Action: Ensure commercial hives/nests are disease free
One randomised controlled trial in Canada found that the antibiotic fumagillin is not effective against Nosema bombi infection in managed colonies of the western bumblebee Bombus occidentalis. One replicated controlled trial in South Korea found that Indian meal moth Plodia interpunctella in commercial bumblebee colonies can be controlled with the insect pathogen Bacillus thuringiensis (Bt) Aizawai strain, at a strength of 1 g Bt/litre of water.
Supporting evidence from individual studies
A randomised controlled trial in a large greenhouse in Ladner, British Columbia, Canada found that the antibiotic fumagillin dicyclohexylammonium did not affect the incidence or intensity of infection by the internal parasite Nosema bombi, in managed colonies of the western bumblebee Bombus occidentalis (Whittington & Winston 2003). The antibiotic was given to 32 colonies in sugar water at doses of 26 mg/L and 52 mg/L, and 17 control colonies were not treated. The study found that samples of frass or five or more worker bees could reliably test for the presence or absence of the parasite, but could not be used to quantify the intensity of infection.
Kwon et al. (2003) tested methods of controlling the Indian meal moth Plodia interpunctella, which can be problematic to bumblebee colonies in commercial rearing conditions or greenhouses. This moth's eggs are transported in pollen from honey bee colonies, and survive normal frozen storage conditions. Replicated controlled experiments showed that storage at -60°C for 70 days killed all Indian meal moth eggs (three replicates of each treatment). Storage at -20°C killed 80-90% of the eggs. In a separate experiment, treating B. terrestris colonies with the insect pathogen Bacillus thuringiensis (Bt) Aizawai strain at a concentration of 1 g Bt/litre of water killed 98-100 % of moth larvae after seven days, but did not cause bumblebee mortality after 10 days. Treatment with 2 g Bt/litre of water caused high bumblebee mortality. There were five Bt treated colonies and five control colonies.
- Whittington R. & Winston M.L. (2003) Effects of Nosema bombi and its treatment fumagillin on bumble bee Bombus occidentalis colonies. Journal of Invertebrate Pathology, 84, 54-58
- Kwon Y.J., Saeed S. & Duchateau M.J. (2003) Control of Plodia interpunctella (Lepidoptera: Pyralidae), a pest in Bombus terrestris (Hymenoptera: Apidae) colonies. The Canadian Entomologist, 135, 893-902