Canadian Forest Service Publications
Anatomy of the stridulation apparatus of the beech leaf-mining weevil (Coleoptera: Curculionidae) and behavioural responses to stridulation sounds. 2019. Goodwin, J.; Hillier, N.K.; Roscoe, L.E.; Sweeney, J.D. Entomologia Experimentalis et Applicata 167 (11).
Issued by: Atlantic Forestry Centre
Catalog ID: 40549
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We investigated auditory signals and morphology of the stridulatory apparatus of the European beech leaf-mining weevil, Orchestes fagi L. (Coleoptera: Curculionidae), an invasive herbivore now established in Nova Scotia, Canada, to determine their potential for enhancing survey tools to monitor the spread of the species in Canada. We recorded and described sounds produced by adult O. fagi, analyzed the morphology of the stridulatory mechanism for intersexual differences and asymmetry, and examined behavioral responses elicited in conspecifics by playback of stridulation recordings. Adult O. fagi produced sounds under three conditions: male in distress, female in distress, and male in the presence of female. Female distress chirps lasted significantly longer than male distress chirps and male chirps in the presence of females, but peak frequencies and mean number of chirps per s did not differ significantly among the three groups. Morphology of the stridulation structures in male and female O. fagi was compared using scanning electron microscopy. Orchestes fagi have an elytro-tergal file- and scraper-type sound production apparatus, through which sound is produced upon anterior motion of the abdomen. Female O. fagi have a ‘pars stridens’ that is longer and has more ridges than males. Width and number of ridges per length of pars stridens did not differ between the sexes. Evidence of asymmetry was found in male pars stridens, with the right side being longer than the left. Playback of recorded sounds to adult weevils suggests female O. fagi were repelled by sounds produced by distressed males.
Plain Language Summary
The beech leaf-mining weevil is an invasive forest insect pest from Europe now established and spreading in Nova Scotia. More than 5 years of successive defoliation by the weevil has caused more than 90% mortality of American beech in infested stands. Mitigation of the beech weevil’s impact requires effective survey tools to monitor its spread in Nova Scotia and the rest of North America. Other studies have shown that combining visual, auditory, and olfactory cues can greatly increase attraction of certain insects compared to any one modality alone. This study explored whether sounds produced by the weevil could be used to enhance the efficacy of a survey trap. The morphology of stridulatory organs (file and scraper) was examined, and sounds made by the weevils under distress and during presumed courtship were recorded and played back to male and female weevils to observe their behavioral responses (e.g., attraction). Male distress sounds repelled female weevils, but other sounds by males or females had no apparent effect on behavior of either sex.