3. Measuring pollen on bees and pollen deposition on stigmas

Pollinator performance can be thought about with at least three organizing concepts: (1) measuring fruit- or seed-set that results after flower visitation, (2) measuring pollen load on pollinators and their pollen deposition onto stigmas, or (3) measuring plant reproductive success post-pollination, i.e., fertilization efficiency (Gross, 2005; Ne’emen et al., 2010). For our purposes, we are focusing on the first two concepts because reproductive success depends not only on the amount of pollen vectored by pollinators but also on additional factors such as pollen pistil interaction and female choice (Herrero and Hormaza, 1996). In order to evaluate pollinator performance we can study the pollen carried by bees as well as the pollen effectively deposited on the stigmas.

Most of the following methods have been discussed in detail in pollination methodology books (Kearns and Inouye, 1993; Dafni et al., 2005).

3.2. Evaluating pollen identity, quantity and quality on stigmas