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INVESTIGATIONS INTO THE NUTRITION OF THE ASH‐BARK BEETLE, HYLESINUS FRAXINI PANZ.
Author(s) -
HOPF H. S.
Publication year - 1938
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.1938.tb02340.x
Subject(s) - biology , bark (sound) , starch , frass , botany , maltose , amylase , carbohydrate , food science , biochemistry , enzyme , ecology , larva
SUMMARY From investigations into the enzymes of the alimentary canal and a comparative analysis of ash bark and the frass of Hylesinus fraxini it appears that the food relations of the ash‐bark beetle are as follows:1 Proteins are derived directly from the bark. The adult after emergence excretes more nitrogen than it consumes; this excess excretion may be regarded as representing waste‐products of metamorphosis.(a) The carbohydrates are derived from the following bark constituents: ( a ) The simple sugars. ( b ) Disaccharides, simple oligoses etc., probably all with α‐linkagee. (c) The α‐glucans up to starch, but with a definite preference for sugars of smaller chain‐length. Starch as such has disappeared from the bark of attacked trees. ( d ) The hexosan parts of the hemicelluloses.3 The protein‐hydrolysing enzymes are of the tryptase and pepti‐dase type, in accordance with the alkaline p H of the gut. 4 The carbohydrate‐hydrolysing enzymes are of the following types: saccharase, a weak lactase, maltase, amylase (dextrinase), galact‐anase. 5 Cellulose is clearly not attacked. The same applies to all pentoaana. 6 The breakdown of starch in the attacked bark may serve as an attractant to the bark beetles, and may help to explain their preference for trees suffering from physiological or pathological disturbance. 7 A way has been shown in which the hemicelluloses are utilized by the insect in question, and the probable fate of the breakdown products of these substances in the frass has been indicated.