Vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), is an economically important insect pest of horticultural crops. To identify an effective and reliable monitoring system for adult vine weevil, this study investigated the influence of colour, height and entrance position on the efficacy of a model monitoring tool using modified paper cups as refuges. Vine weevil preferences were determined by the number of individuals recorded within a refuge. When provided with a binary choice between black or white refuges, vine weevil adults showed a preference for black refuges. Vine weevils provided with a range of coloured refuges (blue, green, red and yellow) in addition to black and white refuges showed a preference for black and blue over the other colours and white refuges in group choice experiments. Refuge height and entrance position also influenced vine weevil behaviour with individuals exhibiting a preference for taller refuges and those with entrance openings around the refuge base. These results provide insights into refuge selection by adult vine weevils, which can be exploited to improve monitoring tool design. The importance of developing an effective monitoring tool for vine weevil adults as part of an integrated pest management programme is discussed.

BACKGROUND: Monitoring is an integral component of integrated pest management (IPM) programmes used to inform crop management decisions. Vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), continues to cause economically significant losses in horticultural crops due to an inability to reliably detect the presence of this species before crop damage occurs. To improve vine weevil monitoring we investigated the behavioural responses of adult vine weevils to visual (monitoring tool shade/colour, height and diameter as well as the effect of monitoring tool and plant density) and olfactory (host plant and conspecifics) cues under glasshouse conditions.RESULTS: Monitoring tool shade, height and diameter all influenced monitoring tool efficacy, with individuals exhibiting a preference for black, tall and wide monitoring tools. The total number of individuals recorded in monitoring tools increased with monitoring tool density. By contrast, plant density did not influence the number of individuals recorded in monitoring tools. Yew‐baited monitoring tools retained a larger number of individuals compared to unbaited ones. Similarly, more vine weevils were recorded in monitoring tools baited with yew and conspecifics than in unbaited monitoring tools or those baited with only yew. Baiting monitoring tools with conspecifics alone did not enhance the number of vine weevils recorded in monitoring tools.CONCLUSIONS: Our study confirms that visual and olfactory cues influence vine weevil behaviour. This provides information on key factors that influence vine weevil monitoring tool efficacy and can be used to inform the development of a new monitoring tool for this pest. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Plant protection products derived from plant material are proposed to be a sustainable alternative to conventional synthetic chemical pesticides. This study determines the efficacy of a commercially available bioinsecticide based on garlic (Allium sativum L.; Asparagales: Amaryllidaceae) extract against vine weevil (Otiorhynchus sulcatus F.; Coleoptera: Curculionidae) eggs and larvae in contact, fumigation and a combination of contact and fumigation bioassays under laboratory conditions. Results showed that garlic significantly reduced egg hatch rate compared to the control group when applied as a fumigant. Similarly, the egg hatch rate was reduced compared to the control group when garlic was applied as combined contact and fumigant applications. No effect was observed when the garlic product was applied as a contact application. The bioinsecticide significantly reduced larval survival when either contact or fumigant applications were used. A combined contact and fumigant effect was shown also when vine weevil eggs were exposed to the bioinsecticide for 30 days in plastic containers containing growing media. The number of larvae recovered after this period was significantly reduced compared to the control group. This study demonstrates the potential of garlic-based bioinsecticides, such as Pitcher GR, for vine weevil control. Further studies are, however, needed to determine the efficacy of such bioinsecticides under field conditions and investigate how these products can be most effectively used as a part of a wider vine weevil integrated pest management program.

Vine weevil ( Otiorhynchus sulcatus Fabricius; Coleoptera: Curculionidae) is an economically important pest of soft fruit and ornamental crops worldwide. Despite extensive research over three decades, the development of an effective semiochemical lure to improve monitoring for this pest remains a challenge. This study investigated the behavioural and electrophysiological responses of adult vine weevils to apple sauce volatiles under laboratory conditions, using Y‐tube olfactometer bioassays and headspace analysis using gas chromatography coupled to mass spectrometry (GC–MS) and GC coupled to electroantennographic detection (GC‐EAD). In Y‐tube bioassays, more adults selected the olfactometer arm containing apple sauce volatiles compared to the control arm at lower doses (0.1, 1 and 10 g) but not at higher doses (20 g). Thirteen compounds were identified in volatiles collected from apple sauce, with the major components being furfural and sorbic acid. Consistent electrophysiological responses were recorded to (E)‐2‐heptenal, 1‐hexanol, (Z)‐3‐hexenol and (E)‐2‐hexenol. The behavioural response of vine weevil adults to refuges baited with semiochemical lures was also tested under glasshouse conditions. In this scenario, a greater proportion of individuals were recorded in refuges baited with apple sauce compared to unbaited refuges. A similar behavioural response was also recorded when refuges were baited with a combination of apple sauce and Fortune's spindle ( Euonymus fortunei (Turcz.) Hand.‐Maz.; Celastrales: Celastraceae) compared to those that were unbaited or individually baited with Fortune's spindle or apple sauce. This study indicates that apple sauce positively influences positively vine weevil behaviour and could serve as a basis for developing a novel lure for improved monitoring.

Vine weevil ( Otiorhynchus sulcatus ) is a major pest of soft fruit and ornamental crops whose nocturnal habits make monitoring challenging and understanding their diel activity is critical for improving detection and informing the timing of control measures. A smart monitoring tool equipped with imaging and environmental sensors was used to monitor adult vine weevil behaviour under semi‐field conditions, capturing 794 detections across 720 ten‐min intervals over 5 monitoring days. Weevil detections were higher during photophase than scotophase (mean ± SE: 9.48 ± 0.76 vs. 1.10 ± 0.50 weevils h ⁻¹ ), indicating refuge‐seeking behaviour in response to increasing light intensity. Generalised linear mixed models identified a strong effect of light condition on weevil activity, with detections 9.5 times more likely during daylight (rate ratio = 9.47, 95% confidence interval [CI]: 4.84–18.52) and presence odds 81 times greater (odds ratio = 81.0, CI: 10.2–645.2; p < 0.001) These results provide direct behavioural evidence of diel activity rhythms in vine weevil, supporting its classification as a nocturnal forager that aggregates in refuges during the day. Smart monitoring systems offer a scalable method for characterising pest behaviour in horticultural environments and can support more effective, behaviourally informed integrated pest management interventions.