English name: Western Corn Rootworm
Nordic names: Majsrodbille (DK), Majsrotbagge (SE)
Estonian name: Maisi-juureuss
Major host plants
Species of Diabrotica attack mainly maize, the larvae feeding on the roots and the adults feeding on the leaves and silks. Other species within Poaceae occasionally serve as hosts for the larvae. Adults may also feed on other species of Poaceae, furthermore species of Asteraceae, Fabaceae and Cucurbitaceae.
Larval feeding on the roots causes root pruning. As a result the force needed to pull the plant from the soil decreases, and the plants have a greater tendency to fall. The older larvae dig channels in the central root tissue. Tunnels in maize roots are thus a characteristic symptom, though they may be due to other species. Adult feeding does not cause any particularly characteristic symptom.
D. virgifera has spread to Europe from North- and Central-America. Infestation begun at Belgrad, and D. virgifera has continued to spread westward and eastward. Other Diabrotica-species (e.g. D. barberi) exist only in North- and Central-America.
A map can be downloaded from EPPO's website. See instructions here.
D. virgifera overwinters as eggs, which are laid in the top 15 cm of soil, at the base of maize plants. The larvae develop in and on the roots, the young larvae feeding on fine rootlets and the older ones invading the root core. Pupation takes place in the soil. The emerging adults move to the maize plant, feeding on the leaves and silks.
The adults fly to maize fields and can migrate over short and longer distances. Within Europe, D. virgifera can progressively spread by adult flight, and has in this way extended its range significantly. It can be carried by consignments and vehicles of vegetables and plants and as hitchhikers, on other type of consignments, too.
Detection and inspection
Early symptoms in maize crop are difficult to recognise, later on infestation can be observed by reduced plant growth or fallen plants.
Pest status and importance
D. virgifera represents a serious threat in maize-growing areas. It may easily establish in new areas due to its potential to adapt to different environmental conditions and its high reproductive rate. In the future, its area of distribution is anticipated to extend in accordance with the climate change.
Source of information
See further information here:
Author: Jorma Rautapää
Editor: Elise T. Yamamoto Buch