What’s new with Varroa?

The UF/IFAS Honey Bee Lab has collaborated on research that led to two recent Varroa-related publications. Below are summaries of that research as well as links to the full publications.

Varroa feeding

This research was conducted through the collaborative efforts of the University of Maryland (lead institution), the USDA, the UF/IFAS Honey Bee Lab, and North Carolina State University.

Key finding: Varroa primarily feed on the fat bodies of honey bees, rather than on the bees’ hemolymph as previously thought.

Significance: This finding can lead to the development of better, more targeted Varroa control options, in addition to a greater understanding of Varroa biology.

For more details, read the publication here: https://www.pnas.org/content/pnas/116/5/1792.full.pdf

Ramsey, S. D., Ochoa, R., Bauchan, G., Gulbronson, C., Mowery, J. D., Cohen, D. L., Joklik, J., Cicero, J., Ellis, J. D., Hawthorne, D., & vanEngelsdorp, D. (2018). Varroa destructor feeds primarily on honey bee fat body tissue and not hemolymph. Proceedings of the National Academy of Sciences of the United States of America, 116(5), 1792-1801.

Varroa invasion

The movement of adult female Varroa (“foundress” Varroa) into honey bee brood cells to lay eggs is known as cell invasion. After the brood cell is capped, the offspring of the foundress Varroa mate and leave the cell with the emerging adult honey bee.

Key findings:

  1. There is no relationship between a foundress Varroa’s decision to invade a cell and her relatedness to other foundress Varroa already in the cell. They do not detect or consider whether or not they are related to the other foundress Varroa already in a cell before invading.
  2. Even given this random invasion, cells are co-invaded by unrelated mites more often than not (>75% of the time) when two foundress Varroa invade a cell.

 

Significance: This cell selection tends to favor outcrossing (i.e. mating between the offspring of unrelated Varroa). Random cell invasion, in combination with the knowledge that Varroa frequently move between colonies in an apiary, could be a possible contributor to the rapid spread of pesticide resistance and other undesirable traits that beekeepers see in Varroa.

For more details, read the publication here: https://onlinelibrary.wiley.com/doi/pdf/10.1111/1744-7917.12529

Beaurepaire, A. L., Ellis, J. D., Krieger, K. J., Moritz, R. F. A. (2019). Association of Varroa destructor females in multiply infested cells of the honeybee Apis melliferaInsect Science, 26, 128-134.