IPS BARK BEETLE ATTACKS AND BROOD DEVELOPMENT ON A LIGHTNING-STRUCK PINE IN RELATION TO ITS PHYSIOLOGICAL DECLINE'

A study was made of the attacks and brood development of Ips calligraphus (Germ.), Ips grandicollis (Eichh.), and Ips avulsus (Eichh.' on a large lightning-struck pine tree to determine how these activities were affected by certain factors associated with the physiological decline of the tree. Results show a definite relationship between oleoresin exudation rate (O.E.R.) and incidence and success of Ips attacks. No attacks succeeded where O.E.R. exceeded 0.1 ml/hr. from a standard wound. Moreover, the incidence of attack was less where O.E.R. was greater than 0.1 ml/hr. Inner bark moisture limited brood development only where severe dessication occurred. The pH of the inner bark was within the range found on normal, healthy trees. An hypothesis concerning Ips bark beetle invasion and colonization of lightning-struck pine trees is offered.