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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Bee Research Laboratory » Research » Publications at this Location » Publication #320550
Title: Colony failure linked to low sperm viability in honey bee (Apis mellifera) queens and an exploration of potential causative factors

Author
item Pettis, Jeffery
item Rice, Nathan
item JOSELOW, KATIE - University Of Maryland
item VANENGELSDORP, DENNIS - University Of Maryland
item CHAIMANEE, VEERANAN - Maejo University

Submitted to: PLOS ONE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/30/2016
Publication Date: 5/1/2016
Citation: Pettis, J.S., Rice, N.D., Joselow, K., Vanengelsdorp, D., Chaimanee, V. 2016. Colony failure linked to low sperm viability in honey bee (Apis mellifera) queens and an exploration of potential causative factors. PLoS One. doi: 10.1371/journal.pone.0147220.

Interpretive Summary: Queen health is closely linked to colony performance in honey bees as a single queen is normally responsible for all egg laying within the colony. In the U. S. in recent years, queens have been failing at a high rate; with 50% or greater of queens replaced in colonies within 6 months when historically a queen might live one to two years. In the current research, surveys of sperm viability in US queens were made to determine if sperm viability could play a role in queen or colony failure. Queens removed from colonies rated in good health averaged high viability (ca. 85%) while those rated as failing or in poor health had significantly lower viability (ca. 50%). Thus low sperm viability was indicative of, or linked to, colony performance. This information will help queen breeders produce better queens and will help beekeepers if queens live longer in their colonies.

Technical Abstract: Queen health is closely linked to colony performance in honey bees as a single queen is normally responsible for all egg laying and brood production within the colony. In the U. S. in recent years, queens have been failing at a high rate; with 50% or greater of queens replaced in colonies within 6 months when historically a queen might live one to two years. This high rate of queen failure coincides with the high mortality rates of colonies in the US, some years with >50% of colonies dying over the course of a year in commercial beekeeping operations. In the current research, surveys of sperm viability in US queens were made to determine if sperm viability could play a role in queen or colony failure. Wide variation was observed in sperm viability from four sets of queens removed from colonies that were rated as in good health (average viability = 92%), were having their queens routinely replaced (re-queened) (57%) or where two beekeepers provided queens from colonies they rated as failing (54% and 55%). Two additional paired set of queens showed a statistically significant difference in viability between colonies rated by the beekeeper as failing or in good health from the same apiaries. Queens removed from colonies rated in good health averaged high viability (ca. 85%) while those rated as failing or in poor health had significantly lower viability (ca. 50%). Thus low sperm viability was indicative of, or linked to, colony performance. To explore the source of low sperm viability, six commercial queen breeders were surveyed and wide variation in viability (range 60-90%) was documented between breeders. This variability could originate from the drones the queens mate with or temperature extremes that queens are exposed to during shipment. The role of shipping temperature as a possible explanation for low sperm viability was documented as queens in shipment can indeed be exposed to high and low temperature spikes and these temperatures (<8 and > 40C) are sufficient to kill greater than 50% of the sperm in live queens. Lastly, two chemicals, amitraz and imidacloprid, were shown to artificially kill sperm when these chemicals were applied directly to queens; more data are needed to determine if such chemical exposure occurs and could contribute to the low sperm viability observed in queens. Clearly low sperm viability is linked to colony performance and laboratory and field data provide evidence that temperature extremes or chemical exposure are potential causative factors. More research is needed on general drone health and exposure to pesticides prior to mating and on the possible role of pesticides in queen health at the colony level.