To receive reliable measurements of pesticide residue in nectar, pollen, leaves and flower tissue, chemical analytical labs need researchers to collect reasonably large volumes of nectar or pollen. When our project began, our lab needed about 1 mL of nectar, 1 mg of pollen, and 1 g of leaf and flower tissue to produce reliable measurements.
We soon found that collecting these quantities of nectar and pollen was not an easy task. Many of the flowers we sampled produced little-to-no nectar and a miniscule amount of pollen. For nectar, for example, we found flowers often had either no nectar, sometimes an average of 0.002 mL of nectar, and every once in a while we’d find a flower with upwards of 0.05 mL or more. In this case, to reach 1 mL of nectar required finding about 500 flowers that produced an average of 0.002 mL of nectar. In our experience, finding this amount of nectar within the time block we had to sample flowers was difficult.
Thankfully, our analytical chemists have been working to reduce the volume of nectar and pollen needed for reliable pesticide residue analysis. The refined analytical procedure (known as QuEChERs) can now detect neonicotinoid amounts as low as 2.5 parts per billion in only 0.1 mL of nectar. While our researchers will continue to strive to collect much more than the minimum 0.1 mL of nectar, we can now proceed with more confidence of attaining enough nectar and pollen for reliable pesticide residue measurement.