The Primary Inoculum Sources in the Epidemiology of Pepper Yellow Leaf Curl Indonesia Virus on Chili Plants

Abstract

Pepper yellow leaf curl Indonesia virus (PepYLCIV), a Begomovirus in Geminiviridae, is transmitted in a persistent manner by Beminisa tabaci Genn. (Hemiptera: Aleyrodidae). The virus has caused tremendous damages to chili plants in Indonesia. The disease had been reported non seed-transmissible and exclusively transmitted by whitefly, however, our field observations and previous reports showed that high disease incidence was present in the absence of vector. Therefore, the present study was conducted to determine the roles and the importance of seed, vector in the seedbed, and vector in the field as a source of primary inoculum for disease development. To determine whether the disease is seed-transmissible, seeds from PepYLCIV-infected plants were sown in cage and sprayed with insecticide weekly to prevent B. tabaci infestation. Vector population and PepYLCIV incidence were monitored weekly. To determine whether the vector acted as inoculum source in the seedbed, certified seeds of chili cv. Pilar were sown in caged and uncaged seedbeds. To determine whether vector acted as inoculum source in the field, caged seedlings were planted in open field (uncaged). Our results indicated that PepYLCIV is seed transmissible with an incidence of 2.5%. The highest disease infection was found on uncaged plants both in the seedbed and in the field. Therefore, the use of healthy seeds and protecting seedbed from vector infestation is very important in preventing infection on the seedlings. Besides that, any control measures in a frame of integrated pest management should be employed to suppress the vector population in the field.