Study on Ferrisia virgata and Planococcus minor as vectors of mottle disease in black pepper

Abstract

Two species of mealybug, Ferrisia virgata and Planococcus minor were previously reported as vectors of Piper yellow mottle virus (PYMoV), the causal agent of mottle disease in black pepper (Piper nigrum). Several activities were performed to study the PYMoV transmission through F. virgata and Pl. minor, involving transmission experiment in ISMCRI greenhouse (Bogor, West Java), field observation of mealybugs, and mottle disease incidence at ISMCRI field station (Sukabumi, West Java). The result showed that the transmission rate of PYMoV through F. virgata and Pl. minor in black pepper reached 40.00 and 46.67%, respectively. Field temperature >33 °C, light intensity >700.00 lux, wind speed <1.10 m/s, and rainfall <80 mm/month were recorded during the occurrence of a peak population of mealybugs. Mealybugs population in the field was affected by insecticide application. Its population was lower in a block with insecticide spraying than in a block without insecticide spraying. Furthermore, mottle disease incidence was correlated with the population level of mealybugs. Based on PCR detection, the frequency of viruliferous mealybugs did not differ in a block with or without insecticide spraying, i.e., 6/39 and 6/37, respectively. This indicated that other factors than insect vectors might play an important role in disease spread.