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The influence of fleas on weight and body size in nestlings of Starlings was studied. Insecticide applied to nest material influenced flea larvae but not imagines. The presence of larvae and imagines in nests were considered indicators of nestlings and adult birds, respectively, being parasited. In general the presence of flea larvae or imagines in nests did not affect nestling weight or body size. However, when broods of different sizes were analyzed, there was a strong negative influence on the weight and body size of nestlings in bigger broods (4 nestlings). The presence of imagines had a much stronger influence on nestling condition than the presence of larvae. It was therefore suggested, that flea parasitism of adult Starlings affect nestling condition more than direct parasitism on nestlings.
The survivability and behaviour of worker bees of the Middle European, Carnolian and Caucasian breed at low air temperature was examined. Worker bees were individually placed in plastic cages and exposed to low temperatures - 5, 7 and 9°C - in a cooling incubator for a period of 60 and 120 min. After the fixed time elapsed, the number of moving worker bees as well as of chill-coma ones was recorded at a room temperature. The time after which worker bees recovered their vital activity, manifesting in abdomen, legs or antennae motion and assumption of full locomotor efficiency, was determined. All worker bees staying at 5, 7 and 9°C for a period of 60 and 120 min fell into the chill-coma state, irrespective of their breed and age (5, 10, 15 and 20 days). However, the time when bees remained motionless after removal from incubator differed. Worker bees kept at 5°C for, respectively, 60 and 120 min were motionless for the longest time, i.e. 163±71-236±84 s. On the other hand, worker bees exposed to 9°C for 60 min as well as for 120 min were in the chill-coma for the shortest time, i.e. 111±35 and 123±42 s, respectively. The youngest, 5 day old, bees were the most susceptible to low temperature, both to 5, 7 and 9°C. The time of staying motionless in the worker bees examined as well as of returning to full locomotor efficiency was determined by their breed. The Middle European worker bees were being distinguished by the shortest time, whereas the Carnolian ones by the longest.
The study aimed at determining the efficacy of controlling Varroa destructor mites with Apitraz strips in honey-bee colonies. Moreover, the amount of an active ingredient (amitraz) freed from the strips during their 6-week-long exposure in colonies was examined. The efficacy of parasite control with Apitraz was high. On the average, 816.37 mites were killed when using Apitraz. The control application of Bayvarol resulted in a fall-off of 5.05 parasites. Assuming the total parasite fall-off as 100%, the efficacy of Apitraz against varroosis amounted to 99.38%. Up to the fourth week of drug administration, over 80% of the mites died in honey-bee colonies. Out of 453.6 mg of the amitraz contained in a micro-layer of two strips, 104 to 223 mg (162 mg on the average) had been freed during their exposure in honey-bee colonies. Regarding the efficacy of varroosis control in honey-bee colonies to the amount of active ingredient freed from the strips that it was determined that it was not conditioned by the amount of freed amitraz (within the range examined), as the calculated coefficient of the correlation was insignificant (r = - 0.77).
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