Earlier flowering of winter oilseed rape compensates for higher pest pressure in warmer climates

authored by

Ute Fricke, Sarah Redlich, Jie Zhang, Caryl S. Benjamin, Jana Englmeier, Cristina Ganuza, Maria Haensel, Rebekka Riebl, Sandra Rojas‐Botero, Cynthia Tobisch, Johannes Uhler, Lars Uphus, Ingolf Steffan‐Dewenter

Abstract

Global warming can increase insect pest pressure by enhancing reproductive rates. Whether this translates into yield losses depends on phenological synchronisation of pests with their host plants and natural enemies. Simultaneously, landscape composition may mitigate climate effects by shaping the resource availability for pests and their antagonists. Here, we study the combined effects of temperature and landscape composition on pest abundances, larval parasitism, crop damage and yield, while also considering crop phenology, to identify strategies for sustainable management of oilseed rape (OSR) pests under warming climates. In all, 29 winter OSR crop fields were investigated in different climates (defined by multi-annual mean temperature, MAT) and landscape contexts in Bavaria, Germany. We measured abundances of adult pollen beetles and stem weevil larvae, pollen beetle larval parasitism, bud loss, stem damage and seed yield, and calculated the flowering date from growth stage observations. Landscape parameters (proportion of non-crop and OSR area, change in OSR area relative to the previous year) were calculated at six spatial scales (0.6–5 km). Pollen beetle abundance increased with MAT but to different degrees depending on the landscape context, that is, increased less strongly when OSR proportions were high (1-km scale), interannually constant (5-km scale) or both. In contrast, stem weevil abundance and stem damage did not respond to landscape composition nor MAT. Pollen beetle larval parasitism was overall low, but occasionally exceeded 30% under both low and high MAT and with reduced OSR area (0.6-km scale). Despite high pollen beetle abundance in warm climates, yields were high when OSR flowered early. Thereby, higher temperatures favoured early flowering. Only among late-flowering OSR crop fields yield was higher in cooler than warmer climates. Bud loss responded analogously. Landscape composition did not substantially affect bud loss and yield. Synthesis and applications: Earlier flowering of winter OSR compensates for higher pollen beetle abundance in warmer climates, while interannual continuity of OSR area prevents high pollen beetle abundance in the first place. Thus, regional coordination of crop rotation and crop management promoting early flowering may contribute to sustainable pest management in OSR under current and future climatic conditions.

External Organisation(s)

Julius Maximilian University of Würzburg

Type

Article

Journal

Journal of Applied Ecology

Volume

60

Pages

365-375

No. of pages

11

ISSN

0021-8901

Publication date

02.02.2023

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Ecology

Sustainable Development Goals

SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.1111/1365-2664.14335 (Access: Closed)