Cold Storage of 1- to 5-Day-Old Mummies and Newly Emerged Adults of Aphelinus maculatus for Biological Control of Myzus persicae

Abstract

Production and field-release schedules are often asynchronous in augmentative biological control. We evaluated the cold-storage tolerance of 1- to 5-day-old mummies and newly emerged adults of Aphelinus maculatus, a parasitoid of Myzus persicae, at 4 and 8 °C. Adult emergence from stored mummies and survival of directly stored adults were recorded. Poststorage longevity, host-feeding capacity, parasitism capacity, offspring production, and offspring sex ratio were evaluated for selected cohorts stored at 8 °C. Storage at 8 °C generally resulted in higher mummy emergence and adult survival than storage at 4 °C. Among the tested mummy-age cohorts, 3-day-old mummies showed the highest emergence under the tested conditions. At 8 °C, emergence from this cohort was 90.0, 78.3, 64.7, 54.7, and 21.3% after 7, 14, 21, 30, and 60 d, respectively. Directly stored females survived better than males; female survival was 72.0% after 30 d and 20.3% at the 90-day storage endpoint. Increasing storage duration reduced poststorage longevity, host-feeding, parasitism, and offspring production. The female-to-male offspring sex ratio remained relatively stable during the 30 d poststorage assessment period. Under the tested conditions, storing 3-day-old mummies at 8 °C provides an option for delayed emergence, whereas direct adult storage at 8 °C may be useful for short-term holding.