4) Ms. Norah Saabna

Conservation biological control often relies on adding herbaceous vegetation within and around crop fields to support native natural enemies. In arid ecosystems, however, this is limited by water scarcity. Many drylands contain abundant and diverse parasitoid assemblages, yet such local parasitoids are rarely used for conservation biocontrol. Ziziphus spina-christi L. (Rhamnaceae), a common wild tree in Middle Eastern drylands, thrives under hot and dry conditions and flowers for several months in summer. To explore Z. spina-christi’s potential to provide resources for local biocontrol agents, we characterized its parasitoid community across seasons and in four sites along a climate gradient (200-600 mm annual rainfall) in Israel. A leafminer parasitoid wasp (Zagrammosoma ramotensis, Eulophidae) dominated the samples, followed by two braconids (Glyptapanteles sp. and Gnamptodon sp.) that parasitize various lepidopterans. Parasitoid abundance showed no clear geographic trend but peaked in summer, correlating with the trees’ flower number and with the wasps’ frequency of sugar feeding. These findings suggest that adult parasitoids feed on nectar from Z. spina-christi flowers during the hot summer, when other nectar sources in the desert are limited. Thus, Z. spina-christi may support natural enemies without requiring irrigation. We will test this hypothesis by placing tomato plants, infested by the leafminer pest Tuta absoluta, at increasing distances from flowering Z. spina-christi trees. We will assess whether parasitism by Zagrammosoma ramotensis and pest damage vary with distance. Insights from this research will advance sustainable agriculture and shed light on plant–pest–natural enemy interactions in dryland ecosystems.