STUDIES ON CITRUS LEAF MINER (CLM) IN RELATION TO ABIOTIC FACTORS ON DIFFERENT HOST PLANTS IN PUNJAB, PAKISTAN

Studies on the relationships between seasonal ambient temperatures (weekly average, maximum and minimum) and the relative abundance and incidence of citrus leaf miner (CLM) on plants of different citrus varieties were conducted in citrus nurseries and orchards at two experimental farms in Pakistan by sampling infestations of CLM at weekly intervals from May through September. Significant relationships were found between CLM abundance and incidence and the temperature variables by correlation and regression analyses. Maximum, minimum and average weekly temperatures had consistent positive relations with CLM abundance and incidence, whereas, rainfall and relative humidity had either a negative or no correlation to insect infestation. Relative humidity at one site had a positive correlation with CLM abundance and incidence (R2 value ranged from 0.29 to 0.72). Linear regression models were formulated with a CLM abundance as a response variable and stepwise addition of max. temp., min. temp, ave. temp. and RH as concomitant variables. Models explained 10-72% of the variation in the data sets based on the values of the regression coefficient. These results are discussed in view of previous studies of relationship of CLM infestation and its environment.