Adult bee depopulation

Signs or indications

Apparent often sudden, inadequate adult population to cover brood cells. May occur naturally and temporarily during spring colony development, during heavy flight activity, following a pesticide poisoning incident, or due to disease such as viral epidemics. Colony absconding in the fall or swarming in spring reduces adult population rapidly. Colony collapse disorder (CCD) can also result in sudden (2-4 week) loss of adult bee population. 

Description

The adult population of healthy bee colonies should be sufficient to blanket developing brood and patrol the hive interior to keep scavenger pests such as small hive beetles, ants, yellowjackets, and wax moth from entering or developing. Adult bee depopulation may occur when there are too few adults relative to the brood population, which may occur in early spring, when older bees die at a faster rate than a colony can rear replacements, or in the fall, when hygienic bees uncap and remove pupae as they seek reproducing mites in capped brood cells, which results in inadequate rearing of new adult bees.

Severe disease infestations such as American foulbrood or viruses transmitted by mites, i.e., parasitic mite syndrome (PMS), also affect rate of replacement of older adults, leading to too few adults in a colony. Sudden depopulations of adults occur with behaviors of absconding, swarming, starvation, and pesticide poisoning.

Syndromes such as CCD and bee PMS often include sudden adult bee depopulation, both of which can lead to overwinter deadouts. Earlier descriptive terms such as colony disappearing disease, autumn collapse, May disease, or spring dwindling were used to describe depopulation of adults (and sometimes brood), especially for instances of regional colony declines.

Most closely resembles

absconding, CCD, bee PMS, pesticide poisoning, starvation, swarming

Resources

Sagili R, Hooven L. 2020 update. Bee Colony Collapse Disorder. National Pesticide Information Center. Accessed 2023. http://npic.orst.edu/envir/ccd.html

Ellis J, 2016 update. Colony Collapse Disorder. University of Florida/IFAS Extension. Accessed 2023. https://sfyl.ifas.ufl.edu/agriculture/colony-collapse-disorder/

vanEngelsdorp D, et al. 2009. Colony Collapse Disorder: A Descriptive Study. PLoS ONE 4(8):e6481. https://doi.org/10.1371/journal.pone.0006481

Synder R. 2013. Parasitic Mite Syndrome (PMS). BeeInformed. Accessed 2023. https://beeinformed.org/2013/10/15/parasitic-mite-syndrome-pms/

Inglin K. 2020. Euthanizing a colony. The Beekeeper’s Corner. Accessed 2023. https://www.bkcorner.org/euthanizing-a-colony/

 Adult bee depopulation due to apparent pesticide poisoning; photo by Dewey M. Caron
Adult bee depopulation due to apparent pesticide poisoning; photo by Dewey M. Caron
 Too few adult bees to properly care for and maintain proper temperature for brood; photo by The BeeMD photo collection
Too few adult bees to properly care for and maintain proper temperature for brood; photo by The BeeMD photo collection
 Apparent low adult population to adequately ripen honey; small hive beetles, which also appear in the photo, could be the reason for the reduced adult presence; photo by Jennifer Berry, bugwood.org
Apparent low adult population to adequately ripen honey; small hive beetles, which also appear in the photo, could be the reason for the reduced adult presence; photo by Jennifer Berry, bugwood.org
 Normal frame with a good adult population; photo by The BeeMD photo collection
Normal frame with a good adult population; photo by The BeeMD photo collection
 Sudden heavy depopulation; dead bees on screen of bottom board due to a spring starvation event; photo by Dewey M. Caron
Sudden heavy depopulation; dead bees on screen of bottom board due to a spring starvation event; photo by Dewey M. Caron