Abstract

A REVIEW OF THE INSECTICIDAL ACTIVITIES OF NEEM AND GARLIC PLANTS

Jagessar R. C.* and Metzger T.

ABSTRACT

This review focuses on the insecticidal activities of neem (Azadirachta indica) and garlic (Allium sativum) plants. Twenty-five journals (thirteen (13) on garlic and twelve (12) on neem) were reviewed using seven (7) main points: (i) different methods used, (ii) different insects used, (iii) potency of extracts, (iv) statistical analyses used, (v) study area, (vi) solvent type extracts used and (vii) the natural products or chemical constituents isolated. In summary, the four (4) bioassay methods used by researchers were the contact or residual method, fumigation method, topical application method and dipping method. A total of thirty-one (31) insects were used, fourteen (14) insects against garlic, and seventeen (17) against neem. High mortality was indicated for both neem and garlic against target pests in twenty-four (24) articles. Lower mortality rate was seen against a non-target insect for neem; however, moderate morbidity rate was documented. Seventeen (17) statistical analyses were used to further investigate lethal effects of the extracts, with ANOVA being the most common. Additionally, researchers used six (6) different solvent type extracts; with water being the most common. Moreover, various parts of each plant were used to evaluate insecticidal effects such as, for garlic, the leaves and bulb were used (where some articles further processed the bulb into oil) and for neem, the leaves, roots, stems, barks, flowers and seeds were used (where some articles further processed seed kernels into oil). These experiments were conducted in eleven (11) different countries. Both neem and garlic prove to be very effective natural insecticides that are relatively inexpensive, eco-friendly and readily available in less developed countries such as Guyana. However, since they have shown some lethal effects on non-target species, it is necessary to use with caution.

Keywords: Natural Insecticide, Neem, Garlic, Plant, Extract, Allium sativum, Azadirachta indica, Target Insect, Non-target Insect, Mortality, Morbidity.