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The aim of this paper was to compare the residues of chlorinated hydrocarbons in bees from one of the apiaries of Piska Forest in 1996-2005. Furthermore, the content of HCH and DDT was examined in bees from this apiary where, in 2005, a very intensive cultivation of rape seed took place and by 1989 a large amount of pesticides had been applied. It was ascertained that in bees from P. apiary, which for more than ten years had been users of the same field crops (berries, lime-tree), the HCH level decreased from 0.0127 µg/g of l.s. (1996) to 0.0016 µg/g of l.s. (2005), whereas the DDT content was not reduced. This fact seems to indicate a considerably more rapid HCH decomposition in the environment. In bees staying nearly 3 weeks at the site of rape cultivation and examined after their return to the maternal apiary the content of HCH was 0.0236 µg/g of l.s. which was 15 times higher than in bees staying at the same place. The obtained results indicate that chlorinated hydrocarbons are still occurring in the environment and their amount depends on the type of pesticide used. It seems that on sandy soils the decomposition of HCH is considerably more rapid than on heavy clay soils. The diverse level of DDT in bees in P. apiary testifies to a considerable concentration of this pesticide in Piska Forest and to its slow decomposition in the environment or its permanent penetration with air streams from other regions of the world.
In the available literature there is lack of information concerning the influence of chlorinated hydrocarbons on bee behavior during the winter which is why it was decided to estimate HCH and DDT concentration in bees leaving the hive and staying inside it during the winter. To gain bees leaving the hive, on 15th of December 2005 traps were put on the entrances of 10 hives. Traps were emptied at one week intervals till 31 January, 2006. Samples of insects were weighted and counted in the laboratory and then the concentration of HCH and DDT was determined. Regardless of external temperature, individual bees left the hive. There was no observed dependence of the influence of external air temperature on the number of bees leaving the hive. The average concentration of HCH in bees leaving the hive during the winter was 0.0031 µg/g of lipid substance (l.s.) and total DDT was 0.0226 µg/g l.s., whereas in bees from the winter cluster 0.0010 µg/g l.s. and 0.0149 µg/ g l.s., respectively, and from the scatter 0.0011 and 0.0112 µg/g l.s. The results obtained indicate that in insects, as opposed to vertebrates, even a slight amount of pesticides seems to cause metabolic disorders and in this way lead to their leaving the hive in the winter.
The aim of the study was to determine the influence of Varroa destructor invasions on HCH and DDT concentration in bees from infected colonies. Studies were carried out on 7 apiaries in the Olsztyn area. It was found that HCH and DDT content in bees depended on both apiary location and V. destructor presence in colonies. Bees from infected colonies contained less amounts of chlorinated hydrocarbons. The greatest concentration of HCH and DDT was found in bees from apiaries located on the verge of forests, near allotment gardens, and the least in bees flying around rape, white mustard and weeds on waste ground. Higher HCH and DDT concentrations in bees free from V. destructor invasion indicates their greater activity in the environment and bringing flow to the hive, the amount of which influences the increase of chlorinated hydrocarbons in the organism.
It is unknown whether bees flying around entomophilous plants at a radius of several kilometers from their hives accumulate similar amounts of HCH and DDT. In view of this, the study aimed to determine the percentage (%) of bee colonies accumulating HCH and DDT in relation to apiary location. Studies were carried out on 4 apiaries with a variety of different nectars. The presence of HCH and DDT was ascertained in bee samples from 2 apiaries, and only HCH in the remaining apiaries. The greatest percentage of colonies in which both pesticides were found was in an apiary located on the outskirts of Olsztyn. 0.0101-0.0500 µg/g of lipid matter (l.m.) of HCH and DDT was found in 20-33% of the colonies in this apiary, vestigial amount of these pesticides (up to 0.0101 µg/g l.m.) in 6.7-13.3%, and the largest concentration of chlorinated hydrocarbons (0.0701-0.0800 µg/g l.m.). Only HCH was contained in 6.7% of the colonies of bees flying around nectar located on sandy soils; 20-40% of the colonies accumulated 0.0201-0.0500 µg/g l.m. of this pesticide, whereas in apiaries where bees mainly accessed Lindens, 66.7% of the colonies had a low HCH concentration and 20% were within a range of 0.00401-0.0500 µg/g l.m. and 6.7% had more than 0.0501 µg/g l.m. In an apiary in the Piska Forest where chlorinated hydrocarbons had been used for pest control as recently as in the 1980's, the presence of trace amounts of HCH and DDT were found in all bee colonies, and HCH in 50%. The remaining bee colonies contained only HCH (0.0201-0.0700 µg/g l.m). The results indicate the consistency in bee's habits of collecting nectar from particular plants and that there is variability within the levels of environmental pollution with chlorinated hydrocarbons. To ensure a conclusive evaluation of residues of chemical compounds in bees and bee products, at least 15 colonies should be examined within each apiary.
Taking into consideration the use of Apis mellifera as an indicator of environmental pollution, the residues of chlorinated hydrocarbons were examined in bees flying around the perennial entomophilous plants and rape cultivation. Studies were carried out in two apiaries. In the spring, bees from P apiary flew around the plants in forests, willow trees, dandelion and fruit trees, while those from N apiary flew around dandelion, weeds and maple trees. At the end of May, bees from both apiaries were taken to the rape cultivation, where in the 1980s plants were intensively grown and pesticides were used. Samples of bees were collected twice: in May (before being taken to the rape cultivation) and in July (after return to their previous places). In bees from both apiaries only residues of HCH and DDE were found. Concentration of HCH in bees from P apiary was 0.00097 µg/g of lipid matter (l.m.) and after their return from rape cultivation its level increased to 0.00293 µg/g of l.m. and it was 331% higher than in May. In May, the DDE content was 0.00178 µg/g of l.m. and in July 0.00312 µg/g of l.m. and it was about 57% higher. Residues of chlorinated hydrocarbons in bees from N apiary in May were: 0.00130 µg/g of l.m. for HCH and 0.00319 µg/g of l.m. for DDE. In July, after returning the apiary to its place of residence, the HCH level was 0.00224 µg/g of l.m. and increased by 58% and the DDE concentration was 0.00422 µg/g of l.m. (an increase of 76%). Differences in the level of chlorinated hydrocarbons in bees flying around two various cultivations, in completely different locations with respect to plant cover, confirms the usefulness of bees for monitoring the environment.
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