LE3 .A278 2022

2022

Hillier, Kirk
Koerte, Sarah

Acadia University

Bachelor of Science

Honours

Biology

Biology

Long’s Braya (Braya longii) is a member of the Brassicaceae family and an endangered plant species found only in the Northern Peninsula of Newfoundland. Every year, B. longii is subject to infestations of the diamondback moth (Plutella xylostella), wherein their larvae consume and eventually kill B. longii. Around the world, P. xylostella is a notorious agricultural pest that is difficult to manage due to its resistance to both chemical and biological insecticides. In this study, volatile organic compounds (VOCs) of B. longii and other members of the Brassicaceae were collected and their composition were analysed. Volatile compositions from previous studies of Brassica spp. were also compared with B. longii to identify key compounds that may cause behavioural attraction in P. xylostella. Afterwards, P. xylostella were subject to these host plant volatiles as well as individual key compounds using Gas Chromatography coupled with Electroantennographic Detection (GC-EAD), Electroantennography (EAG) and oviposition assays to study antennal responses and egg-laying behaviour. A putative attractive compound eliciting an antennal response in P. xylostella identified from broccoli and rutabaga GC-EAD trials was 1-undecanol, however positive identification remains to be conducted through comparison with analytical standards on Gas Chromatography Mass Spectrometry (GC-MS). Compounds chosen for EAG screenings were hexanal, octanal, nonanal, ethyl palmitate, 1-octanol and (Z)-3-hexenol, and were diluted to 10 ng/μL-10 μg/μL concentrations. We found that (Z)-3-hexenol, octanal and 1-octanol at concentrations of 1 and 10 μg/μL elicited antennal responses in P. xylostella during EAG recordings. Afterwards, octanal, nonanal and (Z)-3-hexenol were selected for behavioural assays. We noted that P. xylostella was more attracted to (Z)-3-hexenol treated radish at 10 μg at oviposition sites. However, there was no preference to either control or treatment when lures were raised to 100 μg loads. EAG screening found differences in antennal responses to key alkanals. While octanal and nonanal elicited antennal responses, they did not provide any significant behavioural preference for either control or treatment. The data collected from this study provides electrophysiological and behavioural responses of P. xylostella to VOCs emitted from Braya longii and Brassica host plants. Future studies should replicate GC-EAD trials and provide a definite identification of potential key compounds so a host-finding mechanism can be found. This knowledge could then be used to develop novel tools for the pest management of P. xylostella.

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https://scholar.acadiau.ca/islandora/object/theses:3754