DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 5-6/1999 str. 15 <-- 15 --> PDF |
B. Hrašovcc i M. Ilarapin: DIJACiNOZNO - PROCiNO/NI-, METODIi I GRADAC. ZNAČAJNIJIH ŠThT. KUKACA... method is prediction of flowering capacity. As in many neighboring countries, situation in Croatia, regarding more important insect pests is in many ways similar. There is more than twenty species of defoliators, sap suckers and xylophages screened regu-larly or on a periodical basis with various survey methods used in Croatian forests and forest nurseries. The most serious pests in the lowland riparian forests and partly in the hilly belt of continental Croatia are L. dispar, T viridana and several geometrid species among which E. defoliaria and O. brumata lead in severity of attack. During the past two decades three major peaks in L. dispar population density occurred. The highest one was by the beginning of eighties with more than 130000 hectares atta-cked. Second peak followed by the late eighties and the third one peaked in 1994 (Androić & Harapin 1996). Among other defoliating insects some deserve special attention due to their periodical and regional defoliating impact. Euproctis chrysorrhoea and Malacosoma neustria are good examples. Both are constantly present throughout the whole lowland region but not causing damages in larger areas. Apethymus abdominalis and A. braccatus are the two tenthredinids which were recorded in lowland oak forests by late fifties and have periodically entered gradation stages since then. Latest gradation was in mid-eighties. Stereonychus fraxini is causing severe damages on Fraxinus angustifolia and there are several factors that hamper our efforts to efficiently survey and suppress this serious defoliator. Among other defoliating insects we would like to point out some rising populations of ten-thredinid species among which Caliroa annulipes seems to have the leading role in the last three years. It started damaging young plants in some forest nurseries but in 1998 it heavily attacked some young oak stands. Pine processionary moth is widespread and sometimes very important pest in whole coastal region. It is regularly monitored since it is always present in some parts in relatively large numbers. Abies alba, as our most important conifer species, has specific guild of defoliators. However, one lepidopterous species emerged as far most important and destructive. During mid-fifties Argyresthia fundella started its devastating gradation in the hearth of mountainous region. It remained important pest with this first eruption being the strongest. Problems regarding xylophages can be categorized in three main groups: technical damages occurring on logged and dying trees both in lowland oak forests as in fir and spruce forests of mountainous region (Trypodendron spp., Xyleborus spp. and Platypus cylindrus), physio-logical damages with resulting tree dyout (Agrilus spp., Pityokteines spinidens, I. typogra- phus, Pytiogenes chalcographus) and combined technical and physiological damages in pop-lar and willow cultures caused by various Coleoptera and Lepidoptera. Diagnostic and survey procedures practiced in Croatian forestry play important role in imple-menting the sustainable forestry principles. All the serious and most damaging insect pests are regularly monitored and their damage impact properly and aptly prognosed. Suppressive measures, coordinated from DPS service, are shifting toward ecologically more appropriate biotechnical and biological compounds. Less and less synthetic pesticides are used and when necessary, only those with lesser toxicity and shorter persistency are used. Key words: diagnose, prognose, insect pests, population dynamics, gradation. Šumarski list br. 5 6, C XXIII (1999). 183-193 |