Differential toxicity of juglone (5-hydroxy-1,4-naphthoquinone) and related naphthoquinones to saturniid moths

Abstract

The preferred hosts of the saturniid mothActias luna include members of the Juglandaceae, whose foliage contain the toxin juglone (5-hydroxy-1,4-naphthoquinone). The performance ofActias luna andCallosamia 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 toC. promethea, caused negative growth rate, and a 3.6-fold decrease in consumption rate. The performance ofA. 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 onA. 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-instarA. luna are clearly resistant to juglone compared toC. promethea, and early-instarA. 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.