Abstract
When Lygus disponsi LINNAVUORI fed on pumpkin fruits, their stylets passed through intercellularly to reach the vascular system, where a feeding cavity often formed. The cells surrounding the stylet track and feeding cavity went on swelling till 6 days after the injury and turned so that they were arranged regularly along the stylet track, the feeding cavity and the epithelium. Starch granules disappeared from or decreased in number in the enlarged cells.Polyphenoloxidase activity rose just after the infestation period. but soon dropped and remained at the control level from the 3rd day on. Acid phosphatase activity was the highest at the 6th day after the infestation period. IAA-oxidase activity rose markedly as a result of the injury, but decreased very quickly. The mechanism of tubercle formation is discussed.
