Plasma trace metals change due to development and baculovirus infection in larval Heliothis

We studied how biologically relevant trace metals (i.e, micronutrients) in the plasma of larvae of Heliothis virescens and Helicoverpa zea (Lepidoptera:Noctuidae) changed in response to larval development, per os baculovirus infection, and injection of heat-killed bacteria. Levels of plasma 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 plasma trace metal levels in response to development and baculovirus infection than did H. zea larvae. In fourth instar H. virescens plasma, all metal levels changed during development except Ni while only levels of Cu, Fe, Mg, and Zn changed during development of fifth instar H. virescens. For both H. zea instars, Cu, Fe, Mg, Mn, Mo, and Zn levels changed significantly. In response to H. zea single nucleopolyhedrosis virus infection, the levels of Cu, Fe, Mg, Mn, Mo, and Zn were altered significantly 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. For both H. virescens and H. zea, no metal levels changed in response to bacterial injection in fifth instar larvae. Based on this analysis, metals were identified whose levels changed during development in both species and during the immune response of H. virescens larvae.