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-hydrox y-1,4-naphthoquinone). The performance of Actias luna and Callosamia p romethea 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 deve lopmental time or mortality compared to a diet without juglone. In con trast, juglone-supplemented diets, when fed to C promethea, caused neg ative growth rate, and a 3.6-fold decrease in consumption rate. The pe rformance of A. luna also was compared on birch and walnut; larvae dev eloped and grew more rapidly on an all-walnut vs. an all-birch diet. T o examine the effect of 1,4-naphthoquinone structure on A. luna surviv al, first instars were fed on birch supplemented with varying concentr ations of juglone (J), menadione (M), plumbagin (P), or lawsone (L). I n diets supplemented at 0.05% (w/w), none of the compounds produced ef fects significantly different from controls. In diets supplemented at 0.5% (w/w), the treatments produced significant toxic effects in the o rder P > M = L > J for mortality, and P > L > M = J for increased deve lopmental time. Late-instar A. luna are clearly resistant to juglone c ompared to C promethea, and early-instar A. luna are resistant to seve ral related 1,4-naphthoquinones. These results suggest a chemical basi s for host choice among saturniids. In addition, the luna-walnut syste m may be a valuable model for studying quinone detoxication.