The efficacy of entomopathogenic biocontrol agents against Scirtothrips aurantii

PROJECT TITLE: The efficacy of entomopathogenic biocontrol agents against Scirtothrips aurantii

Project Leader: Dr Noma Stokwe

Duration: 1 January 2022 – 31 December 2022

Project Summary:

South African citrus thrips, Scirtothrips aurantii Faure (Thysanoptera: Thripidae), is a  pest of various fruit types in South Africa, including grapes. It develops rapidly, has many generations annually, a broad host range and readily develops resistance to insecticides. Adult thrips and larvae cause superficial scarring by feeding on the surface of the fruit. Severely blemished fruit are not suitable for export.

S. aurantii primarily feeds on new growth and usually only comes into vineyards in large numbers just as grapes start to ripen and the second flush of new growth starts. Thrips feeding causes scarring damage on grapevine shoots and leaves, which can lead to inhibition of shoot growth and even shoot die-back in severe cases. This has a negative impact on the grapevine’s ability to store reserves for budding in the next season, thereby also affecting production. There is a need to identify control methods as alternatives to chemical control options. Entomopathogenic nematodes (EPNs) and fungi (EPF) are insect pathogens with potential as biological control agents for foliar and soil dwelling pests. These would provide an environmentally acceptable alternative to insecticide applications.

The aim of the project is to screen available EPN and EPF isolates for their potential against S. aurantii.