Pollen Digestion Research Articles

The digestion of dandelion pollen by adult worker honeybees

ABSTRACT. The digestion of dandelion (Taraxacum officinale) pollen by adult worker honeybees (Apis mellifera Linn.; Hymenoptera: Apidae) was initiated at the germination pores. 30 min after feeding, pollen had reached the anterior midgut and the germination pores had become swollen. This permitted further removal of protoplasm during the next 2 h of digestion as the pollen passed into the middle portion of the midgut. 3 h after feeding, pollen grains had reached the posterior midgut where some had ruptured to release both ‘naked’ protoplasm and masses of protoplasm but many remained intact or were only partially digested; undigested pollen grains passed unchanged to the rectum. The lipid‐rich pollenkitt layer was removed from the exine during digestion. Our studies indicate that dandelion pollen was not utilized completely by honeybees.

A photographic account of pollen digestion by adult hoverflies

ABSTRACT. The method of pollen digestion by adults of the hoverfly Cheilosia albitarsis Mg. (Diptera: Syrphidae) was investigated by observing pollen grains at different stages in their progression along the gut. No form of mechanical ‘grinding’ to break up the grains was observed, as suggested by some previous authors. Instead, there was an exudation of the pollen grain contents through one of the pores in the pollen exine. This exudation may start as a growing pollen tube. The exact conditions which cause the pollen grains to give up their contents in this way are unknown, but it is suggested that nectar sugar within the gut may provide the necessary stimulus.

Osmotic Shock as a Prerequisite to Pollen Digestion in the Alimentary Tract of the Worker Honeybee

SummarySome observations are reported suggesting that, in the worker honeybee, a difference in osmotic pressure between the contents of the honey sac and ventriculus causes pollen grains to burst during their passage through the alimentary tract. Neither gnawing nor enzymatic degradation of the hard pollen wall seems to be necessary for pollen digestion. A similar mechanism may allow Nosema apis to extrude its polar filament in the ventriculus, and thus infect its host.

Reactions to the Alcohol-Insoluble Fraction of Ragweed Pollen

It was shown by Coca and Grove1 that tryptic digestion of pollen did not destroy its ability to elicit a positive reaction in allergic individuals, although after dialysis no trace of its original nitrogen-content remained. Stull, Cooke and Chobot2 found that the active principle of ragweed pollen is present in that fraction which is insoluble in 90-95% alcohol. Black3 by repeated precipitation of ragweed pollen extract in 60% alcohol and redissolving of the precipitate in acid saline, obtained an extract which contained very little nitrogen, and which gave many of the chemical reactions characteristic of polysaccharides. This fraction also gave typical allergic reactions in 43 ragweed-sensitive patients, and no reactions in 50 normals. The highest dilution giving a reaction when injected intradermally was 1:240,000. Unger, Moore, Cromwell and Seeber,4 in desensi-tization experiments using both purified protein derivatives and purified polysaccharide fractions, concluded that the specifically active subst...