Response of Two Pieris (Lepidoptera: Pieridae) Species to Fertilization of a Host Plant

Abstract

study, we explored relationships among plant fertilization, plant phytochemical compositions, and the perfor-mance of Pieris butterfly larvae. Cabbages (Brassica oleracea var. capitata L.) were grown under 2 levels of nutrients, and their foliar chemistry (water, nitrogen, and total glucosinolates) was measured. Two species of cabbage white butterflies, Pieris rapae crucivora and P. canidia canidia, were reared on foliage from each of the 2 treatments to measure insect performance. Oviposition responses of P. rapae crucivora and P. canidia canidia to fertilized vs. unfertilized host plants were compared using choice tests. Foliar water and nitrogen contents increased with increased nutrient availability. Concentrations of total glucosinolates, however, decreased with increased nutrient availability. For the most part, insect performance varied significantly between the 2 nutrient treatments. Both insect species performed well on the fertilized treatments which con-tained high water and nitrogen, but low glucosinolate contents. Ovipositional female butterflies of both species were also found to prefer fertilized plants. Finally, our results also indicate that P. rapae crucivora performed relatively better on high-nutrient plants.