DIFFERENTIAL TOXICITY OF JUGLONE (5-HYDROXY-1,4-NAPHTHOQUINONE) AND RELATED NAPHTHOQUINONES TO SATURNIID MOTHS

The preferred hosts of the saturniid moth Actias luna include members of the Juglandaceae, whose foliage contain the toxin juglone (5-hydroxy-1,4-naphthoquinone). The performance of Actias luna and Callosamia promethea was compared when fourth-instar larvae of each were fed birch foliage, a mutually acceptable food plant, or birth supplemented with 0.05% (w/w) juglone. A. luna fed juglone exhibited no changes in developmental time or mortality compared to a diet without juglone. In contrast, juglone-supplemented diets, when fed to C promethea, caused negative growth rate, and a 3.6-fold decrease in consumption rate. The performance of A. luna also was compared on birch and walnut; larvae developed and grew more rapidly on an all-walnut vs. an all-birch diet. To examine the effect of 1,4-naphthoquinone structure on A. luna survival, first instars were fed on birch supplemented with varying concentrations of juglone (J), menadione (M), plumbagin (P), or lawsone (L). In diets supplemented at 0.05% (w/w), none of the compounds produced effects significantly different from controls. In diets supplemented at 0.5% (w/w), the treatments produced significant toxic effects in the order P > M = L > J for mortality, and P > L > M = J for increased developmental time. Late-instar A. luna are clearly resistant to juglone compared to C promethea, and early-instar A. luna are resistant to several related 1,4-naphthoquinones. These results suggest a chemical basis for host choice among saturniids. In addition, the luna-walnut system may be a valuable model for studying quinone detoxication.