اثرات تنش آبی بر تغییرات جمعیت(Heteroptera: Tingidae) oschanini Stephanitis

The Persian walnut with the scientific name of Juglans regia L. belongs to the family Juglandaceae, native of Iran, which has the highest economic and commercial value among all species of this genus. Persian walnut, like other living organisms during its life, face a wide range of stresses, including living stressors (pests) and non-living stressors (drought and temperature changes), which lead to reduced growth, development, and crop production. In this study, in order to investigate the effect of drought stress on population and the amount of pear lace bug damage, an experiment was performed in a completely randomized design on 60 one-year walnut seedlings with four irrigation treatments including 40, 60, 80, and 100% water requirement. Simultaneously with the application of stress, an artificial infestation of seedlings with pear lace bug was also performed. For this purpose, whole insects were placed on the leaves of the seedlings by a fine brush. After three weeks and with the establishment of insects on plants, the study of insect population began. For this purpose, twice a week, five seedlings were randomly selected and four leaves were selected from each seedling. The leaves were photographed from two surfaces and the number of adult insects and nymphs located behind the leaves were counted. To measure the damage of the pest, the ratio of bleached surface to insect-fed total leaf area was selected as a criterion and using ImageJ software, the area of bleached parts of the leaf, the total leaf area, and then its ratio was calculated. In order to confirm the occurrence of stress in plants treated with different irrigation levels, chlorophyll a and b levels were measured. The results of the analysis of chlorophyll a, b and total data showed a significant difference between the treatments (F: 3.84, F: 4.14, F: 5.25; df: 15; P≤0.05) so that with increasing levels of Stress, chlorophyll a, b and their sum are reduced. The results of the analysis of variance of data related to counting the number of insects and the effects of their damage did not show significant differences among treatments (F: 0.21; F: 0.76, F: 2.05; df: 19; P≤0.05). Therefore, it seems that despite the drought stress that occurred in the seedlings, the lace bugs did not react significantly to this stress. According to the studies conducted in this field, it seems that the reason for not observing significant differences among different irrigation treatments in this study is the different response of herbivorous insects to natural and artificial stresses.