Essential Oils as Fumigants Against Grain Moths and Allies

Jim Crocker
18th March, 2024

Essential Oils as Fumigants Against Grain Moths and Allies

Image of Sitotroga cerealella eggs showing, (a) emergence holes of parasitized S. cerealella eggs, and (b) black parasitized S. cerealella eggs with T. evanescens.

Image adapted from: Elbehery et al. / CC BY (Source)

Key Findings

  • Garlic and peppermint oils can kill 100% of grain moths in 24 hours
  • These oils have minimal impact on beneficial pest-controlling insects
  • The study supports using these oils for eco-friendly pest management in agriculture
In the world of agriculture, the battle against pests is ongoing and critical for protecting food supplies. One such pest, Sitotroga cerealella, commonly known as the Angoumois grain moth, wreaks havoc on stored cereal grains, causing significant economic losses. Traditional chemical insecticides have been the go-to solution for pest control, but their use raises concerns about human health, environmental safety, and the development of pest resistance. This has led scientists to explore alternative, more sustainable methods of pest management. The National Research Centre has recently conducted a study[1] that offers a promising solution to this problem, using natural essential oils as a fumigant to control S. cerealella. The study focused on the essential oils of Allium sativum (garlic) and Mentha piperita (peppermint), which were tested for their effectiveness in killing the adult moths of S. cerealella and their impact on the egg parasitoid Trichogramma evanescens, a beneficial insect that helps control pest populations. The research identified Diallyl trisulfide and DL-Menthol as the main components in A. sativum and M. piperita essential oils, respectively. These compounds are responsible for the insecticidal properties of the oils. The study found that A. sativum essential oil at concentrations of 10.0, 5.0, and 2.5 µL/L air could achieve 100% mortality of S. cerealella adults within 24 hours. Similarly, M. piperita oil at 10.0 and 5.0 µL/L air resulted in 100% and 96% mortality, respectively. Importantly, the study also considered the effects of these essential oils on non-target species, specifically T. evanescens, which is used in integrated pest management (IPM) strategies. The findings showed that the parasitoid adult emergence in the first generation (F1) was only slightly reduced when exposed to the highest concentration (LC99) of the essential oils from A. sativum and M. piperita, by 10.89% and 9.67%, respectively. Additionally, the parasitism rates of the emerged parasitoid decreased by 9.25% and 5.84%, which falls into class I (harmless), indicating a low level of harm to this beneficial insect. These results are significant because they suggest that A. sativum and M. piperita essential oils can effectively control S. cerealella while being compatible with the use of T. evanescens in IPM programs. This dual effectiveness is crucial for developing a pest control strategy that is both effective and environmentally friendly. The current study builds upon previous findings. For instance, a prior study[2] suggested that M. piperita oil could be slightly harmful to T. pretiosum, another parasitoid used in pest management, highlighting the importance of selecting the right essential oils and concentrations to minimize negative impacts on beneficial insects. Moreover, the fumigant toxicity of various plant essential oils, including M. piperita, was previously assessed against stored product pests[3], further supporting the potential of essential oils as fumigants. The synergistic effects of M. piperita essential oil with other antimicrobials were also demonstrated in earlier research[4], indicating that essential oils can enhance the effectiveness of certain drugs against bacteria and fungi. This property could potentially be leveraged in pest control to create more potent and multifaceted treatment options. In conclusion, the study from the National Research Centre demonstrates that essential oils from garlic and peppermint hold great promise as natural fumigants for pest control in stored grains. Their ability to effectively kill S. cerealella while having minimal impact on beneficial parasitoids like T. evanescens aligns with the goals of IPM and offers a more sustainable approach to pest management. As the world moves towards greener agricultural practices, studies like this pave the way for safer and more environmentally conscious pest control methods.

BiochemEcologyPlant Science

References

Main Study

1) Potential fumigant toxicity of essential oils against Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) and its egg parasitoid Trichogramma evanescens (Hymenoptera: Trichogrammatidae).

Published 15th March, 2024

https://doi.org/10.1038/s41598-024-56611-3

Related Studies

2) Quantifying the harmful potential of ten essential oils on immature Trichogramma pretiosum stages.

https://doi.org/10.1016/j.chemosphere.2018.02.083

3) Chemical composition and fumigant toxicity of some essential oils against Ephestia kuehniella.

Journal: Journal of economic entomology, Issue: Vol 104, Issue 4, Aug 2011

4) Elucidation of the synergistic action of Mentha Piperita essential oil with common antimicrobials.

https://doi.org/10.1371/journal.pone.0200902


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