Restricted expansion of Tetranychus evansi (Acari: Tetranychidae) in New Zealand: insights from comparison of its development and reproduction on black nightshade (Solanum nigrum) and tomato (Solanum lycopersicum)

Tetranychus evansi Baker & Pritchard (Acari: Tetranychidae) is a significant agricultural pest in Europe, Africa, Oceania, and Asia, causing severe damage to Solanaceae crops such as tomatoes. However, although T. evansi invaded New Zealand in 2020, it is restricted to Auckland. It primarily inhabits black nightshade (Solanum nigrum) and has not caused notable harm to local tomato crops. This study compared the developmental and reproductive performance of the invasive T. evansi population in New Zealand on black nightshade and tomato plants. The results showed that T. evansi had a significantly longer development time on tomato plants compared to black nightshade. In addition, both virgin and mated female of T. evansi laid significantly fewer eggs on tomato leaves than on black nightshade ones; and the average size (diameter) of eggs produced on tomato leaves were smaller than those produced on black nightshade. These findings suggest that the invasive T. evansi population in New Zealand are less able to adapt to tomatoes as hosts than to black nightshade. This study supplements the fundamental life history data of the invasive T. evansi population in New Zealand and provides scientific insights for its management strategies.