Evaluation of plant based dusts against rice bug nymph, Leptocorisa oratorious under laboratory conditions

摘要

Use of plant origin compounds is comparatively less toxic, safer, biodegradable and ecologically compatible without posing environmental pollution problem as compared to synthetic insecticides. About 2400 plant species reportedly possess pest controlproperties (Koul, 2004). Neem has been evaluated so far against more than 300 species from different orders of insects. In India itself, it has been tested against more than 100 species including important pests of agriculture and found varied effects oninsects (Singh et al, 1988). These effects include repellency, deterrency against feeding and oviposition, insect growth regulatory (IGR), physiological, sterilant, ovicidal activity, besides systemic action. Neem is rich in terpenoids, azadirachtin, atetra nortriterpenoid, isolated from the neem seed kernel, is the most active one. Azadirachta indica has shown antifeedant, repellent, growth regulating and ever sterilizing properties on several insect species (Ascher,1993; Chitra et al, 1993). The major biologically active constituents of neem are azadirachtin, nimbin, meliantriol and solanin followed by minor constituents of nimbidin, nimbidinin, nimbidol etc. (Jotwani and Srivastav, 1981). Soapnut, Sapindus trifoliatus L. has also attracted the attention of many workers like Kumar et al, (1988); Ribeiro et al, (1965), but has not been tested extensively so far. The major biologically active constituents of soapnut are a monodesmosidic acetylated saponin and a mixture of two monodesmosidic saponins (Ribeiro et al, 1965).