The effect of host plant secondary metabolites on development and survival of Grammia spp. (Lepidoptera: Erebidae: Arctiinae: Arctiini)

Larvae of the Arctiinae use an impressive arsenal of defenses to protect themselves against natural enemies. Several species within this subfamily have been studied for their defensive capabilities, specifically the use of plant secondary metabolites. Life history and sequestration patterns of secondary metabolites have been well documented for Grammia incorrupta; however, little information exists for other species of Grammia. Furthermore, information on sequestration patterns during the larval instars of several Grammia spp. is largely unknown. To address these gaps in knowledge, we conducted a comparative study of the chemical ecology and life history traits for the virgin tiger moth (Grammia virgo), the little virgin tiger moth (Grammia virguncula) and the figured tiger moth (Grammia figurata) throughout larval development. We divided larvae into four diet treatment groups: white clover (Trifolium repens), broadleaf plantain (Plantago major), narrowleaf plantain (Plantago lanceolata), and wheat-germ based artificial diet. Plant secondary metabolites found in these Plantago species impact larval development and growth. We collected data on weight gain, development time and overall survivorship for all three species to determine if there were any significant impacts to their overall development. Larval growth and development was maximized in groups feeding on the artificial diet; the second most successful groups varied by species of Grammia, which fed on P. major or P. lanceolata. These results indicate that species of Grammia have differing responses to species of Plantago, which may result in local adaptations between moth species in this lineage.