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The aims of this work were to evaluate antifeedant, horizontal transfer and repellent activities of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT), free and microencapsulated, at different doses against Oryzaephilus surinamensis and Tribolium castaneum on peanut kernels. In general, negative values for the percentage feeding deterrence index (FDI) were found for Oryzaephilus surinamensis in the presence of these chemical treatments, suggesting a phagostimulant activity. In addition, untreated individuals died within 20 days of coming into contact with insects previously exposed to both antioxidants (BHA and BHT) and formulations (F- BHA and F-BHT), regardless of the dose, while the insects in the controls died after this time. Since this work revealed evidence for the transfer of both free and microencapsulated antioxidants from treated to untreated individuals, we can confirm that horizontal transfer of these compounds takes place between treated and untreated insects. The evaluated compounds showed no repellent activity against O. surinamensis, which continued unaffected with its life cycle on both treated and untreated peanuts. On the other hand, Tribolium castaneum exhibited high FDI values, especially for the formulations, with mean values of 0.68 and 0.91 for F-BHA and F-BHT, respectively. No horizontal transfer was observed for this insect, but repellency was higher than 80% for free and encapsulated BHT. We can conclude that the mechanism of insecticidal action of antioxidants and their formulations was dependent on the type of insect evaluated. The insecticidal effect on Oryzaephilus surinamensis could have been due to the direct intake of the chemical compounds added, whereas the negative effect on Tribolium castaneum could have been caused by starvation. [ABSTRACT FROM AUTHOR]

m.a. passone, s.l. resnik and m.g. etcheverry. 2005. The effectiveness of the food-grade antioxidants butylated hydroxytoluene (BHT), trihydroxybutyrophenone (THB), propyl paraben (PP) and butylated hydroxyanisole (BHA) at 1, 10 and 20 mmol l−1 concentrations on germination, growth, and aflatoxin B1 (AFB1) production by Aspergillus section Flavi strains was determined. Assays on the lag phase of germination, germination percentage, germ tube elongation rate, lag phase, growth rate and AFB1 production by three strains of Aspergillus flavus and three of Aspergillus parasiticus were carried out in vitro on peanut extract meal agar conditioned at different water activities ( aw: 0·982, 0·971, 0·955, 0·937). The antioxidants PP and BHA efficiently inhibited the germination of the two species tested at the doses 10 and 20 mmol−1. The antioxidants PP and BHA at 1 mmol l−1 and THB at 20 mmol l−1 reduced the germ tube elongation rate most effectively, regardless of aw levels. An increase in the lag time and a reduction in the growth rate of 100% of the strains was observed, this was due to the action of BHT at the doses 10 and 20 mmol−1 at 0·982, 0·971 and 0·955 aw, although these treatments stimulated the AFB1 accumulation in most of the fungi tested. The more effective antioxidants were PP and BHA, which increased the lag phase, reduced the growth rate and AFB1 production in all of the strains at the four aw assayed. At concentrations 10 and 20 mmol l−1, these antioxidants totally inhibited fungal development. The study shows that the antioxidants BHA and PP are effective fungal inhibitors to peanut Aspergillus section Flavi in wide range of water activity. The results suggest that phenolic antioxidants, BHA and PP, can be effective fungitoxicants on aflatoxigenic strains in peanut at industrial level. [ABSTRACT FROM AUTHOR]