A Review of the Biology and Control of the Obscure Mealybug, Pseudococcus viburni (Hemiptera: Pseudococcidae), with Special Reference to Biological Control Using Entomopathogenic Fungi and Nematodes

Abstract

The obscure mealybug, Pseudococcus viburni (Signoret) (Hemiptera: Pseudococcidae), is an important polyphagous, cosmopolitan insect pest of fruit crops, including apples, pears and grapes. The mealybug negatively affects fruit production both in South Africa and globally by feeding on phloem sap, excreting large amounts of sugar and water as a carbohydrate-rich sugary substance, known as honeydew, onto the leaves and fruit. Honeydew causes severe secondary damage, as it promotes the growth of sooty mould, which decreases the amount of photosynthesis, thus affecting the development of the host plant. Fruit consignments with fruits stained with sooty mould or suspected of containing live or dead mealybugs are rejected when exported, due to the strict phytosanitary standards. Managing mealybugs in agroecosystems is difficult, due to their small body size and cryptic nature. Currently, control relies on the use of chemicals and, to some extent, on biological control. However, using such methods has proven to be ineffective in the management of P. viburni. Entomopathogens, such as entomopathogenic fungi (EPF) and entomopathogenic nematodes (EPNs), have been used across agricultural production areas to control a wide range of agricultural pest insects. The current review provides an overview of the biology and control of P. viburni, with special reference to biological control using EPF and EPNs in South African orchards, in an integrated pest management system.