Assessment of current and potential geographic distribution of the papaya mealybug, Paracoccus marginatus (Hemiptera:Pseudococcidae) in Mozambique

Papaya mealybug, Paracoccus marginatus is a polyphagous pest that can damage several genera of host plants. Since its first detection in Pemba (northern of Mozambique) in 2013, there has been no information on its current geographical distribution and spread patterns to other areas in the country. Thus, this study aimed at assessing the distribution and predicting the potential geographic distribution of P. marginatus in Mozambique. A field survey was conducted from September 2015 to February 2016 in Cabo Delgado, Nampula and Sofala provinces. Field data on P. marginatus occurrence and infestation levels were collected in 3 to 6 districts from each province. An ecological niche model was used based on presence and absence data to predict the potential geographical distribution of the pest. Results showed that papaya mealybug occurred at high densities and was well established and widely spread in most of the sampled sites in the northern provinces of Cabo Delgado and Nampula. There was no occurrence of P. marginatus in the sampling sites of Sofala province, in the central region of the country. The present results confirm the occurrence of P. marginatus only in the northern provinces of Nampula and Cabo Delgado. This is an indication that the distribution of P.marginatus was restricted to the northern region of the country. The ecological niche model (ENM) indicated that much of the coastal area of Mozambique had favourable environmental conditions for P. marginatus occurrence. The ecological niche model predicted for the next 50 years showed that the probability of occurrence of P. marginatus in Tete, Sofala and Zambezia would increase. Since P. marginatus was not detected in the central and southern of Mozambique it is imperative that its spread is monitored continuously to define pest free areas and establish management strategies in order to reduce the impact of the pest in the country, including the establishment of domestic quarantine measures and reinforcement of boarder control inspection services.