ABSTRACT Macrobial biological control agents, such as parasitoids, play a pivotal role in Integrated Pest Management (IPM), yet their success depends on compatibility with agrochemicals commonly applied in cropping systems. The egg parasitoid Trichogrammatoidea cryptophlebiae Nagaraja, 1979 (Hymenoptera: Trichogrammatidae), widely released in South Africa for tortricid moth management, remains understudied regarding its responses to pesticides used in orchards. This study evaluated the acute and sublethal effects of a representative range of insecticides, fungicides, and biopesticides on multiple life stages of T. cryptophlebiae , applying the International Organisation for Biological Control (IOBC) classification system together with measures of parasitism, sex ratio, and pre‐imaginal development. Adult survival alone was not a reliable indicator of chemical compatibility. The non‐target effects of agrochemicals on T. cryptophlebiae varied across treatments and life stages, influencing adult survival, reproductive output, and developmental success. Several insecticides, particularly pyrethroids and other neuroactive compounds, permitted adult survival but were associated with pronounced reductions in parasitism, consistent with strong sublethal effects on parasitoid performance. In contrast, several fungicides and biopesticides were comparatively benign, having no effect on survival and reproduction. Sex ratios were largely unaffected across treatments. While IOBC mortality thresholds are a useful tool for initial screening of pesticide compatibility with T. cryptophlebiae , these results demonstrate that mortality‐based classifications alone may underestimate incompatibility by failing to capture effects on reproduction and development that are critical to biological control efficacy. By providing the first published assessment of pesticide effects on T. cryptophlebiae , this study offers data relevant to IPM programmes in macadamias and other crops in South Africa and contributes evidence toward refining pesticide‐natural enemy compatibility assessments.
Thompson et al. (Sat,) studied this question.