Rapid identification of environmental isolates of Pseudomonas aeruginosa, P. fluorescens and P. putida by SDS-PAGE analysis of whole-cell protein patterns

Abstract Environmental isolates of fluorescent pseudomonads grown to early stationary phase in glucose-enriched Luria broth were treated with proteinase K in sodium dodecylsulphate (SDS) lysis buffer and subsequently analyzed by polyacrylamide gel electrophoresis (PAGE). Four silver-staining protein-fragment bands could be used for rapid identification at the species level. Pseudomonas aeruginosa isolates were easily recognized by a unique banding pattern. Isolates considered to be P. fluorescen from biochemical and physiological tests (classical biotypes I, II, III, IV and V) also had a characteristic banding pattern, which in turn was different from that of P. putida isolates (classical biotype A). A residual group representing intermediate isolates of P. fluorescens (new biotype VI of Barrett et al., J. Gen. Microbiol. 132, 1986) or P. putida (biotype B) had a banding pattern similar to that of classical P. fluorescens biotypes. On the other hand, a group representing other intermediate isolates of P. putida (new biotype C of Barrett et al., J. Gen. Microbiol. 132, 1986) had a unique banding pattern resembling that of classical P. putida biotype A. A small number of protein fragment bands appearing in SDS-PAGE analysis of whole-cell lysates seems adequate for a rapid identification at the species level of P. aeruginosa, P. fluorescens and P. putida isolated from natural environments.     

Relative toxicity of nC24 agricultural mineral oil to Tetranychus urticae Koch (Acari: Tetranychidae) and Phytoseiulus persimilis Athias-Henriot (Acari: Phytoseiidae) and its possible relationship to egg ultrastructure

The relative toxicity (LC₅₀ values based on µg oil/cm²) is evaluated of aqueous n C24 agricultural mineral oil (AMO) emulsions to the egg, six-legged nymph (larva), eight-legged protonymph and adult stages of two-spotted mite ( Tetranychus urticae ) and its predator, Phytoseiulus persimilis , on French bean leaf discs, using a Potter spray tower to apply of the oil. The egg of P. persimilis was the least susceptible stage (LC₅₀ 444.84) and its LC₅₀ was significantly higher than all other stages tested of either P. persimilis or T. urticae . The LC₅₀ for adult female T. urticae (LC₅₀ 63.89) was significantly lower than the larva (LC₅₀ 93.86); however, there was no significant difference in response between the protonymph (LC₅₀ 70.44) and the larva, which were both higher than T. urticae eggs (LC₅₀ 17.55). LC₅₀s for P. persimilis larva (LC₅₀ 43.87), protonymph (LC₅₀ 41.55) and adult female (LC₅₀ 53.34) were similar. Scanning electron microscopy showed that the egg surface of T. urticae is usually well covered with fine silk that may trap more oil and increase AMO efficacy. Other possible differences in AMO efficacy between T. urticae and P. persimilis may be due to differences in egg size, egg incubation period, egg surface structure and the presence of vulnerable respiratory cones in T. urticae eggs. Dose of 0.2–0.3% (w/w) is considered to be the most appropriate for n C24 AMOs use against T. urticae in combination with P. persimilis in integrated pest management programs.     

烟粉虱生物型对浅黄恩蚜小蜂寄主选择及个体发育的影响

为探讨寄生蜂在Q型烟粉虱Bemisia tabaci替代B型烟粉虱的过程中是否起作用, 我们在实验室条件(温度27±1℃, 光周期16L∶8D, 相对湿度RH 70%～80%)下, 观察了浅黄恩蚜小蜂Encarsia sophia寄生B型和Q型烟粉虱若虫的行为, 研究了浅黄恩蚜小蜂对B型和Q型烟粉虱若虫的选择性、 烟粉虱生物型对浅黄恩蚜小蜂取食数量及个体发育的影响。结果发现, 浅黄恩蚜小蜂体外检测时间在B型和Q型烟粉虱若虫间差异不显著, 而寄生Q型烟粉虱若虫时的体内检测和产卵时间(190.2±14.6 s）显著高于寄生B型时所用时间(140.0±7.5 s)。在非选择条件下, 浅黄恩蚜小蜂寄生B型烟粉虱若虫的数量(8.1±0.5头)及总产卵量（9.3±0.6粒）显著高于仅提供Q型烟粉虱的寄生数量(6.3±0.5头)及总产卵量(7.0±0.6粒); 而被寄生若虫单头着卵量在处理间差异不显著。在选择性条件下, 该蜂寄生B型烟粉虱若虫量(3.1±0.4头)、总产卵量(3.8±0.5粒)及被寄生若虫单头着卵量(1.2±0.1粒)都显著高于寄生Q型烟粉虱时的情况(1.8±0.3头、1.8±0.4粒、0.7±0.1粒)。被寄生蜂取食的B型与Q型烟粉虱数量间差异不显著, 但对于同一生物型而言, 交配过的雌蜂能够取食更多的烟粉虱若虫。以B型烟粉虱为寄主时, 浅黄恩蚜小蜂雌蜂卵-黑蛹(7.2±0.1 d)、黑蛹-羽化(5.2±0.1 d)的发育时间与以Q型烟粉虱若虫为寄主时的相应发育时间(7.3±0.1 d, 5.6±0.1 d)间无显著性差异。以B型烟粉虱为寄主时寄生蜂的羽化率（73.55%±1.42%）与以Q型烟粉虱为寄主时的羽化率（68.42%±13.01%）间差异不显著。这些结果表明, 虽然浅黄恩蚜小蜂发育时间、 羽化率在烟粉虱2种生物型间无显著差异, 但该小蜂倾向于B型烟粉虱若虫作为寄主, 而且, 以B型烟粉虱若虫为寄主时, 小蜂的产卵量和寄生若虫数量均增加。但田间浅黄恩蚜小蜂的存在是否有助于Q型烟粉虱成为B型和Q型混合种群的优势种群, 还需进一步研究。     

Differential response of etiolated pea seedlings to inoculation with rhizobacteria capable of utilizing 1-aminocyclopropane-1-carboxylate or L-methionine

The majority of soil microorganisms can derive ethylene from L-methionine (L-MET), while some rhizobacteria can hydrolyze 1-aminocyclopropane-1-carboxylate (ACC) due to their ACC-deaminase activity. In this study, three strains having either ACC-deaminase activity (Pseudomonas putida biotype A, A7), or the ability to produce ethylene from L-MET (Acinetobacter calcoaceticus, M9) or both (Pseudomonas fluorescens, AM3) were used for inoculation. The highly ethylene specific bioassay of a classical "triple" response in pea seedlings was used to investigate the effect of the inoculation with the rhizobacteria in the presence of 10 mM ACC or L-MET. The exogenous application of ACC had a concentration-dependent effect on the etiolated pea seedlings in creating the classical "triple" response. The inoculation with P. putida diluted the effect of ACC, which was most likely due to its ACC-deaminase activity. Similarly, the application of Co2+ reduced the ACC-imposed effect on etiolated pea seedlings. In contrast, the inoculation of A. calcoaceticus or P. fluorescens in the presence of L-MET caused a stronger classical "triple" response in etiolated pea seedlings; most likely by producing ethylene from L-MET. This is the first study, to our knowledge, reporting on the comparative effect of rhizobacteria capable of utilizing ACC vs L-MET on etiolated pea seedlings.     

Cloning, nucleotide sequence, and overexpression of the gene coding for delta 5-3-ketosteroid isomerase from Pseudomonas putida biotype B.

The structural gene coding for the delta 5-3-ketosteroid isomerase (KSI) of Pseudomonas putida biotype B has been cloned, and its entire nucleotide sequence has been determined by a dideoxynucleotide chain termination method. A 2.1-kb DNA fragment containing the ksi gene was cloned from a P. putida biotype B genomic library in lambda gt11. The open reading frame of ksi encodes 393 nucleotides, and the amino acid sequence deduced from the nucleotide sequence agrees with the directly determined amino acid sequence (K. Linden and W. F. Benisek, J. Biol. Chem. 261:6454-6460, 1986). A putative purine-rich ribosome binding site was found 8 bp upstream of the ATG start codon. Escherichia coli BL21(DE3) transformed with the pKK-KSI plasmid containing the ksi gene expressed a high level of isomerase activity when induced by isopropyl-beta-D-thiogalactopyranoside. KSI was purified to homogeneity by a simple and rapid procedure utilizing fractional precipitation and an affinity column of deoxycholate-ethylenediamine-agarose as a major chromatographic step. The molecular weight of KSI was 14,535 (calculated, 14,536) as determined by electrospray mass spectrometry. The purified KSI showed a specific activity (39,807 mumol min-1 mg-1) and a Km (60 microM) which are close to those of KSI originally obtained from P. putida biotype B.     

Predation and oviposition by predatory Stethorus japonicus, Oligota kashmirica benefica, and Scolothrips takahashii in egg patches of various spider mite species

Predation and oviposition by three predacious insects [ Scolothrips takahashii Priesner (Thysanoptera: Thripidae), Stethorus japonicus H. Kamiya (Coleoptera: Coccinellidae), and Oligota kashmirica benefica Naomi (Coleoptera: Staphylinidae)] were examined using egg patches of three spider mite species [ Amphitetranychus viennensis (Zacher), Tetranychus urticae Koch, and Panonychus mori Yokoyama (all Acari: Tetranychidae)] that are pest species on Japanese pear [ Pyrus serotina Rehder (Rosaceae)]. Scolothrips takahashii females consumed more prey and laid more eggs in A. viennensis and T. urticae egg patches than in P. mori egg patches. Females also left P. mori egg patches sooner than they left other egg patches even at high prey density. Predation and oviposition of S. takahashii in a prey patch were greatly enhanced by the complicated webs produced by A. viennensis . Stethorus japonicus females consumed significantly more prey and laid more eggs in A. viennensis egg patches than in P. mori egg patches, with intermediate values in T. urticae egg patches, reflecting the quality of each spider mite species as prey. Oligota kashmirica benefica females consumed more prey and laid more eggs in A. viennensis and T. urticae egg patches than in P. mori egg patches, particularly at high prey density. However, predation and oviposition by O. kashmirica benefica increased greatly with increasing prey density, even in P. mori egg patches, indicating that prey density was the most important factor in predation and oviposition by this species. These results are discussed in relation to the potential effect of each predator on the suppression of different spider mite species on Japanese pear.     

Comparative Immunological Studies of Two Pseudomonas Enzymes

Crystalline preparations of muconate lactonizing enzyme and muconolactone isomerase, two inducible enzymes that catalyze successive steps in the catechol branch of the beta-ketoadipate pathway, were used to prepare antisera. Both enzymes were isolated from a strain of Pseudomonas putida biotype A. The antisera did not cross-react with enzymes of the same bacterial strain that catalyze the chemically analogous steps in the protocatechuate branch of the beta-ketoadipate pathway, carboxymuconate lactonizing enzyme and carboxymuconolactone decarboxylase. The antisera gave heterologous cross-reactions of varying intensities with the muconate lactonizing enzymes and muconolactone isomerases of P. putida biotype B, P. aeruginosa, P. stutzeri, and all biotypes of P. fluorescens, but did not cross-react with the isofunctional enzymes of P. acidovorans, of P. multivorans, and of two bacterial species that belong to other genera. The evolutionary and taxonomic implications of the findings are discussed.     

Effect of dietary cortisol administration on growth and reproductive success of channel catfish

The effect of cortisol administration on reproductive performance was investigated in channel catfish Ictalurus punctatus broodfish. Cortisol was added to a commercial catfish feed by dissolving in ethanol and spraying the feed to yield a dietary concentration of 150 mg kg⁻¹ feed. The cortisol diet and the control (no cortisol) diet were offered at a rate of 1% of biomass to three replicate ponds each containing 28 female and 14 male broodfish, respectively, three times per week for 11 weeks. Spawning began 10 days after the start of the experiment, and continued for 10 weeks. In fish fed cortisol, body mass and the hepato‐somatic index were reduced ( P  ≤ 0·02) and concentrations of plasma cortisol and glucose were significantly higher ( P  ≤ 0·0003) compared to those of controls. The relative frequency of spawning was similar between the two treatments; however, cortisol‐fed channel catfish had an average of 47·1% more spawns than the control‐fed fish. On average, there were 25·5 spawns per pond in the treated groups compared to 12·3 spawns per control pond ( P  = 0·10). No effect was observed on egg production, with individual egg mass, fecundity, and hatching success being similar ( P  ≥ 0·27) for both treatments. Despite the observed negative effects of cortisol on somatic and hepatic growth, the increased reproductive output coupled with no observable effects on the eggs or hatching success demonstrates that cortisol does not suppress channel catfish reproduction.     

Hatchery performance in a major rainbow trout (Oncorhynchus mykiss,Walbaum, 1792) seed production area of Turkey

This study aims to determine the production characteristics and performance of rainbow trout hatcheries in Seydikemer, Mu?la, Turkey where over half of the total production of eyed eggs and juveniles take place. For this purpose six hatcheries with different production scales were selected and coded A, B, C, D, E and F (with capacities of 60, 15, 5.6, 4, 0.95 and 0.6 million juveniles per year, respectively). From each hatchery, 20 females were selected and their egg qualities (egg number, diameter and weight, fertilization, eyed egg, hatching, swim‐up fry and survival rates at 120 days after hatching) and juvenile growth rates were monitored until the 120^th day after hatching under each farms own conditions. The sperm characteristics of 10 broodstock males from each hatchery were also examined. Although fertilization and eyed egg rates were similar among the farms, hatching, swim‐up fry, and survival rates at the 120^th day after hatching differed significantly. The average eyed egg, hatching and survival rates (calculated from selected 20 females) were 72, 55, and 32%, respectively. While sperm characteristics except duration of motility (s), were significantly different among the farms, average sperm concentration (per ml), motility (%) and duration of motility (s) in the region were 11.8 × 10⁹, 55.3, and 56.4, respectively. The best hatchery performance was observed in Farm A because of better records and management applications than in the other farms.     

豇豆轻斑驳病毒CPMMV感染菜豆对B型烟粉虱寄主选择和生物学特性的影响

豇豆轻斑驳病毒（Cowpea mild mottle virus,CPMMV）的流行与其媒介昆虫烟粉虱Bemisia tabaci密切相关,但CPMMV感染寄主植物对B型烟粉虱寄主选择行为和生物学特性的影响尚不清楚。本研究探究了1）CPMMV感染菜豆Phaseolus vulgaris不同时间对B型烟粉虱寄主选择和产卵偏好性的影响;2）CPMMV感染菜豆对B型烟粉虱生物学特性的影响。结果发现：1）相较于健康菜豆,摩擦接种CPMMV后1周,B型烟粉虱却偏好在CPMMV感染的植株上停留和产卵;而摩擦接种后4周,B型烟粉虱却偏好在健康的植株上停留和产卵;2）无论是在摩擦接种后1周和4周的CPMMV感染植株上,B型烟粉虱在健康和CPMMV感染植株上的产卵量和存活率差异不明显。可见,CPMMV感染菜豆对于B型烟粉虱的寄主选择偏好性具有时间效应,而CPMMV感染菜豆对于B型烟粉虱的生物学特性没有显著影响。     

Development and reproduction of ‘B＇ biotype Bemisia tabaci （Gennadius） （Homoptera： Aleyrodidae） on four ornamentals

Abstract Effects of four commercial ornamentals on the development, survivorship and reproduction of the whitefly B biotype Bemisia tabaci (Gennadius) were studied in the laboratory (temperature 26 ± 1 °C; relative humidity 75%–90%; L: D 14:10). The total survivorship from egg to adult on hibiscus ( Hibiscus rosa-sinensis L.), poinsettia ( Euphorbia pulcherrima Will), cottonrose hibiscus ( Hibiscus mutabilis L.) and variegated leafcroton ( Codiaeum variegatum'Aucubaefolium' ) were 33.69%, 40.55%, 79.11%, and 29.39%, respectively. The developmental periods from egg to adult varied from 23.12 days on cottonrose hibiscus to 32.13 days on hibiscus. The average longevity of adult females ranged from 6.87 days on variegated leafcroton to 21.07 days on poinsettia. The average numbers of eggs laid per female were 9.20, 25.13, 54.45, and 26.79 on the above respective hosts. The intrinsic rates of natural increase ( r_m ) for B biotype B. tabaci on cottonrose hibiscus was the highest. Based on life table analyses of whitefly populations, cottonrose hibiscus was the most suitable host for B biotype B. tabaci in this study.     

Flexibility of reproductive tactics and their consequences in the brood parasitic fish Pungtungia herzi (Teleostei: Cyprinidae)

Although previous studies have claimed that Pungtungia herzi (Cyprinidae) is an obligate brood parasite, in this study a significant proportion of P. herzi egg masses was found in crevices formed by stones and rocks, which was not guarded by hosts. Egg masses were also found in almost all nests of a goby Odontobutis obscura , suggesting that P. herzi has two alternative reproductive tactics: brood parasitic spawning and non-parasitic crevice spawning, the latter of which may occur when a shortage of reproductive resources ( i.e . host nests) exists. The hatching rates of parasitic egg masses were significantly higher than those of non-parasitic egg masses, and the hatching rate of P. herzi eggs exhibited a strong positive correlation with continuous egg guarding by a reproductive O. obscura male. These results indicate that brood parasitism effectively improves reproductive success in P. herzi . The alternative reproductive tactic of this species suggests that brood parasitism has evolved directly from crevice spawning via the sharing of spawning habitat with host species.     

Multiple generation effects of high temperature on the development and fecundity of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B

Insects are ectotherms and their ability to resist temperature stress is limited. The immediate effects of sub‐lethal heat stress on insects are well documented, but longer‐term effects of such stresses are rarely reported. In this study, survival, development and reproduction of the whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) biotype B, were compared over five consecutive generations at 27, 31 and 35 °C and for one generation at 37 °C. Both temperature and generation significantly affected the fitness of the whitefly. These impacts were more dramatic with increasing generations and temperatures. Among the experimental temperatures, the most favorable for development and reproduction were 27 °C and 31 °C. At 27 °C, survival, development and fecundity were all stable over these five generations. At 31 °C, immature survival rate was the highest in the fifth generation, but female fecundities decreased in the fourth and fifth generations. At 35 °C, egg hatching rate, immature survival rate and female fecundity decreased significantly in the fourth and fifth generations. At 37 °C, survival of B. tabaci was not adversely affected, but female fecundity at 37 °C was less than 10% of that at 27 °C or 31 °C. These results demonstrate that the lethal high temperature for B. tabaci is over 37 °C, and the whitefly population continued expanding in the five generations at 35 °C. The ability of B. tabaci biotype B to survive high temperature stress will play an important role in its population extension under global warming.     

Egg shell quality,clutch size and hatching success of the great tit (Parus major) and the pied flycatcher (Ficedula hypoleuca) in an air pollution gradient

Egg shell thickness, egg volume, clutch size and hatching success of Parus major and Ficedula hypoleuca were studied at 14 study sites around a copper smelter complex in Harjavalta, south-west Finland, in 1991–1993. In 1991–1992 unhatched eggs were collected to measure shell quality. F. hypoleuca was more susceptible to pollutants than P. major, the response of which was weaker in all aspects studied. Egg shells of F. hypoleuca were about 17% thinner and eggs were about 8% smaller in volume near the factory than at a distance of 10 km. The clutch size of F. hypoleuca was significantly smaller and hatching success markedly lower at a study site next to the factory complex than at all other sites. In P. major, variation in shell thickness and egg volume was not significantly related to the distance from the pollution source. Clutch size and hatching success of P. major did not significantly differ among study sites, although the trend in hatching success was in the same direction as in F. hypoleuca. Clutches of both species contained less shell material and both species had more nests without eggs near the factory than further away. The surface structure of the eggshells was studied by scanning electron microscope. Especially in F. hypoleuca, the egg shell surface was more rough and porous near the factory. The roles of Ca and heavy metals in shell thinning are discussed.     

Comparative effects of some botanicals for the control of the seed weevil Caryedon serratus Olivier (Col., Bruchidae)

Abstract:   Comparative efficacy of eco-friendly botanicals extracted from leaves and seed kernel of Azadirachta indica A. Juss (neem) and Eucalyptus camaldulensis Dehn was tested against the noxious weevil Caryedon serratus Olivier. Leaf powder, seed kernel powder and oil extracted from the seeds of A. indica and leaf powder and oil extracted from the leaves of E. camaldulensis and benzene hexachloride (BHC) were tested at 1, 3 and 5% (w/w or v/w) against C. serratus . Eucalyptus leaf oil (ELO) and neem oil (NO) at 3 and 5% were as efficient as BHC and significantly (P=0.0001) reduced egg laying by C. serratus, whereas Eucalyptus leaf powder (ELP) had no significant effect. Neem seed kernel powder (NSKP) at 5%, ELO (3 and 5%) and NO (3 and 5%) significantly (P=0.0001) reduced egg hatching more than BHC at all doses. NO (3 and 5%) and ELO (3 and 5%) significantly (P=0.0001) reduced larval development more than BHC, whereas ELP and Neam Leaf Powder had no significant effect. Adult emergence and mortality were also significantly (P=0.0001) affected by some botanicals tested, especially oils. Oils were more effective as compared with powder. The study indicated that the botanicals tested have a good potential in replacing conventional pesticides because of their high efficacy and environmental safety.     

Toxicity of three acaricides to Tetranychus urticae (Tetranychidae: Acari) and Orius insidiosus (Anthocoridae: Hemiptera)

Management for twospotted spider mite, Tetranychus urticae Koch, populations in peanut, Arachis hypogaea L., relies on acaricides. The outcomes of acaricide applications are most predictable when complete information on their toxicity and specificity is available. Specifically, the degrees to which acaricides impact different stages of T. urticae and natural enemies combined determine the overall efficacy of an acaricide application. The objectives of this study were to determine stage-specific direct and residual efficacies of three acaricides (fenpropathrin, etoxazole, and propargite) against T. urticae, and the direct and residual toxicity of the acaricides to Orius insidiosus (Say) adults. Direct toxicity of acaricides to T. urticae was measured on peanut cuttings. All acaricide treatments caused significant mortality to a mixed stage population of T. urticae, and mortality did not differ among the acaricides 7 d after treatment. When toxicity to eggs was tested, the proportion of eggs that hatched for all acaricide treatments was significantly lower than the control, with etoxazole and propargite causing 100% mortality. Exposure to acaricide residues caused < 30% mortality of T. urticae adults 1 and 2 d after treatment and was not significantly different from the control. Fenpropathrin and propargite caused 100% mortality and etoxazole caused > 50% mortality of O. insidious adults after direct exposure to the acaricides. Residual toxicity of acaricides to O. insidiosus adults varied but remained toxic to O. insidiosus longer than to T. urticae. Fenpropathrin had the longest residual effect on O. insidiosus adults, causing > 95% mortality after 14 d; etoxazole and propargite caused < 30% mortality after 14 d.     

Selectivity Studies of the Benzene cis -Dihydrodiol Dehydrogenase Enzyme from Pseudomonas putida ML2 with Vicinal Diol Substrates

The enantiopure (1 S, 2 S )- cis -dihydrodiol metabolites 2B - 5B have been obtained in low yield from the corresponding monosubstituted halobenzene substrates 2A - 5A, using a wild-type strain of Pseudomonas putida (ML2) containing benzene dioxygenase (BDO). Benzene cis -dihydrodiol dehydrogenase (BCD) from P. putida ML2 and naphthalene cis -dihydrodiol dehydrogenase (NCD) from P. putida 8859 were purified and used in a comparative study of the stereoselective biotransformation of cis -dihydrodiol enantiomers 2B - 5B. The BCD and NCD enzymes were found to accept cis -dihydrodiol enantiomers of monosubstituted benzene cis -dihydrodiol substrates 2B - 5B of opposite absolute configuration. The acyclic alkene 1,2-diols 10 - 17 were also found to be acceptable substrates for BCD.     

Selectivity Studies of the Benzene cis -Dihydrodiol Dehydrogenase Enzyme from Pseudomonas putida ML2 with Vicinal Diol Substrates

The enantiopure (1 S , 2 S )- cis -dihydrodiol metabolites 2B - 5B have been obtained in low yield from the corresponding monosubstituted halobenzene substrates 2A - 5A , using a wild-type strain of Pseudomonas putida (ML2) containing benzene dioxygenase (BDO). Benzene cis -dihydrodiol dehydrogenase (BCD) from P. putida ML2 and naphthalene cis -dihydrodiol dehydrogenase (NCD) from P. putida 8859 were purified and used in a comparative study of the stereoselective biotransformation of cis -dihydrodiol enantiomers 2B - 5B . The BCD and NCD enzymes were found to accept cis -dihydrodiol enantiomers of monosubstituted benzene cis -dihydrodiol substrates 2B - 5B of opposite absolute configuration. The acyclic alkene 1,2-diols 10 - 17 were also found to be acceptable substrates for BCD.     

诱导水稻抗褐飞虱的化学激发子筛选

【目的】化学激发子具有毒性低、不易产生抗药性等特点,因此开发基于化学激发子的害虫防控技术,能够降低农药的使用量,促进农业生产的可持续发展。本研究旨在筛选能够诱导水稻产生对褐飞虱Nilaparvata lugens抗性的化学激发子。【方法】将茉莉酸(JA)、茉莉酸甲酯(MeJA)、水杨酸(SA)、水杨酸甲酯(MeSA)、油菜素内酯(BR)、苯甲酸苄酯(BB)、独脚金内酯(SLs)、萘乙酸(NAA)、吲哚丁酸(IBA)、草酸钠(SO)、硅酸钾(PS)和叶枯唑(Bis)12种化合物以根吸或叶鞘涂抹处理水稻,测定这些化合物处理水稻后褐飞虱的卵孵化率和24 h总产卵量。【结果】12种候选化合物中,仅茉莉酸甲酯、油菜素内酯和苯甲酸苄酯对褐飞虱卵孵化率和24 h总产卵量有显著影响。5 mg/L MeJA根吸处理水稻使褐飞虱的卵孵化率显著降低(达58.8%,降低了20.1%),而0.5 mg MeJA叶鞘涂抹处理水稻同时降低了褐飞虱的卵孵化率(达53.3%,降低了35.4%)和24 h总产卵量(达203.5粒/株,降低了15.6%),且其涂抹的浓度越高,褐飞虱的卵孵化率和24 h总产卵量越低。5 mg/L BR根吸处理水稻可以显著降低褐飞虱的卵孵化率(达59.5%,降低了22.1%),但是不影响褐飞虱的24 h总产卵量;褐飞虱的卵孵化率随BR处理浓度增高而降低,其浓度为20 mg/L时,褐飞虱的卵孵化率下降了41.8%。5 mg/L BB根吸处理水稻可以显著降低褐飞虱的24 h总产卵量(达100.3粒/株,降低了26.2%)。体外试验结果表明,MeJA和BR处理对褐飞虱卵孵化率无明显影响,说明两者对褐飞虱卵无直接毒害作用。【结论】化合物茉莉酸甲酯、油菜素内酯和苯甲酸苄酯可以提高水稻对褐飞虱的抗性,其中茉莉酸甲酯和油菜素内酯具有化学激发子的作用。     

Mating interactions between two biotypes of the whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae) in Australia

The biological consequences of mating interactions between indigenous and exotic biotypes of Bemisia tabaci (Gennadius) in Australia were studied using a combination of field and laboratory experiments. The key results of the interaction between the B and eastern Australian biotypes were reduced population increase, a marked increase in the proportion of male progeny, fewer eggs produced by females paired with males of different biotype and no difference in the numbers of eggs per unmated female and females paired with males of the same biotype. In addition, there was no change in the proportion of eggs hatching, mixed biotype pairs spent more time courting than single biotype pairs and a low level of hybridization in field cages and small containers was observed. These observations suggest three possibilities. The first is the 'distracting male hypothesis' in which mating pairs made up of different biotypes apportion more time to courtship and less time to egg laying than single biotype pairs. The second invokes the 'single-locus complementary sex determination model' in which the production of non-viable diploid male zygotes may explain the reduction in eggs laid. The third is cytoplasmic incompatibility between biotypes caused by Wolbachia. The results also suggest that the geographical distribution of clusters of related biotypes both overseas and in Australia may be explained by between-biotype interactions leading to the formation of parapatric populations.