How Orange Oil Affects Mosquito Egg Laying

Jenn Hoskins
15th May, 2024

How Orange Oil Affects Mosquito Egg Laying

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Instituto Oswaldo Cruz (Fiocruz), Brazil, studied the impact of yeast-encapsulated orange oil (YEOO) on the egg-laying behavior of Aedes aegypti mosquitoes
  • YEOO particles strongly deterred mosquito egg-laying within the first 72 hours, showing a significant repellent effect compared to water
  • The yeast encapsulation of orange oil enhances its repellent efficacy, likely by protecting the active ingredients for a more consistent release
Mosquito-borne diseases like dengue, Zika, chikungunya, and yellow fever pose significant global health challenges. These diseases are primarily transmitted by Aedes aegypti and Aedes albopictus mosquitoes, making effective vector control crucial[2][3]. Traditional methods, such as insecticides and repellents, are facing limitations due to emerging resistance and the need for more sustainable solutions[2][4]. A recent study by researchers at Instituto Oswaldo Cruz (Fiocruz), Brazil, explores a novel approach to mosquito control using yeast-encapsulated orange oil (YEOO) as a larvicide[1]. The study aimed to evaluate the impact of YEOO particles on the oviposition behavior of Aedes aegypti mosquitoes. Oviposition refers to the process by which female mosquitoes lay their eggs. Understanding how YEOO affects this behavior is vital for assessing its potential as a vector control tool. The researchers conducted oviposition assays with gravid (egg-carrying) Aedes aegypti females under both laboratory and semi-field conditions, which included natural light and temperature fluctuations. In the experiments, the number of eggs laid was manually counted in both the wooden paddles and the solution within each ovitrap (a device used to attract and capture egg-laying mosquitoes). The results showed that the proportion of eggs varied between substrates depending on the conditions. In laboratory settings, females displayed a lower preference for laying eggs on paddles compared to semi-field conditions. This behavior shift indicates that laboratory results may not always be directly applicable to field conditions, highlighting the importance of conducting studies in both environments. The study found that YEOO particles had a strong repellent or deterrent effect on mosquito oviposition within the first 72 hours of application. This effect was quantified using the Oviposition Activity Index (OAI), with values ranging from -0.559 to -0.760 when compared to water, indicating a strong deterrent effect. However, when compared to inactivated yeast, the deterrent effect was weaker (OAI = -0.220). Control ovitraps containing water were more likely to have eggs than those treated with YEOO particles, while ovitraps with YEOO particles and inactivated yeast had similar numbers of positive ovitraps. The repellent effect of YEOO appears to be influenced by the delivery system. Citrus sinensis (orange) essential oil alone typically shows a weak repellent effect, suggesting that the yeast encapsulation enhances its efficacy. This encapsulation likely protects the active ingredients, ensuring a more consistent release and prolonged effect. Interestingly, live yeast is generally considered an attractant for mosquito oviposition, which raises questions about how the yeast wall surrounding the orange oil affects this behavior negatively. This study aligns with previous findings that emphasize the need for innovative vector control strategies[3]. Traditional insecticides are becoming less effective due to resistance, and alternative methods are essential for sustainable mosquito management[2]. The use of YEOO as a larvicide represents a promising approach, combining natural repellents with innovative delivery systems to enhance efficacy. Additionally, the study's findings contribute to the broader understanding of repellent efficacy. For instance, earlier research highlighted the effectiveness of DEET as a repellent against Aedes mosquitoes, showing that DEET outperformed other synthetic and natural repellents in terms of protection time and repellency[4]. The current study's focus on YEOO provides an alternative that could complement existing repellents like DEET, offering a diversified toolkit for mosquito control. In conclusion, the research conducted by Instituto Oswaldo Cruz (Fiocruz) demonstrates the potential of yeast-encapsulated orange oil as a novel larvicide with significant repellent effects on Aedes aegypti oviposition. This innovative approach could play a crucial role in integrated vector management strategies, addressing the growing challenge of insecticide resistance and enhancing the effectiveness of mosquito control programs worldwide.

BiotechGeneticsAnimal Science

References

Main Study

1) The impact of yeast-encapsulated orange oil in Aedes aegypti oviposition.

Published 14th May, 2024

https://doi.org/10.1371/journal.pone.0301816

Related Studies

2) Contemporary status of insecticide resistance in the major Aedes vectors of arboviruses infecting humans.

https://doi.org/10.1371/journal.pntd.0005625

3) Alternative strategies for mosquito-borne arbovirus control.

https://doi.org/10.1371/journal.pntd.0006822

4) Efficacy and safety of repellents marketed in Brazil against bites from Aedes aegypti and Aedes albopictus: A systematic review.

https://doi.org/10.1016/j.tmaid.2021.102179


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