Diverse cropping systems lead to higher larval mortality of the cabbage root fly (Delia radicum)

Peter N. Karssemeijer, Luuk Croijmans, Karthick Gajendiran, Rieta Gols, Dirk F. van Apeldoorn, Joop J.A. van Loon, Marcel Dicke, Erik H. Poelman*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)


Root herbivores pose a major threat to agricultural crops. They are difficult to control and their damage often goes unnoticed until the larvae reach their most devastating late instar stages. Crop diversification can reduce pest pressure, generally without compromising yield. We studied how different diversified cropping systems affected the oviposition and abundance of the specialist cabbage root fly Delia radicum, the most important root herbivore in Brassica crops. The cropping systems included a monoculture, pixel cropping, and four variations of strip cropping with varying intra- and interspecific crop diversity, fertilization and spatial configuration. Furthermore, we assessed whether there was a link between D. radicum and other macroinvertebrates associated with the same plants. Cabbage root fly oviposition was higher in strip cropping designs compared to the monoculture and was highest in the most diversified strip cropping design. Despite the large number of eggs, there were no consistent differences in the number of larvae and pupae between the cropping systems, indicative of high mortality of D. radicum eggs and early instars especially in the strip cropping designs. D. radicum larval and pupal abundance positively correlated with soil-dwelling predators and detritivores and negatively correlated with other belowground herbivores. We found no correlations between the presence of aboveground insect herbivores and the number of D. radicum on the roots. Our findings indicate that root herbivore presence is determined by a complex interplay of many factors, spatial configuration of host plants, and other organisms residing near the roots.

Original languageEnglish
Pages (from-to)337-353
Number of pages17
JournalJournal of Pest Science
Issue number1
Early online date5 May 2023
Publication statusPublished - Jan 2024


  • Aboveground–belowground interactions
  • Cabbage root fly (Delia radicum)
  • Crop diversification
  • Root herbivory
  • Strip cropping
  • White cabbage (Brassica oleracea)


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