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Smarter pest control for faba bean
Published: 04 April 2025
Faba beans have the potential to replace imported soybeans for plant-based protein products. They are however, threatened by the broad bean beetle. Now, SLU researchers present a new promising, sustainable method to outsmart this insect pest.
Faba beans are a valuable crop with high protein content and environmental benefits that are cultivated worldwide. In Europe, there are some challenges with the cultivation, for example damage from the broad bean beetle. This pest lays eggs on developing pods, and the larvae burrow into the beans, reducing their quality—especially for human consumption.
Beetles hiding in the beans
Faba bean plants have a high efficiency to fix atmospheric nitrogen which can reduce reliance on nitrogen fertilizers. Their beans have a high protein content and could potentially replace imported soybeans in animal feed and even provide plant-based protein for human consumption, but broad bean beetles infesting the beans remain major spoilsports for this. Because the beetles are so good at hiding away, chemical pesticides have had little success to control them and are increasingly scrutinized due to environmental and health concerns.
– Pesticide resistance and stricter regulations for chemical pesticides mean that we need alternative pest management strategies. Trap cropping, where an early-flowering faba bean variety attracts beetles away from the main crop, could be one solution, says Chloë Raderschall.
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Trap cropping was combined with semiochemical traps that lure and capture the insects. Photo: Chloë Raderschall.
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The broad bean beetle’s larvae burrow into the beans and reduces their quality. Here, fully developed insects emerge from a bean. Photo: Chloë Raderschall.
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To effectively control broad bean beetles, an integrated pest management strategy is needed. Photo: Chloë Raderschall.
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Natural scents to lure pest into traps
The trap crop approach can be enhanced using semiochemicals—natural scents that lure pests into traps. Now, SLU researchers have tested this strategy by combining an early-flowering faba bean "trap crop" with traps baited with scents that mimic that of faba bean flowers and pods and that to attract the pest insects. The goal was to concentrate pest damage in the trap crop and reduce infestation in the main crop. In the experiment beetle numbers, egg-laying, bean damage, and crop yield was monitored to assess how effective the method was.
– We combined trap cropping with semiochemical traps that lure and capture the insects. We studied 24 fields in Sweden over two years and had both treated fields, with trap crops and traps, and control fields with neither, says Ylva Johansson.
Less bean damage in the centre of the fields
The results showed that beetles heavily targeted the trap crop, with 147% more eggs per pod and 73% more emergence holes than in control fields. Meanwhile, the main crop in treated fields had 28% fewer eggs and 18% less bean damage—but only in the centre of the fields, not near the edges.
–In our experiments we saw modestly reduced pest damage, but further improvements could make trap cropping with semiochemical traps a viable option to reduce bean damage in faba bean. Our method requires extra time, labour, and land, making it most suitable for high value faba bean production for human consumption and not for animal feed, says Ola Lundin.
More pollination with extended flowering
An unexpected benefit of this approach could be improved pollination, as the extended flowering period of two different faba bean varieties may attract more insect pollinators. This could enhance yields and make the strategy more cost-effective.
– To effectively control broad bean beetles, we need an integrated pest and pollinator management strategy. This might include smarter crop rotations—such as avoiding planting faba beans near previous fields—to disrupt pest life cycles. We also need better post-harvest methods to remove damaged beans and insects for high quality products, concludes Chloë.