Poster Display
Physiology, Biochemistry, and Toxicology
Tobias E. Ziemke
Middlebury College
Ithaca, New York
Christophe Duplais
Cornell University
Geneva, New York
Ping Wang
Cornell University
Ithaca, New York
Phytophagous insects employ a variety of detoxification strategies to counteract chemical defenses in their host plant. While enzymatic detoxification and target site mutagenesis are well-documented, the quantitative contribution of excretion remains understudied. We focus on the cabbage looper (Trichoplusia ni), a generalist herbivore, to elucidate the detoxification of a steroidal alkaloid, solanidine, produced in potato (Solanum tuberosum). Through feeding experiments and high-resolution mass spectrometry, we identify solanidine 3-O-b-glucopyranoside and solanidine 3-phosphate as major detoxification metabolites. Consequently, we find that UDP-glycosyltransferases and phosphate transferases, not previously observed in T. ni, are key detoxification enzymes of solanidine. Modified solanidine derivatives exhibit reduced lipophilicity, preventing passive transport from the gut, as predicted by physicochemical analyses. Correspondingly, only solanidine was detected in body tissue. A Bt-resistant strain of T. ni, with a mutated cadherin gut membrane protein, shows lower solanidine uptake compared to the wild-type strain but similar excretion kinetics. Our study expands the detoxification enzyme repertoire in T. ni, emphasizing the complexity of detoxification mechanisms in generalist herbivores. Understanding these processes contribute to developing effective pest control strategies using RNA interference.