Table 6.

Contrasts among types of food (degrees of freedom, df; t statistic, t; P value, P) to examine the effects of Bt on the choice of food by Hylobius abietis

	Area debarked (mm2) during 3 days of feeding			Area debarked (mm2) during 5 days of feeding			Area debarked (mm2) during 7 days of feeding
Contrasts	df	t	P	df	t	P	df	t	P
BC vs BH	54	3.43	0.01	54	2.57	0.12	54	1.61	0.59
VC vs VH	54	0.01	1.00	54	−0.33	0.99	54	0.17	1.00
NC vs NH	54	−0.80	0.96	54	−1.27	0.79	54	−1.33	0.76

Total consumption (mean area debarked, mm²) during 3, 5 and 7 cumulative days of feeding were compared among control (water‐treated) and Bt‐treated Picea abies stem pieces (high concentration of the individual formulation). Treatments are abbreviated as follows: control and Bt galleriae treated food (BC, BH); control and Bt israelensis (VC, VH); control and Bt tenebrionis (NC, NH). Significant effects (P < 0.05) are shown in bold.