Selection of hibernation sites by Anthonomus pomorum: preferences and ecological consequences

Abstract

The apple blossom weevil, Anthonomus pomorum (L.) (Coleoptera: Curculionidae), has a long period of aestivo‐hibernation in the adult stage lasting from summer to early spring of the following year. Potential hibernation sites within an apple orchard consist of high‐stem rough‐bark trees or dwarf smooth‐bark trees. Field release‐recapture experiments in 2 consecutive years showed that 64 and 47% of the weevils remained in the vicinity of the release sites in an area of high‐stem trees and dwarf trees, respectively. The dispersing weevils moved over an average distance of 5.5 m in the dwarf tree area, as compared to 3.8 m in the high‐stem tree area. The prevalent direction of dispersal was along tree rows in both areas. Some weevils displayed, after release in mid‐July, a directional dispersal to the adjacent forests. Others, released in the dwarf tree area, dispersed towards the area of high‐stem rough‐bark apple trees. Experiments simulating various hibernation sites demonstrated that the litter of dry leaves was the most preferred overwintering shelter, yielding a relatively high survival rate. Branches with rough bark ranked second, while branches with smooth bark, grass and pure soil were not favourable for overwintering. Flight tendency in newly emerged weevils of summer generation was significantly higher in June/July than in August/September. This corresponds to the dispersal behaviour in the field. The timing of spring colonisation of apple trees was similar for weevils overwintering within the orchard and for those from outside. These results suggest that modern, dwarf apple orchards offer unfavourable conditions for overwintering, but that the relatively small proportion of weevils which manage to reach the adjacent forests find optimal hibernation sites there.

Are landscape structures insurmountable barriers for foraging bees? A mark-recapture study with two solitary pollen specialist species

“…While recapture rates found in the present study are well within the range of recaptures measured for species of other insect groups in search of their key resources (Toepfer et al, 1999(Toepfer et al, , 2000Haddad et al, 2008), they are lower than those reported in other studies with pollen specialist bee species (Bischoff, 2003;Franzen et al, 2009).…”

Phenological analysis of spring colonisation of apple trees by Anthonomus pomorum

“…Thus, in summer-autumn overwintering weevils are obliged to leave the orchard and to hibernate in adjacent forests or woodlands (Toepfer et al, 2000), and following early spring overwintered weevils must disperse into orchards to colonize apple trees (Toepfer et al, 1999). A modern dwarf apple orchard does not offer adequate shelter under loose bark and leaf litter for overwintering weevils.…”

Differential susceptibility and suitability of domestic and wild apple species for a florivorous weevil and its parasitoids

“…Tree bark structure (bark roughness), which may represent shelter and hibernation sites for the weevils (Troitzky ; Toepfer et al. ), was recorded in three categories: (i) smooth bark, (ii) partially rough bark (mostly in the lower parts of the trunk) and (iii) rough bark (along the whole trunk). Bud density, which was suggested to influence host preference of A. pomorum by Brown et al.…”