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A Comparison of Bee Cell X-ray Results from 
Three Laboratories

D.T. Fairey, L.P. Lefkovitch, J.A.C. Lieverse, K. Strickler, and D.W. Lundahl

Agriculture & Agri-Food Canada, Beaverlodge and Ottawa, Canada; University of Idaho, and Montana Department of Agriculture

This article was revised and published in the International Herbage Seed Group Newsletter :  Fairey, D. T., N. A. Fairey , K. Strickler  and D. Lundahl   2003.  A comparison of the quality of alfalfa leafcutting bee cocoons at three North American laboratories.  International Herbage Seed Group Newsletter  , July 2003, 36:3-5

  

Table 1: A comparison of cell quality indices between laboratories

Table 2: A comparison of 1994 results

Table 3: A comparison of 1995 results

  

Seed producers in Canada and the Pacific Northwest use the services of one of three laboratories - the Canadian Cocoon Testing Centre at Brooks, Alberta, the University of Idaho, at Parma, USA and the Montana Department of Agriculture at Helena, USA, to determine the quality of leafcutting bee cells. In these laboratories, cell quality is determined from an X-ray of the cells.  A study to determine whether there are differences in the results obtained from these three laboratories was made in 1995. Twenty samples from the same Canadian sources with coded identifications were sent to each of the three laboratories for quality tests. The proportions (%) of live larvae (range between laboratories of 76 to 83%), dead larvae (range from 0.01 to 0.07%), cells containing only pollen provisions (range from 7 to 13%) and the number of live larvae per kilogram of cells (range from 9,605 to 10,281), were significantly different between the three laboratories (Table 1). There was no difference between the proportions (%) of second-generation or parasitized cells. Despite the statistical significance, the magnitude of these differences were too small to be of practical significance. A relationship could not be discerned when the mean values from the laboratories were plotted against each other. It was therefore impossible to predict which laboratory to use to obtain a desired result.

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Table 1

A comparison of cell quality indices between laboratories taking into account sample & producer effects.

Predicted means (standard error)

Laboratory

Live larva (%)

Live larvae per kg

Dead larvae  (%)

Cells containing pollen

Brooks

77.0 (0.9)

9712 (80)

1.4 (0.3)

13.0 (0.8)

Parma

76.2 (0.1)

9605 (79)

7.2 (0.6)

10.7 (0.7)

Helena

83.2 (0.8)

10281 (89)

0.5 (0.2)

6.5 (0.6)

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TABLE 2

A comparison of 1994 results, mean (range): present study, Canada, Idaho, and Montana

 

Present study (201)

Canada2
(3281)

Idaho3
(331)

Montana4  
(1231)

Live larva (%)

78.2
(50-90)

75.3
(25-91)

50.5
(17-75)

61.0
(31-92)

Live larva per kg

9719
(5580-11578)

9214
(2994-12173)

5222
(2011-9472)

7285
(3288-11571)

Dead larvae (%)

3.1
(0-13)

1.7
(0-17)

6.1
(0.7-22)

7.4
(2.8-15.8)

Cells with pollen
(%)

10.3
(3-33)

14.7
(3-61)

21.5
(5-40)

23.3
(3.8-54.6)

Second generation bees (%)

0.8
(0-4)

0.6
(0-15)

0.4
(0-2)

0.62
(0-4.4)

Parasites (%)

1.1
(0-4)

0.8
(0-12)

2.3
(0-16)

0.62
(0-4.4)

Chalkbrood  (%)

0

0.4
(0-11)

12.2
(1-31)

5.78
(0-17)

1 Sample size; 2From Fairey & Lieverse unpublished data; 3 From University of Idaho, Parma Research & Extension Centre; includes Idaho, Oregon & Nevada; 4 From Montana Department of Agriculture, Helena.

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Table 3

A comparison of 1995 results, mean (range): Canada and Idaho, to date

(Feb. 26, 1996)

 

Canada
N=99

Idaho
N=16

Live larva (%)

74.9
(41-93)

43.4%
(23-60)

Live larva per lb.

4118
(2240-5361)

2066
(1074-3221)

Dead larvae
(%)

1.5
(0-4.8)

8.5
(4-12)

Cells with pollen
(%)

15.30
(5-44)

25.9%
(13-40)

Second generation bees (%)

0.5
(0-3)

0.4
(0-1.3)

Parasites
(%)

1.10
(0-16)

5.1%
(0-13)

Chalkbrood
(%)

0.169
(0-5.7)

9.2
(2-14)

Note: For information on the status of the Parma Cocoon Testing Lab after 2000, contact PSES at UI

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Revised July 20, 2000.