Mother’s choice of the oviposition site: balancing risk of egg parasitism and need of food supply for the progeny with an infochemical shelter?

Summary. Oviposition site selection of herbivorous insects depends primarily on host plant presence which is essential for offspring survival. However, parasitoids can exploit host plant cues for host location. In this study, we hypothesised that herbivores can solve this dilemma by ovipositing within high plant diversity. A diverse plant species composition might represent an ‘infochemical shelter’, as a potentially complex volatile blend can negatively affect the host location ability of parasitoids. We examined this exemplarily for the egg-laying response of the generalist leaf beetle, Galeruca tanaceti, in relation to (1) host plant availability and (2) plant species diversity in the field. Further, we investigated the effect of odours from mixed plant species compositions on (3) leaf beetle oviposition site selection and on (4) the orientation of its specialised egg parasitoid, Oomyzus galerucivorus. In the field, egg clutch occurrence was positively related to the presence and quantity of two major host plants, Achillea millefolium (yarrow) and Centaurea jacea, and to the number of herbaceous plant species. In two-choice bioassays, female beetles oviposited more frequently on sites surrounded by an odour blend from a diverse plant species composition (including yarrow) than on sites with a pure grass odour blend. In the presence of yarrow odour and an odour blend from a diverse plant mixture (including yarrow) no difference in the oviposition response was recorded. Experienced parasitoid females were attracted to yarrow odours, but showed no response when yarrow odours were offered simultaneously with odours of a non-host plant. In conclusion, it could be shown in laboratory bioassays that the parasitoid responds only to pure host plant odours but not to complex odour blends. In contrast, the herbivore prefers to oviposit within diverse vegetation in the field and in the laboratory. However, the laboratory results also point to a priority of host plant availability over the selection of a potential ‘infochemical shelter’ for oviposition due to high plant diversity.     

Suppressive effect of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls transfer from feed to eggs of laying hens by activated carbon as feed additive

In this study, we investigated the suppressive effect of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) transfer from the feed to the eggs of laying hens by using activated carbon as a feed additive. Four groups of six hens (White Leghorn egg-layers; age, 11 weeks) were housed as two control groups and two exposure groups for a period of 20 weeks. Two control groups were fed with either the basal feed “Control” or basal feed additing activated carbon “Control + C”. Another two exposure groups were fed with feed contaminated (about 6 ng TEQ kg⁻¹ feed) by standard solutions of PCDDs/PCDFs and DL-PCBs “Exposure” alone and contaminated feed adding activated carbon “Exposure + C”. There was no significant effect on each groups for the growth rate, biochemical blood components, and egg production: these were around the standard levels for poultry in general. Moreover the results in this study showed the availability of activated carbon as a feed additive owing to the reduction in the risk of food pollution by PCDDs/PCDFs and DL-PCBs. The concentration in the eggs of the Exposure group gradually increased following the start of egg-laying but reached a steady state after about 1 month. In contrast, the concentration for the Exposure + C group was stationary and below the maximum EU level (6 pg TEQ g⁻¹ fat). In comparison to the Exposure group, the Exposure + C group showed a significant decline in the percentage of bioaccumulation into the egg. This reduction due to activated carbon was also observed in the muscle and abdominal fat. The reductions were compound- and congener-dependent for DL-PCBs as follows: PCDDs/PCDFs, non-ortho-PCBs, and mono-ortho-PCBs were more than 90%, 80%, and 50%, respectively, irrespective of the type of tissues. Fat soluble vitamin concentrations in the eggs of the Exposure + C group showed lower trends than the Exposure group. The γ-tocopherol and α-tocopherol concentrations in eggs of Exposure + C group showed a significant reduction of about 40%. However, the addition of activated carbon into animal feed could obviate the remote potential for accidents causing unintentional food pollution with PCDDs/PCDFs and DL-PCBs.     

鞘氨醇单胞菌完整细胞对溴氨酸的好氧降解

文章考察了鞘氨醇单胞菌QYY完整细胞对溴氨酸的好氧降解条件,并对其降解途径进行了分析。研究表明,该完整细胞在最佳条件为:温度30℃、初始pH7.0～8.0、摇床转速150r/min,磷酸缓冲溶液浓度为0.01～0.04mol/L时将溴氨酸完全脱色后产生3种产物:2-氨基-3-羟基-5-溴苯磺酸、2-氨基-4-羟基-5-溴苯磺酸为终产物;邻苯二甲酸为中间产物。其脱色过程中,大部分溴氨酸直接降解为终产物,仅有一小部分溴氨酸在降解过程中形成邻苯二甲酸。邻苯二甲酸则通过苯甲酸代谢途径开环。     

Potentiality of different isolates of wilt fungus Fusarium oxysporum collected from rhizosphere of tomato against root-knot nematode Meloidogyne incognita

This investigation was undertaken to determine the effect of culture filtrates of different isolates of Fusarium oxysporum f. sp. lycopersici on mortality of Meloidogyne incognita juveniles and egg hatching. It was observed that different concentrations including standard extract (S.E), 1:10 and 1:100 dilutions of all fungal filtrates inhibited egg hatch when compared with control. Minimum mortality and maximum hatching was observed in BRT (showing least mortality) isolate of F. oxysporum, while maximum mortality and minimum egg hatching was recorded in BGT (showing maximum mortality) isolate. Larval mortality was decreased with a decrease in concentration and the least mortality was observed in 1:100 when compared with SE and 1:10. The potentiality of both the isolates (BRT and BGT) against root-knot nematode M. incognita was confirmed by the pathogenicity test on tomato. These observations confirmed that F. oxysporumisolates possesses variability in pathogenicity ranging from pathogenic to bio-control agent. The plants inoculated with BRT isolate failed to show wilt symptoms while plants inoculated with BGT isolate showed wilt indices.     

根肿(Plasmodiophora brassicae)休眠孢子的纯化和超声波破碎方法研究

根肿(Plasmodiophora brassicae Woronin)是严重危害十字花科植物的世界性病害.采用蔗糖密度梯度离心和超声波处理方法从油菜染病根部组织分离和提纯根肿休眠孢子.众多因素可以影响提纯休眠孢子的纯度,为了得到更高纯度和均匀度的休眠孢子的优化方法,我们对一系列影响因素如超声波破碎功率、pH、孢子破碎浓度、处理时间和不同的水溶物质等进行了研究.在pH值5.5左右、添加0.5%的二甲基亚砜、孢子浓度约为7×108、345W功率下超声波处理10min条件下获得了最优数量和均匀度的孢子,杂菌数量减少了51%以上,杂菌种类减少超过75%.超声波处理50min后,孢子破碎率稳定地达到90%以上,除菌率达99%以上.用此方法能在较短时间内获得高纯度和高均匀度的休眠孢子,为休眠孢子的深入研究提供了资料.图4表3参10     

含硫芳香族化合物降解酶的定域及胞内产物的鉴定

为研究含硫芳香族化合物的生物降解途径 ,采用静息细胞技术提取假单胞杆菌 (Pseudomonas sp.)不同部位的酶 .结果表明 ,对硝基苯砜基乙酸异丁酯降解酶主要定域在细胞膜周及膜内 .被试化合物在膜内酶的作用下 ,发生碳硫键断裂 ,降解产物是对硝基苯磺酸 .在膜周酶的作用下 ,发生碳硫键和酯的烷氧键 2种方式的断裂 ,生成对硝基苯磺酸和对硝基苯砜基乙酸 .     

鸡蛋壳废料对水体中Cr(Ⅵ)的吸附特征与机理

利用鸡蛋壳废料对水中的Cr(Ⅵ)进行吸附处理,研究溶液pH、振荡时间、投加量和温度对鸡蛋壳废料吸附水体中Cr(Ⅵ)的特征和吸附机理。结果表明,在含有1 mg/L的Cr(Ⅵ)溶液的100 mL吸附体系中,鸡蛋壳废料可在30 min内完成吸附过程。溶液pH=2.5时,吸附量最大。鸡蛋壳投加量为1.0 g时,平衡吸附容量为0.0917 mg/g。利用鸡蛋壳去除水中Cr(Ⅵ)的最佳工艺参数为振荡时间30 min,初始pH为3.0,投加量2.0 g,体系温度35℃。鸡蛋壳对Cr(Ⅵ)的吸附过程用Langmiur和Freundlich方程能较好拟合,其中理论饱和吸附量在20℃、30℃和40℃时分别为0.1944、0.2034和0.2096 mg/g。吸附的焓变为8.76×10-3 kJ/mol,熵变为-45.96 J/(mol·K),吉布斯自由能变均为正值,变化范围是4.357~9.693 kJ/mol。鸡蛋壳对Cr(Ⅵ)的吸附过程主要为物理性的单分子层和多分子层吸附。     

Concentrations of selected metals in chicken eggs from commercial farms in Southern Nigeria

This work presents the results of the determination of concentrations of the trace metals Ni, Zn, Mn, Pb, Cd, Cr, Co, Cu, and Fe in eggs from farms in Southern Nigeria. The mean concentrations (µg?g^?1 fresh weight) ranged from 0.6 to 1.2 for Ni, 3.1 to 8.9 for Zn, 0.45 to 0.65 for Mn, 0.4 to 1.2 for Pb, <0.09 to 0.3 for Cr, 0.1 to 0.3 for Cd, 0.26 to 0.34 for Co, 0.9 to 1.2 for Cu and 19.5 to 24.0 for Fe. The concentrations and estimated dietary intakes of these metals were below the respective statutory limits. The Target Hazard Quotient (THQ) values for the individual metals in all zones are less than 1, i.e., within safe levels. The combined THQ values for the different zones were greater than 1but less than 2, with a significant contribution of cobalt.     

Peregrine falcon egg pollutants

The role of the peregrine falcon (Falco peregrinus) as a bioindicator for the accumulation of organohalogen compounds and other persistent organic pollutants has been established in field studies. Biometric indices for damage caused by pollutants such as the shell thickness and the shell index were determined and the egg contents were analyzed for various pollutants by gas chromatography/mass spectrometry. A wide range of chemically activated luciferase expression (CALUX®) bioassays were performed on subsamples of the eggs.

The following organohalogen compounds were found in the eggs of 2009: dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethane, heptachlor epoxide, hexachlorobenzene, dieldrin, hexachlorocyclohexane, polychlorobiphenyls and polychlorodibenzodioxins and polychlorodibenzofurans, polybromodiphenyl ethers, hexabromocyclododecane, tetrabromobisphenyl A, perfluoro compounds, and mercury. The DDT metabolite, dichlorodiphenyldichloroethene (DDE) (11,800 ng/g dry matter), was found to be the most highly concentrated egg contaminant followed by 2,2′,4,4′,5,5′-hexachlorobiphenyl (3800 ng/g). After a past general drop in pollution level, most egg contaminants presently plateau at levels that may still exceed limit values in foods of animal origin (DDE) or even toxicological thresholds (polychlorobiphenyls + polychlorodibenzodioxins, polybromodiphenyl ethers, perfluorooctanesulfonate, methylmercury).

Accumulation of DDE could be shown in peregrine falcon eggs from the uplands of Southwest Germany with elevations up to 1500 m, presumably due to its global distribution and its cold condensation in higher altitudes. In contrast, the concentration of polychlorobiphenyls in falcon eggs decreases with elevation, indicating that these pollutants originate mainly from conurbations and local industrial sites.

Significant negative correlations were found between both shell index and thickness and the concentration of Hg. A deleterious effect is also evident from a no-observed-adverse-effect level of 120 ng MeHg per gram egg determined by other authors in chronic feeding studies with ibises, which resulted in decreased egg productivity and male homosexual nesting and courtship behavior. The average Hg concentration in the peregrine falcon eggs from 2009 is almost four times higher than this level. MeHg accounted for 82.5% of the Hg present in the eggs of 2009 and 2010.

The cell test DR CALUX® for screening of dioxin-like activities can be used to detect not only the 29 regulated dioxin-like substances but also many other persistent organic pollutants with dioxin-like potencies, such as mixed halogenated dioxins/biphenyls. In our case, the results of bioanalytical screening methods showed no additional effect of other compounds with dioxin-like activity.

Ninety-three out of 177 analytes sought could be detected in the eggs. Chlorinated paraffins, organotin compounds, some pesticides that are still in use, and phthalic esters with the exception of traces of diethylhexyl phthalate could be excluded. All pollutants found in the eggs belong to substance classes banned by the Stockholm and Minamata Conventions.     

The Effect of Oil Spraying on Eggs of Double-Crested Cormorants

Spraying eggs with oil has been used as a method of decreasing the reproductive success of super abundant avian species. Double-crested Cormorant (Phalacrocorax auritus) abundances have created a potential disturbance to some endangered species of birds, sport fishing communities and aquaculture facilities. The hatching success of oil sprayed Double-crested Cormorant eggs was investigated. Oil spraying was done during the first, second, or third week of the eggs incubation to determine the most effective time during the incubation period for a one-time treatment. The oil spraying technique was 95–98% effective at preventing hatching. Hatching success was independent of the week of incubation that an egg was sprayed with oil. The maximum number of eggs on the colony occurred four weeks after the first egg was laid. This would be the most efficient week to spray the colony to decrease hatching success.