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Open Access Publications from the University of California

The Development of Semiochemical Lures for Invasive Rats: An Integrated Chemical Image and Response-Guided Approach

  • Author(s): Jackson, Michael D.
  • Linklater, Wayne L.
  • Keyzers, Robert A.
  • et al.

Olfactory lures are important tools in pest-species management, being widely used to monitor and trap populations. For vertebrates like rats, lures are most commonly foods such as peanut butter. However, these are perishable and require frequent replenishment; factors that decrease control operation efficacy and increase costs. Synthetic semiochemical-based lures might address these limitations, but their identification and use for vertebrate population management remains an underexploited opportunity. We used headspace solid-phase microextraction and gas chromatography-mass spectrometry to characterise the volatile chemical profiles of 19 food products previously presented to wild, free-ranging rats and assessed for attraction. Partial least squares regression identified 10 of the 111 compounds found in two or more analysed products to be statistically significant predictors of attraction. The identity of nine of the compounds was verified using authentic samples, while one was not commercially available. Field trials used tracking tunnels to present compounds at seven different concentrations from 10,000 ppm to 0.01 ppm. Inked cards inside tracking tunnels were used to quantify visitations using species tracking marks, with the presence of rat tracks on inked cards scored to provide a tracking rate. Five compounds outperformed peanut butter while eight individual semiochemical-based lures each statistically outperformed peanut butter. Nearly half of all confirmed visits to compounds were with lures presented at 0.1 and 0.01 ppm. A trend of increasing tracking rates with decreasing lure concentration was identified for aggregated compound data. Our results suggest a number of compounds have the potential for onward development as synthetic attractants for rats. Further, the results support our integrated chemical image and response-guided approach that statistically associated behavioural responses to a range of products with the volatile compounds in those products. This approach has the potential to identify semiochemical compounds, either allelochemical or pheromone, for use as olfactory lures for managing and monitoring a range of vertebrate pest species.

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