The effect of drifting honey bees on the spread of American foulbrood infections

SUMMARY

Twenty-five pairs of honey bee (Apis mellifera) colonies were established with the hives in each pair touching and the entrances facing the same direction. One colony in each pair had a light American foulbrood (AFB) infection (<50 larvae with clinical symptoms) while the other (control) was uninfected. The pairs remained together for 5–388 days (average 103 days). Any heavily infected colonies (< 50 larvae with clinical symptoms) were removed from the trial. Only 2 of the control colonies developed AFB. In a separate trial with two pairs of colonies established in the same way, an average of 5.72% of marked bees were in the wrong hive after two days. Trials where 20 uninfected nucleus colonies were fed 50 000, 500 000 or 5 million Bacillus larvae spores in sugar syrup indicated that the control colonies were not particularly resistant to AFB; four of five colonies fed 5 million spores developed AFB. The results suggest that drifting of honey bees is not a particularly important cause of the spread of AFB.

Keywords:

• honey bees
• Apis mellifera
• American foulbrood
• Bacillus larvae
• drifting
• disease transmission