Non-host habitat at local and landscape scales promotes overwintering success of a specialist insect pest

Sharing the burden: Cabbage stem flea beetle pest pressure and crop damage are lower in rapeseed fields surrounded by other rapeseed crops

“…This has recently been reported for P. chrysocephala, with fields within 0-2 km of a previous crop having a higher probability of experiencing damage than fields that are further away (Hausmann et al, 2023). In contrast, if host crop proportions are higher in the cropping year than the previous year, this may facilitate the dispersal of insects across the landscape and lead to lower densities (dilution) in individual fields (Zavalnitskaya et al, 2022). However, these effects tend to vary considerably between herbivore species (Boetzl et al 2023) and are likely to depend strongly on the spatial scale of consideration.…”

“…Similar effects on other herbivorous pests of rapeseed have been observed, including for pollen beetle, stem weevil, brassica pod midge, and other flea beetle species. This includes lower abundance of the asparagus beetle (Crioceris asparagi) in fields surrounded by a greater proportion of host crop over a 1 km spatial scale (Zavalnitskaya et al, 2022); Zaller et al, 2008b reported a similar relationship between host crop proportion and pollen beetle insect abundance across several spatial scales. Scheiner and Martin (2020) also observed a reduction in the abundance of leafchewing herbivorous pests (including other flea beetle species) in cabbage fields where a greater proportion of host crop was grown in the surrounding landscape, and Josso et al (2013) described a decrease in the number of cabbage root fly eggs in fields surrounded by a higher proportion of Brassica crops over a 1 km circumference.…”

“…Rapeseed confers myriad benefits to agricultural systems; for example, rapeseed acts as an economically attractive break crop in crop rotations and supports a diverse ecological habitat (Alford, 2000;Forleo et al, 2018;Kirkegaard et al, 1993). Rapeseed can be attacked by a range of herbivorous pests that inflict crop damage (Alford et al, 2003;Edde, 2021;Zheng et al, 2020). Of these, the cabbage stem flea beetle, Psylliodes chrysocephala, is of significant importance (Edde, 2021;Tixeront et al, 2023), having been recently ranked as the top biotic threat facing European rapeseed production (Zheng et al, 2020).…”

“…Rapeseed can be attacked by a range of herbivorous pests that inflict crop damage (Alford et al, 2003;Edde, 2021;Zheng et al, 2020). Of these, the cabbage stem flea beetle, Psylliodes chrysocephala, is of significant importance (Edde, 2021;Tixeront et al, 2023), having been recently ranked as the top biotic threat facing European rapeseed production (Zheng et al, 2020). P. chrysocephala adults damage plants through leaf feeding between July and October, causing up to 25% yield loss (Conrad et al, 2021;Edde, 2021;Ferguson et al, 2003).…”

“…Bottom-up approaches involve manipulating habitat availability (proportion of host crops) or crop heterogeneity (the diversity of crops) in a landscape to decrease the density and population pressure of herbivorous pests by limiting resources (Almdal and Costamagna, 2023;Boetzl et al, 2023). Bottom-up approaches have been described to contribute towards herbivorous pest regulation in similar crop-beetle systems (Boetzl et al, 2023;Zavalnitskaya et al, 2022), and could potentially be used for the sustainable management of P. chrysocephala. One variable that is relatively easy to manipulate is the proportion of host crop in the landscape; indeed, increased host crop proportion within the growing season has been shown to decrease the abundance of several other herbivorous pests of rapeseed, including pollen beetle, stem weevil, and brassica pod midge (Rusch et al, 2013;Thies and Tscharntke, 1999;Zaller et al, 2008a;Zaller et al, 2008b).…”