The abiotic stress as a factor responsible for gypsy moth outbreaks

The close quantitative interrelation between the reaction of birch to abiot ic stress (spring-summer droughts) (the degree to which the yearly radial i ncrement of trees decreases) and entomoresistance has been established. Tre e stands that were heavily defoliated by gypsy moth showed a much stronger reaction to the droughts which preceded the outbreaks by the decrease in th eir radial increment than those weakly defoliated by this phytophagous inse ct. The reaction of trees to the abiotic stress is regarded as the key fact or that controls the drop in their entomoresistance during outbreaks of gyp sy moth in woods damaged by anthropogenic effects.