STUDIES ON THE NUTRITIONAL STATE AND THE RESPONSE TO AGGREGATION PHEROMONES IN THE BARK BEETLE, IPS-TYPOGRAPHUS (L) (COL, SCOLYTIDAE)

The correlation between nutritional state and behaviour was studied in an overwintering population of bark beetles, Ips typographus (L.). It was found that 3 groups of the bark beetles could be distinguished with respect to their nutrient contents and reactivity to the traps with aggregation pheromone in the field. Group A - newly emerged beetles searching for food ignored the pheromone traps, were shown to have low protein and glycogen contents. Group B - feeding beetles with high lipid and glycogen contents but relatively low protein content probably due to degeneration of flight muscles. They were taken as control with regard of nutrient contents. Group C - beetles, attracted to the pheromone traps, were divided into two subgroups: C1 - beetles with high content of glycogen and lipid but low protein. They represented about 25-30 % of captured beetles and they were from local population. C2 - characterized by a low content of glycogen and lipid but high protein, probably due to well developed flight muscles. They represented about 70 % and probably belonged to migrating beetles. A possible correlation between reactivity to pheromones and nutrient reserves is discussed.