Improving floral nectar storage on filter paper for sugar recovery

Abstract

Nectar analysis has been used to understand pollination systems, but nectar storage methods have rarely been considered as potential sources of inaccuracy in the recovery of data. Prompt nectar sugar analysis is not always possible and storage methods can affect results. We aimed to develop an effective method to store nectar on filter paper. Nectars from two subspecies of Eremophila maculata (Scrophulariaceae) and Strelitzia reginae (Strelitziaceae) were spotted on filter papers. Nectars were redissolved and assayed by high-performance liquid chromatography to determine the masses of sugars recovered from the papers from Day 0 to Day 30. We evaluated the effects of the method of elution, paper type and size, and storage treatments on sugar recovery. Liquid nectars were also stored in the refrigerator. Sugars were best eluted from filter papers in 15mL of water and agitated for 1min. Nectar sugars stored on small papers tended to be recovered more successfully than those stored on larger papers (significantly for glucose). Paper performed better than nylon for glucose. Desiccant had a marginal positive effect on nectar sugar recovery, and filter paper performed better than did refrigeration of liquid nectar for storage. If highly accurate measurements are needed, nectars should be eluted with large volumes of water from small filter papers stored with desiccant within a few days of collection.