Articles
Combining an entomopathogenic fungus with predators for biocontrol of spider mites in strawberry tunnel production
Article number
1427_11
Pages
85 – 92
Language
English
Abstract
Strawberry plants are attacked by a complex of arthropods, making it challenging to design biological control strategies for all pest assemblages.
Further, below-ground pests are concealed, creating difficulties in the delivery of biocontrol agents.
Entomopathogenic fungi (EPF) can be applied to the growth medium to target insects directly by infection.
However, several EPF species can also affect insects and mites indirectly through the plant by modulating plant physiology and plant defenses.
Thus, EPF can potentially be utilized to antagonise pests both below- and above-ground allowing for spatially separated application of biocontrol agents.
We evaluated the biocontrol effects of spider mites, Tetranychus urticae, in strawberry production in Denmark, where the EPF Metarhizium brunneum was applied to the growing substrate as biocontrol strategy against soil-borne insect stages.
The below-ground M. brunneum application led to reduced spider mite population growth on above-ground parts of strawberry plants.
Spider mites were also targeted with the predatory mites Neoseiulus cucumeris as macro-biological control agent.
The combined effect of M. brunneum and N. cucumeris was additive in climate room experiments indicating a potential of integrating indirect effects of EPF in biocontrol programmes against T. urticae. Further, the strategy was tested in two commercial strawberry tunnels during one growing season from April till September with a single application of M. brunneum at the start of the season and regular releases of N. cucumeris. The above-ground arthropod pest communities were monitored regularly.
The plots with combined biocontrol applications showed delayed pest population build-up or no difference in comparison to single application or control plots.
In September, M. brunneum successfully infected insect bait larvae in substrate samples.
In this way, belowground application of M. brunneum can have effects against pests above-ground in strawberry production.
Further, below-ground pests are concealed, creating difficulties in the delivery of biocontrol agents.
Entomopathogenic fungi (EPF) can be applied to the growth medium to target insects directly by infection.
However, several EPF species can also affect insects and mites indirectly through the plant by modulating plant physiology and plant defenses.
Thus, EPF can potentially be utilized to antagonise pests both below- and above-ground allowing for spatially separated application of biocontrol agents.
We evaluated the biocontrol effects of spider mites, Tetranychus urticae, in strawberry production in Denmark, where the EPF Metarhizium brunneum was applied to the growing substrate as biocontrol strategy against soil-borne insect stages.
The below-ground M. brunneum application led to reduced spider mite population growth on above-ground parts of strawberry plants.
Spider mites were also targeted with the predatory mites Neoseiulus cucumeris as macro-biological control agent.
The combined effect of M. brunneum and N. cucumeris was additive in climate room experiments indicating a potential of integrating indirect effects of EPF in biocontrol programmes against T. urticae. Further, the strategy was tested in two commercial strawberry tunnels during one growing season from April till September with a single application of M. brunneum at the start of the season and regular releases of N. cucumeris. The above-ground arthropod pest communities were monitored regularly.
The plots with combined biocontrol applications showed delayed pest population build-up or no difference in comparison to single application or control plots.
In September, M. brunneum successfully infected insect bait larvae in substrate samples.
In this way, belowground application of M. brunneum can have effects against pests above-ground in strawberry production.
Publication
Authors
S.K. Jacobsen, N.V. Meyling
Keywords
Fragaria × ananassa, ‘Rumba’, microbial control, indirect effects
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