The value of white clover Trifolium repens L., Cultivar S100 planted on motorway verges to honeybees Apis mellifera L

  • Published source details Free J.B. & Williams I.H. (1980) The value of white clover Trifolium repens L., Cultivar S100 planted on motorway verges to honeybees Apis mellifera L. Biological Conservation, 18, 89-92.


In England in the 1970s, motorway verges were commonly sown with a mixture of grasses and white clover Trifolium repens (cultivar S100). Beekeepers considered that honeybees Apis mellifera obtain little forage from the S100 cultivar, and suggested replacing it with one yielding more nectar. Trials were undertaken at Rothamsted Experimental Station (south-east England) to assess preferences of honeybees and bumblebees Bombus spp. for five white clover cultivars: S100, S184, Sabeda, Kent Wild and New Zealand Huia.

In 1974, four 5 x 12 m plots (separated by 1 m-wide paths) of each cultivar were sown (randon block design). In 1975 and 1976, when flowering, honeybee and bumblebee counts were made. The presence of pollen loads on honeybees was recorded and bumblebees were identified. A total of 21 counts were made on eight days in June-July 1975, and 16 counts on six days in June 1976. At the end of each observation day, the numbers of open flower heads in each plot was estimated from counts within two 4 m² quadrats. In both years, corolla tube measurements were made on 10 florets from each of 10 flower heads of each cultivar to assess if floret size influenced bee preference.

In 1975 and 1976, 6,139 and 654 honeybees, and 363 and 416 bumblebees (B.terrestris/lucorum, B.pratorum, B.pascuorum and B.hortorum) were counted, respectively.
In both years bumblebees preferred S100 to the other cultivars (average number of bees/1000 flowers both years combined): S100 (12.9); Sabeda (9.6); NZ Huia (8.8); S184 (8.8); and Kent Wild (6.3).
Honeybees preferred S100 in 1975: S100 (243.7); NZ Huia (219.5); Sabeda (186.6); S184 (164.0); and Kent Wild (133.1). In 1976 when honeybee numbers were much lower, S100 was the third most preferred but differences in visitation were marginal: NZ Huia (13.5); Sabeda (12.7); S100 (11.9); S184 (9.2); and Kent Wild (7.9).
In 1975, a similar proportion of honeybees foraging on the different cultivars collected pollen (range 57-61%). In contrast in 1976, differences were apparent: S184 (33.3%); Sabeda (23.7%); NZ Huia (20.9%); S100 (20.3%); and Kent Wild (8.2%).
The preferences of bees for different cultivars seemed unrelated to floret size.
In conclusion, honeybees and bumblebees visited all the cultivars but S100 was one of the most attractive whilst Kent Wild was consistently least preferred.
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