TOMATO LEAF MINER, TUTA ABSOLUTA (LEP., GELECHIIDAE), POPULATION FLUCTUATION AND SEASONAL ACTIVITY IN THE FIELD

Seasonal activity and population fluctuation of tomato leaf miner, Tuta absoluta (Meyrick), a dangerous pest of tomato fields in Tehran province, were determined in Varamin region, south of Tehran province in 2015-2016. Number of moths in pheromone trap and number of larvae per plant were counted weekly in a trail tomato field. The trap capture began on mid-April in warm dry spring of 2015 and on mid-May in cool wet spring of 2016. The first and highest moth peaks in trap occurred about one month earlier in 2015 than 2016. The larval density per plant at the highest peak reached 2.34 and 10.8 in 2015 and 2016, respectively. A temperature range of 25-30°C was desirable to the pest in which the interval of successive peaks decreased. In both years, the pest created three generations over a growing season, according to larval peaks, but 11 over a year, according to trap data, that the 11th generation overwintered. The temperature of 35°C and above limited larval activity and decreased the population. After the crop removed, the pest population declined due to host shortage, but it increased with the access of hosts in the second cultivation since mid-September until the cold season.