Functional plants supporting predatory ladybirds in a peach orchard agroecosystem

Abstract

Predatory ladybirds are key natural enemies of a diversity of crop pests. Conserving ladybirds in agroecosystems to benefit from their biocontrol potential requires to understand the ecological interactions between them and functional plants. A diversity of functional plants is known to offer resources improving ladybirds’ fitness and pest control effects. Yet, there is a lack of knowledge on the relationship between a diversity of functional plants found at the field scale and the dynamic of ladybird population. In this study conducted over three consecutive years, we investigated from early May to mid-August, the weekly abundance of predatory ladybirds on 15 functional plants and peach trees (Prunus persica) in a peach orchard agroecosystem in the Beijing Province of China. Seven plant species hosted 90% of the ladybird population throughout the study period. Through them, two abundance peaks of ladybirds were observed, with Vitex negundo and Prunus persica supporting the ladybirds in the first peak, Artemisia sieversiana, Vigna unguiculata, Cosmos bipinnata, Zea mays and Helianthus annuus playing a major role in the second peak. The plant species were either at their seedling, blooming or fructification stage when hosting the ladybirds, suggesting that these lasts used the diversity of resources (prey, nectar and pollen of flowers and extra-floral nectar) offered at the agroecosystem level. The present results enrich the screening of functional plants supporting predatory ladybirds in perennial agroecosystems and emphasize the need to pay attention to the long-standing plants in the surrounding habitats. It suggests that maintaining and managing a diversity of functional plants at the field scale is needed to offer a spatial and temporal continuity of resources to ladybirds.