Oviposition preference of the forest cockchafer (Melolontha hippocastani Fabr. 1801) at the stand scale depends on oak proportion, canopy openness and ground accessibility

Key message

Melolontha hippocastani is a major pest in European mixed and broadleaf forests. Investigating its oviposition behavior, we observed that a dense shrub layer reduces the density of egg clusters and eggs in the soil. Conversely, canopy openness and a large proportion of oak appear as favoring conditions.

Abstract

Context Melolontha hippocastani is a major pest in European mixed and broadleaf forests. In north-eastern France, an epidemic phase has been observed since 2007, characterized by a high mortality rate of seedlings and young trees, and by massive swarming flights every 4 years.
Aims We investigated the oviposition behavior of M. hippocastani in the northern Vosges Mountains.
Methods We set up study plots in the infected area after adults had emerged and the females had laid their eggs. We excavated pits and counted the eggs and egg clusters they contained. We also carried out dendrometric surveys.
Results A dense shrub layer had a negative effect on the density of egg clusters and the number of eggs in the soil, while canopy openness and the proportion of oak basal area had positive effects.
Conclusion We hypothesized that a dense shrub layer could create a barrier for females. On the other hand, an open canopy may improve conditions for the larvae in the soil, just as a high proportion of oak trees in the surrounding area may provide a good food source for both larvae and adults. We suggest several research orientations and propose guidelines for forest management in view of our results.

Keywords
Forest dieback; Forest health; Egg-laying site; Insect ecology; Integrated pest management; Optimal oviposition theory; Optimal foraging theory; Associational resistance

Publication
Cours, J., Nageleisen, LM., Touffait, R. et al. Oviposition preference of the forest cockchafer (Melolontha hippocastani Fabr. 1801) at the stand scale depends on oak proportion, canopy openness and ground accessibility. Annals of Forest Science 78, 53 (2021). https://doi.org/10.1007/s13595-021-01066-z

For the read-only version of the full text:
https://rdcu.be/cmElA

Data availability
The datasets generated during and/or analyzed during the current study are available in the Knowledge Network for Biocomplexity (KNB) repository, https://doi.org/10.5063/7D2SJ6

Topical Collection
This article is part of the Topical Collection “Entomological issues during forest diebacks

Handling Editor
Erwin Dreyer

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