Is annual reports of DEPARTMENT OF AGRICULTURE, 1952 
Time-Saving Technique for Diagnosing Fonlbrood Developed 
An improved method of preparing a water mount for the micro- 
Bcopic diagnosis of American Eoulbrood has been developed at the 
Beltsville, Md., bee culture laboratory. A cover-lip containing a 
stained smear is inverted on a glass slide covered with a iil in of immer- 
sion oil. This results in the water on the coverslip becoming en- 
trapped in the form of droplets in the oil. If -port'- of Bacillus larvae 
are present, they will be concentrated in these droplets. Advantages 
of this method are simplicity of preparat ion. ease of locating the con- 
centrated spores, and elimination of "streaming" of spores. It also 
saves time since the mounts do not dry out : many slides can he pre- 
pared at once and their examination delayed several days. 
In other work at Beltsville, differential media were devised for 
distinguishing between various organisms associated with European 
fonlbrood. For example, addition of 2,3,5-tetrazolium chloride to 
nutrient agar antagonism plates increases the ease with which these 
plates may be read and improves their use for diagnostic purposes. 
In such a media Streptococcus apis grows as a deep red. compact col- 
ony. Bacillus alvei and B. para-alwei still grow as spreaders hut at 
a reduced rate. However, B. alvei colonies have a light pink, smooth 
center, surrounded by a white zone and then a pink zone. 1>. para- 
alvei colonies have a dark pink granular center surrounded by a light 
pink zone, then a clear zone, and finally an orange-pink zone. 
Hybrid Queens Produce Colonies Highly Resistanl to 
American Fonlbrood 
Tests for resistance to American fonlbrood were made on three 
groups of colonies at Laramie, Wyo. These colonies were headed by 
4-way hybrid queens produced in l!>r>(> on Kclleys Island in Lake Brie. 
These queens carried the blood of resistanl strain-. All showed high 
resistance to American fonlbrood. ( )ne group of 9 colonies remained 
free of disease. In a second group of L5 colonies only 1 developed 
disease but quickly recovered. In a third group of 7 colonies 6 re 
mained disease-free, but one colony contracted disease and had not 
recovered when winter set in. r rhe lirst two groups also showed 
remarkable colony development and very good surplus honey 
production. 
Pollinators of Cotton Blossoms in Arizona Identified 
I Ionev bees and rial ive bees of the genus M< lis8oa\ 8 were found io be 
the chief insect visitors of value as pollinators <»f cotton blossoms in 
Arizona. Bees of the genus Elu for the most part visited extra-floral 
nectaries. Wasps in the main vi<ited leaf nectaries, Although 
hone} bees collected nectar primarily and contacted the stigma acci- 
dentally when entering or leaving the flower, Melissodes primarily 
collected pollen and is, therefore, a more effective pollinator. In cages 
with a high concent rat ion of bees per plant, honey bee- collected COtton 
pollen without difficulty, indicating that they could be effective pol- 
linators under proper conditions. Using honey bees in cotton polli- 
nation will probably require concentrations of colonic- in the held 
similar to that recommended for alfalfa seed production. 
