The successful development of the final larval stage of the pine processi̇onary mont (Thaumetopoea wilkinsoni tams, 1924 (Lepidoptera: notodontidae)) over a one-year peri̇od.

In this study, the effect of the size and weight on the transition from larva to pupa and from pupa to the adult stage of the Pine Processionary Moth (Thaumetopoea wilkinsoni), which damages pine trees in Turkey, has been compared and examined. In April, larvae were collected from the campus of Düzce University located in the Düzce province of the Western Black Sea Region, during the period when the larvae left their silk nests to enter the soil. In the laboratory of Düzce University, the weights and lengths of the larval and adult stages of the Pine Processionary Moth were measured. The Pine Processionary Moth larvae were grouped based on their weights as Small (<0-0.600 g), Medium (0.601-0.900 g), and Large (>0.900 g). The average weight of 300 individuals collected from the 5th instar larvae of the Pine Processionary Moth for pupation was calculated as 0.752 g ± 0.214, and the average length was 3.12 cm ± 0.42. The average length of the larvae classified as Small was 2.72 cm ± 0.29, and the average weight was 0.515 g ± 0.071. The average length of the larvae classified as Medium was 3.13 cm ± 0.22, and the average weight was 0.740 g ± 0.094. The average length of the larvae classified as Large was 3.53 cm ± 0.26, and the average weight was 1.001 g ± 0.063. In addition to 90 larvae from each group, a total of 270 larvae were randomly selected and weighed without grouping, and their lengths were measured in millimeters. Ten experimental environments, labeled as K1, K2, K3, O1, O2, O3, B1, B2, B3, and Control, were established, and their entry into the soil was monitored. The time of entering the soil was considered as the start (end of April), and the transition to the adult stage was observed until the end of September. None of the larvae that entered the soil to pupate were successful in becoming pupae. Out of the total 300 larvae, 175 of them (58%) transitioned to the pupal stage. This ratio was highest in the Medium-sized group (66%) and lowest in the Control group (33%). In Düzce province, the first emergence of the Pine Processionary Moth adults was observed on July 16th, and the last emergence from the pupa was detected on August 1st. Out of the 300 larvae placed in the soil for pupation, 38 adults were obtained in the first year. The success rate of becoming an adult in the first year was 13%. Adult emergence was observed in 10 individuals from the Small group, 14 individuals from the Medium group, 11 individuals from the Large group, and 3 individuals from the Control group. It was observed that in the first year of the pest, the Pine Processionary Moth with a weight categorized as Medium (0.601-0.900 g) had the highest rate of transitioning to the adult stage.