Population fluctuation of the predacious insects of the pear psylla (Cacopsylla pyri L.) in Attica (Greece)

Abstract

In a pesticide free pear-orchard, in Koropi, Attica (Greece) during the
year 1994-1996 it was found a satisfactory number ofpredacious insects belonging
to the farnilies Chrysopidae and Anthocoridae; the most representatives were
Chrysoperla carnea Steph. and Anthocoris nemoralis F. The role of C. carnea
and A. nemoralis is proven and justifiably so, both are considered to be the most
active in the control of pear psylla populations ( Cacopsylla pyri L.). Additionally
in the same pear orchard were found many predacious Coccinellidae while their
activity does not appear to play an important role in the control of the psylla
population since their presence in the field is rather incidental. In the field C.
carnea appears first in February or March and A. nemoralis follows in March.
The population of these insects increases gradually following the population
increases of their host. The highest density is observed from the end of April till
the end of July. Reduction of their population follows during the summer months
to reach again satisfactory levels in the end of September. Especially A. nemoralis
will survive in nature until the end of November and its population will disappear
contemporary with the psylla population.