Distance Between Honey Bee Apis mellifera Colonies Regulates Populations of Varroa destructor at a Landscape Scale

Abstract

Inter-colony distance of Apis mellifera significantly affects colony numbers of the parasitic mite Varroa destructor. We set up 15 apiaries, each consisting of two colonies. Each apiary pair was assigned an inter-colony distance of 0, 10, or 100 m. Colonies were rendered nearly mite-free, then one colony in each pair was seeded with 300 female mites (mite-donor colony), while the other remained uninoculated (mite-recipient colony). After four months of monitoring, a whole model analysis showed that apiaries in which colonies were spaced 100 m apart contained lower average mite numbers than 0 m or 10 m apiaries. There were interactions among colony type, distance, and sampling date; however, when there were significant differences mite numbers were always lower in 100 m apiaries than 10 m apiaries. These findings pose the possibility that Varroa populations are resource regulated at a landscape scale: near-neighbor colonies constitute reproductive resource for mites in the form of additional bee brood.

Keywords: Apis mellifera; colony collapse; host-parasite interaction; parasite transmission.

Figure 1.

Interaction between colony donor type (mite-donor or -recipient) and sampling episode. Episodes before donor colonies were inoculated with mites are omitted. Different letters indicate significant differences between colony type within sampling episode. Error bars represent SE of the least squares means separation.

Figure 2.

Interaction between apiary inter-colony distance and sampling episode. Episodes before donor colonies were inoculated with mites are omitted. Different letters indicate significant differences among colony distances within sampling episode. Error bars represent SE of the least squares means separation.

Figure 3.

Interaction between colony distance, colony donor type (mite-donor or -recipient), and sampling episode. Episodes before donor colonies were inoculated with mites are omitted. Different letters indicate significant differences among colony distances within colony donor type (mite-donor or -recipient) and sampling episode. Error bars represent SE of the least squares means separation.