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Activity levels, feeding rate and mortality

The activity level did not differ between the control bees and bees given different doses of imidaclopird. The individuals given different doses of imidacloprid did not show a higher or lower activity pattern compared to the control bees. The bees given the highest dose of imidacloprid (125 µg/L), did not show any difference in activity level compared to the control bees.

Figure 1: Average activity (Mean ± S.E.) of the honeybees in meters per hour, as a function of pesticide concentration. The first data point on the left is for the control bees (imidacloprid concentration 0µg/L) .


The feeding rate between control bees and bees given the pesticide, were not significantly different.   Bees given the doses 0.082 µg/L and 125 µg/L had the highest feeding rate but it was not significantly higher compared to the control bees.

Figure 2: Average feeding rate (Mean ± S.E.) per bee per day as a function of imidacloprid concentration. The first data point on the left is for the control bees (imidacloprid concentration 0µg/L) .


No significant difference was found in mortality rate between control bees and bees given imidacloprid.   The individuals given the highest dose of imidacloprid (125 µg/L) lived approximately for six days, which was the lowest number of days lived. The control bees lived one day longer compared to the bees given the highest dose.

Figure 3: Averaged number of days (Mean ± S.E.) the bees lived as a function of imidacloprid concentration. The first data point on the left is for the control bees (imidacloprid concentration 0µg/L).


Olfactory learning and memory

There were significant difference between control bees and bees given different doses of imidacloprid in the last conditioning trial (C3) and the two memory retention tests (15min,60min). The decrease in performance was found for all doses of imidacloprid tested ( 0.512 µg/L, 1.28 µg/L, 3.2 µg/L, 8 µg/L), The bees given the highest dose of imidacloprid (8µg/l) had the poorest performance on all three tests. Overall, imidacloprid do affect the honeybees’ olfactory learning and memory formation.

 

Figure 4: C3 shows the learning performance in the last conditioning trial. 15 min shows the percentage of bees that remembered 15 min after the last conditioning trial. 60 min shows the percentage of bees that remembered 60 min after the last conditioning trial.


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Last updated: 05/18/11