Phyllopertha horticola (Coleoptera: Scarabaeidae) larvae in eastern Austrian mountainous grasslands and the associated damage risk related to soil, topography and management

Abstract

The soil-dwelling larvae of several Scarabaeidae species (white grubs), like the cockchafer (Melolontha melolontha) and the garden chafer (Phyllopertha horticola), are serious pests in European cultivated grassland, reducing grass yield and destroying the turf by root-feeding. Nevertheless, the factors responsible for the development of large grub populations and the associated damage risk are poorly understood. The objectives of the study were to survey grub densities in grassland sites with different damage histories and find correlations with environmental and management variables. Data on grub densities were collected at 10 farms in the eastern Austrian Alps in September and October 2011. At each farm, one recently damaged site (high risk) and one site at which grub damage had never been observed by the farmers (undamaged site = low risk; each site: 500 m2) were sampled. All sites were dominated by P. horticola (99% of 1,422 collected individuals; maximum density 303 grubs/m2), which indicates that grub damage there is mainly caused by that species. Recently damaged sites tended to higher grub densities than undamaged sites. However, 3 out of 10 undamaged sites harbored high grub populations as well. Humus content together with the depth of the A-horizon significantly explained 38% of P. horticola grub density variance, with highest densities in deeper humus-rich soils. The risk of grub damage was positively connected to the humus content and negatively related to the cutting frequency. For the investigated mountainous grassland sites, these results suggest an important role of humus for the development of high grub densities and an effect of management intensity on grub damage.

First field estimation of greenhouse gas release from European soil-dwelling Scarabaeidae larvae targeting the genus Melolontha

“…Worldwide, larvae of several Scarabaeidae species are regarded as economically important pest insects [ 42 , 43 ]. Regionally, these pest insects can reach biomass levels comparable to or considerably higher than those used for upscaling termite GHG emissions [ 21 ], but we have no estimates of the total biomass of soil-dwelling Scarabaeidae larvae in Europe. Furthermore, for CH 4 it is important to differentiate between gross and net soil fluxes.…”

“…hippocastani ) because they have a soil pest status in Europe and they represent two different distribution patterns of Scarabaeidae larvae in soils. Due to the pest status, they are one of the few European Scarabaeidae species for which regular monitoring programs exist, and thus, knowledge on larval ecology is relatively good [ 20 , 21 ]. M .…”

Environmental gradients and the evolution of tri‐trophic interactions

“…Heavy plant infestations are mainly restricted to low‐elevation areas with relatively high annual mean temperatures (Hann et al . ), where soil biodiversity (Fig. a) and carnivore activity (Fig.…”

Beheersing van bodemplaaginsecten via bodemgezondheidsmaatregelen : Een overzicht van de beschikbare kennis voor een selectie van akkerbouwgewassen met hun bijbehorende bodemplaaginsecten

“…• Hogere populatiedichtheden engerlingen van de rozenkever worden aangetroffen op plekken met een hoger percentage organische stof. Dit komt overeen met meerdere studies (Hann et al, 2015).…”

“…• Primaire schade door engerlingen komt vooral voor in warme en droge jaren met weinig neerslag (Hann et al, 2015). Deze schade, al of niet gecombineerd met secundaire schade, is zichtbaar en kan visueel worden vastgesteld, voorafgaand aan een aardappelteelt.…”