In Vitro Metabolism of Aflatoxin B_1by Larvae of Navel Orangeworm, Amyelois transitella (Walker) (Insecta, Lepidoptera, Pyralidae) and Codling Moth, Cydia pomonella (L.) (Insecta, Lepidoptera, Tortricidae)

摘要

Larvae of the navel orangeworm (NOW), Amyelois transitell(J (Walker), a major pest of almonds and pistachios, and the co. dling moth (CM), Cydia pomonella (L.), the principal pest oj walnuts and pome fruits, are commonly found in tree nut ker. nels that can be contaminated with aflatoxin, a potent carcino. gen. The ability of larvae of these insects to metabolize aflatoxil1 BI (AFB1) was examined. A field strain of NOW produced threE AFB1 biotransformation products, chiefly aflatoxicol (AFL), anrl minor amounts of aflatoxin B2a (AFB2a) and aflatoxin M] (AFM1). With AFL as a substrate, NOW larvae produced AFB] and aflatoxicol MI (AFLM1). A lab strain of CM larvae producerl no detectable levels of AFB1 biotransformation products il1 comparison to a field strain which produced trace amounts oj only AFL. Neither NOW nor CM produced AFBI-8,9-epoxidE (AFBO), the principal carcinogenic metabolite of AFB1. In com. parison, metabolism of AFB1 by chicken liver yielded mainlJi AFL, whereas mouse liver produced mostly AFM1 at a ratE eightfold greater than AFL. Mouse liver also produced AFBO. The relatively high production of AFL by NOW compared t(J CM may reflect an adaptation to detoxify AFB1. NOW larvaE frequently inhabit environments highly contaminated with fungi and, hence, aflatoxin. Only low amounts, if any, of this mycotoxin occur in the chief CM hosts, walnuts, and pomE fruits. Characterizations of enzymes and co-factors involved in biotransformation of AFB1 are discussed.