WINETECH Technical Yearbook 2020

being recorded during our survey, namely Anastatus and Baryconus spp. Their populations peaked during January 2014 in our study and were reared from field- collected katydid eggs. It was found that the wasps were well synchronised with egg laying of the katydids and could therefore have a significant impact on naturally- occurring biological control, if chemical inputs are kept to a minimum during this time period. An entomopathogenic fungus, Metar- hizium anisopliae , was isolated from a P. graminea individual collected in a Stel-

tend to hide behind foliage when they detect any disturbances. Egg counts were positively and significantly correlated with adult counts, with a lag time of 10 weeks, which can be used to estimate if population outbreaks of either species will occur. Monitoring for eggs should occur from June to August and can therefore be incorporated into the winter monitoring

lenbosch vineyard. This isolate was ac- cessioned as PPRI 12353 at the National Collection of Fungi (ARC-Plant Protection Research Institute, Pretoria) and indicates that P. graminea is indeed susceptible to pathogenic fungi. With further testing, this biocontrol option could also be incorporat- ed into an IPM strategy. CONCLUSION Katydids are sporadic pests and we do not yet fully understand the factors influencing their occurrence. It is therefore critical to monitor at all times, as this can prevent larger-scale outbreaks from occurring.

protocols for vine mealybug. BIOLOGICAL CONTROL

For more information, contact Pia Addison at pia@sun.ac.za.

Parasitic wasps were found to contribute to parasitism rates of 22% in Western Cape vineyards, with two wasp species

WINETECH TECHNICAL YEARBOOK 2020 43