Cuticular volatiles,attractivity of worker larvae and invasion of brood cells by Varroa mites. A comparison of Africanized and European honey bees

Summary. Africanized honey bees (AHBs) of Brazil and Mexico have proven to be tolerant to Varroa destructor mites. In contrast, European honey bees (EHBs: Apis mellifera carnica) at the same tropical study site are highly intolerant to these ectoparasites. A lower attractiveness of Varroa-tolerant AHB larvae has been hypothesised to be an important trait in reducing the susceptibitlity of AHBs to these mites. Thus, selection for EHB brood that is less attractive to mites is thought to be one possibility for limiting mite population growth and thus increase the tolerance of EHBs to the mite.?In Ribeir?o Preto, Brazil, European A. m. carnica bees and AHBs were tested with respect to their rate of brood infestation and brood attractiveness to Varroa mites. For the comparison of brood infestation rates, we introduced combs with pieces of EHB and AHB brood into honey bee colonies (18 repetitions). The relative infestation rate of EHB brood was significantly higher compared to AHB brood.?The preference behaviour of single Varroa mites was tested in a laboratory bioassay where either living host stages were offered or host extracts were presented on dummies. By these tests we could confirm the preference of Varroa females for certain developmental host stages and for their corresponding extracts. In contrast to the within-colony results, Varroa mites in the laboratory bioassay showed a slight preference for AHB compared to EHB larvae.?The gas chromatographic analysis revealed differences in the chemical spectrum of extracts obtained from different larvae. In accord with the results of the bioassays, we could detect stage-specific odour differences in larval cuticular compounds, including methyl esters and hydrocarbons that have been described as kairomones. None of these substances, however, revealed significant race-specific differences. Therefore, the quantity and composition of certain cuticular compounds seem to be responsible only for the recognition of a suitable host stage by Varroa females. The different infestation rates in the colonies, however, seem to be caused neither by race-specific differences in attractiveness of bee larvae nor by an extended attractive period of EHB larvae: both AHB and EHB larvae become attractive approximately 21 h before capping of the brood cell, and thus have the same window of time when they can be parasitised.?Therefore differential Varroa-infestation rates are not related to larval attraction but probably are determined by other race-specific and colony-related factors. Received 11 June 2001; accepted 19 November 2001.     

浮萍在水体污染治理中的应用

对利用浮萍治理受污染的水体进行了介绍,包括浮萍科植物的生物学特性、治理水体污染的特点以及国内外的相关研究状况等.提出了利用浮萍科植物治理受污染水体的前景,同时预测了该领域的应用和研究方向.     

Determination of Toxic Pollutants in Water Using A Marine Phytoplankton Dunaliella Bioculata and Doppler Laser Velocimetry

Abstract

This paper reports an experimental study of the response of the unicellular flagellated algae Dunaliella bioculata to toxic pollutants in water using the ‘Doppler laser velocimetry’ method. the response to toxic pollutants was encouraging and indicates that Dunaliella bioculata is a good biological model for the detection of toxic pollutants in water.     

Tributyltin distribution and producing androgenic activity in water,sediment, and fish muscle

This study investigated the concentrations of Tributyltin (TBT) in water, sediment, and fish muscle samples taken from Kaohsiung Harbor and Kaoping River estuary, Taiwan. TBT concentrations in water and sediment samples ranged from less than 18.5 to 34.1 ng Sn L^?1 and from 2.44 to 29.7 ng Sn g^?1 weight per weight (w/w), respectively. Concentrations in the TBT‐contaminated fish muscle samples ranged from 10.8 to 79.6 ng Sn g^?1 w/w. The TBT concentrations in fish muscle were higher than those in water and sediment samples. The fish muscle/water TBT bioconcentration factor (BCF) ranged from 590 to 3363 L kg^?1. Additionally, the water samples were assessed for androgenic activity with an MCF7‐AR1 human breast cancer cell line. The androgenic activity ranged from 0.94 to 3.1 ng‐dihydrotestosterone per litre water (ng‐DHT L^?1). Higher concentrations of TBT in water and sediment samples occurred in the dry season, but the androgenic activity had higher values in the rainy season.     

腹泻性贝毒素软海绵酸的昆明系小鼠生物学检测法的建立

为完善腹泻性贝毒素软海绵酸(Okadaic acid,OA)的小鼠生物学检测技术,以昆明系小鼠为实验材料,应用小鼠生物学检测法检测了OA的毒性.用不同浓度OA标准溶液通过腹腔注入19～21g昆明系小鼠体内,观察其中毒症状,确定1个鼠单位(MU)所代表的毒素剂量,并且建立剂量-死亡时间曲线.结果表明,昆明系小鼠经OA腹腔注射后中毒症状和死亡时间具有明显剂量效应关系,其剂量-死亡时间曲线方程为y=600.57x-2.257,其中y代表致死时间(h),x代表剂量(μg);将死亡时间t变为时间倒数1/t,对OA的毒性MU取对数(即logMU),得直线回归方程为y=0.5363x+0.1295,R2=0.9488,p<0.01,其中y代表OA毒素剂量单位的对数(1ogMU),x代表小鼠死亡时间倒数(1/t),R2为可决系数.通过该方程计算得出,1个鼠单位(MU)所对应的OA剂量值约为4.015μg,其95%置信限为3.826～4.204μg.     

Sorption and mobility of polyethylene glycol (PEG 4000) in tropical soils

Millions of tons of polyethylene glycols (PEGs) are manufactured worldwide and most of them will reach conventional sewage disposal systems after industrial utilization. This raises environmental concerns, but not much is known about the environmental fate of these polymers. The main goals of this research were to evaluate sorption and mobility of PEG in sandier soils of Brazil. PEG 4000 was applied to the soils either freely in solution or as a simulated bioassay residue. The bioassay was prepared to simulate PEG as it is present in the animal feces. It allowed us to compare PEG mobility for both forms of environment disposal. PEG showed very low sorption (<22% of the applied PEG) and high mobility potential (>43% of the applied amount in the free-PEG and >24% of the applied amount in the bioassay-PEG experiment) in the studied soils. When PEG was applied, simulating its supply to animal diets, about 30% of its applied amount was retained into the bioassay residues and its leaching potential was reduced, whereas the remaining amount (about 70%) was readily available in solution and could be directly released into the environment.     

Phytotoxicity of fuel to crop plants: influence of soil properties,fuel type,and plant tolerance

The aim of the present study was to determine the effect of fuel-contaminated soils on the germination, survival, and early growth of six crop plants, viz. Brassica oleracea, Trifolium repens, Lactuca sativa, Avena sativa, Pisum sativum, and Zea mays, grown on Cambisol A and B horizons contaminated with gasoline and diesel (0%, 1.25%, 2.5%, 5%, and 10%, w/w). Fuel toxicity was more evident in the B horizon than in the A horizon, and diesel was more toxic than gasoline, probably due to the higher evaporation rate of the latter. Fuels affected the germination and survival of small-seeded plants to a higher extent, reflecting the importance of the seed coat and nutrient reserves for successful plant development in fuel-contaminated soils. In general, root growth was more strongly affected than shoot growth, and plant biomass was more strongly affected than elongation, leading to a less plant branching in the presence of fuel. The findings of this study can be useful for selecting the least fuel-tolerant species as soil contamination bioindicator and for determining the risks of fuel contamination. Due to the low residence time of gasoline components in soil, this phytotoxicity test resulted in an unsuitable bioassay to assess gasoline toxicity.     

Assessing the toxicity of chemical compounds associated with marine land-based fish farms: The use of mini-scale microalgal toxicity tests

Many chemicals that are currently used in aquaculture have not been evaluated with regard to their specific effects on the aquatic environment. In the present study, the toxic effects of several chemicals associated with land-based marine fish farming activities were assessed using two species of marine microalgae (Phaeodactylum tricornutum and Isochrysis galbana). Mini-scale toxicity tests were performed with six antibiotics (amoxicillin, ampicillin, flumequine, oxytetracycline, streptomycin and sulfadiazine) and two disinfectants (formaldehyde and hypochlorite). Amoxicillin and streptomycin did not exert toxic effects. Sulfadiazine was the most toxic chemical; the EC₅₀ values were 0.11 mg/L and 1.44 mg/L for P. tricornutum and I. galbana respectively. As expected, the disinfectants displayed high toxicity, and P. tricornutum was particularly sensitive to these compounds. Although the differences in microalgal sensitivity depended on the chemical considered, both species were highly sensitive to most of the compounds tested. We recommend the inclusion of mini-scale microalgal toxicity tests in environmental risk assessment (ERA) and environmental monitoring plans because they are cost-effective and rapid.     

中国南部沿海近岸西加鱼毒素研究

为了查清我国南部沿海珊瑚礁鱼类体内的西加鱼毒素状况,首次在海南三亚、琼海、广西涠洲岛、珠海担杆列岛、广东徐闻县灯楼角和福建东山岛收集渔民从附近珊瑚礁海域捕捞的野生鱼类,采用酶联免疫法、小白鼠生物法和高效液相色谱质谱联用法进行毒素测定.结果表明,6个调查海区均检测出染毒鱼类,总阳性检出率达50%,其中福建东山岛(77.8%) >广东徐闻县灯楼角(66.7%) >广东珠海担杆列岛(55.6%) >广西涠洲岛(37.5%) >海南三亚(37.5%) >海南琼海(16.7%),与海域环境质量可能存在一定的关联.鱼组织毒素含量为0~169ng P-CTX-1/kg肉,8个样品 (占总样17.4%) 超过100ng P-CTX-1/kg肉,达到可致人中毒水平.染毒鱼种类繁多,主要包括蝴蝶鱼科(Chaetodontidae)、鹦嘴鱼科(Scaridae)、鳂科(Holocentridae)、笛鲷科(Lutjanidae)和鮨科(Serranidae).酶联免疫法与小鼠生物法对鱼毒定性检测结果基本一致,但仅在福建东山岛2个鱼样中检测到P-CTX-1成分.染毒鱼类的毒素含量和鱼体重/体长没有相关性,也与其食性无关.     

北京市污水厂污泥中的内分泌干扰效应物质

采用重组基因酵母法检测了北京市16个污水处理厂污泥的雌激素、雄激素和孕激素效应.结果表明,各污水厂污泥中均可检测到雌激素受体诱导效应,范围在0.587～6.76ngEEQ·g-(1dw)之间.各水厂污泥均未检测出雄激素诱导效应和孕激素诱导效应,大部分污水厂污泥样品表现出较明显的雄激素抑制效应和较强的孕激素抑制效应.与国外相比,北京市污水厂污泥中的雌激素活性值相对较低.堆肥处理不能有效去除雌激素类物质和孕激素抑制物质,但对雄激素抑制物质的去除明显.