Population fluctuation of pre- adult stages and determining the most suitable plant area for sampling of Tuta absoluta Meyrick (Lep.: Gelechiidae) under greenhouse conditions in Jiroft

Tomato leaf miner, Tuta absoluta Meyrick (Lep.: Gelechiidae) is a invasive pest for country since 2010 and spread rapidly in different regions including Jiroft. Regarding the increased area of tomato cultivation under greenhouses conditions in this region, the unknown status of pest and its high potential for damage, the study of population fluctuation and determining the best area of the plant for sampling of pre-adult stages is very important to make reliable management decisions. In this study in a tomato cultivated greenhouse, leaves were weekly sampled to check various stages of insect growth including eggs, larvae, and leaf mines. The results showed that the insect activity observed from the middle of growing season and population density gradually increased to its peak in April and May. During this period of time, it reproduces 4-5 generations. The highest number of insect eggs was found on the upper half of the plants and mainly in the lower surface of the leaves. In addition, it was revealed that the sampling of leaf mines was more accurate than counting different developmental stages in estimating the population density of this pest. Based on Correlation test, it was found that there is a positive correlation between the changes in the number of leaf mines and density of larval population in the upper half of the plant. Accordingly, the population density of larvae can be estimated only by sampling the leaves in this section and counting the number of leaf mines.