Cucurbit Genetics Cooperative Report 2:5 (article 2) 1979
Breeding Glabrous Cucumber Varieties to Improve the Biological Control of the Glasshouse Whitefly
0. M. B. de Ponti
Institute for Horticultural Plant Breeding, Wageningen, The Netherlands
On glasshouse tomatoes in the Netherlands, the biological control of the glasshouse whitefly (Trialeurodes vaporariorum Westwood) with the parasitic wasp (Encarsia formosa Gahan) is successfully applied on an ever increasing scale. On glasshouse cucumbers, however, despite repeated and large introductions of the parasitic wasp, sufficient control is rarely achieved. This failure of control was ascribed to the many large hairs on the cucumber leaf and the honeydew on the hairs. These factors reduce the mobility and consequently, the parasitization activity of the wasp. If this hypothesis is true, the parasitization frequency would be improved on hairless (glabrous) leaves.
From the N.I. Vavilov All-Union Institute of Plant Industry in Leningrad, seeds of glabrous mutants were received. First, the mobility of the wasp was studied. It appeared that on the glabrous leaves, the wasp was no longer hampered by hairs or honeydew and covered per unit of time a distance 3.5 times larger than on normal hairy leaves (1). At the moment, the expected positive influence of this enhanced mobility on the parasitization frequency is investigated.
Anticipating the results of these investigations, the breeding of glabrous cucumber varieties has already been started.
Recently, eight advanced breeding lines have been released to private breeding firms in the Netherlands. Besides glabrous, these lines are bitterfree, gynoecious, parthenocarpic, and producing slicers of a good quality. Because of the simple inheritance (one recessive gene) and selectability of the character concerned glabrous varieties, may be awaited rather soon.
So far, no unfavorable characteristics have been discovered with respect to the glabrous character. On the contrary, it is expected that growers will welcome these varieties, which cause less fruit damage and skin irritation.
- Hulspas-Jordaan, P. M. and J.C. van Lenteren. 1978. The relationship between host-plant leaf structure and parasitization efficiency of the parasitic wasp Encarsia formosa Gahan (Hymenoptera: Aphelinidae). Meded. Fac. Landbouww. Rijksuniversiteit Gent: in press.