Insecticidal Evaluation of essential oils of Citrus sinensis L. (Myrtales: Myrtaceae) against housefly, Musca domestica L. (Diptera: Muscidae)

The housefly, Musca domestica L., is one of the most common insects, associated with vectoring of various etiological agents. In order to search for effective control agent, the essential oil of sweet orange [Citrus sinensis (L.) Osbeck] was evaluated for its insecticidal activity against the larvae and pupae of housefly using contact toxicity and fumigation bioassays. In the contact toxicity assay, lethal concentration, LC50 of C. sinensis essential oil against housefly larvae, varied between 3.93 and 0.71 mu l/cm(2) for different observation days, while lethal time, LT50, varied between 5.8 to 2.3 days. Mortality of larvae were significant with different concentrations (F = 2.79, df = 4, P < 0.05) and time (F = 6.69, df = 3, P < 0.01). In fumigant assay for housefly larvae, LC50 of 71.2 and 52.6 mu l/l was obtained in 24 and 48 h, respectively. Scanning electron microscopy of oil treated larvae revealed extreme dehydration and surface distortion while control larvae were free from any of the above symptoms and presented smooth surface, conforming effect of essential oil on housefly larvae. Percentage inhibition rate of oil against housefly pupae was 27.3-72.7% for contact toxicity and 46.4-100% for fumigation assay. Compositional analysis of C. sinensis essential oil using gas chromatography/mass spectrometry (GC-MS) revealed d-limonene (73.24%), alpha-pinene (5.86%) and myrcene (4.45%) as major components whereas its vapour profile (solid-phase micro extraction-GC/MS) was dominated by d-limonene at 92.57%. Significant activity of C. sinensis essential oil against larvae and pupae of housefly, pave the way for its use as eco-friendly housefly control measure.