Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Studies on the occurrence and parasitization of the spruce seed pests, Megastigmus strobilobius Ratz. (Hym., Torymidae) and Plemeliella abietina Seit. (Dipt., Cecidomyiidae) in Poland during a poor seed year.

Abstract

The occurrence and parasitism of Megastigmus strobilobius and Plemeliella abietina, pests of spruce (Picea abies), were studied in various regions of Poland during a poor seed year (1987-88). A total of 32 970 seeds was dissected, obtained from cones collected from 149 trees in 22 localities. Plemeliella abietina was common in the south-western and north-eastern range of Picea abies. M. strobilobius was widely distributed in Poland, although it was not found in the north-eastern range in 1987. These 2 species caused little damage to spruce seeds when the crop was poor, but losses caused by Plemeliella abietina were on average 15 times greater than those due to M. strobilobius. However, in some years the 2 pests can cause damage to more than 50% of the seed crop. Larvae of Anogmus sp., a pteromalid parasitoid of P. abietina, occurred in only 8 localities, and the average percentage parasitism of P. abietina was only 0.12%.