Sneak in or repel your enemy: Dufour's gland repellent as a strategy for successful usurpation in the slave-maker Polyergus rufescens

Summary. The dulotic queen ant, Polyergus rufescens, must first penetrate a host colony and kill the resident queen in order to successfully founding a new colony. Successful usurpation by a newly mated queen predictably depends on a dual strategy. Although, it can sneak in by being “chemically insignificant” with respect to cuticular hydrocarbons, it may also need to deter prospective host-worker aggressors. Chemical analysis of Dufour's gland secretion of P. rufescens queens and workers by GS/MS revealed that queen secretion is typified by esters of butanoic acid and acetic acid, of which decyl butanoate comprises over 80%. Butanoates and acetates are also present in the workers' secretion, but these are of higher molecular weight, and octadecyl butanoate represents the major compound. Using synthetic mixtures of queen and worker Dufour's gland, we tested the hypothesis that these secretions modify the aggressive behavior of the host species Formica cunicularia>. The queen-like synthetic mixture significantly reduced aggression of the host workers towards alien conspecifics, but neither pentane nor the worker-like synthetic mixture showed this effect. Although Dufour's gland content of >Polyergus queens was suggested to function as an appeasement pheromone (Topoff et al. 1988; Mori et al. 2000), we hypothesized that it may in fact act as a repellent. In order to test this hypothesis we exposed starved F. cunicularia workers to a droplet of honey on a glass slide applied with one of the following compounds: decyl butanoate (queen major compound), octadecyl butanoate (worker main compound), limonene (a reported ant repellent), and pentane (solvent control). Of these, the workers were repelled only by the decyl butanoate and did not approach the honey. We conclude that during usurpation the queen actively repels aggressive workers by emitting Dufour's gland repellent, comprising the alternative tactic in the usurpation dual strategy. This represents another chemical weapon in the diverse arsenal used by parasites to overcome the host's resistance. Received 7 April 2000; accepted 17 May 2000     

Variation in Pesticide Tolerance of Tadpoles among and within Species of Ranidae and Patterns of Amphibian Decline

Abstract: There is significant variation among and within amphibian species with respect to reports of population decline; declining species are often found in environments that are physiograpically similar to environments where the same species is thriving. Because variability exists among organisms in their sensitivity to environmental stressors, it is important to determine the degree of this variation when undertaking conservation efforts. We conducted both lethal (time-to-death) and sublethal (activity change) assays to determine the degree of variation in the sensitivity of tadpoles to a pesticide, carbaryl, at three hierarchical levels: among ranid species, among several populations of a single ranid species (   Rana sphenocephala ), and within populations of R. sphenocephala . We observed significant variation in time to death among the nine ranid species and among the 10 R. sphenocephala populations we tested. Four out of eight R. sphenocephala populations exhibited significantly different times to death among families. The magnitude of the activity change in response to exposure to sublethal carbaryl levels was significantly different among species and within R. sphenocephala populations. Chemical contamination, at lethal or sublethal levels, can alter natural regulatory processes such as juvenile recruitment in amphibian populations and should be considered a contributing cause of declines in amphibian populations.     

Prüfung und Bewertung der Auswirkungen von Pflanzenschutzmitteln auf terrestrische Organismen nach der EG-Richtlinie 91/414/EWG

EU Directive 91/414/EEC describes the authorization procedure for plant protection products. According to annex VI of this directive, the EU member states have to ensure that a plant protection product does not have unacceptable effects on the environment. The data requirements and the function of laboratory and field tests in the assessment procedure are discussed for the terrestrial compartment.     

熵析污水处理资源与能源化

熵为热力学第二定律中的抽象概念.按熵之理论,自然熵增和逆熵增维系着生态平衡.人类生产、生活过程中摄取资源并排放污/废水等熵增产物会促进物质熵增并破坏生态平衡,加速生物消亡.而缓释、甚至抵消这种“人为熵增”则乃实现蓝色发展目标的重要一环.如今,人为熵增所引发的自然物质熵变循环塌陷是不争的事实,“自然熵增”之原生态方法显然已不适合大规模处理城市污水,“加速熵增”的传统污水处理技术显然也已不合时宜,只有发展“逆熵增”的污水处理资源、能源化技术才是人间正道.通过对熵的具象化释义,揭示出传统污水处理技术以及污泥填埋方式为“加速熵增”过程,对人类可持续发展十分不利.只有模拟元素循环的自然的“逆熵增”过程,才能使得污水处理走向可持续发展水平.因此,污水资源化与能源化首当其冲,一定是未来污水处理的发展方向.只有通过人工缓释熵增(高效低耗污水处理技术)和促进逆熵增手段(资源与能源化技术)才能抵消人为熵增造成的影响,从而维持生态平衡.     

地下水铀污染的原位微生物还原与固定:在美国能源部田纳西橡树岭放射物污染现场的试验

总结了美国斯坦福大学和橡树岭国家实验室等在美国能源部田纳西州橡树岭综合试验基地进行的铀污染原位微生物修复阶段性试验结果.本试验利用微生物以乙醇为电子供体还原地下水和沉积物中的六价铀为不溶解的四价铀,使之原位固定化.随后通过加入溶解氧和硝酸盐来试验微生物还原后的地下水层中还原固定态铀的稳定性.通过预处理和长期间隔注入乙醇...     

The identification of readily bioavailable pollutants in lake shkodra/skadar using semipermeable membrane devices (SPMDs), bioassays and chemical analysis

GOAL, SCOPE AND BACKGROUND: Lake Shkodra/Skadar is the largest lake in the Balkans region and located on the border between Albania to the south and Montenegro to the north. Because of the wide range of endemic, rare or endangered plant and animal species it supports, Lake Shkodra/Skadar and its extensive associated wetlands are internationally recognised as a site of significance and importance (Ramsar site). In recent years, social and economic changes in both Albania and Montenegro have lead to unprecedented levels of urban and industrial effluent entering the lake. Of particular concern is the increasing input of toxic hydrophobic organic pollutants (HOPs) into the lake and the degree to which these compounds are available for uptake by aquatic biota. Semipermeable membrane devices (SPMDs) have been shown to sample the readily bioavailable fraction (dissolved phase) of waterborne HOPs and in doing so provide relevant data for exposure assessment. The aim of the current study was to use SPMD-based sampling in conjunction with appropriate bioassays and chemical analysis to identify readily bioavailable HOPs in the lake. METHODS: SPMDs were constructed and deployed at three sites in the Albanian sector and three sites in the Montenegrin sector of Lake Skadar/Shkodra for 21 days. Following the dialytic recovery of target analytes and size exclusion chromatographic clean-up, aliquots of SPMD samples were subjected to GC-MS scan analysis for major components, GC-MS SIM analysis for 16 priority pollutant polycyclic aromatic hydrocarbons (PP-PAHs) and assayed for EROD-inducing, estrogenic and mutagenic potential using rainbow trout liver cells (RTL-W1), the yeast estrogen screen (YES) and the Ames Test, respectively. RESULTS AND DISCUSSION: A total of 39 compounds were tentatively identified in SPMD samples from the six sampling sites. Alkylated PAHs were the most abundant and ubiquitous compounds present along with various sterols and sterol derivatives. Numerous other compounds remain unidentified. 15 of the 16 targeted PP-PAHs were present in samples from one or more of the sampling sites indicating these compounds are both readily bioavailable and widely distributed in Lake Shkodra/Skadar. Total PP-PAH concentrations ranged between 3991 ng/SPMD and 10695 ng/SPMD. Bioassays carried out on SPMD samples revealed significant EROD-inducing and estrogenic potential at five of the six sampling sites indicating toxicologically relevant compounds are readily available for uptake by resident aquatic biota. EROD-inducing potential was positively correlated with targeted PP-PAH concentration (r2 = 0.74). However, comparison of bioassay- and analytically-derived toxicity equivalents revealed targeted PP-PAHs were responsible for less than 0.06% of the total EROD-inducing potential. CONCLUSIONS AND OUTLOOK: The combination of SPMD-based sampling with appropriate bioassays and chemical analysis provided an effective tool for the identification of environmentally relevant waterborne pollutants in Lake Shkodra/Skadar. Our results show that toxicologically relevant HOPs including EROD-inducing and potentially estrogenic compounds are widely distributed in the lake and readily available for uptake by aquatic biota. Our results also suggest that alkylated PAHs rather than parent compounds may be of greater toxicological relevance in the lake. As anthropogenic influences continue to increase, SPMD-based sampling is expected to play a central role in future research concerned with the identification, monitoring and assessment of the risk posed by HOPs to Lake Shkodra/Skadar's aquatic biota.     

Comparison of two screening level risk assessment approaches for six disinfectants and pharmaceuticals

For three examples of both groups (the disinfectants biphenylol, 4-chloro-m-cresol and triclosan and the pharmaceuticals ivermectin, ibuprofen and oxytetracycline) a relative initial risk assessment (RIRA) was performed assuming a standard emission of 1 kg/d to the most relevant environmental compartment. In addition the hazard of the compounds was evaluated based upon their persistence, toxicity and bioaccumulative properties (PTB). Both estimated and measured parameters were used for this purpose. In addition to an analysis of the risks of the pharmaceuticals and disinfectants per se, the capacity to discern between the intrinsic risk of different compounds is evaluated for both criteria used. It is concluded that the RIRA has a higher discriminative value and yields more information compared to the PTB-criterion.     

In vitro EROD induction equivalency factors for the 10 PAHs generally monitored in risk assessment studies in The Netherlands

The ethoxy resorufin dealkylase (EROD) inducing potency of 10 polycyclic aromatic hydrocarbons (PAHs) is measured in the H4IIE in vitro bioassay and the results are compared to those reported in literature. The selected PAHs varied considerably in their potency to induce EROD activity. Anthracene (Ant) and phenanthrene (Phe) showed consistently no response. Naphthalene (Nap) showed no or a very weak response on EROD activity. Fluoranthene (Fla) and benzo[g,h,i]perylene (BghiP) showed weak responses at the highest doses. The other PAHs, including indeno[1,2,3-cd]pyrene (IP), benz[a]anthracene (BaA), benzo[a]pyrene (BaP), chrysene (Chr) and benzo[k]fluoranthene (BkF), showed full bell shaped dose-response curves. BaP EROD induction equivalency factors (BaP-1EF) were calculated and increased in the order Ant approximately Phe < Fla < Nap < BghiP < IP < BaA < BaP < Chr < BkF. Comparison of BaP-IEFs based on 50% effect concentration (EC50) or lowest effect concentration (LEC), yielded a significant relationship between both methods described by the equation log(BaPIEF(EC50) = 0.55 x log(BaPIEF(LEC)) + 0.07 (r2 = 0.913). BaP-IEFs as derived from our measurements and as reported in literature and measured in other in vitro assays deviated up to a factor of 17 among the different studies, but the potency rankings were comparable. For the PAH mixture as on average present in the human diet an overall tetrachlorodibenzo-p-dioxin (TCDD)-IEF of 1 x 10(-4) was estimated. The total PAH based TCDD induction equivalents (IEQ) intake then was calculated 300 pg/day, which is approximately 2 times higher then the PHAH based TCDD-EQ intake reported for humans.     

A one year investigation of the occurrence of illicit drugs in wastewater from Brussels, Belgium

Daily 24 hour composite influent wastewater samples were collected from the wastewater treatment plant of Brussels-North (Belgium) for eight months to study variations in the concentrations and mass loads of nine illicit drugs and metabolites: cocaine (COC) and its metabolites benzoylecgonine (BE) and ecgonine methyl ester (EME), amphetamine (AMP), methylenedioxymethamphetamine (MDMA), methamphetamine (METH), methadone (MTD) and its metabolite 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) and the specific metabolite of heroin, 6-monoacetylmorphine (6-MAM). Samples were analyzed using a validated analytical method based on solid-phase extraction and hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry. The selected compounds could be detected and quantified in all samples. The measured concentrations were in agreement with earlier published concentrations, when available. All illicit drugs showed significant differences in mass loads between months. Daily variations were observed for MDMA, AMP and COC and metabolites, with higher mass loads observed during the weekend. This is probably related to their recreational consumption pattern and was further confirmed when holiday periods (New Year's Eve, Belgian national holiday) were in detail investigated. For METH, 6-MAM, MTD and EDDP, stable and consistent amounts were observed during the week. In all samples, the ratio of the concentration of the parent compound to its metabolite(s) was calculated to evaluate whether measured concentrations reflect human excretion of the illicit drugs. For MTD, the ratio of parent compound/metabolite was in agreement with the excretion pattern, while for COC some deviations were observed, resulting from excretion pattern uncertainties, and stability and discharge issues.