Anikó Hirka

Forest insects and climate change: long‐term trends in herbivore damage

Long-term data sets, covering several decades, could help to reveal the effects of observed climate change on herbivore damage to plants. However, sufficiently long time series in ecology are scarce. The research presented here analyzes a long-term data set collected by the Hungarian Forest Research Institute over the period 1961–2009. The number of hectares with visible defoliation was estimated and documented for several forest insect pest species. This resulted in a unique time series that provides us with the opportunity to compare insect damage trends with trends in weather patterns. Data were analyzed for six lepidopteran species: Thaumetopoea processionea, Tortrix viridana, Rhyacionia buoliana, Malacosoma neustria, Euproctis chrysorrhoea, and Lymantria dispar. All these species exhibit outbreak dynamics in Hungary. Five of these species prefer deciduous tree species as their host plants, whereas R. buoliana is a specialist on Pinus spp. The data were analyzed using general linear models and generalized least squares regression in relation to mean monthly temperature and precipitation. Temperature increased considerably, especially over the last 25 years (+1.6°C), whereas precipitation exhibited no trend over the period. No change in weather variability over time was observed. There was increased damage caused by two species on deciduous trees. The area of damage attributed to R. buoliana decreased over the study period. There was no evidence of increased variability in damage. We conclude that species exhibiting a trend toward outbreak-level damage over a greater geographical area may be positively affected by changes in weather conditions coinciding with important life stages. Strong associations between the geographical extent of severe damage and monthly temperature and precipitation are difficult to confirm, studying the life-history traits of species could help to increase understanding of responses to climate change.

Canopy recovery of pedunculate oak, Turkey oak and beech trees after severe defoliation by gypsy moth (Lymantria dispar): Case study from Western Hungary

Abstract We investigated the canopy recovery of 3 tree species (pedunculate oak, Turkey oak, European beech) at two locations in the Veszprém county (Western Hungary) after severe defoliation by gypsy moth caterpillars in the spring of 2005. The Turkey oak has evidently the best recovery potential, and it almost completely replaced the lost foliage in 4 months. The pedunculate oak and beech needed 2 years to reach the same level of recovery. The pedunculate oak suffered from a heavy infection of Microsphaera alphitoides after defoliation and it probably slowed down its recovery. Neither the presence of Agrilus biguttatus in the oak plot nor the appearance of Agrilus viridis in the beech plot was observed during the study period. Population density of the buprestid Coraebus floerentinus showed a considerable increase in the oak plot, but remained under the damage level. Neither other harmful appearance of other pests nor significant tree mortality were observed within 4 years from the defoliation. These results provide information for the evaluation of longer term influences of the gypsy moth defoliation and may support the decisions concerning pest control.

Phytophagous larvae occurring in Central and Southeastern European oak forests as a potential host of Entomophaga maimaiga (Entomophthorales: Entomophthoraceae) – A field study

We evaluated the presence and impact of Entomophaga maimaiga on both target and non-target phytophagous larvae. All six study plots, with low gypsy moth population density, were situated in Central and Southeastern European oak forests and E. maimaiga had previously been reported from these plots. Totally, 45 of 4,045 (1.13%) collected non-target larvae died due to fungal infections. No non-target insect specimen was infected by E.maimaiga, although the presence of the pathogen could not be fully excluded in three cadavers. Out of 1,780L.dispar larvae collected, 15individuals (0.84%) were infected by E.maimaiga.

Long‐term species loss and homogenization of moth communities in Central Europe

As global biodiversity continues to decline steeply, it is becoming increasingly important to understand diversity patterns at local and regional scales. Changes in land use and climate, nitrogen deposition and invasive species are the most important threats to global biodiversity. Because land use changes tend to benefit a few species but impede many, the expected outcome is generally decreasing population sizes, decreasing species richness at local and regional scales, and increasing similarity of species compositions across sites (biotic homogenization). Homogenization can be also driven by invasive species or effects of soil eutrophication propagating to higher trophic levels. In contrast, in the absence of increasing aridity, climate warming is predicted to generally increase abundances and species richness of poikilotherms at local and regional scales. We tested these predictions with data from one of the few existing monitoring programmes on biodiversity in the world dating to the 1960s, where the abundance of 878 species of macro-moths have been measured daily at seven sites across Hungary. Our analyses revealed a dramatic rate of regional species loss and homogenization of community compositions across sites. Species with restricted distribution range, specialized diet or dry grassland habitat were more likely than others to disappear from the community. In global context, the contrasting effects of climate change and land use changes could explain why the predicted enriching effects from climate warming are not always realized.