Evaluating the persistence of fluorescent and protein powders on adult blue orchard bees, Osmia lignaria (Hymenoptera: Megachilidae), for mark-capture studies

Abstract

The managed, solitary bee, Osmia lignaria Say, is an efficient pollinator of orchard crops. One limitation to their commercial success is high dispersal of populations away from orchards, resulting in low establishment in provided nest cavities even when optimal pollination is achieved. While exact causes for dispersal are unknown, many existing theories remain untested due to complications with evaluating O. lignaria establishment in field settings. We describe relatively simple and reliable methods for passively marking O. lignaria with egg albumin and casein powdered proteins combined with orange fluorescent powder as they emerge from cocoons. Marked adults were examined microscopically at 0, 3, 6, 9, 12, 15, and 18 days after emergence for the fluorescent powder followed by an anti-albumin and anti-casein enzyme-linked immunosorbent assay to detect the protein powders. The orange powder and egg albumin were highly persistent on adults throughout the 18-day study, suggesting the utility of these markers for studying dispersal and retention of O. lignaria in the field.

A Nonlethal Method to Examine Non-Apis Bees for Mark-Capture Research

“…These unmarked bees served as a negative control treatment to which positive detection was compared. The protein-treated bee samples were scored positive for the presence of egg albumin if the ELISA optical density reading exceeded the mean negative control treatment value by 6 SDs ( Hagler et al 2011a , Boyle et al 2018 ).…”

“…A 1:1 (wt) mixture of egg white powder (The Barry Farm, Wapakoneta, OH) and bovine milk powder (Sigma-Aldrich, St. Louis, MO; catalog #C7078) was prepared. Bovine milk protein was included in the mixture because of its ability to adhere well to solitary bee cocoon surfaces and was deemed an effective delivery agent of the egg albumin powder ( Boyle et al 2018 ).…”

“…For O. lignaria , upon their emergence from cocoons and consequential self-marking, 60 marked female adults were collected and stored at 26°C in groups of 10 in large plastic containers (30 × 20 × 10 cm) that were replaced daily and fed a 1:1 solution of honey and distilled water. The containers were lined with a thin layer of play sand to improve bee traction to the surface of the dish and to capture protein marker residues as they potentially wore off of the bees ( Boyle et al 2018 ). To minimize a risk of secondary contact with the protein, bees were introduced to a new, clean container and given fresh honey water daily.…”

“…While somewhat effective, the microscopic detection of minute traces of fluorescent pigments is tedious and subject to human error (J. R. H, personal observation). More recently, protein powders (such as egg albumin or bovine casein) were proven effective for mass-marking a variety of insect species, including bees ( Hagler et al 2011a , b ; Boyle et al 2018 ). Protein marks can be applied by a single, broadcast application ( Sivakoff et al 2012 , Swezey et al 2013 , Klick et al 2016 ) or by the installation of a self-marking device placed at strategic locations in the field ( Hoggsette 1983 , Hagler et al 2011b , Biddinger et al 2013 ).…”

“…A notable drawback of the protein mark-capture technique is that current protocols require destructive sampling of individuals for protein analysis ( Sivakoff et al 2012 , Swezey et al 2013 , Klick et al 2016 , Boyle et al 2018 ). Due to the large size of honey bee colonies, the loss of a few hundred individuals for ELISA analysis will not have a major impact on a colony’s welfare or to the pollination services they provide.…”