title: Midgut serine proteases and alternative host plant utilization in Pieris brassicae L.
abstract: Pieris brassicae L. is a serious pest of cultivated crucifers in several parts of the world. Larvae of P. brassicae also feed prolifically on garden nasturtium (Tropaeolum majus L., of the family Tropaeolaceae). Proteolytic digestion was studied in larvae feeding on multiple hosts. Fourth instars were collected from cauliflower fields before transfer onto detached, aerial tissues of selected host plants in the lab. Variable levels of midgut proteases were detected in larvae fed on different hosts using protein substrates (casein and recombinant RBCL cloned from cauliflower) and diagnostic, synthetic substrates. Qualitative changes in midgut trypsin activities and quantitative changes in midgut chymotrypsin activities were implicated in physiological adaptation of larvae transferred to T. majus. Midgut proteolytic activities were inhibited to different extents by serine protease inhibitors, including putative trypsin inhibitors isolated from herbivore-attacked and herbivore-free leaves of cauliflower (CfTI) and T. majus (TpTI). Transfer of larvae to T. majus significantly influenced feeding parameters but not necessarily when transferred to different tissues of the same host. Results obtained are relevant for devising sustainable pest management strategies, including transgenic approaches using genes encoding plant protease inhibitors.
authors: Insect-Plant Interactions Group, Department of Botany, Delhi University Delhi, India.
authors: Rakesh
authors: R
authors: Kumar
authors: Insect-Plant Interactions Group, Department of Botany, Delhi University Delhi, India.
authors: Usha
authors: U
authors: Bhardwaj
authors: Insect-Plant Interactions Group, Department of Botany, Delhi University Delhi, India.
authors: Pawan
authors: P
authors: Kumar
authors: Insect-Plant Interactions Group, Department of Botany, Delhi University Delhi, India.
authors: Sudeshna
authors: S
authors: Mazumdar-Leighton
keywords: digestive physiology; lepidoptera; nutrition; plant protease inhibitors; serine proteases