Specifically, inhibitors of reactive oxygen and nitrogen species, phenoloxidase, and eicosanoid biosynthesis were fed to Angiogenesis inhibitor larvae to assess their effect on larval susceptibility to B. thuringiensis toxin. Five compounds, acetylsalicylic acid, indomethacin, glutathione, N-acetyl CH5183284 chemical structure cysteine, and S-methyl-L-thiocitrulline, delayed mortality compared to larvae fed B. thuringiensis toxin alone. None of the compounds significantly affected final mortality and six had no effect on either the final mortality or survival time of larvae fed B. thuringiensis (Table 3). 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 learn more 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 crotamiton 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. Dose-response assays with acetylsalicylic acid, glutathione, piroxicam, and indomethacin demonstrated complex relationships between inhibitor concentration and larval survival (Figure 4; see also additional file 4). Acetylsalicylic acid extended larval survival in the presence of B. thuringiensis toxin, but only at the high concentration (100 μg); the survival time of larvae treated with lower concentrations did not differ significantly from toxin alone.