Evaluation of the systemic action of neem (Azadirachta indica A. juss) seed products against the desert locust immature Schistocerca gregaria (Forskal) (Orthoptera: Acrididae)

摘要

The current study was done to investigate the potential of the systemic growth regulatory effects of various neem seeds products against immature stages of desert locust infesting potted millet plants in Sudan. The tests also covered the stability of the systemic action of neem seed powder (NSP) under conditions of water stress. Some (33-80%) of the exposed nymphs developed to the third stage without further moulting. Medium lethal time for neem seed water extracts (NSWE), neem seed organic extract (NSOE) and NSP ranged from 166 to 248 hours. All neem seed product induced significant systemic antifeedant activity, ranging from 52 to 99% against the immatures. Based on these findings, NSP, the simplest form, was found to possess systemic activity comparable to complicated forms of neem products. NSP was stable under conditions of delayed watering up to 10 days and the latter had effects on development, mortality and feeding comparable to immediate watering. All aspects studied indicated the superior systemic activity of various neem seed products. The fact that they were able to delay development, prevent further moulting of instars, stabilize under conditions of delayed watering, enabled them to confine the desert locust to their breeding sites as immatures without threat of swarm formation and limited damage to local growers.