin, cefoperazone and imipenem and practically no isolates were susceptible to gentamicin. The S.epidermidis isolates were susceptible to rifampicin and vancomycin and in rare cases to fusidin and amikacin and resistant to oxacillin. When the treatment course was more than 15 days, the isolates proved to be susceptible to 1/3 of the presently available antibiotics. Because of the host low protective forces, peculiarities of the infection pathways and high frequency of the resistant strains it is valid to include netilmicin, imipenem, cefoperazone and ceftriaxone to the complex therapy of the newborns along with the substitution immunotherapy.     

Identification of resistance source in wheat germplasm against spot blotch disease caused by Bipolaris sorokiniana

Four hundred and twenty-two spring wheat germplasm (Triticum aestivum L.) lines belonging to Indian, CIMMYT and Chinese wheat programme were evaluated for their tolerance against natural epiphytotic conditions of spot blotch caused by Bipolaris sorokiniana at the hot spot location, Pusa, Bihar, India. Of the 422 entries screened, none of the genotype showed immunity to the disease, whereas 52 were resistant, 180 moderately susceptible, 171 susceptible and 19 highly susceptible. Indian germplasm lines tended to be more susceptible than lines originated from CIMMYT and China. Chirya 3, Chirya 7 and Mayoor from CIMMYT showed high degree of resistance to the disease both under field and polyhouse conditions. On the basis of the disease severity under field conditions, 20 promising resistant genotypes and 10 highly susceptible lines were isolated for further testing under artificial epiphytotic conditions in polyhouse for genetic analysis and their potential for spot blotch resistance breeding.     

Influence of olfactory stimulants on resistance/susceptibility of pearl millet, Pennisetum americanum to the rice weevil, Sitophilus oryzae

The orientation responses of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) as influenced by the olfactory stimulants emanating from either resistant or susceptible pearl millet, Pennisetum americanum, kernels were studied using a Y-tube olfactometer. The rice weevils were more attracted towards odours from millet grains than to blank controls and to susceptible entries more than to resistant entries, in general. However, there were exceptions. Odours from some resistant entries caused statistically the same, or even more positive orientations than those from some susceptible entries, and this suggests that the relative resistance of an entry and its olfactory attractiveness may not be strongly related, or that the resistance to infestation might be influenced by factors other than attractiveness. The partial damage of the millet kernel pericarp by abrasion slightly increased the orientational response of the weevils to odours from some susceptible and some resistant entries alike.     

小菜蛾碱性磷酸酶基因cDNA片段的克隆及其序列分析

利用DNAman设计简并引物,通过反转录一多聚酶链式反应(RT-PCR)克隆小菜蛾Plutella xylostella(L.)抗性、敏感种群中可能与苏云金芽孢杆菌(Bt)抗性相关的碱性磷酸酶基因。琼脂糖电泳结果显示扩增条带与预期片段长度一致,阳性克隆经测序获得了403bp的基因片断。经blast比较得出所克隆基因属于碱性磷酸酶基因。与敏感种群相比,抗性种群中该基因片段有18个碱基发生变化,有1个氨基酸发生替换(缬氨酸转变为苏氨酸)。研究结果对于进一步研究小菜蛾全基因结构、功能有重要的意义。     

Endometritis in the mare: A comparison between reproductive history and uterine biopsy as techniques for predicting susceptibility of mares to uterine infection

Thirty mares with no clinical signs of endometritis were categorized as being susceptible or resistant to uterine infection depending on whether or not they had a history of recurrent endometritis. The same mares were then independently classified as susceptible or resistant on the basis of their uterine biopsies; those with significant endometrial degeneration were considered to be susceptible to endometritis. The mares then received an intrauterine inoculation of pathogenic Streptococcus zooepidemicus . Those mares which eliminated bacteria by 10 d after inoculation were considered truly resistant to endometritis, whereas those still infected at 10 d were considered susceptible. The original classifications based on history or biopsy were compared to the inoculation results. A history of recurrent endometritis provided a more sensitive (0.90) and specific (0.95) indication of susceptibility to uterine infection than a uterine biopsy with significant endometrial degeneration (sensitivity 0.5, specificity 0.75).     

Impact of Host Resistance on the Variability in Virulence of Xanthomonas campestris pv. oryzae

Twenty isolates of Xanthomonas campestris pv. oryzae (Ishiyama) Dye each from susceptible and resistant rice cultivars, were inoculated on the susceptible genotype IR-8 and resistant M Sungsong to measure the impact of host selection pressure on virulence change. Isolates virulent on resistant genotype tended to be less adaptive on susceptible cultivars. While isolates from susceptible genotype showed 2.2 times more general virulence (GV) than specific virulence (SV), isolates of resistant host origin had only 1.3 times GV, indicating that the resistant host plant displays considerable increase in virulence. The SV value increased 1.64 times after one cropping with resistants indicated the potential of the pathogen to change to be slow.     

敏感和抗性棉铃虫对溴氰菊酯毒力反应的机理研究

通过生物测定和生物化学方法比较了棉铃虫玎Helicoverpa armigera敏感和抗性种群对溴氰菊酯毒力反应及其3种解毒酶的差异。结果表明,田间抗性种群和室内药剂汰选的抗性种群对溴氰菊酯均有较高的抗性,其抗性倍数分别达到195.8和37 375倍。水解酯酶和多功能氧化酶是导致棉铃虫对溴氰菊酯产生高抗性的重要酶系。特异性抑制剂活体内外抑制作用测试发现,敏感种群和抗性种群均含有较高量的乙酰胆碱酯酶,但两个种群对抑制剂的亲和力反应不同,表明乙酰胆碱酯酶在敏感种群和抗性种群中发生了不同的变化,这种变化可能与棉铃虫对溴氰菊酯的抗性有关。由此推断,棉铃虫对拟除虫菊酯这类中枢神经系统神经毒剂产生抗性,乙酰胆碱酯酶发生变化可能也是一个重要因子。     

花魔芋抗软腐病植株的鉴定及其抗性机理的初步研究

通过筛选获得了对魔芋(Amorphophallus konjac)软腐病具有较强抗性的花魔芋抗病植株, 经核型分析发现, 其染色体数目与普通植株一致, 均为2n=26。抗病实验结果表明, 该抗病植株对魔芋软腐病的抗性较普通植株强。采用酶联免疫吸附法, 测定了软腐病病原菌接种30小时内的抗病与普通植株叶片中内源植物激素(SA与JA)的含量变化。结果显示, 抗病和普通植株叶片中SA和JA含量变化的总体趋势明显不同。主要表现在, 抗病和普通植株叶片中SA和JA积累的时间不同; 此外, 积累的量也有明显差异。推测魔芋抗病植株可能存在与目前大多数植株不同的抗病机制。     

Screening and Assessment of Selected Chilli (<i>Capsicum annuum</i> L.) Genotypes for Drought Tolerance at Seedling Stage

This study was undertaken to investigate oxidative stress tolerant mechanisms in chilli (Capsicum annuum L.) under drought genotypes through evaluating morphological, physiological, biochemical and stomatal parameters. Twenty genotypes were evaluated for their genetic potential to drought stress tolerant at seedling stage. Thirty days old seedlings were exposed to drought stress induced by stop watering for the following 10 days and rewatering for the following one week as recovery. Based on their survival performance, two tolerant genotypes viz. BD-10906 and BD-109012 and two susceptible genotypes viz. BD-10902 and RT-20 were selected for studying the oxidative stress tolerance mechanism. Drought reduced root and shoot length, dry weight, ratio, petiole weight and leaf area in both tolerant and susceptible genotypes, and a higher reduction was observed in susceptible genotypes. Lower reduction of leaf area and photosynthetic pigments were also found in tolerant genotypes. Moreover, tolerant genotypes showed higher recovery than susceptible genotypes after the removal of stress. A higher reduction of relative water content (RWC) may cause an imbalance between absorbed and transpirated water in susceptible genotypes. Higher accumulation of proline in tolerant genotypes might be helpful to for better osmotic maintenance than that in susceptible genotypes. Tolerant genotypes showed higher antioxidant activity as they showed DPPH radical scavenging percentage than the susceptible genotypes. Moreover, closer stomata in tolerant genotypes than susceptible ones helped to avoid dehydration in tolerant genotypes. Thus, the above morphological, physiological, biochemical and stomatal parameters helped to show better tolerance in chilli under drought stress.     

Screening for Barley Yellow Dwarf Luteovirus Resistance in Barley on the Basis of Virus Movement

The movement of barley yellow dwarf luteovirus (BYDV) was evaluated in susceptible and resistant barley and bread wheat genotypes. After leaf inoculation, the virus infected the root system and the growing point of susceptible earlier than resistant, barley genotypes. No difference in virus movement occurred in resistant and susceptible wheat genotypes. It was possible to reliably differentiate susceptible from resistant genotypes when root extracts of 41 barley genotypes were tested by DAS-ELISA 3 or 4 days after inoculation at the oneleaf stage. When barley plants inoculated at the two- or three-leaf stage were assayed by tissue-blot ELISA on nitrocellulose membrane, virus was detected in the phloem vessels of the growing points of the susceptible, but not of the resistant genotype, 4–6 days after inoculation. Our results thus suggest that screening for BYDV resistance in barley could be done quickly and cheaply especially when assays are made by the tissue-blot test.