Analyzing the Composition of Necromone Solutions Intended as Pest Deterrents
Harmonia axyridis are known pests in the wine industry, as they secrete 2-isopropyl-3-methoxypyrazine (IPMP) when stressed, a compound with an unpleasant taste and odour. When H. axyridis secrete IPMP on grapes, it negatively impacts wine produced from the grapes. Upon death, the beetles also release necromones, a class of fatty acid pheromones, which alert other beetles of danger and to avoid an area. To evaluate the potential of necromones as pest deterrents, we proposed an experiment where H. axyridis bodies are placed in 95% ethanol for five days to create necromone solutions, and the presence of the compounds is confirmed through GC-FID-MS. The fatty acid necromones are derivatized with 8% methanolic hydrochloric acid to form fatty acid methyl esters (FAMEs), while IPMP does not undergo derivatization. Sodium bicarbonate neutralizes any remaining acid, and the FAMEs and IPMP are extracted with hexane. C18D35 is spiked into each solution as an internal standard, and 1 ‘_L of solution is injected into the GC-FID-MS. To estimate the presence of the analytes, the signal peaks are compared to those of pure standard solutions to determine the presence of the analytes. The presence of the necromones in these solutions would indicate the potential of the solutions as pest deterrents, while the presence of IPMP would negate the purpose of the necromones as the quality of the wine would still be compromised. Determining the potential of necromone solutions as pest deterrents would benefit the wine industry by contributing to the preservation of wine taste and odour.