12 
Journal of Agricultural Research 
Vol. XXXI, No. 1 
Transmission of Mosaic from the Wild to the Cultivated Cucumber 
by the Cucumber Aphis 
In these experiments, a number of cucumber aphids, Aphis gossypii 
Glover, were colonized on mosaic and healthy wild cucumber plants. 
The aphids from mosaic plants were later transferred to healthy 
cucumber plants under cages, and the aphids from healthy 
Micrampelis plants were placed on healthy cucumbers in other cages 
as controls. As shown in Table III, infection occurred on all plants 
to which aphids from mosaic wild cucumber plants were trans¬ 
ferred, while the controls remained healthy in each experiment. 
Table III. — Transmission of cucurbit mosaic from Micrampelis lobata to healthy 
cucumber plants by Aphis gossypii 
Date 
Condition of plants used as source of aphids 
Number 
of plants 
Number 
of mosaic 
plants 
Date ob¬ 
served 
July 14,1919_ 
Mosaic_ . _ _ 
4 
4 
July 23,1919 
Do. 
Do_ 
Healthy (control). ... __ _ 
3 
0 
Aug. 18,1919_ 
Mosaic__ ___ _ 
7 
7 
Aug. 30,1919 
Do. 
Do_ 
Healthy (control) _ . 
3 
0 
July 10,1920_ 
Mosaic_ 
8 
8 
July 21,1920 
Do. 
Do_ 
Healthy (control)__ 
8 
0 
July 21,1920_ 
Mosaic_ __ __ _ ___ 
6 
6 
Aug. 2,1920 
Do. 
Do__ 
Healthy (control)_____ _ 
6 
0 
Aug. 9,1920_ 
Mosaic____ __ 
6 
6 
Aug. 20,1920 
Do. 
Do_ 
Healthy (control)_ __ _ __ 
6 
0 
Transmission of Mosaic from the Wild to the Cultivated Cucumber 
by the Striped Beetle and by the 12-Spotted Beetle 
The transmission of mosaic from the wild to the cultivated 
cucumber by the striped beetle, Didbrotica vittata , and by the 12- 
spotted beetle, D. 12-punctata y has been demonstrated by a number 
of experiments with both insects. The two species of Diabrotica 
are so similar in habit, however, that definite evidence of transmission 
by either species would indicate that both were concerned in carrying 
the disease. 
In these experiments, beetles were collected at points supposedly 
distant from any sources of cucurbit mosaic infection, and then 
placed in cages containing healthy cucumber plants and allowed to 
feed for three days. The beetles were then removed and the plants 
were kept under observation for two weeks to determine whether any 
of the insects were carrying the mosaic virus when collected. In 
all cases, however, the test plants remained healthy. After the beetles 
had been tested in this manner, they were placed in cages containing 
healthy cucumber plants in 4-inch pot£, together with a few potted 
plants of mosaic Micrampelis. The Micrampelis plants were so 
placed as not to be in contact with the cucumbers, thus insuring 
that no infection took place through contact of the leaves. The 
beetles were allowed to feed indiscriminately on both the cucumber 
and Micrampelis plants for periods ranging from three to seven days, 
and were then removed from the cages. Mosaic Micrampelis and 
healthy cucumber plants were placed in the control cages, but no 
insects were admitted. The results given in Tables IV and V indicate 
that the disease is readily transmissible by these insects under the 
conditions of these experiments. 
i 
