Microb Ecol (1985) 11:51-58
MICROBIAL ECOLOGY 9 1985 Springer-Verlag
Yeasts Associated with Pollinating Bees and Flower Nectar D h a n w a n t K. S a n d h u a n d Manjit K. Waraich Department of Biology, Guru Nanak Dev University, Amritsar-143005, India A study o f the yeast flora o f 328 h o n e y s t o m a c h s f r o m 7 different pollinating bee species, a n d 342 flower nectar samples o f 9 different flower species yielded 766 yeast isolates c o m p o s e d o f 16 genera and 47 species. M o s t o f the yeast species f r o m b o t h the sources belonged to the genus Candida, while the m o s t frequently isolated yeasts were Dekkera intermedia f r o m h o n e y s t o m a c h a n d Candida blanMi f r o m flower nectar. A m o n g the h o n e y bees, Xylocopa sp., and a m o n g flowers, Citrus medica, yielded the highest n u m b e r o f yeast species. N i n e t e e n species o f yeasts belonging to 9 genera were c o m m o n to b o t h the sources. Abstract.
Introduction
The occurrence o f yeasts in nature is widespread. T h e y h a v e been isolated from soil, air, plant a n d a n i m a l surfaces, p r e s e r v e d foods, a n d sugary substrates, including flower nectar a n d fruit juices [ 10, 12, 16]. T h e association o f yeasts with insect guts is well k n o w n [3], a n d pollinating bees in particular h a r b o r yeasts in their nectar sacs. Similarly, flower nectar constitutes a rich source o f yeasts. T h e association o f particular yeast species with flowers and insects is k n o w n [2, 6, 16] because a n u m b e r o f insects bring a b o u t pollination a n d simultaneously transfer yeasts to flower nectar during their visits to entom o p h i l o u s flowers. T h e present study has been a i m e d at a survey o f the yeasts associated with h o n e y s t o m a c h s o f s o m e pollinating bees a n d nectary glands o f flowers o f cultivated or wild plants.
M a t e r i a l s and M e t h o d s
Collection o f S a m p l e s
Seven different pollinating bees, i.e., Apis dorsata, A. mellifera, A. florae, A. indica, A. cerana, Xylocopa sp., and Halictus sp., were trapped outdoors in the fields from insect-pollinated, cultivated, or wild plants. The bees were kept in the refrigerator after collection to make them inactive and easy to handle. The nectary glands of 9 different flowers, i.e., Citrus medica, C. acida, Murraya exotica, Raphanus sativus. Brassicajuncea, B. rapa, B. campestris, Eruca sativa, and Euphorbia helioscopia, were investigated for the presence of yeasts. The flowers were collected from the fields of suburban Amritsar in sterile polyethylene bags, brought to the laboratory, and processed immediately.
52
D.K. Sandhu and M. K. Waraich
Processing of Samples Pollinating bees and flowers were dissected aseptically to remove the nectar sacs and nectary glands, respectively, which were transferred to 5 ml of sterile distilled water and shaken to obtain a uniform suspension. The appropriate amount of inoculum was streaked liberally on yeast-extract-maltextract agar [20] plates which were incubated at 28~ for 72 hours. The colony types appearing on the culture plates were isolated on yeast-extract-malt-extract agar slants on the basis of gross colonial and microscopic morphology of vegetative cells. The identification of the yeast isolates was done according to the methods of Lodder [13] and Barnett and Pankhurst [1].
Results T h e physiological characteristics o f the yeasts isolated f r o m h o n e y b e e s a n d flower nectar were m o r e or less similar, but with s o m e differences. A b o u t 10% m o r e f e r m e n t a t i v e yeasts were isolated f r o m flower nectar. All 13 substrates used in the identification p r o c e d u r e [13] were fermented, with the exception o f soluble starch. Glucose a n d sucrose were f e r m e n t e d by the m a j o r i t y o f the yeasts. N o n e o f the yeasts f r o m bees f e r m e n t e d melibiose, while only 1 f r o m the flower nectar h a d this ability.
Prevalence of Yeasts in the Honey Stomach of Pollinating Bees A total o f 328 samples o f h o n e y s t o m a c h o f pollinating bees was investigated. All the s a m p l e s were culturally positive, yielding 473 isolates, belonging to 13 genera and 30 species (Table 1). T h e two m o s t c o m m o n species e n c o u n t e r e d were Dekkera intermedia (6.71% o f the samples positive) a n d Saccharomyces cerevisiae (6.1%). A m o n g the other c o m m o n speeies were Candida humicola, C. incommunis, C. ishiwadae, a n d C. membranaefaciens, each occurring in 5.5% o f the samples investigated. T h e prevalence o f other species varied between 1.57 a n d 4.57%. O n e - t h i r d o f the species identified belonged to the genus Candida, while Cryptococcus was represented by 4 species, Rhodotorula by 3, Debaryomyces, Hansenula, and Torulopsis by 2 species each, a n d the r e m a i n i n g 7 genera b y 1 species each. T h e highest n u m b e r o f yeast species was isolated f r o m Xylocopa sp. (13 spp.), followed b y A. mellifera (11 spp.), A. dorsata (9 spp.), A. florae, A. indica, a n d A. cerana (6 spp. each), a n d Halictus sp. (5 spp.).
Prevalence of Yeasts in the Nectary Glands o f Flowers O u t o f the 342 s a m p l e s o f n e c t a r y glands o f flowers, 232 (67.84%) were culturally positive, yielding 293 isolates (Table 2). T h e s e belonged to 12 genera a n d 36 species. T h e m o s t frequently isolated species was C. blankii, occurring in 4.68% o f the samples, followed by C. cacaoi a n d S. cerevisiae, each isolated f r o m 4.09% o f the total s a m p l e s investigated. T h e genus Candida was f o u n d m o s t often, with as m a n y as 16 species, while Hansenula was represented b y 4 species, Debaryomyces a n d Rhodotorula by 3 species each, Pichia a n d Torulopsis by 2 species each, a n d the r e m a i n i n g 6 genera by one species each. T h e nectary
Yeasts, Bees, and Nectar
53
glands ofEruca sativa yielded the highest number of positive cultures (92.11%), followed by Brassica campestris (81.57%). However, the highest number of yeast species was obtained from Citrus medica (12 species), followed by Raphanus sativus (11 species).
Discussion
Apparently no systematic study of this kind has previously been undertaken in India, which should explain the paucity of information on yeasts associated with bees and flowers. Thus, out of the 47 species of yeasts isolated, 42 are being reported for the first time from these two sources. Candida is by far the most common genus associated with pollinating bees, accounting for 33.33% of their yeast flora, a finding that is in accord with some of the earlier reports [9, 18, 19]. All the 4 species of Cryptococcus were isolated from honey stomachs only, as also reported by other workers [7, 9, 13, 15, 17], perhaps indicating their better adaptability for the insect gut. The largest number of yeast species was isolated from Xylocopa sp. followed by A. mellifera. It may be noted that, so far, beetles, Drosophila spp., and A. mellifera have been found to be rich in yeast flora [2, 7, 8, 11, 18]. Since little information is available on Xylocopa sp., it may be suggested that this bee, even in other geographical regions, may yield an equally rich variety of yeasts. No yeast species was common to all the pollinating bees. The occurrence of particular yeast species in more than 1 pollinator with variation in prevalence may be related to their common feeding habits, preference for particular plant species, and/or the time interval between culture and the last feeding of the insect, allowing subsequent digestion of the ingested yeasts [5, 6, 16]. However, even so, only a maximum of 4 yeast species were found to be common between any 2 pollinating bees, e.g., Xylocopa sp. and A. indica or A. florae and A. cerana. As many as 12 yeast species were isolated only from one or the other species of the 7 pollinating bees, suggesting that at least some yeasts may have preferential or even exclusive associations with particular hosts. The yeast flora ofnectary glands of flowers has revealed an even larger variety of yeast species. In particular, the flower nectar of C. medica and R. sativus has proven to be a rich source of isolates, yielding 12 and 11 yeast species respectively. The genera already reported from flowers by other workers include Candida, Endomycopsis, Hansenula, Saccharomyces, Pichia, and Rhodotorula spp. [2, 14, 16]. Out of the 36 yeast species cultured from flowers, only S. cerevisiae has been reported earlier from flower nectar [2, 13]. Thus, as many as 35 species of yeasts seem to be newly discovered from the nectary glands of flowers. On the other hand, there are a few species that are known to be frequently associated with flowers, but have not been encountered in the present study. These include Candida reukaufiL Rhodotorula rubra, R. glutinis, and Torulopsis stellata [4, 14, 16]. Probably, the yeast floras of flower nectar vary in different geographical regions. Out of the 36 yeasts encountered, 23 species occurred in the nectary glands of 2 or more flowers, although each had varying prevalence. For instance, C. blankiL which had a very high prevalence in the flower nectar of B. campestris
Yeasts
Dekkera intermedia Saccharomyces cerevisiae Candida humicola C, incommunis C, ishiwadae C. membranaefaciens Rhodotorula lactosa Candida parapsilosis Cryptococcus albidus Hansenu[a beijerinckii Debaryomyces marama Hansenu[a polymorpha Torulopsis etchellsii Candida requinyii Rhodotorula rnarina Pichia terricola Torulopsis versatilis
5 (10,43) 3 (6.25) 1 (2.08) 1 (2.08)
1 (2.08)
1 (2.08) ~
Xylocopa sp.
2 (4.16)
3 (6.25) 6 (12.5)
2 (4.16) 5 (10.42) 5 (10,42)
11 (22.92) 5 (10.42)
3 (6.25)
A. mellifera
13 (19.12) 10 (14.71)
10 (14.71)
15 (22.06)
11 (16.18)
A. dorsata
8 (16.67)
8 (16.67) 7 (14.58) 5 (10.42)
13 (27.08)
A. florea
10 (20.83) 8 (16.67)
6 (12.50) 6 (12.50)
10(20.83)
A, indica
Number of posilive samples
Table 1. Prevalence of yeasts in the honey stomach of pollinating bees
13 (27.08)
5 (10.42) 6 (12.50) 8 (16.67) 10 (20.83)
6 (12.50)
3 (15)
12 (6)
1 (5)
A. cerana Halictus sp.
22 20 18 18 18 18 16 15 15 15 13 13 13 11 11 11 11
6.71 6.10 5.5 5.5 5.5 5.5 4.88 4.57 4.57 4.57 3.96 3.96 3.96 3.35 3.35 3.35 3.35
Number Percent
Positive samples
ID
l:r
r~
tan 4~
l0 (20.83) 10 (20.83) 1 (2,08) 8 (16.67)
11 83
1 (2.08)
5 (10.43)
A. mellifera
9 101
1 (1.47)
3 (4.40)
4 (5.88)
1 (1.47)
A. dorsata
6 50
7 (14.58)
A. florea
6 48
8 (16.67)
A. indica
Number of positive samples
6 48
A. cerana
5 42
3 (15)
1 (5)
Halictus sp.
10 10 10 8 7 6 5 5 3 3 1 1 1 3O 473
3.05 3.05 3.05 2.45 2.13 1.83 1.52 1.52 0.91 0.91 0.30 0.30 0.30
Number Percent
Positive samples
Figures in parenthesis denote the percent of positive samples examined from each type of pollinating bee All the samples were positive (48 samples were examined from each type of pollinating bees, excepting A. dorsata (68) and Halictus so. (20)
13 101
1 (2.08)
1 (2.08)
5 (10.43)
Xylocopa sp.
Yeasts
Continued
Candida curvata Debaryomyces tamarii Candida blankii Cryptococcus laurentii Cr. dimennae Rhodotorula graminis Brettanomyces anomalus Wingea robertsii Candida psuedotropicalis C. sake Cryptococcus aler Endomycopsis fibu[igera Kluveromyces fragilis Number of species identified Number of isolates
Table 1.
z
Yeasts
2 (5.26) 5 (13.16) 1 (2.63) 1 (2.63)
4 (10.54) 1 (2.63)
5 (13.16)
1 (2.63)"
C. medica
1 (2.63) 1 (2.63) 1 (2.63)
3 (7.89)
R. sativus
3 (7.89)
4 (10.53)
3 (7.89) 5 (13.16)
4 (10.53)
4 (10.53)
4 (10.53)
E. sativa
2 (5.26) 2 (5.26) 6 (15.79)
3 (7.89)
2 (5.26) 1 (2.64)
5 (13.16)
M. exotica
2 (5.26)
2 (5.26) 1 (2.63) 1 (2.63)
6 (15.79)
7 (18.42)
B. rapa
3 (7.89)
5 (13.16)
1 (2.63) 10 (26.32) 6 (15.79)
B. juncea
Number of positive samples
6 (15.79)
8 (21.05) 9 (23.68)
8 (21.05)
B. campestris
Prevalence of yeasts in the nectary glands of flowers (38 samples examined from each type of flower)
Candida blankii C. cacaoi Saccharomyces cerevisiae Candida kefyr C. parapsilosis Oosporidium margaritiferurn Rhodotorula lactosa Torulopsis versatilis Candida incommunis Pichia polymorpha Candida ishiwadae Hansenula beijerinckii H. muscicola Candida bogoriensis C. membranaefaciens C. valdiviana Debaryomyces castellii Endomycopsisfibuligera Hansenula anomala Rhodotorula graminis
Table 2.
3 (7.89)
10 (26.32)
C. acida
9 (23.68)
16 14 14 10 10 10 9 9 8 8 7 7 7 6 6 6 6 6 6 6
4.68 4.09 4.09 2.92 2.92 2.92 2.63 2.63 2.34 2.34 2.05 2.05 2.05 1.75 1.75 1.75 1.75 1.75 1.75 1.75
C. Numhefioscopia bet Percent
Positive samples
Izr
g
26(68.42)
11 45
12 44
1 (2.63)
1 (2.63)
4 (10.54) 1 (2,63) 3 (7.89)
5 (13.16) 5 (13.16)
R. sativus
28(73.68)
2 (5.26) 1 (2.63) 2 (5.26)
3 (7.89)
C. medica
9 35
35(92.11)
3 (7.89)
5 (13.16)
E. sativa
9 34
25(65.79)
2 (5.26)
2 (5.26)
M. exotica
8 30
21(55.26)
1 (2.63)
1 (2.63)
B. rapa
7 30
30(78.94)
2 (5.26)
3 (7.89)
B. juncea
Number of positive samples
a Figures in parenthesis denote the percent positive of samples examined from each type of flower
Wingea robertsii Candida claussenii C. curvata C. psuedotropicalis Pichia terricola Rhodotorula marina Torulopsis pignaliae Trichosporon cutaneum Candida diversa C. fragicola C. humicola Debaryomyces phaffii Deb. tamarii Geotrichum candidum Candida tropicalis Hansenula polymorpha Number of positive samples Number of species identified Number of isolates
Yeasts
Table 2. Continued
4 31
31(81.57)
B. campestris
4 26
21 (55.26)
5 (13.16)
3 (7.89)
C. acida
4 18
15(39.47)
l (2.64) 3 (7.89)
2 (5.26)
C. helioscopia
36 293
232
6 5 5 5 5 5 5 4 3 3 3 3 3 3 2 l
67.84
1.75 1.47 1.47 1.47 1.47 1.47 1.47 1.16 0.88 0.88 0.88 0.88 0.88 0.88 0.58 0.29
Numher Percent
Positive sampies
Z
"
MICROBIAL ECOLOGY 9 1985 Springer-Verlag
Yeasts Associated with Pollinating Bees and Flower Nectar D h a n w a n t K. S a n d h u a n d Manjit K. Waraich Department of Biology, Guru Nanak Dev University, Amritsar-143005, India A study o f the yeast flora o f 328 h o n e y s t o m a c h s f r o m 7 different pollinating bee species, a n d 342 flower nectar samples o f 9 different flower species yielded 766 yeast isolates c o m p o s e d o f 16 genera and 47 species. M o s t o f the yeast species f r o m b o t h the sources belonged to the genus Candida, while the m o s t frequently isolated yeasts were Dekkera intermedia f r o m h o n e y s t o m a c h a n d Candida blanMi f r o m flower nectar. A m o n g the h o n e y bees, Xylocopa sp., and a m o n g flowers, Citrus medica, yielded the highest n u m b e r o f yeast species. N i n e t e e n species o f yeasts belonging to 9 genera were c o m m o n to b o t h the sources. Abstract.
Introduction
The occurrence o f yeasts in nature is widespread. T h e y h a v e been isolated from soil, air, plant a n d a n i m a l surfaces, p r e s e r v e d foods, a n d sugary substrates, including flower nectar a n d fruit juices [ 10, 12, 16]. T h e association o f yeasts with insect guts is well k n o w n [3], a n d pollinating bees in particular h a r b o r yeasts in their nectar sacs. Similarly, flower nectar constitutes a rich source o f yeasts. T h e association o f particular yeast species with flowers and insects is k n o w n [2, 6, 16] because a n u m b e r o f insects bring a b o u t pollination a n d simultaneously transfer yeasts to flower nectar during their visits to entom o p h i l o u s flowers. T h e present study has been a i m e d at a survey o f the yeasts associated with h o n e y s t o m a c h s o f s o m e pollinating bees a n d nectary glands o f flowers o f cultivated or wild plants.
M a t e r i a l s and M e t h o d s
Collection o f S a m p l e s
Seven different pollinating bees, i.e., Apis dorsata, A. mellifera, A. florae, A. indica, A. cerana, Xylocopa sp., and Halictus sp., were trapped outdoors in the fields from insect-pollinated, cultivated, or wild plants. The bees were kept in the refrigerator after collection to make them inactive and easy to handle. The nectary glands of 9 different flowers, i.e., Citrus medica, C. acida, Murraya exotica, Raphanus sativus. Brassicajuncea, B. rapa, B. campestris, Eruca sativa, and Euphorbia helioscopia, were investigated for the presence of yeasts. The flowers were collected from the fields of suburban Amritsar in sterile polyethylene bags, brought to the laboratory, and processed immediately.
52
D.K. Sandhu and M. K. Waraich
Processing of Samples Pollinating bees and flowers were dissected aseptically to remove the nectar sacs and nectary glands, respectively, which were transferred to 5 ml of sterile distilled water and shaken to obtain a uniform suspension. The appropriate amount of inoculum was streaked liberally on yeast-extract-maltextract agar [20] plates which were incubated at 28~ for 72 hours. The colony types appearing on the culture plates were isolated on yeast-extract-malt-extract agar slants on the basis of gross colonial and microscopic morphology of vegetative cells. The identification of the yeast isolates was done according to the methods of Lodder [13] and Barnett and Pankhurst [1].
Results T h e physiological characteristics o f the yeasts isolated f r o m h o n e y b e e s a n d flower nectar were m o r e or less similar, but with s o m e differences. A b o u t 10% m o r e f e r m e n t a t i v e yeasts were isolated f r o m flower nectar. All 13 substrates used in the identification p r o c e d u r e [13] were fermented, with the exception o f soluble starch. Glucose a n d sucrose were f e r m e n t e d by the m a j o r i t y o f the yeasts. N o n e o f the yeasts f r o m bees f e r m e n t e d melibiose, while only 1 f r o m the flower nectar h a d this ability.
Prevalence of Yeasts in the Honey Stomach of Pollinating Bees A total o f 328 samples o f h o n e y s t o m a c h o f pollinating bees was investigated. All the s a m p l e s were culturally positive, yielding 473 isolates, belonging to 13 genera and 30 species (Table 1). T h e two m o s t c o m m o n species e n c o u n t e r e d were Dekkera intermedia (6.71% o f the samples positive) a n d Saccharomyces cerevisiae (6.1%). A m o n g the other c o m m o n speeies were Candida humicola, C. incommunis, C. ishiwadae, a n d C. membranaefaciens, each occurring in 5.5% o f the samples investigated. T h e prevalence o f other species varied between 1.57 a n d 4.57%. O n e - t h i r d o f the species identified belonged to the genus Candida, while Cryptococcus was represented by 4 species, Rhodotorula by 3, Debaryomyces, Hansenula, and Torulopsis by 2 species each, a n d the r e m a i n i n g 7 genera b y 1 species each. T h e highest n u m b e r o f yeast species was isolated f r o m Xylocopa sp. (13 spp.), followed b y A. mellifera (11 spp.), A. dorsata (9 spp.), A. florae, A. indica, a n d A. cerana (6 spp. each), a n d Halictus sp. (5 spp.).
Prevalence of Yeasts in the Nectary Glands o f Flowers O u t o f the 342 s a m p l e s o f n e c t a r y glands o f flowers, 232 (67.84%) were culturally positive, yielding 293 isolates (Table 2). T h e s e belonged to 12 genera a n d 36 species. T h e m o s t frequently isolated species was C. blankii, occurring in 4.68% o f the samples, followed by C. cacaoi a n d S. cerevisiae, each isolated f r o m 4.09% o f the total s a m p l e s investigated. T h e genus Candida was f o u n d m o s t often, with as m a n y as 16 species, while Hansenula was represented b y 4 species, Debaryomyces a n d Rhodotorula by 3 species each, Pichia a n d Torulopsis by 2 species each, a n d the r e m a i n i n g 6 genera by one species each. T h e nectary
Yeasts, Bees, and Nectar
53
glands ofEruca sativa yielded the highest number of positive cultures (92.11%), followed by Brassica campestris (81.57%). However, the highest number of yeast species was obtained from Citrus medica (12 species), followed by Raphanus sativus (11 species).
Discussion
Apparently no systematic study of this kind has previously been undertaken in India, which should explain the paucity of information on yeasts associated with bees and flowers. Thus, out of the 47 species of yeasts isolated, 42 are being reported for the first time from these two sources. Candida is by far the most common genus associated with pollinating bees, accounting for 33.33% of their yeast flora, a finding that is in accord with some of the earlier reports [9, 18, 19]. All the 4 species of Cryptococcus were isolated from honey stomachs only, as also reported by other workers [7, 9, 13, 15, 17], perhaps indicating their better adaptability for the insect gut. The largest number of yeast species was isolated from Xylocopa sp. followed by A. mellifera. It may be noted that, so far, beetles, Drosophila spp., and A. mellifera have been found to be rich in yeast flora [2, 7, 8, 11, 18]. Since little information is available on Xylocopa sp., it may be suggested that this bee, even in other geographical regions, may yield an equally rich variety of yeasts. No yeast species was common to all the pollinating bees. The occurrence of particular yeast species in more than 1 pollinator with variation in prevalence may be related to their common feeding habits, preference for particular plant species, and/or the time interval between culture and the last feeding of the insect, allowing subsequent digestion of the ingested yeasts [5, 6, 16]. However, even so, only a maximum of 4 yeast species were found to be common between any 2 pollinating bees, e.g., Xylocopa sp. and A. indica or A. florae and A. cerana. As many as 12 yeast species were isolated only from one or the other species of the 7 pollinating bees, suggesting that at least some yeasts may have preferential or even exclusive associations with particular hosts. The yeast flora ofnectary glands of flowers has revealed an even larger variety of yeast species. In particular, the flower nectar of C. medica and R. sativus has proven to be a rich source of isolates, yielding 12 and 11 yeast species respectively. The genera already reported from flowers by other workers include Candida, Endomycopsis, Hansenula, Saccharomyces, Pichia, and Rhodotorula spp. [2, 14, 16]. Out of the 36 yeast species cultured from flowers, only S. cerevisiae has been reported earlier from flower nectar [2, 13]. Thus, as many as 35 species of yeasts seem to be newly discovered from the nectary glands of flowers. On the other hand, there are a few species that are known to be frequently associated with flowers, but have not been encountered in the present study. These include Candida reukaufiL Rhodotorula rubra, R. glutinis, and Torulopsis stellata [4, 14, 16]. Probably, the yeast floras of flower nectar vary in different geographical regions. Out of the 36 yeasts encountered, 23 species occurred in the nectary glands of 2 or more flowers, although each had varying prevalence. For instance, C. blankiL which had a very high prevalence in the flower nectar of B. campestris
Yeasts
Dekkera intermedia Saccharomyces cerevisiae Candida humicola C, incommunis C, ishiwadae C. membranaefaciens Rhodotorula lactosa Candida parapsilosis Cryptococcus albidus Hansenu[a beijerinckii Debaryomyces marama Hansenu[a polymorpha Torulopsis etchellsii Candida requinyii Rhodotorula rnarina Pichia terricola Torulopsis versatilis
5 (10,43) 3 (6.25) 1 (2.08) 1 (2.08)
1 (2.08)
1 (2.08) ~
Xylocopa sp.
2 (4.16)
3 (6.25) 6 (12.5)
2 (4.16) 5 (10.42) 5 (10,42)
11 (22.92) 5 (10.42)
3 (6.25)
A. mellifera
13 (19.12) 10 (14.71)
10 (14.71)
15 (22.06)
11 (16.18)
A. dorsata
8 (16.67)
8 (16.67) 7 (14.58) 5 (10.42)
13 (27.08)
A. florea
10 (20.83) 8 (16.67)
6 (12.50) 6 (12.50)
10(20.83)
A, indica
Number of posilive samples
Table 1. Prevalence of yeasts in the honey stomach of pollinating bees
13 (27.08)
5 (10.42) 6 (12.50) 8 (16.67) 10 (20.83)
6 (12.50)
3 (15)
12 (6)
1 (5)
A. cerana Halictus sp.
22 20 18 18 18 18 16 15 15 15 13 13 13 11 11 11 11
6.71 6.10 5.5 5.5 5.5 5.5 4.88 4.57 4.57 4.57 3.96 3.96 3.96 3.35 3.35 3.35 3.35
Number Percent
Positive samples
ID
l:r
r~
tan 4~
l0 (20.83) 10 (20.83) 1 (2,08) 8 (16.67)
11 83
1 (2.08)
5 (10.43)
A. mellifera
9 101
1 (1.47)
3 (4.40)
4 (5.88)
1 (1.47)
A. dorsata
6 50
7 (14.58)
A. florea
6 48
8 (16.67)
A. indica
Number of positive samples
6 48
A. cerana
5 42
3 (15)
1 (5)
Halictus sp.
10 10 10 8 7 6 5 5 3 3 1 1 1 3O 473
3.05 3.05 3.05 2.45 2.13 1.83 1.52 1.52 0.91 0.91 0.30 0.30 0.30
Number Percent
Positive samples
Figures in parenthesis denote the percent of positive samples examined from each type of pollinating bee All the samples were positive (48 samples were examined from each type of pollinating bees, excepting A. dorsata (68) and Halictus so. (20)
13 101
1 (2.08)
1 (2.08)
5 (10.43)
Xylocopa sp.
Yeasts
Continued
Candida curvata Debaryomyces tamarii Candida blankii Cryptococcus laurentii Cr. dimennae Rhodotorula graminis Brettanomyces anomalus Wingea robertsii Candida psuedotropicalis C. sake Cryptococcus aler Endomycopsis fibu[igera Kluveromyces fragilis Number of species identified Number of isolates
Table 1.
z
Yeasts
2 (5.26) 5 (13.16) 1 (2.63) 1 (2.63)
4 (10.54) 1 (2.63)
5 (13.16)
1 (2.63)"
C. medica
1 (2.63) 1 (2.63) 1 (2.63)
3 (7.89)
R. sativus
3 (7.89)
4 (10.53)
3 (7.89) 5 (13.16)
4 (10.53)
4 (10.53)
4 (10.53)
E. sativa
2 (5.26) 2 (5.26) 6 (15.79)
3 (7.89)
2 (5.26) 1 (2.64)
5 (13.16)
M. exotica
2 (5.26)
2 (5.26) 1 (2.63) 1 (2.63)
6 (15.79)
7 (18.42)
B. rapa
3 (7.89)
5 (13.16)
1 (2.63) 10 (26.32) 6 (15.79)
B. juncea
Number of positive samples
6 (15.79)
8 (21.05) 9 (23.68)
8 (21.05)
B. campestris
Prevalence of yeasts in the nectary glands of flowers (38 samples examined from each type of flower)
Candida blankii C. cacaoi Saccharomyces cerevisiae Candida kefyr C. parapsilosis Oosporidium margaritiferurn Rhodotorula lactosa Torulopsis versatilis Candida incommunis Pichia polymorpha Candida ishiwadae Hansenula beijerinckii H. muscicola Candida bogoriensis C. membranaefaciens C. valdiviana Debaryomyces castellii Endomycopsisfibuligera Hansenula anomala Rhodotorula graminis
Table 2.
3 (7.89)
10 (26.32)
C. acida
9 (23.68)
16 14 14 10 10 10 9 9 8 8 7 7 7 6 6 6 6 6 6 6
4.68 4.09 4.09 2.92 2.92 2.92 2.63 2.63 2.34 2.34 2.05 2.05 2.05 1.75 1.75 1.75 1.75 1.75 1.75 1.75
C. Numhefioscopia bet Percent
Positive samples
Izr
g
26(68.42)
11 45
12 44
1 (2.63)
1 (2.63)
4 (10.54) 1 (2,63) 3 (7.89)
5 (13.16) 5 (13.16)
R. sativus
28(73.68)
2 (5.26) 1 (2.63) 2 (5.26)
3 (7.89)
C. medica
9 35
35(92.11)
3 (7.89)
5 (13.16)
E. sativa
9 34
25(65.79)
2 (5.26)
2 (5.26)
M. exotica
8 30
21(55.26)
1 (2.63)
1 (2.63)
B. rapa
7 30
30(78.94)
2 (5.26)
3 (7.89)
B. juncea
Number of positive samples
a Figures in parenthesis denote the percent positive of samples examined from each type of flower
Wingea robertsii Candida claussenii C. curvata C. psuedotropicalis Pichia terricola Rhodotorula marina Torulopsis pignaliae Trichosporon cutaneum Candida diversa C. fragicola C. humicola Debaryomyces phaffii Deb. tamarii Geotrichum candidum Candida tropicalis Hansenula polymorpha Number of positive samples Number of species identified Number of isolates
Yeasts
Table 2. Continued
4 31
31(81.57)
B. campestris
4 26
21 (55.26)
5 (13.16)
3 (7.89)
C. acida
4 18
15(39.47)
l (2.64) 3 (7.89)
2 (5.26)
C. helioscopia
36 293
232
6 5 5 5 5 5 5 4 3 3 3 3 3 3 2 l
67.84
1.75 1.47 1.47 1.47 1.47 1.47 1.47 1.16 0.88 0.88 0.88 0.88 0.88 0.88 0.58 0.29
Numher Percent
Positive sampies
Z
"
