Chemical Nature of an Insect Gall Growth-Factor

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Abstract
It is known that material from an accessory gland and accompanying sac of a gall wasp, Pontania pacifica can cause the formation of small galls on Salix alba. In this study, growth-promoting substances in extracts of these organs were detected by means of an assay which involves application of the test material to immature P. pacifica galls (on S. alba) from which the larvae have been removed. Growth-promoting activity was found to diffuse through dialysis membranes. Chromatographic examination of the extracts revealed the presence of glutamic acid (about 5 [mu]g/gland) as well as 5 compounds which absorb UV light. Of these, 2 have been identified by means of Rf values and absorption spectra as uridine and uric acid; 2 appear to be unusual adenine derivatives, while the 5th remains unidentified. It is estimated that these UV absorbing compounds are present to the extent of 0.3-1.0 [mu]g/gland. Since glutamic acid (0.8 [mu]g/ treatment) and uric acid, or either of the 2 adenine derivatives (0.1 [mu]g/ treatment) stimulate the growth of larva-less galls, it is suggested that these compounds are of importance in the natural growth and development of Pontania galls.