Improving the monitoring tool for banana-spotting bug: chemical analysis and behavioural assays

<p dir="ltr">The banana-spotting bug, <i>Amblypelta lutescens lutescens</i> is a highly polyphagous, native pest insect posing a significant concern to growers of macadamia, avocado and other important horticultural crops in northern NSW and Queensland. Early detection is crucial for informed decision making in pest management. Monitoring the insect, however, is challenging due to their highly cryptic behaviour. Despite a commercially available lure system, the banana-spotting bug is still a top horticultural threat, necessitating improvement.</p><p dir="ltr">This thesis aims to improve the current system by investigating and analysing the volatiles emitted by male and pair banana-spotting bugs, and the commercially available lure. The study seeks to identify differences in the chemical profiles, understand their role in olfactory-mediated behaviour, and determine if the insect expresses any clear preferences.</p><p dir="ltr">Using gas chromatography-mass spectrometry, we analysed headspace profiles of banana-spotting bug males, mating pairs, and the commercial lure composition. Y-tube olfactometer bioassays tested adult male and female responses to the volatiles of live males, pairs, the commercial lure, and modified volatile blend ‒ designed based on insect headspace and commercial lure analyses – against a blank control. We also compared live males against pairs, and the commercial lure against the modified blend.</p><p dir="ltr">The bioassays revealed that males and females demonstrate significant preference for the volatiles from live males and mating pairs, over the blank control. Male insects expressed a significant preference for the commercial lure and modified blend over a blank control. Females chose the lure and modified blend at a higher, but not statistically significant rate. When two volatile options were exposed to the insects, neither males, nor females expressed preference. These findings, including the distinct volatile profiles and the behavioural responses highlight promising avenues for optimising the banana-spotting bug monitoring tool.</p>