Avoidance Behavior to Guava Leaf Volatile Oil by Three Medically Important Mosquito Vectors

Area of Science:

• Entomology
• Natural Product Chemistry
• Vector Control

Background:

• Volatile organic compounds from plants are explored for eco-friendly insect-repellent properties.
• Mosquitoes like Anopheles minimus, Anopheles epiroticus, and Culex quinquefasciatus are significant disease vectors.

Purpose of the Study:

• To evaluate the excito-repellency, contact excitation, and knockdown effects of guava leaf oil against three key mosquito species.
• To identify the major organic components of guava leaf oil responsible for its activity.

Main Methods:

• Gas chromatography-mass spectrometry (GC-MS) was used to analyze guava leaf oil composition.
• An excito-repellency assay system assessed noncontact and contact effects on mosquitoes.
• Different concentrations of guava oil were tested against Anopheles minimus, Anopheles epiroticus, and Culex quinquefasciatus.

Main Results:

• Guava oil exhibited 100% escape for Anopheles minimus at 2.5-5.0% in contact assays and 96-98% in noncontact assays.
• Potent irritant (92% escape) and repellent (61-86% escape) effects were observed against Culex quinquefasciatus.
• Anopheles epiroticus showed lower repellency (17-20% escape) but was susceptible to knockdown effects (44% KD at 5.0% concentration).
• Major components identified included dl-limonene, cymene, and α-terpinene.

Conclusions:

• Guava leaf oil is a promising plant-based mosquito repellent with potential for use in vector control programs.
• Its efficacy varies among mosquito species, with notable activity against Anopheles minimus and Culex quinquefasciatus.
• Further research could support the inclusion of guava oil in insecticide formulations.