According to Singaravelan et al. (2005) naturally occurring concentrations of secondary compounds such as caffeine, nicotine, anabasine, and amygadaline did not deter insects. Secondary compounds can be regarded as post-ingestion stimulants to pollinators. Low concentrations of psychoactive alkaloids, nicotine and caffeine, increased nectar feeding significantly. These compounds may have been part of the reward. The presence of psychoactive alkaloids, such as these, in nectar, may also impose a dependence or addiction on pollinators, as well as improving the short term and early, long-term memory of honeybees (Singaravelan 2010). The latter effect was recently proved by Wright et al. (2013) demonstrating that honeybees rewarded with caffeine, which occurs naturally in nectar of Coffee and Citrus species, have a higher ability to remember a learned fl oral scent than honeybees rewarded with sucrose alone. 

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