Influence of some environmental conditions on stability and activity of Bacillus thuringiensis formulations against the cotton leaf worm, Spodoptera littoralis (Boisd.) (Lepidoptera: Noctuidae)

Egyptian Journal of Biological Pest Control

Table 6 Effect of photolysis in water for Bacillus thuringiensis formulations

Bioinsecticides	Time/hours	Water source
		Nile water		Ground water		Drain water
		IU/mg	Loss %	IU/mg	Loss %	IU/mg	Loss %
Dipel 2×	0	28,834	0	28,376	0	28,376	0
	1	27,965	3.01	27,644	2.58	27,920	1.61
	2	26,920	6.64	26,834	5.43	26,844	5.40
	4	25,400	11.91	25,465	10.26	25,320	10.77
	24	20,200	29.94	20,320	28.39	18,844	33.59
	72	13,712	52.44	13,200	53.48	13,010	54.15
	120	11,100	61.50	11,134	60.76	10,844	61.78
Regression equation (y =)		− 0.0185x + 10.19		− 0.0162x + 10.19		− 0.0153x + 10.18
Degradation rate (K)		0.01853		0.01621		0.01527
t_½ h		37.40		42.76		45.40
Determination coefficient (R²)		0.97		0.96		0.94
Protecto	0	27,560	0	27,560	0	27,560	0
	1	26,245	4.77	26,263	4.71	26,400	4.21
	2	24,710	10.34	24,534	10.98	24,821	9.94
	4	23,400	15.09	23,279	15.53	23,144	16.02
	24	18,555	32.67	18,979	31.14	17,910	35.01
	72	12,310	55.33	12,266	55.49	12,200	55.73
	120	9117	66.92	9355	66.06	8934	67.58
Regression equation (y =)		− 0.0259x + 10.13		− 0.0263x + 10.13		− 0.0254x + 10.13
Degradation rate (K)		0.02589		0.02632		0.02537
t_½ h		26.77		26.33		27.32
Determination coefficient (R²)		0.98		0.98		0.97