بررسی برازندگی تریپس غربی گل، Frankliniella occidentalis، با القای تغییرات سیستمیک در گیاه میزبان (Capsicum annuum Lorca)

Endophytic fungi are microorganisms that live inside plant tissues but do not cause any symptoms of disease. Insect pests are affected by endophytes in various ways, such as reducing the growth rate, disrupting development, and reducing survival and reproduction. In this study, the bell peppers (Capsicum annuum Lorca) at the 4-5 leaf stage were treated with four treatments including jasmonic acid (JA) (0.5 mmol, synthesized by Sigma Aldrich), Trichoderma harzianum T22 (Th) (10 ml per plant from 107 spore/ml suspension, prepared from Koppert company), the combination of jasmonic acid with T. harzianum (JA + Th), and control (water). Then, the effect of the treatments on the adult attraction and oviposition preference (free-choice and no-choice tests) of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), were investigated in constant environmental conditions (25±1°C, 65±5% RH, and 16:8 h light: dark). In the free-choice test, four five-leaf plants were placed inside a ventilated cage (50×50×50 cm) and 40 pairs of one-day-old adults were released in the center of each cage. After two days, the number of adults established on each plant was counted. The leaves were maintained under constant environmental conditions until the first instar larvae emerged. The number of emerged larvae was recorded. In the no-choice test, a five-leaf plant was placed inside a ventilated cage (25×25×40 cm) and ten pairs of four-day-old adults were released into each cage. The duration of 48 hours was considered for feeding, mating, and oviposition. Then, the leaves of the plants were cut and maintained under constant environmental conditions until the first instar larvae emerged. The results of the free-choice test showed a significant difference in adult attraction and the recorded first instar larvae. The highest and lowest values of adult attraction were observed for control (31.2) and JA+Th (9.6), respectively. The lowest number of first instar larvae was recorded for JA (17.4 larvae) and JA+Th (13.2 larvae) and the highest values were observed for Th (32 larvae) and control (44.8 larvae). In the no-choice test, the number of first instar larvae for the control, JA, Th, and JA+Th treatments were 64.6, 36.4, 45.4, and 25 larvae, respectively, which the lowest and highest values were significantly recorded for JA+Th and control, respectively. Based on the results, the induced resistance in pepper plants with JA+Th treatment decreased the host quality for preference and oviposition of F. occidentalis. It is recommended to conduct field investigations to apply this new method in integrated management programs of F. occidentals in future studies