MORPHOLOGICAL CHARACTERISTIC, VOLATILE COMPOUNDS, NUTRITION OF CHILI FRUIT (Capsicum annuum L.), AND IT’S RESPONSE TO FRUIT FLY INFESTATION (Bactrocera dorsalis)

• Main Author: Kirana, Rinda
• Format: Dissertations
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/41921
• Institution: Institut Teknologi Bandung

Chili fruit is an important horticultural commodity for Indonesia. However, chili cultivation is hampered by Man constrains including fruit flies (Bactrocera dorsalis). Fruit fly oviposition damages chili fruit, hence decrease it yield and became unmarketable, with a potential loss up to 100%. Generally, plants develop antixenosis and antibiosis in response to different stresses. On the other hand, both mechanisms have not been well explored to control fruit fly infestation in chili cultivation. Therefore, this research was aimed to: (1) study the characteristics of resistant and susceptible varieties to fruit fly infestations and (2) study the response of chilies upon fruit fly infestations. Characterization was carried out on six Capsicum annuum varieties, previously identified as having different resistance levels to fruit fly infestation, both by antixenosis and antibiosis. The character of different chili varieties was studied through morphological observation and investigation of chemical compound produced by chili fruit corroborated to the level of antixenosis and antibiosis. The response of chili fruit upon fruit fly attack was evaluated using three basic populations (resistant varieties, susceptible varieties and hybrid / F1 varieties-resulting from a cross between resistant and susceptible varieties). Based on the results of characterization, there were differences in morphological and chemical characters between resistant and susceptible varieties. Different characters contributed to the chili resistance level upon fruit fly attacks. Fruit morphological characters which involve in chili resistance to fruit fly attack were fruit size (fruit width, fruit weight, and thickness of fruit flesh) and the shape of the fruit base. In addition, the chemical characters which associate to fruit fly attack were volatile compounds, water content, and carbohydrate content. Antioxenosis response in chilli fruit was regulated by volatile compounds. The results showed that yield loss increased along with the increasing of ?-Ocimen content among the susceptible chili varieties. Susceptible chili varieties released ?-Ocimen, a volatile compound that attract female fruit flies to lay eggs (oviposition). In contrast, resistant varieties do not produce this compound to avoid female fruit flies oviposition. Therefore, ?-Ocimene may play important role as chemical marker for chili resistance in response to fruit fly attack. Antibiosis response was affected by ethylene production. The puncture of fruit fly ovipositor injured the surface of chili fruit and triggers ethylene production. After oviposition, ethylene content in the susceptible varieties increased significantly compared with the resistant varieties. The results also showed that active defense was related to the expression of chili resistance genes, indicated by different gen expression between susceptible and resistant chili varieties . Taken together, this study provides an overview on how chili responded to fruit fly infestations providing crucial information for integrated pest control program. Furthermore, the resistant variety can be used as a donor for breeding program to create chili varieties which are not only resistant to fruit fly, but also increase their yield. On the other hand, susceptible varieties can be used as basic ingredients to attract female fruit flies and potentially serve as trap-plants. Susceptible varieties also offer plant materials for the identification of genes that play a role in the synthesis of volatile compounds in chilies.