ASSESSMENT OF SUBTERRANEAN TERMITE, Coptotermes curvignathus (ISOPTERA: RHINOTERMITIDAE) INFESTATION SEVERITY INDEX (TISI) AND WATER TABLE ON A PEAT OIL PALM PLANTATION IN SARAWAK

Growing palm in peatlands triggers the growth in the population of insect pests, and one of them is Coptotermes curvignathus , a significant insect pest of oil palm in peatlands. Damage caused by this species can be seen in oil palm as early as 12 months after planting. The initial census is one of the methods to identify the attacks, but the index status guide for each attack by the pest needs to be fully developed. Thus, this study investigates an index of attack by C. curvignathus and the water table at an oil palm plantation in Sri Aman, Sarawak. The Termite Infestation Severity Index (TISI) with water table was assessed based on four parameters recorded during data collection and ground census in the field. Based on the visual symptom guide, a scale from 0 to 9 was used to rate the severity of the termite infestation in which a higher scale denotes a more progressive infestation stage than the lower scales. The study area was arranged into several task plots. Statistical analysis results revealed a significantly higher ( P <0.05) average percentage of infection rates percentage from task 12 at (58.62±1.99%) compared to other plots. The infestation average ranged from 7.92 ± 3.58% to 58.62 ±1.99%. Meanwhile, on the water table level, the reading varied between 41.00 cm (task 17) and 67.50 cm (task 10) in the same area. A moderately negative correlation was found between the TISI and water table from two census sessions, notably during the first and fourth census (r = -0.432 and -0.566, respectively). Overall, correlation analysis for the entire census demonstrated a moderately inverse link (r = -0.326) between the TISI and water table. This study revealed a possible inverse relationship between TISI and water table that influences the severity of termite infestation in the field. Future studies may include additional data such as population density, precipitation and deadwood/log or stump presence in the area.