The Honey Bee Parasite, Nosema ceranae: Biology, Management and Future Directions
Stephen F. Pernal Abdullah Ibrahim, Johan van den Heever and Andony Melathopoulos AAFC Beaverlodge Research Farm Beaverlodge, Alberta Nosema – microsporidia: Highly specialized parasitic fungi Nosema Reduces:
Nursing
Lifespan
Pollen collection
Queen fertility
Queen acceptance
Leads to wintering mortality, poor spring build-up and loss of honey production. What is Nosema ceranae? • Isolated from Apis cerana in China in 1996.
• Reported from Apis mellifera in Taiwan 2005 and later confirmed in Spain. Later confirmations from Germany and France.
• In Spain, N. ceranae characterized by N. ceranae N. apis gradual depopulation, higher fall/winter mortality, low honey production but not (Fries et al. 2006) dysentery or crawling bees seen with N. apis.
• Above symtoms similar to “dry nosemosis” seen in France.
• Widepsread in the U.S., Canada and other countries. Managing Nosema Unknowns
• Susceptibility to fumagillin.
• Disinfection.
• Seasonal Phenology.
• Alternative Therapies. Fumagillin Fumagillin dicyclohexylammonium
Medivet Pharmaceuticals DIN 02231180 (21 mg/g) Fumagillin Efficacy Experiment N. ceranae-infected overwintered singles: 22 April 2009
Pre-experimental infection level: 4.3 ± 0.5 million spores per bee Fumagillin Efficacy Experiment Treatment Formulations – Spring 2009
DUSTING PATTY Icing Sugar Dust Pollen, Soy Flour, Syrup
SYRUP 1:1 Sucrose Drench vs. Full Colonies assessed Volume 30 June, 26 Aug 09. Spring Fumagillin Efficacy Experiment 2009 Treatments applied 22 April, 6 May; Total a.i. = 100 mg
133,000,000 12 Drench Dust 10 8 Patty
)
6 Syrup Untreated a Untreated ab Patty, Syrup, Drench 6 b Dust * a 4 a a
a Untreated ab Patty, Syrup
Spores / Bee (x 10 (x / Bee Spores 2 b Dust, Drench b b b * 0
5-Oct 15-Jul 29-Jul 9-Sept 22-Apr29-Apr06-May13-May20-May27-May03-Jun 11-Aug 23-Sept 19-Nov Comb Disinfection Experiment Inoculating Comb
4.51 × 108 N. ceranae spores per colony Comb Disinfection Experiment
Electron Beam Irradiation Acetic Acid Disinfection Heat Treatment
10 kGy 120 mL 80% acetic acid 49 ± 1°C for 24 h per brood chamber
Comb Disinfection Experiment Sampling Bees for Spores
Weekly samples of 100 foragers (2 May - 4 June), then bi-weekly (monthly during winter).
Spores enumerated microscopically at 400x.
Comb Disinfection Experiment Hived with New Zealand Packages
* a Inoculated 65 b Fumigated Inoculated bc Heated 6 60 bc Irradiated 55 x 10 Heated c Uninoculated (Heated) 55 Fumigated 13.3x 106 Irradiated 50 (Heated) SE) Uninoculated
+
6 12 a 10
a Inoculated a Heated a Inoculated 8 ab Heated ab Uninoculated ab Heated
a ab Irradiated b Inoculated ab Fumigated 6 b Fumigated b Fumigated b Uninoculated a b Uninoculated b Irradiated b Irradiated
Spores / Bee ( x10 ( / Bee Spores 4 *
b * 2 * b 0 2 8 4 2 7 15 21 16 16 30 12 28 10 24 22 13 17 17 17 17 15 29 15 28 16 29 16 29 18 May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug 2009 2010 Comb Disinfection Experiment
N. apis N. ceranae N. apis + N. ceranae 100
80
60
40
% Colonies 20
0
Heated Heated Heated Heated Heated Irradiated Inoculated Irradiated Irradiated Irradiated Irradiated Fumigated InoculatedFumigated InoculatedFumigated InoculatedFumigated InoculatedFumigated Uninoculated Uninoculated Uninoculated Uninoculated Uninoculated May 2 Jun 4 Oct 7 Apr 29 Aug 18 2009 2010 Comb Disinfection Experiment Cumulative Mortality 18 Aug 2010
50 χ2=10.088; df=4.58; P=0.039 40
30
20
% Dead Colonies 10
0
Heat
Irradiated Fumigated Inoculated Uninoculated Alternatives to Fumagillin
Silkmoth Cultivation
Cage Experiments Screening for alternative compounds
Screen for Anti-Nosema Antibiotics (Highest concentrations: liquids 10 mg/kg, powders 1 mg/kg; n = 2-4)
No Inoculum Rifampicin Fumagillin Genistein Naturally-derived Thiabendazole Sulfaquinoxaline Synthetic Carbendazim Nozevit Phenyl salicylate Quinine hemisulfate Itaconazole Apigenin Vita Gold Ofloxacin Chloroquine Benomyl No Treatment Resveratrol Lomefloxacin Vita Green Acetic Acid Honey B Hlthy Cinnamon Oil Thymol Quercetin Aniseed Oil Quinidine sulphate Metronidazole Albendazole Eucalyptus Oil Eugenol
0 5 10 15 20 25 30 35 Spores (x 106) + SE Synthetic Compounds Against N. ceranae Compounds with significant concentration response Antibiotics against to N. ceranae Compounds with significant concentration response
5 ns 4 ns Carbendazim 3 2 * 1 0 0.004 0.04 0.4
SE) 5
+ 4 JP-P1-7a 3 2 1
(millions (millions 0
Spores per beeSpores 5 0.004 0.04 0.4 4 Fumagillin 3 2 1 Not tested 0 0.004 0.04 0.4 Dose (mMol) Summary • Irradiation is the most effective method of disinfecting comb contaminated with N. ceranae.
• Fumagillin is effective at suppressing active infections of N. ceranae. Sampling is critical during spring and fall.
• In northern temperate climates, N. ceranae spore levels appear to naturally decline during mid-summer, similar to patterns seen for N. apis.
• Predictive relationships between N. ceranae infection levels and measures of productivity remain elusive.
• Synthetic analogues of fumagillin may hold promise as an alternative to conventional therapies.
Future Directions
• Transmission?
• Spore survival?
• Treatment thresholds?
• Differential Virulence?
• Competition with N. apis?
• Mechanisms for Resistance?
Acknowledgements
• CANPOLIN • Medivet Pharmaceuticals • Alberta Beekeepers Commission • Canadian Bee Research Fund • Bee Maid Honey • Matching Investment Initiative (AAFC) • Iotron Industries Canada ltd.