Invasive Species Compendium

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Abstract

Caterpillar assemblages on introduced blue spruce: differences from native Norway spruce.

Abstract

Blue spruce has locally been introduced to the forests in Central Europe. It was considered as a suitable substitute tree species in areas where afforestation with the native Norway spruce had not been successful, e.g. in areas heavily affected by air pollution. Young plantations of blue spruce were healthy, without serious insect damage. We studied the moth associates of blue spruce (Picea pungens) and Norway spruce (Picea abies) in the two distant regions (study areas) in Central Europe represented by West Carpathians (Veporské vrchy Mountains, Central Slovakia) and Hercynian Mountains (Děčínská vrchovina hills, north-west Bohemia) and addressed the questions as to whether (1) blue spruce and Norway spruce have similar moth fauna, (2) blue spruce planted in forests is a host for Coleotechnites piceaella (the moth already recorded in urban areas in Central Europe) and/or other moth species introduced from North America and (3) afforestation with the introduced blue spruce affects the diversity of Lepidoptera on the native Norway spruce. Over the growing season 2006 (West Carpathians) and 2007 (Hercynian Mountains) the beating method was used to collect caterpillars from the lower branches of blue spruce and Norway spruce. In addition, photoeclectors in the laboratory were used to record moth caterpillars (or hatched adults) overwintering on blue spruce and Norway spruce in the two study areas in March 2008. The sample branches of blue spruce and Norway spruce were placed into photoeclectors. Moth specimens that had emerged from photoeclectors were collected and identified. A total of 998 caterpillars (or hatched adults) were collected from blue spruce, and a total of 860 caterpillars (or hatched adults) were obtained from Norway spruce. The moth fauna on blue spruce was similar to that on Norway spruce. Blue spruce and Norway spruce were found to host equal number of moth species (31 species). All species recorded on blue spruce are developing on the native Norway spruce. Comparisons between blue spruce and Norway spruce revealed some differences in the species composition of caterpillar assemblages. A significantly higher abundance of needle spinning larvae (Batrachedridae, Gelechiidae and Tortricidae) and significantly lower abundance of bud-boring larvae (genus Argyresthia, Yponomeutidae) on blue spruce compared to Norway spruce, was the most pronounced difference. No moth species introduced from North America were recorded. Based on the results, the introduction of blue spruce to the Central European forests is only slightly influencing the diversity of moth assemblages on Norway spruce.