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INVESTIGATION OF THE NATURE AND CAUSE OF THE DAMAGE TO PLANT TISSUE RESULTING FROM THE FEEDING OF CAPSID BUGS.
Author(s) -
SMITH KENNETH M.
Publication year - 1920
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.1744-7348.1920.tb05105.x
Subject(s) - biology , insect , botany , anatomy
SUMMARY. There are several species of Capsid bugs which normally feed on the leaves and fruit of apple trees but only one causes any damage, i.e. Plesiocoris rugicollis. This species produces the death of the tissue surrounding each puncture in the leaves made in feeding and on the fruit produces great distortion and “russeting.” There are three possible explanations of this damage:1 A purely mechanical injury produced by the insect's stylets in process of sucking. 2 The possibility of the bug acting as a “carrier” of bacteria and by injecting these into the plant along with the saliva so sets up a pathological state. 3 The injection of some secretion from the salivary glands which has a violently toxic effect on the plant tissue.It was found impossible to reproduce by mechanical means the injury resulting from the feeding of P. rugicollis , also the fact that the other species of Capsid bug feed in a similar manner and produce no injury militates strongly against the theory of mechanical injury only. As regards the second theory, no bacteria could be discovered in microtome sections of either damaged plant tissue or the salivary glands of the bug, and all attempts to reproduce the damage by means of bacteria failed. The third theory was proved to be the correct explanation by several experiments and observations. Experiments were made to try and reproduce the bug injury with various dilute poisons; in most cases a very similar appearance was produced in the foliage, but the attempts were unsuccessful in the fruit itself with the exception of the very great retarding effect in the growth of the fruit, which is one of the results of the bug injury. By feeding the bugs on slices of potato instead of apple the same effect was produced, but on a magnified scale. The salivary glands of P. rugicollis and of Lygus pabulinus , a bug harmful to potato foliage, when placed on a freshly cut slice of potato in a petri dish, produced a violent reaction which killed much of the tissue surrounding the glands. The same experiment was carried out with the glands of one of the harmless apple‐feeding bugs Psallus ambiguus , these had no effect whatever on the potato. When the salivary glands of P. rugicollis were pricked into apple buds, the shoots were killed within 24 hours. The salivary glands of P. ambiguus when similarly treated had no effect. Observations were made showing the rate of exudation of sap from the bug's puncture in the potato and these are given for P. rugicollis and Lygus pabulinus. A list of common plants and fruit trees with their various reactions to the feeding of harmful bugs is also given.