ANTIFEEDANT AND GROWTH REGULATORY EFFECTS OF NEEM LEAF EXTRACTS AGAINST SPILARCTIA OBLIQUA (WALKER)

Abstract

The laboratory experiments have been conducted to study the antifeedant and growth regulatory effects of cow urine, Neem leaf extracts prepared in water and Cow urine (5% and 10%) against different stages of Spilarctia obliqua. The cent per- cent mortality of neonate larvae was observed in all neem leaf extracts prepared in water and cow urine whereas in cow urine @ 5% and 10% gave larval survival 26.63% to 13.34%, with significantly less growth index ( 0.284) in comparison to untreated control (3.050).The neem leaf extracts prepared in water and cow urine again found very effective with cent per- cent mortality of 7 days old larvae after feeding on the treated leaves for 5-6 days with less larval survival in NLCUE @5% (13.33%) and CU @10% (16.67 %) followed by CU @5% (30.0%) in comparison to cent percent larval survival in untreated control. Similarly, for 14 days old larvae the mean leaf area consumed at the lower concentration @ 5% was found more (ranges 5.30 cm 2 to 13.50 cm 2 than that at the higher concentration @10% (ranges 4.0 cm 2 to 11 cm2) after 48 hr of feeding on caster treated leaves.whereas again cent per cent larval mortality of 14 days old larvae were found on neem leaf extracts after 120 hrs of feeding in comparison to CU @ 5% and 10% and untreated control where the feeding areas were 10.20cm2, 9.07am2 and 24.50cm2, respectively with significantly less pupal (212.0mg and 201.6mg) and adult weight (118.4mg and 90.0mg) in CU @ 5% and 10% , respectively in comparison to untreated control with pupal weight (342.5mg) and adult weight (238.0mg). The preference index calculated showed the strong antifeedant activity of NLWE @10% (0.45) and NLCUE @10% (0.49), whereas NLWE @5% (0.55),NLCUE @5% ( 0.61) showed moderately antifeedant activity as compared to slightly antifeedant activity observed on CU @10% (0.82) and CU @5% (0.88). These observations clearly demonstrated that the tested leaf extracts and cow urine at their higher concentrations i.e. @10% were having high antifeedant activity in comparison to low concentrations @ 5% and untreated control.