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Eighty cormorants from the area of Ostroda and Mrągowo were used for this study. The analyses were carried out between 1993-1996. Each year 10 two-year-old birds were shot (5 females and 5 males) in two nesting grounds. On average, the amount of concentrated DDT in cormorant liver fat was 4.914 mg/kg and y-HCH was 0.039 mg/kg of wet mass. The average amount of DDT in subsequent years varied and ranged from 2.515 to 7.252 mg/kg; however, the differences were statistically insignificant. The females accumulated higher levels of DDT than the males, on average up to 8.796 mg/kg. The differences in DDT amounts concentrated in liver fat of both cormorant groups in different years appeared to be insignificant. Liver concentrations of γ -HCH in the observed period most frequently showed tendency to increase, from the level of 0.012 in 1993 to 0.106 mg/kg in 1995. This value decreased in 1996 to 0.003 mg/kg. Higher amounts of γ-HCH in liver fat were recorded in birds originating form the Mrągowo area, excluding the individuals shot in 1995. It was shown that the males accumulated higher levels of γ -HCH in their livers than the females (years 1993, 1994 and 1996). The presented study shows the continuous threat of the analyzed xenobiotic agents to water fowl and the need for continuous monitoring of water fowl in respect of their intoxication by DDT and HCH.
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.
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