Vibration-induced freezing in <i>Aegorhinus nodipennis</i> (Coleoptera: Curculionidae): implications for pest management in hazelnuts

The weevil Aegorhinus nodipennis (Coleoptera: Curculionidae) (Hope, 1834) is a polyphagous woodboring beetle of economic concern in Chile and southern Argentina, mainly affecting berries and hazelnut. Although insecticides may be applied in hazelnut orchards, their effectiveness is limited and can be environmentally impactful, underscoring the need for alternative, sustainable control strategies. Attempts to exploit semiochemicals for attraction or repellence have yielded only modest results, failing to support effective trapping or deterrence. This study investigates substrate-borne vibrations as a complementary behavioral management tool by examining their potential to induce defensive responses in A. nodipennis. We demonstrate that walking individuals exhibit a stereotyped freezing response to vibrational stimuli, with peak sensitivity at 50 to 150 Hz (median threshold at 0.71 m/s2) and a secondary sensitivity increase at 1-2 kHz. The duration of the immobile phase increases strongly with stimulus duration, with a median around 200 s following a 5 s stimulus, but is much less affected by amplitude once the threshold is exceeded. In addition, weevils exhibit a marked postfreeze locomotor suppression, with walking speed reduced to 25% to 30% of prestimulus levels. These findings suggest that extended low-amplitude vibrational stimuli could effectively suppress activity and feeding. This offers a novel, nonchemical, and potentially economically viable approach in managing this pest. Deterrent vibrations could be deployed directly on host plants or on structural barriers in orchards. This study provides a foundation for integrating vibrational cues into pest management frameworks for A. nodipennis and related weevils, though results are currently limited to females.