Effect of storage conditions and duration on the potency of Neem (Azadirachta indica A. Juss) seeds as a home-made Insecticide

Abstract

This work was carried out to investigate the effects of grinding, storage conditions and duration on the bio-efficacy of neem seeds as a home-made insecticide against the red flour beetle Tribolium castaneum. Samples of neem seeds (intact and ground) were kept in small jute sacks and stored in the sun, refrigerator (4oC), and room temperature (28 ± 2oC) for two, four and six weeks in each condition. After the respective storage period, a water extract (5%) was prepared and sprayed topically on the 3 rd instar larvae of the beetle as well as on the pupal stage. A significant mortality of 62.83% resulted from the neem seeds stored in the refrigerator on the 7 th day of exposure. The seeds stored in the sun caused a mortality of 48.49%. The water extract from the seeds which were stored at room temperature, resulted in significantly high cumulative larval mortality of 50.30%. The efficacy of neem seeds kept in the sun was negatively affected and correlated with the length of storage period. However, the efficacy of the neem seeds stored in the refrigerator was increased with storage time. The pupal mortality due to spraying with water extract from neem seeds stored in the sun, refrigerator and room temperature was 49.67, 68.12 and 69.43% respectively. The mortality in the control (water treatment) was 7.33%. The results indicated that grinding of neem seeds before storage seems to have no effects on their efficacy.