Date of Award:

5-1-1972

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Biology

Department name when degree awarded

Zoology (Entomology)

Committee Chair(s)

G. E. Bohart

Committee

G. E. Bohart

Committee

D. W. Davis

Committee

W. F. Campbell

Committee

D. V. Sisson

Committee

J. R. Simmons

Abstract

Levels of potassium in nectar of onion, Allium cepa L., varied from 3600 to 13,000 parts per million, about ten times higher than that of nectar of competing flora tested. An open-pollinated amphidiploid derived from the interspecific cross, A. cepa x A. fistulosum L., was the only onion with nectar potassium level as low as that of competing flora, and it was more attractive to honey bees, Apis mellifera L., than was the common onion. Addition of potassium salts to sugar solutions at the rate of 1500, 3000, 4500, 6000, or 7500 parts per million potassium clearly reduced uptake of these solutions by honey bees foraging at artificial-flower feeders. Thus, it appears that levels of potassium in onion nectar are high enough to reduce the attractiveness of onion flowers to honey bees. Honey bee visitation to onion flowers would probably be increased if nectar potassium levels were reduced, possibly through a program of selective breeding or by altering cultural practices. However, the presence of high potassium levels in onion nectar over a wide range of geography, climates, cultivars, and cultural practices suggests that high potassium nectar is characteristic of the species, An alternate solution would be to provide pollinators that readily accept the high potassium level present in onion nectar. This might be accomplished by preconditioning honey bees to accept high potassium levels in sugar solutions before they are moved to the onion seed fields, by developing a strain of honey bees with a preference for onion (high potassium) nectar, or by utilizing other species of pollinators.

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