Chemical modulators of the innate immune response alter gypsy moth larval susceptibility to Bacillus thuringiensis

Table 3 Effect of immune inhibitors on susceptibility of third-instar gypsy moth larvae reared without antibiotics to B. thuringiensis toxin (MVPII; 20 μg).

				Total Mortality (mean proportion ± SE)
Compound added to B. thuringiensis toxin (MVPII)	Compound activity	Compound concentration	N	without B. thuringiensis	with B. thuringiensis	Significance (p-value) of rank analysis
B. thuringiensis toxin control			48	0.06 ± 0.02	0.92 ± 0.15 a
Acetylsalicylic acid	Eicosanoid inhibitor (COX)	100 μg	36	0.00 ± 0.00	0.81 ± 0.16 ab	0.0396
Dexamethasone	Eicosanoid inhibitor (PLA₂)	100 μg	24	0.00 ± 0.00	0.79 ± 0.19 ab	0.4519
Indomethacin	Eicosanoid inhibitor (COX)	10 μg	48	0.04 ± 0.04	0.83 ± 0.14 ab	0.0056
Esculetin	Eicosanoid inhibitor (LOX)	100 μg	24	0.00 ± 0.00	0.83 ± 0.18 ab	0.9757
Piroxicam	Eicosanoid inhibitor (COX)	100 μg	36	0.04 ± 0.02	0.94 ± 0.18 a	0.2417
Glutathione	Nitric oxide scavenger, phenoloxidase inhibitor	1.2 μg	36	0.02 ± 0.02	0.72 ± 0.14 ab	0.0154
N-acetyl cysteine	Reactive oxygen scavenger	100 mM	36	0.03 ± 0.01	0.86 ± 0.15 a	0.0286
Phenylthiourea	Nitric oxide scavenger, phenoloxidase inhibitor	75 mM	36	0.03 ± 0.03	0.81 ± 0.15 ab	0.3382
S-methyl-L-thiocitrulline	Nitric oxide scavenger	100 mM	36	0.03 ± 0.02	0.83 ± 0.15 ab	0.0245
Tannic acid	Phenoloxidase inhibitor	100 μg	24	0.00 ± 0.00	0.79 ± 0.19 ab	0.2740
S-nitroso-N-acetyl-l, l-penicillamine	Nitric oxide donor	100 mM	36	0.00 ± 0.00	0.94 ± 0.18 a	0.4409

The value N refers to the total number of larvae tested per treatment. There were no effects by these compounds without B. thuringiensis. Log-rank analysis was used to compare larval survival for each concentration of inhibitor, treatments with a p-value < 0.05 were considered significantly different from Bt toxin alone. Mean mortality values followed by the same letter do not differ significantly from each other.

ISSN: 1471-2180