Environmental safety of entomopathogenic nematodes – Effects on abundance,
diversity and community structure of non-target beetles in a forest ecosystem
The large pine weevil, Hylobius abietis, is a serious threat to reforestation in Europe that necessitates routine
use of chemical insecticides. Application of entomopathogenic nematodes (EPN) to the coniferous
tree stumps in which weevils breed has the potential to reduce the use of chemical pesticides. During
field trials to assess the efficacy of nematodes against pine weevil, non-target beetles were also identified
and quantified on 10 sites (14 trials). Nematodes were applied to stumps between June and July. Emergence
traps captured beetles exiting from nematode-treated and untreated control stumps. Four trials
were monitored in the months immediately following nematode application and ten were monitored
the year after nematode application.
A total of 65 species of non-target beetles were recovered, including 11 saproxylic species. We found no
evidence of an effect of applied EPN on non-target beetle species richness, abundance, species richness
per individual collected, or Shannon’s entropy (H’) either immediately or a year after nematode application,
when more wood-specialists were recorded. As expected, there were marked differences between
sites and/or tree species in the populations of non-target beetles recovered.
These results indicate that when EPN are applied in a forest ecosystem to suppress H. abietis populations,
the risk to non-target coleopteran populations must be considered negligible