Neonicotinoid Pesticides and Bees - The Food and Environment ...
Neonicotinoid Pesticides and Bees - The Food and Environment ...
Neonicotinoid Pesticides and Bees - The Food and Environment ...
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
metabolite 6-chloronicotinic acid <strong>and</strong> fipronil <strong>and</strong> its metabolites were detected at low levels in<br />
monitoring studies<br />
Studies on residues deposited as dust containing neonicotinoids are summarised obviously this<br />
does not take into account recent EU requirements to limit dust emissions through the use of<br />
professionally treated seeds <strong>and</strong> deflectors. Drift during agricultural treatment determines the<br />
deposition of pesticides within a small distance from the field edge. What is less obvious is how to<br />
calculate the drift onto flowering weeds in the field margin as dust drift is unlikely to behave in the<br />
same way as spray drift due to the wide variations in particle size. Unfortunately the deposition<br />
data generated to date for grasses <strong>and</strong> flowering weeds in flower margins have limitations in terms<br />
of the reporting of sowing rates <strong>and</strong> seed treatment rates.<br />
Contact of bees with treated surfaces may occur through resting on treated leaves or during<br />
foraging on treated flowers. <strong>The</strong> major issue is that bees do not come into contact with the treated<br />
plant over the entire surface of their body but primarily through their feet; however during resting<br />
<strong>and</strong> cleaning they may transfer residues from their feet to other parts of their bodies.<br />
<strong>The</strong> exposure of bees to pesticides in pollen depends on both the residues present <strong>and</strong> the<br />
amounts of pollen collected by the bees. <strong>The</strong> amount of pollen collected by a colony per day is<br />
highly variable <strong>and</strong> depends on pollen availability, crop species <strong>and</strong> the needs of the colony. On<br />
oilseed rape the amount of pollen collected varied with the stage of flowering with most collected in<br />
the latter stage. Bee bread is pollen processed from the pollen loads by bees for storage by<br />
combining with nectar or honey <strong>and</strong> addition of antimicrobial agents. This results in higher<br />
residues in bee bread than in pollen which may relate to differences in availability for residue<br />
analysis following processing of the pollen by bees.<br />
Flower morphology is an important factor in the pesticide content of nectar: flowers in which the<br />
nectar is deeper, such as clover, were less contaminated than shallower flowers such as cabbage<br />
<strong>and</strong> nectar yield/flower was less important in determining pesticide content. To date, there are no<br />
reports of pesticide residues in aphid honeydew after spray application but the intake by bees may<br />
be expected to be similar to that of nectar sources.<br />
Residues in honey formed from contaminated nectar <strong>and</strong> stored within the hive will depend on the<br />
concentration of nectar through evaporation of water to produce honey <strong>and</strong> degradation of<br />
residues through biological <strong>and</strong> chemical factors in honey. Both factors are slow <strong>and</strong> counter each<br />
other to some extent <strong>and</strong> there are differences between honey contained in open <strong>and</strong> sealed cells.<br />
<strong>The</strong> residues of neonicotinoids pesticides detected in stored nectar <strong>and</strong> honey in field studies <strong>and</strong><br />
available monitoring data for samples taken directly from colonies are summarised. Monitoring<br />
data for processed honey has been excluded as honey is combined from a large number of<br />
<strong>Neonicotinoid</strong> pesticides <strong>and</strong> bees Page 8 of 133<br />
Report to Syngenta Ltd