The implementing Decision (EU) 2018/638 lays down emergency measures to protect the Union against the introduction into and the spread within the Community of the harmful organism Spodoptera frugiperda.
Spodoptera frugiperda [(short Sf), German: Heerwurm] is a butterfly species of the owl butterfly family (Noctuidae). It is located in South, Central and North America. Their appearance in West Africa was first reported in 2016. Within a few years, the species has spread to the entire area south of the Sahara, where it has become one of the most important pests, especially on maize.
The species has not yet appeared in Europe.
What are the routes of introduction and how do they spread?
Sf has a very broad host plant cycle and affects a large number of plant families. Species from the sweetgrass family [Poaceae] are preferred. Important crops are maize, millet and rice; however, various vegetable and ornamental plant species are also affected.
The introduction of Sf at the larval and ice-stage may occur through trade in goods from infested countries. Due to the occurrence of the species in the upper Nile valley (in Sudan), a rapid spread along the Nile to Egypt and subsequently in the Mediterranean region is to be expected. Due to the intensive trade with the Mediterranean countries, this increases the probability that the butterfly can also be detected in Austria.
The natural spread occurs over greater distances through the active flight activity of the butterflies (see below).
What is being done to prevent the introduction and spread of the virus?
Sf is currently regulated as a quarantine pest. Special measures apply to the import of plants of dendranthema (chrysanthemum), dianthus (carnation) and pelargonium. With the implementing decision (EU) 2018/638, further measures were adopted to protect the member states against the introduction of Sf. These include extended import controls at the entry points into the EU (airports, ports, land): from 01.06.2018 third countries where Sf is present must also provide certain additional declarations on the phytosanitary certificate for fruits of Capsicum (paprika, chilli), Momordica (bitter cucumber), Solanum melongena, S. aethiopicum and S. macrocarpon (eggplants), as well as plants of maize (e.g. corn on the cob) for import into the EU.
In Austria, BAES carries out the import controls.
The plant protection services of the Länder conduct surveys for the early detection of possible infestations.
The larvae cause non-specific symptoms due to their feeding activity, such as pitting or gluttony on the leaves. Larvae that eat holes through the stems of the host plants can cause the plants to buckle. In contrast to species of other butterfly families, the leaves are not sticky and no webs are formed. Eggs and larvae can be found on all parts of the plant above ground.
The laying of eggs by the adult butterflies takes place in clutches of 100 - 300 eggs. The egg clutches are protected by scales from the abdomen of the butterflies. At temperatures between 20 and 27°C the first larval stage hatches after 2-4 days. The first two stages eat sociably at the young leaves and in the vegetation cone. The 3rd stage spreads a few meters in the stand. In the final larval stage, Sf can be identified by three yellow stripes, the four square hairy spots on the last segment and the Y-shape on the head capsule. After 6 larval stages the pupation takes place in the soil. The butterflies are inconspicuous with a wingspan of 3-4 cm. The total development time from egg to butterfly is 66 days at 18°C and 18 days at optimal temperature of 28°C. In warmer regions up to 6 generations per year are possible.
What significance does the species have for plant production in Austria?
Sf is a butterfly species which is not able to survive in unfavourable conditions due to a stage of dormancy (diapause). At temperatures below 10° no further development takes place. This means that for Sf a permanent settlement in Central Europe is not possible due to the winter frosts and the species can only lead to damage in the warm season. Due to the ability of the butterflies to fly and their distinct migratory behaviour in their original home America, where an annual spread from southern US states (Florida, Texas ...) over several 100 km to Canada is observed, it can be assumed that if the butterflies are introduced into the Mediterranean region, summer populations of the various host plants can also be expected here.
However, the damage potential of this type for Austria is low.