Determination of Mealybug Population Density for Transmission of Pineapple Mealybug Wilt Disease in Central Uganda

Abstract

Pineapple mealybug wilt disease (PMWD) is a complex and most destructive viral disease constraining pineapple production world over. Pineapple mealybug wilt disease is transmitted by mealybugs (Dysmicoccus species). Currently, in Uganda, the population of Dysmicoccus brevipes that can transmit PMWD is not known. Yet, closing this knowledge gap would provide a better understanding of PMWD etiology and development of sound management strategies. Experiment was laid out in a completely randomized design (CRD) with four replications in the screenhouse at the Faculty of Agriculture, Kyambogo University during the period 2017 and 2018. Pineapple variety Smooth Cayenne was inoculated with five levels of viruliferous mealybugs including one (1), five (5), ten (10), fifteen (15), and a control (uninoculated). Data collection commenced on symptoms appearance and continued on a 15-day interval for a period of two months. Data were collected on the incidence and severity of PMWD. All the data collected were analysed using Genstat computer programme. Results showed that the number of mealybugs significantly ($p<0.05$) affected the incidence and severity of PMWD during both trials. Although one viruliferous mealybug was able to transmit PMWD virus, the efficacy of transmission was recorded with the highest number of mealybugs per plant. It was, therefore, concluded that the higher the number of viruliferous mealybugs colonising a pineapple plant, the higher the incidence and severity of PMWD. The result of this study, therefore, adds to the pool of knowledge on the understanding the population density of mealybugs transmitting PMWD as well as provide insights to improvement of mealybug vector monitoring as a key component of integrated PMWD management.