Fumagilin-B is used to treat nosema infection in honey bee colonies; however, it is unclear wheth... more Fumagilin-B is used to treat nosema infection in honey bee colonies; however, it is unclear whether treatment consistently reduces Vairimorpha ceranae (Fries et al.) abundance and improves colony strength and survival in the Canadian Prairies. This study assessed spring and fall fumagillin treatments on nosema abundance, colony strength, and mortality in 2 different beekeeping regions within Alberta, using both indoor and outdoor wintering management at each site. We compared 4 fumagillin treatments: Spring-only, Fall-only, Spring-and-Fall, and Control (no treatment). The spring treatment dose was ~68 mg/colony, whereas the fall treatment dose was 120 or 48 mg/colony, depending on the year. We found that the colonies were infected predominately with V. ceranae, with V. apis (Zander) present only in mixed infections in a subset of colonies. Although treatment in either the spring or fall did reduce nosema abundance in the short term, it did not eliminate the infection, making continued monitoring necessary. Colony strength was improved by spring treatment in some locations but not consistently, possibly due to the treatment timing or low dose. The combined spring and fall treatment increased colony survival over winter in one of 2 yr. Wintering method did not interact with treatment to affect nosema abundance in the spring. There does not appear to be a significant residual benefit of fall treatment as it did not reduce spring nosema abundance or increase colony population. Therefore, spring treatment should be applied to reduce spring V. ceranae abundance rather than relying on residual efficacy from previous fall treatments.
Varroa destructor Anderson and Trueman 2000 (Acari: Varroidae) is an ectoparasitic mite of the ho... more Varroa destructor Anderson and Trueman 2000 (Acari: Varroidae) is an ectoparasitic mite of the honey bee, Apis mellifera L. (Hymenoptera: Apidae). Honey bee colonies require extensive management to prevent mortality caused by varroa mites and the viruses they vector. New miticides (Thymovar and HopGuard) to manage varroa mites were evaluated during the spring and fall treatment windows of the Canadian prairies to determine their effectiveness as part of an integrated management strategy. Thymovar and HopGuard were evaluated alongside the currently used industry standards: Apivar and formic acid. Results demonstrated that Apivar and formic acid remain effective V. destructor management options under spring and fall conditions. Applications of Thymovar during spring were associated with a reduction in brood area, and therefore should be limited to the fall season. The miticide HopGuard was not effective in managing V. destructor, and alteration of the current delivery system is necessary. This study demonstrates the potential for new effective treatment options to supplement currently used V. destructor integrated pest management systems.
Nosema ceranae Fries, 1996, causes contagious fungal nosemosis disease in managed honey bees, Api... more Nosema ceranae Fries, 1996, causes contagious fungal nosemosis disease in managed honey bees, Apis mellifera L. It is associated around the world with winter losses and colony collapse disorder. We used a laboratory in vivo screening assay to test curcumin, fenbendazole, nitrofurazone and ornidazole against N. ceranae in honey bees to identify novel compounds with anti-nosemosis activity compared to the commercially available medication Fumagilin-B®. Over a 20-day period, Nosema-inoculated bees in Plexiglas cages were orally treated with subsequent dilutions of candidate compounds, or Fumagilin-B® at the recommended dose, with three replicates per treatment. Outcomes indicated that fenbendazole suppressed Nosema spore proliferation, resulting in lower spore abundance in live bees (0.36 ± 1.18 million spores per bee) and dead bees (0.03 ± 0.25 million spores per bee), in comparison to Fumagilin-B®-treated live bees (3.21 ± 2.19 million spores per bee) and dead bees (3.5 ± 0.6 million...
Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L.... more Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L., that has been considered a major cause of colony losses. Synthetic miticides have been developed and registered to manage this ectoparasite, however, resistance to registered pyrethroid and organophosphate Varroacides have already been reported in Canada. To test toxicity of miticides, current contact-based bioassay methods are designed to evaluate mites and bees separately, however, these methods are unlikely to give an accurate depiction of how miticides interact at the colony level. Therefore, the objective of this study was to develop a bioassay cage for testing the toxicity of miticides on honey bees and Varroa mites simultaneously using amitraz as a reference chemical. A 800 mL polypropylene plastic cage holding 100–150 bees was designed and officially named “Apiarium”. A comparison of the effects of three subsequent dilutions of amitraz was conducted on: Varroa mites placed in g...
... Available online: 01 Sep 2009 To cite this article: F. Di-Giovanni, PG Kevan & ME Nas... more ... Available online: 01 Sep 2009 To cite this article: F. Di-Giovanni, PG Kevan & ME Nasr (1995): The variability in settling velocities of some pollen and spores, Grana, 34:1, 39-44 ... This articlemay be used for research, teaching and private study purposes. ...
Tracheal mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), are important parasites of honeybe... more Tracheal mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), are important parasites of honeybees, Apis mellifera L. (Morse and Flottum 1997). They enter the prothoracic tracheae and feed through the walls on haemolymph. Currently, these mites are controlled by applying 50 g of menthol crystals in a perforated bag per hive when ambient temperatures are 15°C or more. Even then, it takes 2 weeks for the menthol to perfuse the hive (Herbert et al. 1988; Wilson et al. 1990). In cold climates, sublimation of menthol is too slow to be effective in controlling mites, especially in spring and fall when control is most needed (Scott-Dupree and Otis 1992).Because menthol fumes enter the bees' trachea and kill the mites therein, it may be possible to kill the mites with menthol that is delivered to them via the haemolymph. Therefore, finding if menthol could become systemic when ingested by bees and it could kill tracheal mites by that route, an ingestible menthol medicament for the bees...
BACKGROUND: The Varroa mite (Varroa destructor) is an ectoparasite that can affect the health of ... more BACKGROUND: The Varroa mite (Varroa destructor) is an ectoparasite that can affect the health of honey bees (Apis mellifera) and contributes to the loss of colony productivity. The limited availability of Varroacides with different modes of action in Canada has resulted in the development of chemical resistance in mite populations. Therefore, an urgent need to evaluate new potential miticides that are safe for bees and exhibit high efficacy against Varroa exists. In this study, the acute contact toxicity of 26 active ingredients (19 chemical classes), already available on the market, was evaluated on V. destructor and A. mellifera under laboratory conditions using an apiarium bioassay. In this assay, groups of Varroa-infested worker bees were exposed to different dilutions of candidate compounds. In semi-field trials, Varroa-infested honey bees were randomly treated with four vetted candidate compounds from the apiarium assay in mini-colonies. RESULTS: Among tested compounds, fenazaquin (quinazoline class) and fenpyroximate (pyrazole class) had higher mite mortality and lower bee mortality over a 24 h exposure period in apiariums. These two compounds, plus spirotetramat and spirodiclofen, were selected for semi-field evaluation based on the findings of the apiarium bioassay trials and previous laboratory studies. Consistent with the apiarium bioassay, semi-field results showed fenazaquin and fenpyroximate had high efficacy (>80%), reducing Varroa abundance by 80% and 68%, respectively. CONCLUSION: These findings suggest that fenazaquin would be an effective Varroacide, along with fenpyroximate, which was previously registered for in-hive use as Hivastan. Both compounds have the potential to provide beekeepers with an alternative option for managing Varroa mites in honey bee colonies.
The epidemiology of Nosema spp. in honey bees, Apis mellifera, may be affected by winter conditio... more The epidemiology of Nosema spp. in honey bees, Apis mellifera, may be affected by winter conditions as cold temperatures and differing wintering methods (indoor and outdoor) provide varying levels of temperature stress and defecation flight opportunities. Across the Canadian Prairies, including Alberta, the length and severity of winter vary among geographic locations. This study investigates the seasonal pattern of Nosema abundance in two Alberta locations using indoor and outdoor wintering methods and its impact on bee population, survival, and commercial viability. This study found that N. ceranae had a distinct seasonal pattern in Alberta, with high spore abundance in spring, declining to low levels in the summer and fall. The results showed that fall Nosema monitoring might not be the best indicator of treatment needs or future colony health outcomes. There was no clear pattern for differences in N. ceranae abundance by location or wintering method. However, wintering method af...
Formic acid and Apistan were compared as fall treatments for Varroa jacobsoni (Oudemans), a paras... more Formic acid and Apistan were compared as fall treatments for Varroa jacobsoni (Oudemans), a parasitic mite of the honey bee, Apis mellifera L. Treatment with Apistan resulted in an average mite mortality of 98%, whereas treatment with formic acid resulted in an average 56% mortality. Mortality was not correlated with the level of mite infestation for either treatment. The ratio of the coefÞcient of variation in mite mortality among colonies in the formic acid group to the coefÞcient of variation among colonies in the Apistan group was 43.28, indicating that Apistan is a more reliable control agent than the formulation of formic acid used in this experiment. Overall, only 63% of the 250-ml formic acid treatment evaporated during the 30-d treatment period, resulting in an average daily release of 5.26 g of formic acid, which is below that required for effective treatment. These results demonstrate that formic acid shows promise as an acaricide. However, considerable adjustments in the release characteristics of the delivery device must be made before it can be recommended as a useful control tool.
Annals of the Entomological Society of America, 1984
Histochemical methods were used to study the in situ digestion of the Torula yeast ( Candida util... more Histochemical methods were used to study the in situ digestion of the Torula yeast ( Candida utilis ) in the alimentary canals of adult worker honeybees ( Apis mellifera ). Digestion of yeast particles occurs in the middle and posterior portion of the midgut within 1 to 3 h after feeding. Digestion is initiated by depolymerization of the protein-polysaccharide complex of the yeast cell wall. Later the cell wall breaks, and the “naked” cytoplasm is released and becomes more available for further enzymatic degradation. Histochemical evidence shows that the protein, glycogen, and lipid components of yeast cytoplasm are largely digested, whereas the cellulose and chitin components of the yeast cell wall are not digested and are left in the feces from the rectum. The data suggested that C. utilis can be efficiently digested and utilized by adult worker bees, and is therefore a good protein source for feeding bees.
This study was conducted to determine the prevalence and infection levels of the microsporidia fu... more This study was conducted to determine the prevalence and infection levels of the microsporidia fungi Nosema apis and/or Nosema ceranae in honey bee colonies of two Canadian provinces. Three surveys were conducted in the springs of 2008, 2010 and 2012 and PCR identification of Nosema species were performed in samples from 169 and 181 Ontario colonies and from 76 Alberta colonies that tested positive to Nosema spp. Infection levels of positive colonies were determined by microscopy and analyzed by Nosema spp. Results showed that N. ceranae was the dominant species in all three surveys (prevalence range of 41-91 vs. 4-34 % for N. apis), whereas mixed infections were less frequent than single infections (5-25 %). Infection levels of colonies parasitized by N. ceranae were three to five times higher than those of colonies parasitized by N. apis in the three surveys whereas mixed infections showed the highest spore counts. This is the first field study demonstrating significantly higher infection levels in colonies parasitized with either N. ceranae only or with both, N. ceranae and N. apis, than in colonies parasitized with N. apis only. Taken together, these results suggest that N. ceranae may be more virulent and better adapted than N. apis in cold climates such as Canadian environments.
Une variation significative des caractères du pollen a été observée chez dix cultivars de luzerne... more Une variation significative des caractères du pollen a été observée chez dix cultivars de luzerne dont on connaissait l'origine géographique et l'idioplasme parental. Pour 9 cultivars, la variation pollinique est liée à leurs génotypes parentaux. Les caractères polliniques pouvant contribuer a l'identification du pollen des cultivars de la luzerne sont: : la distance entre les sillons au pole, le diameter équatorial, la densité des perforations de l'apocolpium et leur forme, la largeur de las marge, l'ornementation de las surface su mésocolpium, la forme et la taille des perfoations.Significant variation in pollen characters was observed in 10 alfalfa cultivars of known geographical origin and parental germplasm. The pollen variation in 9 cultivars was related to their parental genotypes. Pollen characters which may contribute to the identification of the cultivar of alfalfa pollen included the distance between colpi at poles, diameter at equator, apocolpium pit ...
Fumagillin (as the dicyclohexylammonium salt) has been found to be extremely unstable when soluti... more Fumagillin (as the dicyclohexylammonium salt) has been found to be extremely unstable when solutions in 50% ethanol are exposed to sunlight in small vials, undergoing a series of degradations with half-lives in the range of seconds to minutes. Similar results were obtained with photolyses of Fumidil B in either 50% ethanol or sugar syrup. Decomposition also occurred in fluorescent room light. Exposure of fumagillin to sunlight for three days caused almost complete disappearance of UV absorption of fumagillin and all its immediate photoproducts. The reactions involved in the photolyses are apparently reversible Z:E rearrangements in the unsaturated ester portion of the molecule, and do not involve the pharmacologically active moiety. Samples of fumagillin in syrup, irradiated for 0, 0.5, 5, 30, or 360 minutes were all effective in protecting caged bees from nosema disease. While long exposures to sunlight probably should be avoided, brief exposure causes no obvious loss of activity.
ABSTRACT. The digestion of dandelion (Taraxacum officinale) pollen by adult worker honeybees (Api... more ABSTRACT. The digestion of dandelion (Taraxacum officinale) pollen by adult worker honeybees (Apis mellifera Linn.; Hymenoptera: Apidae) was initiated at the germination pores. 30 min after feeding, pollen had reached the anterior midgut and the germination pores had become swollen. This permitted further removal of protoplasm during the next 2 h of digestion as the pollen passed into the middle portion of the midgut. 3 h after feeding, pollen grains had reached the posterior midgut where some had ruptured to release both ‘naked’ protoplasm and masses of protoplasm but many remained intact or were only partially digested; undigested pollen grains passed unchanged to the rectum. The lipid‐rich pollenkitt layer was removed from the exine during digestion. Our studies indicate that dandelion pollen was not utilized completely by honeybees.
Seven staining techniques were modified and tested for differentially staining the live and the d... more Seven staining techniques were modified and tested for differentially staining the live and the dead sperm cells for the honey bee (Apis meffifera L.). The eosin Y staining method was found to be a simple technique by which the live cells stain bluish purple whereas the dead cells stain bright yellow to greenish yellow. Therefore, it produces a strong contrast between the dead and live sperm cells, and appears to be the most suitable supravital staining method for evaluating the viability of honey bee sperm cells. The significance of supravital staining techniques in assessing the quality of sperm cells during cryopreserving sperm cells is discussed.
Fumagilin-B is used to treat nosema infection in honey bee colonies; however, it is unclear wheth... more Fumagilin-B is used to treat nosema infection in honey bee colonies; however, it is unclear whether treatment consistently reduces Vairimorpha ceranae (Fries et al.) abundance and improves colony strength and survival in the Canadian Prairies. This study assessed spring and fall fumagillin treatments on nosema abundance, colony strength, and mortality in 2 different beekeeping regions within Alberta, using both indoor and outdoor wintering management at each site. We compared 4 fumagillin treatments: Spring-only, Fall-only, Spring-and-Fall, and Control (no treatment). The spring treatment dose was ~68 mg/colony, whereas the fall treatment dose was 120 or 48 mg/colony, depending on the year. We found that the colonies were infected predominately with V. ceranae, with V. apis (Zander) present only in mixed infections in a subset of colonies. Although treatment in either the spring or fall did reduce nosema abundance in the short term, it did not eliminate the infection, making continued monitoring necessary. Colony strength was improved by spring treatment in some locations but not consistently, possibly due to the treatment timing or low dose. The combined spring and fall treatment increased colony survival over winter in one of 2 yr. Wintering method did not interact with treatment to affect nosema abundance in the spring. There does not appear to be a significant residual benefit of fall treatment as it did not reduce spring nosema abundance or increase colony population. Therefore, spring treatment should be applied to reduce spring V. ceranae abundance rather than relying on residual efficacy from previous fall treatments.
Varroa destructor Anderson and Trueman 2000 (Acari: Varroidae) is an ectoparasitic mite of the ho... more Varroa destructor Anderson and Trueman 2000 (Acari: Varroidae) is an ectoparasitic mite of the honey bee, Apis mellifera L. (Hymenoptera: Apidae). Honey bee colonies require extensive management to prevent mortality caused by varroa mites and the viruses they vector. New miticides (Thymovar and HopGuard) to manage varroa mites were evaluated during the spring and fall treatment windows of the Canadian prairies to determine their effectiveness as part of an integrated management strategy. Thymovar and HopGuard were evaluated alongside the currently used industry standards: Apivar and formic acid. Results demonstrated that Apivar and formic acid remain effective V. destructor management options under spring and fall conditions. Applications of Thymovar during spring were associated with a reduction in brood area, and therefore should be limited to the fall season. The miticide HopGuard was not effective in managing V. destructor, and alteration of the current delivery system is necessary. This study demonstrates the potential for new effective treatment options to supplement currently used V. destructor integrated pest management systems.
Nosema ceranae Fries, 1996, causes contagious fungal nosemosis disease in managed honey bees, Api... more Nosema ceranae Fries, 1996, causes contagious fungal nosemosis disease in managed honey bees, Apis mellifera L. It is associated around the world with winter losses and colony collapse disorder. We used a laboratory in vivo screening assay to test curcumin, fenbendazole, nitrofurazone and ornidazole against N. ceranae in honey bees to identify novel compounds with anti-nosemosis activity compared to the commercially available medication Fumagilin-B®. Over a 20-day period, Nosema-inoculated bees in Plexiglas cages were orally treated with subsequent dilutions of candidate compounds, or Fumagilin-B® at the recommended dose, with three replicates per treatment. Outcomes indicated that fenbendazole suppressed Nosema spore proliferation, resulting in lower spore abundance in live bees (0.36 ± 1.18 million spores per bee) and dead bees (0.03 ± 0.25 million spores per bee), in comparison to Fumagilin-B®-treated live bees (3.21 ± 2.19 million spores per bee) and dead bees (3.5 ± 0.6 million...
Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L.... more Varroa destructor Anderson and Trueman, is an ectoparasitic mite of honey bees, Apis mellifera L., that has been considered a major cause of colony losses. Synthetic miticides have been developed and registered to manage this ectoparasite, however, resistance to registered pyrethroid and organophosphate Varroacides have already been reported in Canada. To test toxicity of miticides, current contact-based bioassay methods are designed to evaluate mites and bees separately, however, these methods are unlikely to give an accurate depiction of how miticides interact at the colony level. Therefore, the objective of this study was to develop a bioassay cage for testing the toxicity of miticides on honey bees and Varroa mites simultaneously using amitraz as a reference chemical. A 800 mL polypropylene plastic cage holding 100–150 bees was designed and officially named “Apiarium”. A comparison of the effects of three subsequent dilutions of amitraz was conducted on: Varroa mites placed in g...
... Available online: 01 Sep 2009 To cite this article: F. Di-Giovanni, PG Kevan & ME Nas... more ... Available online: 01 Sep 2009 To cite this article: F. Di-Giovanni, PG Kevan & ME Nasr (1995): The variability in settling velocities of some pollen and spores, Grana, 34:1, 39-44 ... This articlemay be used for research, teaching and private study purposes. ...
Tracheal mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), are important parasites of honeybe... more Tracheal mites, Acarapis woodi (Rennie) (Acari: Tarsonemidae), are important parasites of honeybees, Apis mellifera L. (Morse and Flottum 1997). They enter the prothoracic tracheae and feed through the walls on haemolymph. Currently, these mites are controlled by applying 50 g of menthol crystals in a perforated bag per hive when ambient temperatures are 15°C or more. Even then, it takes 2 weeks for the menthol to perfuse the hive (Herbert et al. 1988; Wilson et al. 1990). In cold climates, sublimation of menthol is too slow to be effective in controlling mites, especially in spring and fall when control is most needed (Scott-Dupree and Otis 1992).Because menthol fumes enter the bees' trachea and kill the mites therein, it may be possible to kill the mites with menthol that is delivered to them via the haemolymph. Therefore, finding if menthol could become systemic when ingested by bees and it could kill tracheal mites by that route, an ingestible menthol medicament for the bees...
BACKGROUND: The Varroa mite (Varroa destructor) is an ectoparasite that can affect the health of ... more BACKGROUND: The Varroa mite (Varroa destructor) is an ectoparasite that can affect the health of honey bees (Apis mellifera) and contributes to the loss of colony productivity. The limited availability of Varroacides with different modes of action in Canada has resulted in the development of chemical resistance in mite populations. Therefore, an urgent need to evaluate new potential miticides that are safe for bees and exhibit high efficacy against Varroa exists. In this study, the acute contact toxicity of 26 active ingredients (19 chemical classes), already available on the market, was evaluated on V. destructor and A. mellifera under laboratory conditions using an apiarium bioassay. In this assay, groups of Varroa-infested worker bees were exposed to different dilutions of candidate compounds. In semi-field trials, Varroa-infested honey bees were randomly treated with four vetted candidate compounds from the apiarium assay in mini-colonies. RESULTS: Among tested compounds, fenazaquin (quinazoline class) and fenpyroximate (pyrazole class) had higher mite mortality and lower bee mortality over a 24 h exposure period in apiariums. These two compounds, plus spirotetramat and spirodiclofen, were selected for semi-field evaluation based on the findings of the apiarium bioassay trials and previous laboratory studies. Consistent with the apiarium bioassay, semi-field results showed fenazaquin and fenpyroximate had high efficacy (>80%), reducing Varroa abundance by 80% and 68%, respectively. CONCLUSION: These findings suggest that fenazaquin would be an effective Varroacide, along with fenpyroximate, which was previously registered for in-hive use as Hivastan. Both compounds have the potential to provide beekeepers with an alternative option for managing Varroa mites in honey bee colonies.
The epidemiology of Nosema spp. in honey bees, Apis mellifera, may be affected by winter conditio... more The epidemiology of Nosema spp. in honey bees, Apis mellifera, may be affected by winter conditions as cold temperatures and differing wintering methods (indoor and outdoor) provide varying levels of temperature stress and defecation flight opportunities. Across the Canadian Prairies, including Alberta, the length and severity of winter vary among geographic locations. This study investigates the seasonal pattern of Nosema abundance in two Alberta locations using indoor and outdoor wintering methods and its impact on bee population, survival, and commercial viability. This study found that N. ceranae had a distinct seasonal pattern in Alberta, with high spore abundance in spring, declining to low levels in the summer and fall. The results showed that fall Nosema monitoring might not be the best indicator of treatment needs or future colony health outcomes. There was no clear pattern for differences in N. ceranae abundance by location or wintering method. However, wintering method af...
Formic acid and Apistan were compared as fall treatments for Varroa jacobsoni (Oudemans), a paras... more Formic acid and Apistan were compared as fall treatments for Varroa jacobsoni (Oudemans), a parasitic mite of the honey bee, Apis mellifera L. Treatment with Apistan resulted in an average mite mortality of 98%, whereas treatment with formic acid resulted in an average 56% mortality. Mortality was not correlated with the level of mite infestation for either treatment. The ratio of the coefÞcient of variation in mite mortality among colonies in the formic acid group to the coefÞcient of variation among colonies in the Apistan group was 43.28, indicating that Apistan is a more reliable control agent than the formulation of formic acid used in this experiment. Overall, only 63% of the 250-ml formic acid treatment evaporated during the 30-d treatment period, resulting in an average daily release of 5.26 g of formic acid, which is below that required for effective treatment. These results demonstrate that formic acid shows promise as an acaricide. However, considerable adjustments in the release characteristics of the delivery device must be made before it can be recommended as a useful control tool.
Annals of the Entomological Society of America, 1984
Histochemical methods were used to study the in situ digestion of the Torula yeast ( Candida util... more Histochemical methods were used to study the in situ digestion of the Torula yeast ( Candida utilis ) in the alimentary canals of adult worker honeybees ( Apis mellifera ). Digestion of yeast particles occurs in the middle and posterior portion of the midgut within 1 to 3 h after feeding. Digestion is initiated by depolymerization of the protein-polysaccharide complex of the yeast cell wall. Later the cell wall breaks, and the “naked” cytoplasm is released and becomes more available for further enzymatic degradation. Histochemical evidence shows that the protein, glycogen, and lipid components of yeast cytoplasm are largely digested, whereas the cellulose and chitin components of the yeast cell wall are not digested and are left in the feces from the rectum. The data suggested that C. utilis can be efficiently digested and utilized by adult worker bees, and is therefore a good protein source for feeding bees.
This study was conducted to determine the prevalence and infection levels of the microsporidia fu... more This study was conducted to determine the prevalence and infection levels of the microsporidia fungi Nosema apis and/or Nosema ceranae in honey bee colonies of two Canadian provinces. Three surveys were conducted in the springs of 2008, 2010 and 2012 and PCR identification of Nosema species were performed in samples from 169 and 181 Ontario colonies and from 76 Alberta colonies that tested positive to Nosema spp. Infection levels of positive colonies were determined by microscopy and analyzed by Nosema spp. Results showed that N. ceranae was the dominant species in all three surveys (prevalence range of 41-91 vs. 4-34 % for N. apis), whereas mixed infections were less frequent than single infections (5-25 %). Infection levels of colonies parasitized by N. ceranae were three to five times higher than those of colonies parasitized by N. apis in the three surveys whereas mixed infections showed the highest spore counts. This is the first field study demonstrating significantly higher infection levels in colonies parasitized with either N. ceranae only or with both, N. ceranae and N. apis, than in colonies parasitized with N. apis only. Taken together, these results suggest that N. ceranae may be more virulent and better adapted than N. apis in cold climates such as Canadian environments.
Une variation significative des caractères du pollen a été observée chez dix cultivars de luzerne... more Une variation significative des caractères du pollen a été observée chez dix cultivars de luzerne dont on connaissait l'origine géographique et l'idioplasme parental. Pour 9 cultivars, la variation pollinique est liée à leurs génotypes parentaux. Les caractères polliniques pouvant contribuer a l'identification du pollen des cultivars de la luzerne sont: : la distance entre les sillons au pole, le diameter équatorial, la densité des perforations de l'apocolpium et leur forme, la largeur de las marge, l'ornementation de las surface su mésocolpium, la forme et la taille des perfoations.Significant variation in pollen characters was observed in 10 alfalfa cultivars of known geographical origin and parental germplasm. The pollen variation in 9 cultivars was related to their parental genotypes. Pollen characters which may contribute to the identification of the cultivar of alfalfa pollen included the distance between colpi at poles, diameter at equator, apocolpium pit ...
Fumagillin (as the dicyclohexylammonium salt) has been found to be extremely unstable when soluti... more Fumagillin (as the dicyclohexylammonium salt) has been found to be extremely unstable when solutions in 50% ethanol are exposed to sunlight in small vials, undergoing a series of degradations with half-lives in the range of seconds to minutes. Similar results were obtained with photolyses of Fumidil B in either 50% ethanol or sugar syrup. Decomposition also occurred in fluorescent room light. Exposure of fumagillin to sunlight for three days caused almost complete disappearance of UV absorption of fumagillin and all its immediate photoproducts. The reactions involved in the photolyses are apparently reversible Z:E rearrangements in the unsaturated ester portion of the molecule, and do not involve the pharmacologically active moiety. Samples of fumagillin in syrup, irradiated for 0, 0.5, 5, 30, or 360 minutes were all effective in protecting caged bees from nosema disease. While long exposures to sunlight probably should be avoided, brief exposure causes no obvious loss of activity.
ABSTRACT. The digestion of dandelion (Taraxacum officinale) pollen by adult worker honeybees (Api... more ABSTRACT. The digestion of dandelion (Taraxacum officinale) pollen by adult worker honeybees (Apis mellifera Linn.; Hymenoptera: Apidae) was initiated at the germination pores. 30 min after feeding, pollen had reached the anterior midgut and the germination pores had become swollen. This permitted further removal of protoplasm during the next 2 h of digestion as the pollen passed into the middle portion of the midgut. 3 h after feeding, pollen grains had reached the posterior midgut where some had ruptured to release both ‘naked’ protoplasm and masses of protoplasm but many remained intact or were only partially digested; undigested pollen grains passed unchanged to the rectum. The lipid‐rich pollenkitt layer was removed from the exine during digestion. Our studies indicate that dandelion pollen was not utilized completely by honeybees.
Seven staining techniques were modified and tested for differentially staining the live and the d... more Seven staining techniques were modified and tested for differentially staining the live and the dead sperm cells for the honey bee (Apis meffifera L.). The eosin Y staining method was found to be a simple technique by which the live cells stain bluish purple whereas the dead cells stain bright yellow to greenish yellow. Therefore, it produces a strong contrast between the dead and live sperm cells, and appears to be the most suitable supravital staining method for evaluating the viability of honey bee sperm cells. The significance of supravital staining techniques in assessing the quality of sperm cells during cryopreserving sperm cells is discussed.
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