RESEARCH NOTE PHOTOTOXICITY OF CITRAL TO Trichoplusia ni (LEPIDOPTERA: NOCTUIDAE) AND ITS AMELIORATION BY VITAMIN A

Abstract Citral, a monoterpene aldehyde synthesized by several plant families, was recently shown to exhibit ultraviolet A light (320–400 nm) (UVA)-enhanced oxygen-dependent toxicity against bacteria and fungi ( Escherichia coli and Fusarium species). In this study, we report for the first time that citral is phototoxic to insects; at concentrations of 300 ppm in artificial diet, mortality of first instar Trichoplusia ni (cabbage loopers) approached 30% after 120 h of UVA exposure, approximately double the mortality level in the absence of UVA. At 300 ppm, the antioxidant vitamin A reduces citral phototoxicity by about 50% in this species, suggesting that citral phototoxicity against insects is oxygen dependent.