Paper · 2026 · Crop Protection

Abiotic, biotic and intrinsic factors limiting the effectiveness of two new Metarhizium brunneum formulations against wireworms in potato cultivation

Maximilian Paluch; Tanja Seib; Dietrich Stephan; et al.

6
claims
14
verbatim quotes
0
citations
2
research areas
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Open access · cc-by

Abstract

Wireworms ( Agriotes spp.), the soil-dwelling larvae of click beetles (Coleoptera: Elateridae), are a major pest in German potato cultivation. As there are currently no officially approved agrochemicals to protect against tuber damage, biological alternatives such as the use of entomopathogenic fungi are urgently needed. This study investigated the effectiveness of two new formulations of Metarhizium brunneum (AgriMet-granule and AgriMet-powder) for their effectiveness against wireworms under field, greenhouse, and laboratory conditions. Both formulations showed limited effectiveness in reducing tuber damage in field trials (13.6%), with key influencing factors identified as high pest pressure, low soil temperatures during application (9.8-14.7 °C), limited fungal proliferation (max. 959.9 CFU g -1 ) and poor product stability. Greenhouse tests revealed an increase in effectiveness (44-54%) under controlled conditions and at higher application rates (300 kg ha -1 or 1×10 13 conidia ha -1 ), but these levels are neither economically nor technically feasible for practical use. Laboratory bioassays with A. obscurus , A. lineatus and A. sputator confirmed species-specific virulence of the applied M. brunneum isolate JKI-BI-1450, with high mortality observed only in A . obscurus (82%), which considerably limits the control potential against several wireworm species abundant in German arable soils. These findings highlight key challenges for inoculative biocontrol of wireworms using Metarhizium spp. and emphasize the need for biocontrol strategies that consider biotic, abiotic and intrinsic factors to sustainably reduce wireworm populations. • AgriMet formulations reduced potato tuber damage by only 13.6% in field trials. • Low soil temperatures (9.8-16.5 °C) limited fungal proliferation and field effectiveness. • Greenhouse effectiveness (44-54%) required extremely high application rates, which are neither economically nor technically not feasible. • Virulence of the applied M. brunneum isolate differed among Agriotes obscurus , A. lineatus and A. sputator. • Practical application requires improved formulations and an optimized application strategy adapted to the crop rotation.

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Claims 6

Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Both formulations reduced potato tuber damage by 13.6% in field trials.

Treatment
Both formulationse0
Interactor
Wirewormse1pest
Second interactor
Metarhizium brunneumMetarhizium brunneume2biocontrol_agent
Outcome
tuber damagee0
Direction
reducinge0
Value
13.6%e0
Setting
field trialse0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum tuberosum
Solanum tuberosum · TaxonScott Bauer, USDA ARS · Public domain · Wikimedia Commons ↗

Verbatim

t0

“potato cultivation”

✓ located verbatim in the source · title, characters 131–149 · show in text ↑
e0

“Both formulations showed limited effectiveness in reducing tuber damage in field trials (13.6%)”

✓ located verbatim in the source · abstract, characters 544–639 · show in text ↑
e1

“Wireworms ( Agriotes spp.)”

✓ located verbatim in the source · abstract, characters 0–26 · show in text ↑
e2

“Metarhizium brunneum (AgriMet-granule and AgriMet-powder)”

✓ located verbatim in the source · abstract, characters 392–449 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

Greenhouse effectiveness rose to 44-54% at higher application rates.

Treatment
higher application rates (300 kg ha -1 or 1×10 13 conidia ha -1 )e0
Outcome
effectivenesse0
Direction
increasee0
Value
44-54%e0
Setting
Greenhouse testse0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum tuberosum
Solanum tuberosum · TaxonScott Bauer, USDA ARS · Public domain · Wikimedia Commons ↗

Verbatim

t0

“potato cultivation”

✓ located verbatim in the source · title, characters 131–149 · show in text ↑
e0

“Greenhouse tests revealed an increase in effectiveness (44-54%) under controlled conditions and at higher application rates (300 kg ha -1 or 1×10 13 conidia ha -1 )”

✓ located verbatim in the source · abstract, characters 840–1004 · show in text ↑
Associationobservedoriginal resultnegativemeasured

Claim · model-written summary

High pest pressure, low soil temperatures, limited fungal proliferation and poor product stability constrained field effectiveness.

Outcome
effectivenesse0
Qualifier
high pest pressure, low soil temperatures during application (9.8-14.7 °C), limited fungal proliferation (max. 959.9 CFU g -1 ) and poor product stabilitye0
Setting
field trialse0

Not reportedDirection

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum tuberosum
Solanum tuberosum · TaxonScott Bauer, USDA ARS · Public domain · Wikimedia Commons ↗

Verbatim

t0

“potato cultivation”

✓ located verbatim in the source · title, characters 131–149 · show in text ↑
e0

“Both formulations showed limited effectiveness in reducing tuber damage in field trials (13.6%), with key influencing factors identified as high pest pressure, low soil temperatures during application (9.8-14.7 °C), limited fungal proliferation (max. 959.9 CFU g -1 ) and poor product stability”

✓ located verbatim in the source · abstract, characters 544–838 · show in text ↑
Intervention effectobservedoriginal resultpositivemeasured

Claim · model-written summary

The applied isolate caused 82% mortality in A. obscurus.

Treatment
M. brunneum isolate JKI-BI-1450e0
Interactor
A . obscurusAgriotes obscuruse0pest
Outcome
mortalitye0
Direction
highe0
Value
82%e0

Not reportedComparator

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum tuberosum
Solanum tuberosum · TaxonScott Bauer, USDA ARS · Public domain · Wikimedia Commons ↗
Agriotes obscurus
Agriotes obscurus · InteractorAfroBrazilian · CC BY-SA 3.0 · Wikimedia Commons ↗

Verbatim

t0

“potato cultivation”

✓ located verbatim in the source · title, characters 131–149 · show in text ↑
e0

“Laboratory bioassays with A. obscurus , A. lineatus and A. sputator confirmed species-specific virulence of the applied M. brunneum isolate JKI-BI-1450, with high mortality observed only in A . obscurus (82%)”

✓ located verbatim in the source · abstract, characters 1092–1300 · show in text ↑
Observationobservedoriginal resultmeasured

Claim · model-written summary

The isolate showed species-specific virulence among three wireworm species.

Interactor
A. obscurusAgriotes obscuruse0pest
Outcome
species-specific virulencee0
Qualifier
A. lineatus and A. sputatore0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum tuberosum
Solanum tuberosum · TaxonScott Bauer, USDA ARS · Public domain · Wikimedia Commons ↗
Agriotes obscurus
Agriotes obscurus · InteractorAfroBrazilian · CC BY-SA 3.0 · Wikimedia Commons ↗

Verbatim

t0

“potato cultivation”

✓ located verbatim in the source · title, characters 131–149 · show in text ↑
e0

“Laboratory bioassays with A. obscurus , A. lineatus and A. sputator confirmed species-specific virulence of the applied M. brunneum isolate JKI-BI-1450”

✓ located verbatim in the source · abstract, characters 1092–1243 · show in text ↑
Recommendationauthor interpretationoriginal resultbasis n/a

Claim · model-written summary

Practical application requires improved formulations and an optimized application strategy adapted to crop rotation.

Outcome
improved formulations and an optimized application strategy adapted to the crop rotatione0

Organisms pictured · Representative pictures of the matched species, not figures from the paper.

Solanum tuberosum
Solanum tuberosum · TaxonScott Bauer, USDA ARS · Public domain · Wikimedia Commons ↗

Verbatim

t0

“potato cultivation”

✓ located verbatim in the source · title, characters 131–149 · show in text ↑
e0

“Practical application requires improved formulations and an optimized application strategy adapted to the crop rotation”

✓ located verbatim in the source · abstract, characters 2091–2210 · show in text ↑