Comparison of Physiological Responses in Some Pinus Species Attacked by Pine Processionary Moth

Abstract

Pinus species, used in traditional medicine and are an important industrial plant, suffer severe ecological and economic losses with the invasion of Thaumetopoea wilkinsoni (the pine processionary moth). Due to the damage caused by T. wilkinsoni, a biotic stress factor, the changes occur in the ecological and physiological parameters of Pinus species, which also try to cope with abiotic stress. The changes in fresh/dry weight, percent water content, chlorophyll a and b content, the total protein content, malondialdehyde (MDA) amounts, and superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities in leaf samples of the pine processionary moth-infested and non-infested Pinus sylvestris L. and P. nigra Arn. species were compared in the study. The leaf samples of P.nigra and P. sylvestris were collected from the Ondokuz Mayis University Kurupelit Campus in Samsun, Turkey, in 2020. Individuals of the moth-infested and non-infested P. sylvestris and P. nigra formed two distinct experimental groups. It was found that the fresh/dry weight, percent water content, chl a and b content of the moth-infested individuals of both species were significantly decreased compared with non-infested individuals; the total protein contents, lipid peroxidation and SOD, CAT, APX activities were found to be significantly increased. It was also determined that the moth-infested individuals of both species had the most sesquiterpenes and the least monoterpenes. Our results clearly show that P. nigra and P. sylvestris defend themselves when attacked by the pine processionary moth, both by changing the amount of secondary metabolites and by reacting as antioxidative defense responses.