Developing ecostacking techniques for pollen beetle management in oilseed rape

Abstract

In this review, we examine how the principles of ecostacking could be used to manage the pollen beetle Brassicogethes aeneus in oilseed crucifer crops. We further describe hindrances preventing progress of keeping the pest under full biological control across Europe, and for other similar pest management situations. Ecological processes at different levels need to be considered and understood. The beneficial functions, which the various ecosystem service providers offer, need to be combined and exploited in an additive or synergistic manner, i.e., "ecostacked." Levels to consider include landscape and off-crop habitats (e.g., field margins) and their effects on pest management in the rapeseed crop; and possibilities to generate the key ecosystem services within the crop itself; for example, by vegetation management (e.g., undersowing, variety mixtures, companion and trap crops), soil management (biotic and abiotic; fostering and steering soil microbial communities to benefit biocontrol), and crop management, including crop protection treatments and their impacts on ecosystem service provision. All these processes affect the populations of the pollen beetle. Abundant information exists about most of the key processes important in this context. Utilizing this knowledge and stacking the various beneficial ecosystem service functions into a comprehensive management strategy for the pollen beetle, has not been attempted nor described. After illustrating the potential of ecostacking in solving crop protection problems, as it is apparent in the case of the pollen beetle, we analyze a situation where our approach was "lost in translation". The European Union Horizon 2020 program chose to support our vision of ecostacking with a 10 million euro grant. Administrative decisions by the coordinating university (not to accept to host the grant), and subsequent failure of the European Commission and its Research Executive Agency to demonstrate leadership on issues of research policy, integrity, and ethics in the handling of the project, resulted in a shift of emphasis away from solutions based onintegrative biocontrol.

Natural soil suppressiveness against soilborne phytopathogens extends to the control of insect pest

“…Therefore, bacteria present in naturally suppressive Swiss soils could potentially protect plants against both fungal and insect pests. Although augmentation of entomopathogen populations or microbiome management have been proposed as strategies to mitigate pest incidence in soils 30,31 , natural soil suppressiveness towards pest insects has not been documented.…”

Chemical defence in Brassicaceae against pollen beetles revealed by metabolomics and flower bud manipulation approaches

“…The females perform maturation feeding for egg development before ovipositing in closed flower buds (Alford et al, 2003). Since several alternative plant protection strategies are currently not feasible (Hokkanen & Menzler‐Hokkanen, 2018; Nilsson, 2003; Ruther & Thiemann, 1997), direct plant defence of B. napus against the pollen beetle is in the focus of research today. A study of Hervé, Delourme, et al (2014) indicated that a few oilseed rape cultivars such as Liho and Yudal show less feeding damage by adult beetles compared to other B. napus cultivars.…”

Attractiveness of oilseed rape cultivars to Brassicogethes aeneus and Ceutorhynchus obstrictus as a potential control strategy

“…Trap crops divert pest pressure from the main crop because they are more attractive to the pests (Hokkanen 1991, Shelton andBadenes-Perez 2006) and can be plants of a preferred growth stage, cultivar or species. For example, when used as a trap crop, turnip rape (Brassica rapa L.) significantly reduced the abundance of the PB in spring-sown oilseed rape compared to that in plots without this trap crop (Cook et al 2004, Hokkanen andMenzler-Hokkanen 2018). Selective or biological insecticides can be used to reduce pest populations in trap crops.…”