Elucidating novel biopesticide modes of action in insects : physiological, cellular and molecular approaches

Abstract

This PhD project forms a significant, embedded part of the project, "Novel insecticides and synergists from endemic and exotic flora", funded by the Cotton Research and Development Corporation (CRDC), 2015-2018. I aimed to identify and develop new tools for integrated pest management (IPM) in cotton (Gossypium hirsutum). While adoption of transgenic cotton has resulted in reduced synthetic insecticide use against the cotton bollworms Helicoverpa spp., secondary pests such as two-spotted spider mite, cotton aphid, green mirid, and silverleaf whitefly continue to be of concern. Thus, there is an urgent need to investigate and develop novel options, such as biopesticides and semiochemicals for insect pest management. My proof-of-concept study employed two insect cell lines and evaluated three pyrethroid insecticides by combining three in vitro methods, absorbance spectrometry, confocal scanning laser microscopy (CSLM) and microelectrode ion flux estimation (MIFE) to assist in elucidating possible mode of action, which could be adopted to evaluate insecticidal activity of complex, unknown, or multi-constituent formulations. A laboratory direct application insect bioassay utilising a Potter precision spray tower was employed during the initial foundation project to screen over 400 plant extracts for their efficacy on a selection of cotton insects, after which I identified 20 extracts for further experimentation. In summary, by targeting ion transport, ROS production, chemoreceptors and their associated genes in insect cells and insects, there is a great potential to develop reliable laboratory screening methods to identify novel and environmental friendly botanical pesticides for Australian and global agricultural industry in the future.

Date of Award	2020
Original language	English