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Nowadays, plant extracts are extensively used as eco-friendly strategies for biological control of parasitic pests, including the root-knot nematodes, instead of using chemical pesticides. Therefore, the aim of this study was to examine leaf extract of neem plants (Azaddirachta indica) against the root-knot nematode; Meloidogyne spp. The obtained results showed that there was a gradual decrease in egg hatching with increasing the neem leaf extract concentrations and the duration of exposure. The neem extract is highly effective against egg hatching being the IC50 scored 397.1 ppm. Consequently, neem extract caused 75, 79, and 81% inhibition of egg hatching on root-knot nematode at the concentrations of 2000, 4000, and 6000 ppm, respectively at 72h. In contrast, the egg hatching (%) was progressively increased with increasing the exposure time from 24 to 72h. Under the application of plant extract concentrations for different periods, the lowest effective plant extract concentration was 2000 ppm, which gave the least inhibition, followed by 4000 ppm. The highest effective extract concentration was 6000 ppm, conferring the lowest egg hatching. It has been concluded from the results of the present study that the leaf extract of A. indica has the ability to inhibit the egg hatchability of root-knot nematode. Thus, this finding is important in the identification and development of alternative strategies in controlling the root-knot nematodes. There is, however, further work is needed to identify some of these main compounds after purification. This study confirms the presence of nematicidal compounds in petroleum ether fractions of Azadirachta indica, which were responsible for the prevention of egg hatching of root-knot nematodes at some concentrations, especially 6000 ppm.
Haroon et al. (Mon,) studied this question.