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Synergism of aflatoxin B 1 toxicity with the co‐occurring fungal metabolite kojic acid to two caterpillars
Author(s) -
Dowd Patrick F.
Publication year - 1988
Publication title -
entomologia experimentalis et applicata
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.765
H-Index - 83
eISSN - 1570-7458
pISSN - 0013-8703
DOI - 10.1111/j.1570-7458.1988.tb02283.x
Subject(s) - kojic acid , aflatoxin , biology , metabolite , citation , library science , food science , biochemistry , computer science , tyrosinase , enzyme
Kojic acid is a secondary fungal metabolite that is commonly produced by many species of Aspergillus and Penicillium (Manabe et al., 1984). These fungi also produce mycotoxins that occur as components of distinctive secondary metabolite profiles, which can serve as reliable chemotaxonomic characters at the species level (Dorner, 1983; Frisvad & Filtenborg, 1983; Wicklow, 1984a). The mycotoxin aflatoxin B1, which is produced by Aspergillus flavus Link: Fr., is highly toxic (LDs0 of 7.2 mg/kg to rats), mutagenic, and carcinogenic (Cole & Cox, 1981). However, kojic acid, which is also produced by A. flavus, is relatively nontoxic (LDs0 of 1765 mg/kg to mice (Cole & Cox, 1981), and has not been implicated in any naturally occurring toxicoses to man or animals (Wilson, 1981). In fact, kojic acid is produced by most of the strains of the domesticated kojic mold, A. oryzae (Ahlburg) Cohn [ = Aspergillusflavus var. oryzae (Kurtzman et al., 1987)] that are used in the preparation of Oriental fermented foods (Murakami, 1971). Mycotoxins are considered to be of adaptive significance in the defense of fungal thalli from predation (Wicklow & Cole, 1982), or in preventing mammals or birds from consuming seeds infected by the fungi (Janzen, 1977). Invertebrates (i.e. insects) are a likely target for these mycotoxins, since they consume a variety of products that are also infested by mycotoxin-producing fungi (Wicklow, 1984b). For example, A. flavus may colonize the developing maize kernels that may also be fed on by the fall armyworm [Spodopterafrugiperda (J. E. Smith)] and the corn earworm [Heliothis zea (Boddie)] (Fortnum, 1985). In higher plants, chemicals that are of low toxicity and co-occur with plant toxins may act as synergists of these toxins (e.g. myristicin and xanthotoxin), although actual demonstration of this phenomenon has been limited (Berenbaum, 1985). Co-occurring mycotoxins may also cause additive or synergistic toxicity to mammals (Ciegler, 1972). Kojic acid has been reported as a synergist of the plant toxin nicotine (Mayer et al., 1946). However, its native or ecological role when produced by A. flavus may be to act as a synergist of the co-occuring aflatoxins. This research investigates the toxicity of aflatoxin B 1 and kojic acid, alone and in combination, to S. frugiperda and H. zea.