EVALUATION OF Bacillus thuringinesis ALONE OR MIXTURE WITH AMINO ACID FOR CONTROLLING COTTON LEAFWORM , Spodoptera littoralis (Boisd.)

Second instar larvae of Spodoptera. littoralis were fed on caster bean leaves treated with different concentrations of Dipel (Bacillus thuringiensis var. kurstaki). after 72 hours of treatment (estimated LC50) Regarding the LT50 values a negative relationship could be detected between the applied concentration of Dipel and LT50 value; i.e. the LT50 was shortened with the increase in Dipel concentration. The LT50 values being 14.17, 8.81,5.99 and 2.40 days for the used concentrations of 8, 12, 16 and 20 × 104 I.U. The second instar S. littoralis larvae were fed on fresh caster bean leaves treated with different concentrations of Dipel + 05 % Amino. , the corrected mortality percentages after 3 days increased by increasing concentration ranged from 40.00 to 90.00 % at the concentrations of 8 to 28 × 104 I.U., the LC50 value was 11.31 × 104 I.U. for S. littoralis after 3 days., comparing the effects of the two treatments (Dipel and Dipel + 0.5% Amino) on the mortality percentages at same concentration used, Diple + 0.5 % treatment led to increase the percentages of mortality in all concentrations used and thus led to decrease the value of LC50 from 17.14 to 11.31 × 104 S.U. and shortened also the values of LT50 from 14.7, 8.81 and 5.99 to 6.66,3.88 and 2.18 days at concentration of 8, 12 and 16 × 104 I.U. , respectively, The LC50 of Diple2x + 1% Amino Acid was 15.59× 104 I.U. 72 hours post treatment , a negative relationship could be detected between the applied concentration of Dipel + 1% Amino and. the LT50 was shortened with the increase in treatments concentration. These values were 11.61, 7.97, 3.99, 3.07 and 1.72 days for the used concentrations of 8, 12, 16, 20 and 24 × 104 I.U. , respectively . LC50 of Diple2x + 1.5% Amino Acid was 16.06 × 104 I.U. after 3 days of treatment. and LT50 values. were 14.12, 6.73, 3.13 and 1.69 days at concentrations of 8,12,16 and 20× 104 I.U. , respectively.. The LC50 of Diple2x + 2.5% Amino Acid was was 16.62 × 104 I.U.. After3 days from treatment while the LT50 values were 11.18, 6.56, 4.15 and 2.80 days at concentrations of 8, 12, 16 and 20 × 104 I.U., respectively. , LC50 value of Dipel 2x + 0.5 % amino (11.31× 104 I.U.) was the most effective one among all treatments ,also, led to shortened the values of LT50 (6.66, 3.88 and 2.18 days for the used concentrations of 8, 12 and 16 × 104 I.U. , respectively.