关于灾害系统的若干问题

本文简述了灾害系统的某些基本概念,提出了灾害学系统划分的基本原则,讨论了灾害系统的一些重要特征。指出灾害系统是一个非常复杂的大系统,它不仅是一个随着时间演化的开放系统,而且具有非线性、不确知性、不确定性和社会性。灾害系统的分析、综合和广义模型化是当前的重要课题。     

强化综合整治,促进环发协调

论述了实现上海环境保护工作目标的指导思想，具体目标和继续深化城市综合整治，全面加强环境监督管理，促进环境与相协调的主要对策和任务。     

The honey bee’s tremble dance stimulates additional bees to function as nectar receivers

If a forager bee returns to her hive laden with high-quality nectar but then experiences difficulty finding a receiver bee to unload her, she will begin to produce a conspicuous communication signal called the tremble dance. The context in which this signal is produced suggests that it serves to stimulate more bees to function as nectar receivers, but so far there is no direct evidence of this effect. We now report an experiment which shows that more bees do begin to function as nectar receivers when foragers produce tremble dances. When we stimulated the production of tremble dances in a colony and counted the number of bees engaged in nectar reception before and after the period of intense tremble dancing, we found a dramatic increase. In two trials, the number of nectar receivers rose from 17% of the colony’s population before tremble dancing to 30–50% of the population after the dancing. We also investigated which bees become the additional nectar receivers, by looking at the age composition of the receiver bees before and after the period of intense tremble dancing. We found that none of the bees recruited to the task of nectar reception were old bees, most were middle-aged bees, and some were even young bees. It remains unclear whether these auxiliary nectar receivers were previously inactive (as a reserve supply of labor) or were previously active on other tasks. Overall, this study demonstrates that a honey bee colony is able to rapidly and strongly alter its allocation of labor to adapt to environmental changes, and it further documents one of the communication mechanisms underlying this ability. Received: 31 May 1996/Accepted after revision: 9 August 1996     

Division of labor and the evolution of task sharing in queen associations of the harvester ant<Emphasis Type="Italic"> Pogonomyrmex californicus</Emphasis>

Division of labor is a key factor in the ecological success of social groups. Recent work suggests that division of labor can emerge even without specific adaptations for task specialization and that it can appear in incipient social groups as a self-organizational property. We investigated experimentally how selection and self-organization may interact during the evolution of division of labor by examining task performance in groups of normally solitary versus normally social ant queens. We created social pairs of colony-founding queens from two populations of the ant Pogonomyrmex californicus, one in which queens are normally solitary and one in which queens form foundress groups, and observed their behavior during nest excavation. In both populations, one of the two queens usually performed most of the excavation, becoming the excavation specialist. We could predict which queen would become the specialist based on their relative propensities to perform the task in other contexts, consistent with a variance-based model of task specialization. The occurrence of specialization even when group members were not adapted to social life suggests that division of labor may well have been present in incipient queen groups. However, division of labor can result in cost skew among group members, and thus, paradoxically, within-group selection may constrain or even reduce specialization. Consistent with this effect, pairs of normally solitary queens were significantly more asymmetrical in their task performance than normally social pairs, in which both queens nearly always performed the behavior to some degree.Communicated by J. Heinze     

台湾环境教育的特色与大陆环境教育的前瞻

借鉴台湾省开展环境教育的特色，阐述了大陆环境教育的目标任务。     

沈阳市2000年环保产业发展的目标和任务

在阐明了环保产业发展的的总体态势和所面临的形势后 ,着重对沈阳市 2 0 0 0年环保产业发展的目标和实现这一目标应完成的几项任务 ,进行了较为具体的探讨     

Nectar-receiver behavior in relation to the reward rate experienced by foraging honeybees

Since forager honeybees change their food-unloading behavior according to nectar-source profitability, an experiment was performed in order to analyze whether food-receivers modify their within-hive tasks related to different reward conditions. We offered individual foragers two reward conditions at a rate feeder while an additional feeder offered a constant reward and was of free access to the rest of the hive. Both feeders were the only food sources exploited by the colony during the assays since a flight chamber was used. After receiving nectar, hive bees performed processing cycles that involved several behaviors and concluded when they returned to the delivery area to receive a new food sample. During these cycles, receivers mainly performed oral contacts offering food, or inspected cells, and often both. In the latter case, both behaviors occurred simultaneously and at the same distance from the hive entrance. When they performed a single task, either the occurrence of cell inspections increased or contact offerings decreased for the highest reward rate offered to the donor-forager. Receivers also begged for food more often after interacting with low-profit foragers. Thus, the profitability of the food source exploited by nectar-forager honeybees could affect receiver behaviors within the hives based on individual-to-individual interactions.Communicated by R.F.A. Moritz     

Experimental analysis of worker division of labor in bumblebee nest thermoregulation (<Emphasis Type="Italic">Bombus huntii</Emphasis>, Hymenoptera: Apidae)

Bumblebee colonies experience daily and seasonal fluctuations in ambient temperature, but proper brood development requires a stable nest temperature. This study examined how adaptive colony responses to changing ambient temperature are achieved through the in-nest workers’ behavioral plasticity. We studied three Bombus huntii colonies in the laboratory. In the first experiment, we manipulated ambient temperature and recorded brood cell incubation and wing fanning by individually marked, known-age bees. The colonies maintained their nests closer to appropriate brood development temperatures (28 to 32°C) when exposed to a range of ambient temperatures from 10.3 to 38.6°C. Incubation activity was greater in cooler treatment conditions, whereas in the highest temperature treatment, some bees fanned and others moved off the brood. As the ambient temperature dropped, workers increased the duration of their incubating bouts, but, except at the highest temperature, the number of workers that incubated did not differ significantly among treatments. A subset of the bees incubated significantly more than their nest mates, some of which never incubated. Worker body size, but not age, was a good predictor of incubation rates, and smaller bees incubated at higher rates. In the second experiment, we removed the most actively incubating workers. Immediately after removals, the total colony incubation effort was lower than pre-removal levels, but incubation effort rebounded toward pre-removal levels after 24 h. The increased thermoregulatory demand after removals was met primarily by bees increasing their rates of incubation rather than by bees switching from a different task to incubation. We conclude that some B. huntii workers specialize on nest thermoregulation, and that changes in work rates are more important than task switching in meeting thermal challenges.     

Experimental manipulation of colony genetic diversity had no effect on short-term task efficiency in the Argentine ant Linepithema humile

Genetic diversity might increase the performance of social groups by improving task efficiency or disease resistance, but direct experimental tests of these hypotheses are rare. We manipulated the level of genetic diversity in colonies of the Argentine ant Linepithema humile, and then recorded the short-term task efficiency of these experimental colonies. The efficiency of low and high genetic diversity colonies did not differ significantly for any of the following tasks: exploring a new territory, foraging, moving to a new nest site, or removing corpses. The tests were powerful enough to detect large effects, but may have failed to detect small differences. Indeed, observed effect sizes were generally small, except for the time to create a trail during nest emigration. In addition, genetic diversity had no statistically significant impact on the number of workers, males and females produced by the colony, but these tests had low power. Higher genetic diversity also did not result in lower variance in task efficiency and productivity. In contrast to genetic diversity, colony size was positively correlated with the efficiency at performing most tasks and with colony productivity. Altogether, these results suggest that genetic diversity does not strongly improve short-term task efficiency in L. humile, but that worker number is a key factor determining the success of this invasive species.Communicated by L. Sundström     

Task specialization in a wild bee,Apis florea (Hymenoptera: Apidae), revealed by RFLP banding

Workers in a wild in situ colony of the dwarf honey bee, Apis florea, were observed undertaking the following behavior: liquid foraging, pollen foraging, guarding, stinging, fanning and wagging abdomen. Bees of each behavioral class were separately collected and frozen. Collections were made over a period of 10 days. Random samples of brood and workers were also collected. DNA was extracted from each bee and fingerprinted using a probe of unknown sequence obtained from an A. mellifera genomic library. Patterns of fingerprints (Fig. 1) were dissimilar among behavioral classes (Tables 1 and 2), strongly suggesting a genetic component to division of labor in this species. This result supports similar findings in A. mellifera in a species that is not troubled by many of the experimental difficulties inherent in A. mellifera. Correspondence to: B.P. Oldroyd