Preliminary Assessment of Insect-Repellent Activity of Curcuma amada and Curcuma aromatica Rhizome Peel Extracts through Field Application

Abstract

The increasing demand for eco-friendly and sustainable insect control agents has led to the exploration of plant-derived bioactive compounds that possess repellent properties. In this study, the insect-repellent potential of peel Curcuma amada (mango ginger) and Curcuma aromatica (wild turmeric) rhizomes peels using simple direct-area applications under open or semi-open conditions was carried out. Ethanol extracts were applied to exposed surfaces and plant leaves, and repellency was assessed against mosquitoes (Culex spp.), Drosophila melanogaster, and aphids (Aphis craccivora). Both extracts exhibited prompt repellency responses, ranging from initial application upto 10 min, depending on the insect species tested. However, C. aromatica peel extract consistently showed a longer duration of repellent effect across all three insect types, lasting up to 30 h in the case of aphids. C. amada also exhibited significant activity but with shorter persistence. These results highlight the potential of exploring rhizome peels, typically considered agricultural waste, as effective, low-cost botanical repellents. This study emphasizes a practical, real-environment approach to testing without the use of containers or enclosures, thus mimicking field conditions. These findings support further phytochemical and formulation research for the development of natural insect-repellent products using Curcuma peels.

Introduction

Insect pests such as mosquitoes, fruit flies (Drosophila melanogaster), and aphids (Aphis craccivora) are major threats to public health and agriculture. Conventional synthetic insecticides pose risks like resistance, ecological harm, and human toxicity. Therefore, interest in eco-friendly, plant-based repellents is rising.

Plants in the Curcuma genus (family Zingiberaceae), including Curcuma amada (mango ginger) and Curcuma aromatica (wild turmeric), are known for their bioactive secondary metabolites. Their rhizome peels, typically discarded as waste, contain curcuminoids, terpenes, and volatile oils, which may offer insect-repellent properties. This study explores the repellent potential of ethanol extracts from these peels against three insect species in field-relevant, non-laboratory settings.

Materials and Methods:

• Peel Extraction: Peels of C. amada and C. aromatica were dried, powdered, infused in boiling water, and concentrated. Extracts were mixed with ethanol (1:1) for field application.

• Repellency Testing:

  • Mosquitoes: Extracts sprayed on surfaces in active mosquito zones; mosquito landings observed every 15 minutes.

  • Fruit Flies: Treated paper strips placed near fruit baskets; fly behavior monitored over 12 hours.

  • Aphids: Extracts sprayed on infested mango and guava tree leaves; aphid presence checked at intervals up to 30 hours.

• Data Collection: Focused on repellency onset, duration, behavior changes, and reinfestation. No insect mortality was assessed.

Results and Discussion:

1. Mosquitoes:

• C. aromatica provided protection for 60 minutes, outperforming C. amada (45 minutes).

• Both showed immediate repellency by reducing landings and bite attempts.

• Efficacy linked to higher levels of monoterpenes and sesquiterpenes in C. aromatica, such as ar-turmerone.

2. Fruit Flies (Drosophila melanogaster):

• Strong avoidance observed within 5 minutes of exposure.

• C. aromatica was effective for 12 hours, while C. amada lasted 9 hours.

• Volatile compounds likely disrupted sensory behavior, reducing attraction.

3. Aphids (Aphis craccivora):

• Both extracts significantly reduced aphid populations on mango and guava leaves.

• C. aromatica maintained repellency for up to 30 hours with no reinfestation.

• C. amada showed some reinfestation after 22–24 hours.

• Performance differences likely due to varying levels of terpenoids and phenolic compounds.

Key Findings (Table Summary):

Conclusion

This study demonstrated the insect-repellent potential of Curcuma amada and Curcuma aromatica rhizome peel extracts when applied directly to infestation prone surfaces. Both the extracts effectively repelled mosquitoes, fruit flies, and aphids. The peel extract of C. aromatica showed superior and longer-lasting activity, especially in reducing aphid infestation on mango and guava trees. The use of peel extracts, typically discarded as agro-waste, presents a sustainable approach to pest control. Unlike conventional lab-based assays, this study employed simple direct-area applications under open conditions, enhancing its real-world relevance. These results suggest that Curcuma peels may serve as low-cost, eco-friendly alternatives to synthetic repellents.

References

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Copyright

Copyright © 2025 Thangam R, Dharshni K M, Narthanaa S, Pradheeba M, Vasuki Priyadharshini G, Narmatha Sri J, Magi G, Pugalenthi M. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.