Cues for shelter use in a phytophagous insect

Many insects spend a large proportion of their life inactive, often hiding in shelters. The presence of shelters may, therefore, influence where insects feed. This study examines stimuli affecting the use of shelters by adults of the pine weevil, Hylobius abietis (L.) (Coleoptera, Curculionidae). This species is an economically important forest pest in Europe since the adults feed on the stem bark of newly planted conifer seedlings. When there are hiding or burrowing places present in close proximity to a seedling, pine weevils may hide there and repeatedly return to feed on the same seedling. Experiments were conducted in a laboratory arena with above-ground or below-ground shelters and in the presence or absence of wind. Pine weevils were highly attracted to shelters both above and below ground. Weevils in shelters were often observed assuming a characteristic "resting" posture. Experiments with opaque and transparent shelters showed that visual stimuli are used for orientation towards shelters and also increase the probability of an individual remaining in a shelter. The presence of wind increased the weevils' propensity to use shelters both above and below ground. The present study indicates that shelters have a major influence on the behavior of the pine weevil and possible implications of the results are discussed