Abstract
Hop (Humulus lupulus L.) beta acids (HBA) were tested for miticidal effects on varroa destructor Anderson and Trueman, a parasitic mite of the honey bee (Apis mellifera L.). When varroa were placed on bees that had topical applications of 1 % HBA, there was 100 % mite mortality. Bee mortality was unaffected. Cardboard strips saturated with HBA and placed in colonies resulted in mite drop that was significantly greater than in untreated hives. HBA was detected on about 60 % of the bees in colonies during the first 48 h after application. Mite drop in colonies lasted for about 7 days with the highest drop occurring in the first 2–3 days after treatment. There was a reduction in the percentages of bees with HBA and in the amounts on their bodies after 7 days. Bee and queen mortality in the colonies were not affected by HBA treatments. When cardboard strips saturated with HBA were put in packages of bees, more than 90 % of the mites were killed without an increase in bee mortality. HBA might have potential to control varroa when establishing colonies from packages or during broodless periods.
Highlights
Hop (Humulus lupulus L.) beta acids (HBA) were tested for miticidal effects on varroa destructor Anderson and Trueman, a parasitic mite of the honey bee (Apis mellifera L.)
When cardboard strips saturated with hop beta acids (HBA) were put in packages of bees, more than 90 % of the mites were killed without an increase in bee mortality
When HBA strips were placed in colonies, there was no significant increase in bee mortality during any sampling interval (F3,72 = 0.09, p = 0.96) (Table 1)
Summary
Hop (Humulus lupulus L.) beta acids (HBA) were tested for miticidal effects on varroa destructor Anderson and Trueman, a parasitic mite of the honey bee (Apis mellifera L.). The varroa mite (Varroa destuctor Anderson and Trueman) is a major pest of honey bees (Apis mellifera L.) that has caused colony losses throughout the world (De Jong et al 1982; Rosenkranz et al 2010). The mated female mites leave the cell when the bee emerges and in this phoretic stage search for new cells to infest (Sammataro et al 2000). Oxalic acid has been used to control varroa in Europe and Canada (Gregorc and Planinc 2001) Though each of these control methods can be effective in reducing varroa populations, they have limitations. Under cool conditions formic acid can be ineffective while under high temperature it can harm adult bees and brood (Elzen et al 2004) and cause queen loss (Giovenazzo and Dubreuil 2011). Plant essential oils have been tested for varroa control (Sammataro et al 1998; Damiani et al 2009) but difficulty in developing consistent delivery methods, comb and honey contamination and their toxicity to bees have limited their use
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