Analysis of Tea Geometrid (Ectropis grisescens) Pheromone Gland Extracts Using GC-EAD and GC×GC/TOFMS

Abstract

The tea geometrid, Ectropis grisescens Warren, is one of the most severe defoliator insect pests in tea plantations, China. The use of insecticides, etc., is forbidden on organic tea plantations. No female-produced sex pheromones of E. grisescens had been previously identified. In the present study, female gland extracts were analyzed by gas chromatography coupled with electroantennographic detection (GC-EAD) and two-dimensional gas chromatography (GC×GC) using a time-of-flight mass spectrometric detector (TOFMS). Two components, (Z,Z,Z)-3,6,9-octadecatriene (Z3Z6Z9-18:Hy) and (Z,Z)-3,9-6,7-epoxyoctadecadiene (Z3Z9-6,7-epo-18:Hy), were identified from pheromone gland extracts, and their electrophysiological and behavioral activity evaluated. Under laboratory conditions, Z3Z9-6,7-epo-18:Hy elicited a stronger electrophysiological response than Z3Z6Z9-18:Hy. In the field, traps baited with Z3Z9-6,7-epo-18:Hy alone showed better results than traps baited with Z3Z6Z9-18:Hy, and the binary mixture of Z3Z9-6,7-epo-18:Hy and Z3Z6Z9-18:Hy in a ratio of 4:1 (approximate ratio of females emitting pheromone) caught more males than the single components or any other blends. This study showed that Z3Z6Z9-18:Hy and Z3Z9-6,7-epo-18:Hy are the sex pheromone components of E. grisescens and that they prove useful in developing alternative management tools for the pest.

Development and Evaluation of Sex Pheromone Mass Trapping Technology for Ectropis grisescens: A Potential Integrated Pest Management Strategy

“…In this study, the efficiencies of different ratios, dosages, dispensers, and traps were assessed. For the sex pheromone components, Z3,Z6,Z9-18:H and Z3,epo6,Z9-18:H, a ratio of 20:80 was previously found to promote the strongest attraction [9], which is similar to the results of our study. However, we tested a greater number of treatment ratios, and the 30:70 treatment ratio was more attractive than 20:80, although there was no difference.…”

“…Moths of the family Geometridae usually produce type II sex pheromones, i.e., C 17-23 polyunsaturated hydrocarbons and their epoxy derivatives [14]. However, E. grisescens uses two chemical components for chemical communication Z3,Z6,Z9-18:H and Z3,epo6,Z9-18:H [9,15]. In this study, we preferred mass trapping rather than mating disruption to control this pest because mating disruption requires a large amount of pheromone [16], and the synthesis of a uniquely structured sex pheromone or the purification of isomers is a costly process [7,17].…”

“…Previously, both our group and another research team completed the analysis of the sex pheromone of E. grisescens [9,10]. The two published studies show the sex pheromone components of E. grisescens females to be (Z,Z,Z)-3,6,9-octadecatriene (Z3,Z6,Z9-18:H) and (Z,Z)-3,9-cis-6,7-epoxy-octadecadiene (Z3,epo6,Z9-18:H).…”

Comparison of male antennal morphology and sensilla physiology for sex pheromone olfactory sensing between sibling moth species: Ectropis grisescens and Ectropis obliqua (Geometridae)

“…In closely related moth species, females usually emit chemical blends that contain different ratios of similar components to attract conspecific males (Chang et al, ; Foster & Roelofs, ; Martin, Moore, Musto, & Linn, ; Wu, Hou, Huang, Yan, & Wang, ). Each of the components of the blend is essential for maximal behavioral responses (Ma, Bian, et al, ; Ma, Xiao, et al, ; Molnár et al, ; Xu et al, ). Thus, elucidating the mechanisms behind accurate sex pheromone recognition in closely related species is important for understanding interspecific reproductive isolation.…”

“…Ectropis grisescens and Ectropis obliqua are closely related to herbivorous pest species of tea plantations. The principal sex pheromone components of E. grisescens ’ are (Z,Z,Z)‐3,6,9‐octadecatriene (abbreviated as Z3,Z6,Z9–18:H) and (Z,Z)‐3,9‐ cis ‐6,7‐epoxy‐octadecadiene (Z3,epo6,Z9–18:H) at a ratio of 4:6 (Ma, Bian, et al, ; Ma, Xiao, et al, ). For E. obliqua , the components are Z3,epo6,Z9–18:H, Z3,Z6,Z9–18:H, and (Z,Z)‐3,9‐ cis ‐6,7‐epoxy‐nonadecadiene (Z3,epo6,Z9–19:H) at a ratio of 4:2:4 (Luo, Li, Cai, Bian, & Chen, ).…”