Pollen traps as a beekeeping integrated pest management tool: Their use in IPM for varroa mite control and for reducing the impact of microencapsulated pesticides on honey bee colonies

Abstract

Honey bee (Apis mellifera) colonies were equipped with pollen traps obtained from the CC pollen company. One set of studies compared bee deaths and pesticide residues in pollen trap-treated colonies with untreated control colonies placed near agricultural fields that were sprayed with microencapsulated methyl parathion (Penncap-M®). A second set of studies examined the effect of the pollen traps on varroa mite (Varroa destructor) populations compared with mite populations in control colonies that were treated with the labeled chemical treatment for varroa mites.

Pesticide Studies: The pesticide studies were in response to the problem of bee deaths due to poisoning by microencapsulated methyl parathion. The microcapsules are in the size range of pollen grains and poisoning became a problem in fruit orchards where the pesticide drifted onto blooming ground cover where it was accidentally collected along with pollen by foraging honey bees. The studies showed that the microencapsulated pesticide persisted on orchard ground cover (clover) for several days after the pesticide was sprayed. The pesticide was also in the pollen loads that were removed from foragers by the pollen traps, and in the bees that were dying as a result of the pesticide spray. The presence of the pollen traps did not significantly reduce bee deaths or pesticide residues in the treated colonies.

The pesticide studies also showed that under drought conditions, blooming orchard ground cover plants such as clover may be sufficiently unattractive to foraging honey bees to prevent the expected pesticide poisoning that would normally occur after a Penncap-M® spray. In such cases drought may be an IPM tool for managing bee colonies in some potentially dangerous agricultural settings.

Varroa mite studies: The varroa mite studies were in response to the enormous problem of the varroa mite parasite which, over the past twelve years, has killed virtually all feral honey bee colonies and reduced the number of managed colonies by a third. Although there are chemical treatments available for varroa mite control, there are problems with their use such as the development of resistant mites and the contamination of honey and bees wax.

Pollen traps removed large numbers of varroa mites from the bee population, but the removal was slower than chemical treatment so that the mites in pollen trap-treated colonies continued to reproduce. In many instances, mite levels remained below the established economic treatment threshold when the pollen traps were used in July and August. However, when pollen traps were used in December and January, mite levels were in all cases above the treatment threshold. These results show that pollen traps do have a value in varroa mite IPM. Future studies should examine the effect of pollen traps on varroa mite populations when the traps are used earlier in the year to prevent or reduce the chance that mite levels will reach economic threshold levels.