The effect of western conifer seed bug (Leptoglossus occidentalis) on the black pine seeds in the Southern Marmara Region

Black Pine (Pinus nigra) is one of the most important forest trees in Türkiye. Recently, low germination rates have been observed in P. nigra seeds. On the other hand, it is recorded that the western conifer seed bug (Leptoglossus occidentalis) (WCSB) has become widespread in the pine forests of our country in recent years. In forests where WCSB is active, it significantly reduces the sound seed rate and germination percentage. In this study, it was aimed to determine the effect of WCSB P. nigra seeds on the basis of the origins and individual trees in the origins. The research was carried out in 6 different P. nigra origins (Çan, Bigadiç, Dursunbey, Keles, Bozüyük, Armutlu) in the Southern Marmara Region. A total of 1050 cones were collected from 210 trees, 5 cones from 35 trees at each origin. After the seeds were extracted from the cones collected from 30 trees and mixed, a cutting test was applied to 500 (5*100) randomly selected seeds. In addition, the seeds in 25 cones collected from 5 trees at each origin were counted and extracted, and a cutting test was applied to these seeds in order to determine the effects of WCSB on a tree basis. 1000-seed weights and germination percentages of the origins in the study were determined. Significant differences have been recorded between the origins in terms of the proportion of sound and insect infected seeds. The overall average amount of sound seeds of 6 origins was found to be 70.7%, the average amount of insect infected seeds was 29.3% and the average amount of empty seeds was 0.0%. The highest percentage of sound seeds was 77.4 in Bigadiç origin and the highest percentage of insect infected seeds was 45.4 in Armutlu. The percentage of sound seeds in 3 origins (Bigadiç, Dursunbey, Keles) demonstrated significant differences between trees. Significant differences have emerged between the origins in terms of the number of seeds emerging from the cone. The overall average number of seeds from the cone was 42.0, with the highest number of seeds in Bigadiç origin (50.3) and the least in Bozüyük (33.0). The mean weight of 1000-seed was determined as 21.68 g. The overall average germination percentage (GP) of the origins was 59.7% and the average germination rate (MGT) was 7.9 days. The highest germination percentage (79.0%) was in Dursunbey origin and the lowest (43.8%) was in Armutlu. The present study supports the knowledge that WCSB is very effective in pine tree species in our country. Additional studies should be carried out on the activity of the insect in different pine species and regions.