Survey of papaya mealybug, Paracoccus marginatus and its introduced parasitoids on papaya plants in the low country dry zone of Sri Lanka

Abstract

Papaya mealybug, Paracoccus marginatus Willams and Granara Willink, is an invasive hemipteran that attacks several genera of host plants, including economically important tropical fruits and ornamentals. It is an alien invasive species and was reported for the first time in Sri Lanka in 2008 and the biocontrol programme was implemented with the introduction of three natural enemies Acerophagus papayae, Anagyrus loeki, and Pseudleptomastix mexicana imported from Puerto Rico in some selected regions in 2008 and 2009. After a decade following the initial introduction it is essential to investigate the presence of the parasitoids for the management of papaya mealybug pests. Therefore a survey was conducted to study the pest status of papaya mealybugs and to check the availability and the abundance of their introduced parasitoids is some randomly selected locations of the low country dry zone of Sri Lanka during the period from January 2018 to December 2019. The survey revealed that P. marginatus is still spreading in Sri Lanka but is present at lower population levels than in previous years, probably due to the action of introduced hymenopteran parasitoids. Among the three parasitoids the A. papayae and P. mexicana were found to be established on the papaya plants infested with papaya mealybug. The parasitoid with the greatest impact on the mealybug is generally Acerophagus papayae , whereas A.  loeki was failed to establish. The finding would be very essential to tackle if there are any future threats caused by P.marginatus.