Pest categorisation of Dendrolimus superans

Area of Science:

• Plant Health
• Entomology
• Pest Risk Analysis

Background:

• Dendroimus superans, the larch caterpillar, is a major pest of conifer forests in East Asia.
• Its primary hosts include Larix gmelinii and Pinus pumila, with larvae feeding on needles and overwintering in soil.
• While damage is reported on species not grown in EU forestry, Norway spruce (Picea abies) is a known host in Japan.

Purpose of the Study:

• To perform a pest categorisation of Dendroimus superans for the EU territory.
• To assess the potential risk Dendroimus superans poses to EU forests and plant health.
• To determine if Dendroimus superans meets criteria for a potential Union quarantine pest.

Main Methods:

• Review of existing literature on Dendroimus superans biology, distribution, and host range.
• Analysis of potential pathways for introduction into the EU, including plant imports.
• Assessment of climatic suitability and potential host availability within the EU.
• Evaluation based on criteria set by the European Food Safety Authority (EFSA) for quarantine pests.

Main Results:

• Existing import prohibitions for certain conifer species largely close primary pathways for Dendroimus superans.
• A derogation for dwarfed Pinus plants from Japan presents a potential, albeit limited, pathway.
• EU climates are suitable in some regions, and Picea abies is a known host, though impact data is lacking.
• Experiments with a related species, Dendroimus sibiricus, show larval development on EU forestry conifers.
• Dendroimus superans meets EFSA's criteria for a potential Union quarantine pest.

Conclusions:

• Introduction of Dendroimus superans into the EU could potentially impact Picea abies and other ornamental/amenity conifers.
• There is a possibility of host range expansion, similar to observed potential in Dendroimus sibiricus, though this remains uncertain.
• The magnitude of potential environmental and economic impacts requires further investigation, but the pest warrants quarantine status consideration.