Articles containing the keyword 'Neodiprion sertifer'

Concentration of the phytotoxic air pollutant, ozone (O₃) is continually increasing in the lower layer of the troposphere. The purpose of this study was to compare performance of pine sawflies on Scots pine (Pinus sylvestris L.) seedlings in ambient and future levels of ozone. Scots pine seedlings were grown in field fumigation system where the ozone doses in fumigated plots were 1.5–1.6 times the ambient level. Larvae of the European pine sawfly (Neodiprion sertifer Geoffroy and Gilpinia pallida Klug) were reared on the foliage of Scots pine. The levels of resin acids and monoterpenes in foliage were analysed. There were no significant effects of ozone fumigation on sawfly performance or levels of defence compounds in pine foliage. The results suggest that the elevated ozone concentrations do not strongly affect the needle quality of young Scots pine and the importance of these two diprionid sawfly species forest pests.

• Lyytikäinen, E-mail: pl@mm.unknown
• Holopainen, E-mail: jh@mm.unknown
• Kainulainen, E-mail: pk@mm.unknown
• Nerg, E-mail: an@mm.unknown
• Neuvonen, E-mail: sn@mm.unknown
• Virtanen, E-mail: tv@mm.unknown

The European Pine Sawfly (Neodiprion sertifer Geoffroy) is one of the most serious defoliators of Scots pine (Pinus sylvestris L.) in northern Europe. We studied the pattern in the regional occurrence of the outbreaks of N. sertifer in Finland in years 1961-90, and made predictions about the outbreak pattern to the year 2050 after predicted winter warming. We tested whether minimum winter temperatures and forest type and soil properties could explain the observed outbreak pattern. We analysed outbreak patterns at two different spatial levels: forest board- and municipal-level.

The proportion of coniferous forests on damage-susceptible soils (dry and infertile sites) explained a significant part of the variation in outbreak frequency at small spatial scale (municipalities) but not at large spatial scale (forest boards). At the forest board level, the incidence of minimum temperatures below -36 °C (= the critical value for egg mortality) explains 33% of the variation in the outbreak pattern, and at the municipal level the incidence of cold winters was also the most significant explaining variable in northern Finland. Egg mortality due to cold winters seems to be the most parsimonious factor explaining why there have been so few N. sertifer outbreaks in northern and north-eastern Finland. We predict that climate change (increased winter temperatures) may increase the frequency of outbreaks in eastern and northern Finland in the future.

• Virtanen, E-mail: tv@mm.unknown
• Neuvonen, E-mail: sn@mm.unknown
• Niemelä, E-mail: pn@mm.unknown
• Nikula, E-mail: an@mm.unknown
• Varama, E-mail: mv@mm.unknown

Experimental applications of the nuclear polyhedrosis virus (Borrelinavirus diprionis) to control of the European pine sawfly (Neodiprion sertifer Geoff.) was carried out during the last outbreak of this sawfly in in Scots pine (Pinus sylvestris L.) in Finland in 1963. Quantities of polyhedrosis virus preparation, collected and purified in Finland were available as concentrations packed in capsules. Spraying took place in three localities in southwestern Finland when the larvae were in I–III instars.

When Finnish and Swedish preparations were used 83–96% of larval colonies were completely destroyed within 14 days. In addition, an attempt was made to change the virus in latent stage, present already in the area, to acute stage by application of substrates which are probably harmless to pine, but were expected to stress the larvae. Ground quarts as spray had the best lethal effect upon larvae.

The PDF includes a summary in English.

• Nuorteva, E-mail: mn@mm.unknown

Unequivocal evidence on the antagonistic effects of endophytic fungi associated with woody plants against insect herbivores has been documented in only a few cases so far. Experimental evidence of the significance of needle endophytes to coniferous trees has remained scant because it is difficult to obtain trees with needles free of endophytes that could be used as comparable controls for trees infected with endophytes. Previously we reported a new methodology to get Norway spruce (Picea abies (L.)  Karst.) saplings without needle endophytes and to inoculate them with a needle endophyte Lophodermium piceae (Fuckel) Höhn. Here we describe the first trial where spruce saplings with and without needle endophytes were provided as substrate for insect larvae. We transferred larvae of two sawfly species, Neodiprion sertifer Geoffroy and Gilpina pallida Klug, to the seedlings. Even though the main host of these sawfly species is not Norway spruce, but Scots pine (Pinus sylvestris L.), they are also known to occasionally feed on spruce. In this experiment the larvae did not develop to pupae with the provided spruce substrate but consumed measurable amounts of needles. No significant difference was found between the extent of needles consumed by either of the two sawfly species in inoculated and uninoculated saplings.

• Müller, Natural Resources Institute Finland (Luke), Forest Health and Biodiversity, P.O. Box 2, 00791 Helsinki, Finland https://orcid.org/0000-0003-3699-2139 E-mail: micms.muller@gmail.com
• Hamberg, Natural Resources Institute Finland (Luke), Forest Health and Biodiversity, P.O. Box 2, 00791 Helsinki, Finland https://orcid.org/0000-0002-0009-7768 E-mail: leena.hamberg@luke.fi
• Varama, Natural Resources Institute Finland (Luke), Forest Health and Biodiversity, P.O. Box 2, 00791 Helsinki, Finland E-mail: martti.varama@pp.inet.fi