Identification and testing of sex pheromone components of the invasive Australian redback spider (Lactrodectus hasseltii)

Australian redback spiders Latrodectus hasseltii, known for their strong neurotoxic venom, are a quarantine threat for much of the world. Female redback spiders produce a sex pheromone that attracts males of the species, yet the compounds involved in their attraction remain unresolved. Our project set out to identify these compounds and use them to trap male redback spiders as the first step in the development of a pest management/surveillance tool for these spiders. Headspace volatiles from the silk of virgin and mated female redback spiders was collected by solid phase microextraction and analysed by gas chromatography coupled with mass spectrometry. Silk samples were also solvent extracted for analysis by liquid chromatography coupled with mass spectrometry. Comparison with synthetic standards on multiple column phases identified the candidate volatile pheromone components as 2-methylpropanoic acid, (S)-2-methylbutanoic acid and 2-pyrrolidone, while N-3-methylbutanoyl-O-(S)-2-methylbutanoyl-L-serine was identified as the main candidate short-range cue. Bioassays with a combination of these four compounds showed similar levels of attraction to the natural virgin female’s silk. Field trapping trials using a mixture of all four compounds successfully trapped male redback spiders in New Zealand vineyards.