Changes in Trace Metals in Hemolymph of Baculovirus-Infected Noctuid Larvae

We studied how biologically relevant trace metals (i.e., micronutrients) in the hemolymph of larval Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae) changed in response to per os baculovirus infection, larval development, and injection of heat-killed bacteria. Concentrations of hemolymph Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, and Zn were measured using inductively coupled plasma-mass spectrometry. H. virescens larvae exhibited greater fluctuations in hemolymph trace metal levels in response to baculovirus infection and development than did H. zea larvae. H. zea single nucleopolyhedrosis virus infection significantly altered the levels of Cu, Fe, Mg, Mn, Mo, and Zn in fourth instar H. virescens larvae. Conversely, in fifth instar H. virescens and both H. zea instar infections, no metal levels were significantly different between infected and uninfected larvae. In fourth instar H. virescens hemolymph, Cu, Fe, Mo, and Zn increased during development. Cu, Fe, Mg, Mn, Mo, and Zn levels changed significantly during development in fifth instar H. virescens as well as both H. zea instars. Based on this analysis, metals were identified whose levels changed during development in both species and during the immune response of H. virescens larvae.