Five-year results of the impact of pine processionary moth (Thaumetopoea wilkinsoni Tams) on the growth of Turkish red pine (Pinus brutia Ten.)

Pine processionary caterpillar (Thaumetopoea wilkinsoni Tams.) larvae cause defoliation by eating leaves mainly in Turkish red pine, but sometimes in cedar and Crimean pine forests in Mediterranean Region of Turkey. The growth rate of the trees are adversely affected by the defoliation, even it is temporary. On the other hand, defoliation may have an effect on tree growth not only in the current year but also over years due to the renewal of the leaves in every two years. Moreover, the reduction in growth rate may change considerably depending on whether the defoliation occurred only one year or more in following years. In this study, we aimed at determining the over-years effect of defoliation in Turkish red pine forests. The research was conducted in two different sites for five years in Antalya region. At the beginning, trees defoliated in more than 40% were marked and observed in the following five years for their defoliation, and total defoliation rate was calculated by adding up defoliation rate in all years. Total diameter (Dbh) and volume loss of all defoliated trees were measured for five years and comparing to control trees. As a result, significant relationship between added total defoliation rate and total Dbh and volume growth lose for five years were determined and linear regression equations were calculated. Additionally, the relationship between added total defoliation rate and the total number of nests of pine processionary moth for five years was investigated, however, this relationship was not significant in both sites