The Efficacy of the Essential Oils of Sri Lankan Cinnamomum zeylanicum Fruit and Micromelum minutum Leaf against Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Abstract

The bruchid, Callosobruchus maculatus (F.) causes major losses during the storage of cowpea seeds [Vigna unguiculata (L.) Walp.] in Sri Lanka. Essential oils isolated from Cinnamomum zeylanicum fruit and Micromelum minutum leaves were tested for potential insecticidal activity against C. maculatus. The adults of C. maculatus were susceptible to both fumigant and contact toxicity of C. zeylanicum fruit oil and M. minutum leaf oil. In the fumigant toxicity assay LC50 value (0.801 g/L) of M. minutum leaf oil was lower than that of C. zeylanicum fruit oil. LC50 values of 0.071 g/L and 0.795 g/L were obtained for the contact toxicity of M. minutum leaf oil and C. zeylanicum fruit oil, respectively. Oviposition and F₁ adult emergence were significantly inhibited by C. zeylanicum fruit oil and M. minutum leaf oil at concentrations higher than 1.25 g/L and 0.25 g/L, respectively in the contact toxicity and 1.00 g/L and 3.00 g/L respectively in the fumigant toxicity. Repellent activity of M. minutum leaf oil was more potent to C. maculatus than C. zeylanicum fruit oil at doses ranging 10–80 mg. Analysis of the two oils revealed that bicyclogermacene (16.0%) was the major constituent of M. minutum leaf oil and β-ylangene and linalool (13.9 % and 13.2 %, respectively) were in the C. zeylanicum fruit oil.

Key Word Index:

• Cinnamomum zeylanicum
• Lauraceae
• Micromelum minutum
• Rutaceae
• Callosobruchus maculatus
• cowpea
• Essential oil composition