硫脲对酸性红壤 pH值与金属元素有效性的影响

通过实验室模拟,研究了不同浓度硫脲与尿素配施后,对酸性红壤的pH值及其金属元素有效性的影响.结果表明,土壤施加尿素后,其pH值有先升高后逐渐下降的趋势,而硫脲与尿素配施后,其pH值的下降趋势会受到抑制,尤其是当硫脲浓度达到5.0 mmol·kg-1时,土壤pH由最初的4.65上升到6.50以上,并在实验的中后期一直维持在6.0以上.硫脲和尿素配施后,Cu的有效态含量受硫脲浓度的影响较小,Zn、Al的有效态含量随着硫脲浓度的升高而降低,Mn的有效态含量在高浓度硫脲下,其含量保持在一个较高的水平,达到110 mg·kg-1以上.对于Cu、Zn和Al来说,在不同浓度硫脲和尿素配施后,其有效态含量与土壤的pH值呈现出明显的负相关.而对于Mn来说,在单施尿素的情况下,其有效态含量与土壤的pH值呈现出负相关,而在施入硫脲后,其有效态含量与土壤pH并没有呈现出明显的规律性.同时,研究结果还表明酸性红壤Al有效性随着土壤pH的升高而减小,当硫脲与尿素配合使用时,短期内土壤pH上升得更高,从而使得酸性红壤中Al的有效性减小.在硫脲和尿素配施后,土壤中Mn的有效态含量并不简单地取决于土壤的pH值,由于硫脲对Mn的络合作用和氧化还原作用,其含量受到土壤pH值和硫脲的共同影响.     

Predicted taxonomic patterns in pheromone production by longhorned beetles

Males of five species of three tribes in the longhorned beetle subfamily Cerambycinae produce volatile pheromones that share a structural motif (hydroxyl or carbonyl groups at carbons two and three in straight-chains of six, eight, or ten carbons). Pheromone gland pores are present on the prothoraces of males, but are absent in females, suggesting that male-specific gland pores could provide a convenient morphological indication that a species uses volatile pheromones. In this article, we assess the taxonomic distribution of gland pores within the Cerambycinae by examining males and females of 65 species in 24 tribes using scanning electron microscopy. Gland pores were present in males and absent in females of 49 species, but absent in both sexes of the remaining 16 species. Pores were confined to indentations in the cuticle. Among the species that had male-specific gland pores were four species already known to produce volatile compounds consistent with the structural motif. These findings support the initial assumption that gland pores are associated with the production of pheromones by males. There were apparently no taxonomic patterns in the presence of gland pores. These findings suggest that volatile pheromones play an important role in reproduction for many species of the Cerambycinae, and that the trait is evolutionarily labile.     

Major histocompatibility complex and mate choice in a monogamous rodent

A growing number of studies indicate that females can increase the viability of their offspring by gaining direct benefits such as parental care or genetic advantages through selective mating with certain males. Among the best candidates for the genetic basis of mate choice in vertebrates are the genes of the major histocompatibility complex (MHC) because these highly polymorphic genes may increase offspring viability and provide direct cues for mate choice. A free-ranging, pair-living rodent was used as an example to investigate MHC-dependent mate choice in an obligate monogamous species, the Malagasy giant jumping rat Hypogeomys antimena. Two possible mechanisms of mate choice were tested. First, mate choice may occur to increase the heterozygosity of MHC genes in the progeny and, second, mates might choose each other according to the degree of dissimilarity of their functional MHC DRB (exon 2) proteins in order to maximise the allelic divergence in their offspring. Analyses of 65 Hypogeomys couples failed to confirm associations of mating patterns with the MHC genotype to increase heterozygosity or MHC allelic divergence in the progeny. Also, no evidence for mechanisms to increase the allelic divergence was found in sex-specific analyses where a male or female, respectively, migrated to and was accepted by a territory and burrow holder of the opposite sex. However, the frequency distribution of 0, 1 or 2 new alleles potentially available for the progeny differed significantly when a new male was chosen by a territory-holding female. In contrast to current models, genetically similar instead of dissimilar mates seem to be the preferred choice. This is the first study investigating the role of the MHC in mate selection in an obligate monogamous rodent.Communicated by G. Wilkinson     

Fluctuating asymmetry and sperm transfer in male decorated field crickets (Gryllodes sigillatus)

Fluctuating asymmetry (FA) in limb size in female decorated field crickets (Gryllodes sigillatus) was associated with a reduction in the size of the spermatophore and the amount of sperm transferred by males and an increase in the time taken to transfer a spermatophore following introduction of a female. There was a weaker negative relationship between limb asymmetry in males and sperm number but no significant relationship between asymmetry in either sex and spermatophylax size. In line with a previous study, female size did not appear to influence spermatophore production or mating decisions by males. The results imply that developmental instability affects both gamete production and mating decisions among males, although the relationships between spermatophore size, sperm number and asymmetry in females are unlikely to be the result of males perceiving differences in female FA. Received: 24 July 1999 / Received in revised form: 22 November 1999 / Accepted: 31 December 1999     

Application of a Physical Input–Output Table to Evaluate the Development and Sustainability of Continental Water Resources in Spain

Continental waters are complex resources in terms of a measurable physical quantity, and measuring them requires a good knowledge of total water availability. In this research, an accounting physical input–output table (PIOT) was applied to evaluate total water resources and gross annual availabilities at each stage of the natural-artificial water cycle. These stages are considered subsystems of a continental water resource system describing water transfers for an average year within 13 administrative basins of Spain. Water transfers between various subsystems are characterized by internal flows decreasing the water resource availabilities. The PIOT analysis establishes these internal flows, and the origins and final uses of the total resources for each subsystem. The input-output balance registered an unsustainable negative net accumulation in eight water basins. The PIOT analysis also allowed the calculation of significant indicators such as water resource developments (RDI) and their sustainable use (SUI). RDI and SUI demonstrate that groundwater is a critical resource affecting the environment (e.g., wetlands in the upper Guadiana) and the water supply (e.g., irrigation in the Segura basin). The results of this model suggest that above-/below-ground hydrological links are important when decisions have to be made in order to provide a satisfactory supply of water in Spain. The model integrates the different water basins under territorial criteria, and therefore it may be useful for the Spanish National Hydrological Plan.     

Root Exudates Impact on Phenanthrene Availability

In order to improve and optimize phytoremediation of PAH we propose to focus on the rhizospheric processes controlling PAH degradation. In this paper the effect of root exudates on PAH availability is studied. Model organic compounds (malic acid, malonic acid and EDTA) representing root exudates have been tested for their effect on phenanthrene sorption on a reference non polluted agricultural soil material. Phenanthrene adsorption isotherms were first obtained with batch experiments. Results showed linear isotherms and phenanthrene sorption was enhanced as the concentration of organic compounds in the solution increased. Column leaching experiments were then used to simulate the effect of root exudation following the soil pollution. Inlet solutions containing the different organic acids used were flowed through the column containing the artificially polluted soil material. Elution curves showed that the phenanthrene was less easily eluted when the solution injected contained the organic acids. However, magnitude of the phenomena did not fit with adsorption constants obtained in batch experiments. Phenanthrene desorption appeared limited by sequestration but organic acids seemed able to partially disturb the soil material structure to limit the sequestration effect.     

Partial compensation of the sublethal effect of deltamethrin on the sex pheromonal communication of Trichogramma brassicae

Pyrethroid insecticides are widely used and lead to a sizable environmental pollution that could interfere with the population biology of insects. Trichogramma is a beneficial insect used in biological control and which natural populations contribute to the control of Lepidopterus pests. In this work, we determined the effect of a sublethal dose of deltamethrin on the sex pheromonal communication of Trichogramma. The dose used (LD 0.1) induces no detectable mortality (the theoretical mortality is only one insect over 1000) and can be a good representation of contamination by this insecticide from environmental pollution. The insecticide was shown to have opposite effects on the sex pheromonal communication of Trichogramma, depending on which sex was exposed (Delpuech, J.M., Legallet, B., Terrier, O., Fouillet, P., 1999. Chemosphere 38, 729–739). We show that, when both sexes are simultaneously exposed to the insecticide, this effect is only partially neutralized. The mean response of treated males responding to the sex pheromone from treated females is not significantly different from that of controls, but the kinetics of their response is not the same. When both sexes are treated, the response of males to the sex pheromone is lower at the beginning but their response does not decrease during time contrary to controls and becomes finally higher than that of controls. Therefore, the sublethal effect of deltamethrin in the field can be either advantageous or disadvantageous depending on the difficulty in finding females and their scarcity.     

蜂窝煤灰渣和磷肥结合修复铅污染贫磷潮土的研究（Remediation of Lead Polluted Chaotu Soil with Low Phosphorus Availability by Application of Honeycomb Briquette Combustion Residue and Phosphorus Fertilizer）

利用蜂窝煤灰渣和磷肥结合稳定铅污染贫磷(Olsen-P=2.50mg·kg-1)潮土中铅的可行性.采用盆栽试验,设置0和500mg·kg-1两个Pb用量,灰渣用量分别为干土质量的0%和2%,P:Pb分别为0和4.种植黑麦草,植物生长85d后收获,测定植物产量、土壤DTPA-Pb、Olsen-P含量、pH值和电导率(EC).结果表明,在两个Pb用量及两个P:Pb比例下,加入灰渣后,土壤的DTPA-Pb含量均降低,平均降低5.61%.其中加铅未加磷处理灰渣效果达到0.05的显著水平,各加Pb处理中,同时加入磷肥和灰渣处理土壤的DTPA-Pb含量最低;加入灰渣后处理土壤中的Olsen-P含量均增加,平均增加了2.71mg·kg-1,各处理土壤pH值上升约0.1个单位,加入灰渣也导致各处理土壤的EC增加.各处理条件下加入灰渣后植物产量均减小.在未加磷土壤中加入Pb后,土壤Olsen-P含量显著增加(p<0.05),表明高铅有效性下,植物可能通过根系分泌物增加了土壤磷的有效性.以上结果表明,蜂窝煤灰渣有可能用于降低污染土壤中铅的有效性,但其对植物生长的抑制作用需要克服.     

Human Population Numbers as a Function of Food Supply

Human population growth has typically been seen as the primary causative factor of other ecologically destructive phenomena. Current human disease epidemics are explored as a function of population size. That human population growth is itself a phenomenon with clearly identifiable ecological/biological causes has been overlooked. Here, human population growth is discussed as being subject to the same dynamic processes as the population growth of other species. Contrary to the widely held belief that food production must be increased to feed the growing population, experimental and correlational data indicate that human population growth varies as a function of food availability. By increasing food production for humans, at the expense of other species, the biologically determined effect has been, and continues to be, an increase in the human population. Understanding the relationship between food increases and population increases is proposed as a necessary first step in addressing this global problem. Resistance to this perspective is briefly discussed in terms of cultural bias in science.     

To court or not to court: reproductive decisions by male fiddler crabs in response to fluctuating food availability

For males, courting and foraging are often behavioral alternatives, which take time and consume energy. When males have a possibility of mating with receptive females, there may be a behavioral trade-off between courtship and feeding; the outcome of which may be affected by male physiological condition and food availability. Although many mathematical models and empirical studies suggest that the expression of male courtship signals are condition-dependent, decisions about courtship and mating strategies in relation to food availability have not attracted much attention. In this study, we tested whether daily changes in food availability affect males’ decisions about whether to court. We conducted experiments with the fiddler crab Uca lactea by providing males with additional food every other day. In food-supplemented enclosures, males did not increase courtship activity on the days when food was supplemented. However, they built more courtship structures (semidomes) and waved more on the days when they were not given additional food. Male size had a strong influence on the number of days the males courted. We also tested whether the frequency of surface mating, as an alternative reproductive tactic, decreased when food was supplemented. Contrary to our expectation, the number of males that exhibited the surface-mating tactic increased when food was supplemented whereas the number of mate-searching females did not change. Our findings in this field study suggest that reproductive decisions by male fiddler crabs are affected by fluctuating food availability and present body condition, and the alternative mating tactic of this species may be more frequently used by males under good condition.