How Rosemary Scents Repel Cabbage Aphids in Push-Pull Farming

Greg Howard
13th March, 2024

How Rosemary Scents Repel Cabbage Aphids in Push-Pull Farming

Image Source: Natural Science News, 2024

Key Findings

  • In a study on kale crops, rosemary was found to repel the cabbage aphid pest
  • Aphids preferred kale scent over rosemary, but mixed scents reduced kale's attraction
  • Identified rosemary compounds like Linalool could help farmers use fewer pesticides
In the realm of agriculture, one of the most pressing challenges is the battle against pests that can devastate crops. The cabbage aphid, Brevicoryne brassicae, is a notorious adversary for kale farmers, leading to considerable crop damage and economic losses. Traditional methods of control, primarily synthetic insecticides, are losing their effectiveness as aphids develop resistance and concerns over environmental impact grow. This predicament has spurred researchers at the International Centre of Insect Physiology and Ecology to seek out more sustainable, ecologically friendly solutions[1]. The recent study by the International Centre delves into the behavioral patterns of B. brassicae, particularly how these pests are influenced by plant odors. The researchers employed a Perspex four-arm olfactometer, an apparatus used to study insect response to different scents, to compare the attractiveness of kale volatiles to those of rosemary, Rosmarinus officinalis. The goal was to discern whether rosemary could serve as a deterrent, thereby offering a potential plant-based pest management strategy. In this setup, aphids consistently favored the scent of kale over rosemary, spending more time in the kale-scented arms of the olfactometer. Interestingly, when rosemary and kale scents were presented together, the aphids were less attracted to the kale, suggesting that rosemary volatiles have a repelling effect on B. brassicae. To pinpoint the specific compounds responsible for these behaviors, the team used a combination of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-electroantennographic detection (GC-EAD). These techniques allowed them to identify which volatile compounds were being emitted by each plant and which ones the aphids could detect with their antennae. The GC-MS analysis uncovered a diverse array of volatile compounds in rosemary, with higher quantities than in kale. The GC-EAD results showed that the aphids' antennae responded to several compounds from rosemary, including Linalool, α-Terpineol, and Camphor. From kale, the aphids detected compounds like Sabinene and γ-Terpinene. These findings highlight the potential of using rosemary as a 'push' plant in an intercropping system—effectively driving pests away from the valuable kale crop. This study builds upon prior research that has explored how plant odors influence insect behavior. For instance, a previous study[2] demonstrated that certain terpenes, which are types of volatile organic compounds, could attract or repel the fall armyworm, a pest that shares similarities with B. brassicae in its reliance on olfaction for host plant selection. Similarly, research on maize and its wild ancestor, teosinte, showed that these plants could emit volatiles to attract parasitoids, turning the tables on pests like stemborers[3]. Another study[4] identified specific volatile compounds in rosemary that repelled the Ectropis obliqua moth, further underscoring the potential of using plant volatiles in pest management. The implications of the current study are significant. By identifying rosemary as an effective repellent, farmers could reduce their reliance on chemical insecticides, lowering costs and environmental impact. Intercropping kale with rosemary could create a natural defense mechanism, leveraging the repellent properties of rosemary to protect kale crops. This approach is a prime example of how understanding the chemical ecology of plant-insect interactions can lead to innovative, sustainable agricultural practices. In conclusion, the research from the International Centre of Insect Physiology and Ecology offers a promising avenue for pest management. By harnessing the natural repellent properties of rosemary, farmers may soon have a powerful new tool in their arsenal to protect kale crops from the ravages of the cabbage aphid. This study not only sheds light on the intricate dance between pests and plants but also paves the way for eco-friendly solutions in the ongoing effort to achieve sustainable agriculture.

AgriculturePlant Science

References

Main Study

1) Electrophysiological and Behavioral Responses of Cabbage Aphid (Brevicoryne brassicae) to Rosemary (Rosmarinus officinalis) Volatiles, a Potential push Plant for Vegetable push-pull Cropping System.

Published 12th March, 2024

https://doi.org/10.1007/s10886-024-01485-y

Related Studies

2) Responses of the fall armyworm (Spodoptera frugiperda) to different host plants: Implications for its management strategy.

https://doi.org/10.1002/ps.7255

3) Responses of parasitoids to volatiles induced by Chilo partellus oviposition on teosinte, a wild ancestor of maize.

https://doi.org/10.1007/s10886-015-0570-1

4) Electrophysiological and behavioural responses of the tea geometrid Ectropis obliqua (Lepidoptera: Geometridae) to volatiles from a non-host plant, rosemary, Rosmarinus officinalis (Lamiaceae).

https://doi.org/10.1002/ps.3771


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