Anti-feeding Effect of the Extracts from Neem Seed on Diaphania indica (Saunders)

Azadirachtin was extracted from neem seeds by conventional and CO2 supercritical fluid extraction methods, and its anti-feeding activity evaluated on the 3rd and 5th instars of larvae in laboratory. The two extracts with a concentration of 20 |ig/mL were found to display very high anti-feeding effects on the 3rd and 5th instars of larvae. The anti-feeding effects of these two extracts were significantly higher on the 3rd instar of larvae than on the 5th instar of larvae with all concentrations. The high inhibition to the increase of larvae weight was obtained through feeding the 5th instar of larvae with the two extracts at the concentration of 5 |ig/mL, and the larvae weights were 61.92% and 63.16% of their controls respectively. It is concluded that the two extracts had high anti-feeding activity and that the effect of the extract from CO2 supercritical fluid extraction methods was higher than that of conventional methods at the same concentration.