Search

The European (Melolontha melolontha L.) and Forest (M. hippocastani F.) cockchafer are widespread pests throughout Central Europe. Both species exhibit a 3-5-year life cycle and occur in temporally shifted populations, which have been monitored and documented for more than 100 years. Visual identification of adults and larvae belonging to these morphologically similar species requires expertise and, particularly in the case of larvae, is challenging and equivocal. The goal of the study was the development of an efficient and fast molecular genetic tool for the identification and discrimination of M. melolontha and M. hippocastani. We established a collection of both species from Switzerland, Austria and Northern Italy in 2016, 2017 and 2018. An approximately 1550 bp long fragment of the cytochrome c oxidase subunit 1 (CO1) mitochondrial gene was amplified and sequenced in 13 M. melolontha and 13 M. hippocastani beetles. Alignment of the new sequences with reference sequences (NCBI GenBank and BOLDSYSTEMS databases) and subsequent phylogenetic analysis revealed consistent clustering of the two species. After the identification of M. melolontha and M. hippocastani species-specific single nucleotide polymorphisms (SNPs) in the CO1 alignment, we developed an effective SNP tool based on the ABI PRISM (R) SNaPshot (TM) Multiplex Kit for the rapid and accurate species discrimination of adults and larvae., Bulletin of Entomological Research, 111 (5), ISSN:0007-4853, ISSN:1475-2670

To achieve an effective reduction of the damage by root feeding grubs of Melolontha spp. in organic strawberry plantations, we have tested an approach targeting different stages of the insect’s biological cycle. Adult beetles were caught by using light traps or by manual shaking off trees associated to the monitoring of cockchafer swarm flights supported by forecasts models. Phytosanitary pre-crops and the application of biological control agents were tested against the larvae. The three predictive models utilized to forecast the period of emergence of the cockchafer were suitable to support the deployment of the light traps before the adults’ swarm flights. Traps positioned at 4-m height were more effective in attracting the beetles than those kept at 2-m height. Buckwheat in mixtures with either a mustard or leguminous species used as pre-crops was able to reduce the population of grubs, and considering also its capacity in solubilizing recalcitrant phosphorous sources should enter in a rotation with strawberry or any other crop susceptible to grubs damage. The distribution of two different strains of entomopathogenic fungi resulted in a reduction of the damage to plants due to the cockchafer grubs’ activity, even though the efficacy resulted to be dependent on environmental and agronomic factors, including the kind of formulation used. It is concluded that to assure a sufficient level of control of Melolontha spp. in organic strawberry plantations, it is necessary to integrate several methods that are targeting the different biological stages of the insect and are based on different kinds of practices.

International audience; Key message:Melolontha hippocastani is a major pest in European mixed and broadleaf forests. Investigating its oviposition behavior, we observed that a dense shrub layer reduces the density of egg clusters and eggs in the soil. Conversely, canopy openness and a large proportion of oak appear as favoring conditions.Context:Melolontha hippocastani is a major pest in European mixed and broadleaf forests. In north-eastern France, an epidemic phase has been observed since 2007, characterized by a high mortality rate of seedlings and young trees, and by massive swarming flights every 4 years.Aims:We investigated the oviposition behavior of M. hippocastani in the northern Vosges Mountains.Methods:We set up study plots in the infected area after adults had emerged and the females had laid their eggs. We excavated pits and counted the eggs and egg clusters they contained. We also carried out dendrometric surveys.Results:A dense shrub layer had a negative effect on the density of egg clusters and the number of eggs in the soil, while canopy openness and the proportion of oak basal area had positive effects.Conclusion:We hypothesized that a dense shrub layer could create a barrier for females. On the other hand, an open canopy may improve conditions for the larvae in the soil, just as a high proportion of oak trees in the surrounding area may provide a good food source for both larvae and adults. We suggest several research orientations and propose guidelines for forest management in view of our results.

Root-feeding insect herbivores are of substantial evolutionary, ecological and economical importance. Plants can resist insect herbivores through a variety of tolerance and resistance strategies. To date, few studies have systematically assessed the prevalence and importance of these strategies for root-herbivore interactions across different plant species.Here, we characterize the defense strategies used by three different grassland species to cope with a generalist root herbivore, the larvae of the European cockchafer Melolontha melolontha.Our results reveal that the different plant species rely on distinct sets of defense strategies. The spotted knapweed (Centaurea stoebe) resists attack by dissuading the larvae through the release of repellent chemicals. White clover (Trifolium repens) does not repel the herbivore, but reduces feeding, most likely through structural defenses and low nutritional quality. Finally, the common dandelion (Taraxacum officinale) allows M. melolontha to feed abundantly but compensates for tissue loss through induced regrowth.Synthesis: Three co-occurring plant species have evolved different solutions to defend themselves against attack by a generalist root herbivore. The different root defense strategies may reflect distinct defense syndromes.

We investigated the occurrence and pathogenicity of Beauveria spp. (Hypocreales: Cordycipitaceae) in forest soils in Poland, in outbreak areas of cockchafers (Coleoptera: Scarabaeidae): Melolontha melolontha L. and M. hippocastani F. We also examined the occurrence of Beauveria in relation to soil pH. Beauveria spp. isolates were characterised at species and genotype levels using ITS and microsatellite markers. Beauveria spp., which were detected at over 80% of sites, were sensitive to pH, preferring neutral or alkaline soils. This suggests that the acidity of forest soils in Poland can affect their efficacy as biological control agents (BCAs). B. brongniartii (Sacc.) Petch as a pathogen of cockchafers occurred at 41% of sites, but often at densities below the threshold values for infection, and it infected only 1.3% of cockchafer grubs. Our results suggest that B. brongniartii genotype isolated from cockchafers in forest soils can potentially expand the pool of BCAs in this environment.

The common cockchafer (Melolontha melolontha) and the forest cockchafer (Melolontha hippocastani) are among the most destructive insect pests in many European countries. Larvae feed on the roots of numerous plant species, thus inflicting severe damage and heavy economic losses. The two species are often discussed together because they are difficult to distinguish during the larval stage.However, they differ slightly in ecology and development. The aim of this study was to develop a quick PCR-RFLP (polymerase chain reaction-restriction fragment length polymorphism) method for easily identifying the two Melolonthaspecies through tissue samples or larvae, when reliable morphological identification is lacking. The strength of the method was tested on 43 M. melolonthaand 37 M. hippocastani individuals. We demonstrate that the technique is rapid and inexpensive, with strong implications for the effective management of these insect pests.

Purpose The aim of this study was to investigate and document the characteristic electron microscopic features of the oocyst of Adelina melolonthae, a coccidian pathogen of the European cockchafer, Melolontha melolontha (Coleoptera: Scarabaeidae). Methods Larvae of M. melolontha were collected at Ordu, Turkey. Each larva was dissected in insect Ringer solution. Adeleid oocysts from the tissue that is suspected to Contain coccidian infections were examined under a light microscope (Zeiss), a scanning electron microscope (FEI Quanta 200) and transmission electron Microscope (Philips EM 208). Results Spherical to ellipsoidal oocysts measure ca. 24-44.5 mu m (mean 35.6 mu m) in diameter (n = 50) and include up to twelve sporocysts. The oocyst wall has double layers; the outer layer measured 400-500 nm in thickness and the inner one 10-25 nm. Sporocysts including two sporozoites are rounded ca. 11-12.5 mu m (mean 11.7 mu m) in diameter. The sporocyst wall consisted of only one 70-80-nm-thick layer. The sporozoites are ellipsoidal and measured 9-11 mu m length and 3-4 mu m in width. Sporocysts include residual bodies. Conclusion In the present paper, the morphology and ultrastructure of the oocyst of A. melolonthae is documented for the first time and compared with other Adelina and coccidian species infecting insects. The results in this study confirm his identification and justify the classification as a separate species A. melolonthae, which differs from other Adelina species.

In view of climate change the risk of biotic stressors in the forests is expected to be enhanced in addition to severe abiotic stress events, like drought. One biotic stress considered to be increased for oak regeneration is the root feeding of young plants from cockchafer. The cockchafers (Melolontha spp.) belong to the scarab beetles (Scarabaeidae) and are widespread pest species throughout Central Europe. In Germany, the most common species is the European cockchafer (Melolontha melolontha Linnaeus), whereby the forest cockchafer (Melolontha hippocastani Fabricius) is also present, mainly on sandy soils. Specifically, in south-western Germany both European and forest cockchafers cause economic losses in agricultural and forest areas. Besides drought, the feeding of roots from cockchafer larvae, act as an additional stress factor for young oak plants. In the present case study, geographically distant oak stands are infested with different intensity.In the present study, population genetic analysis was used to differentiate the two cockchafer species and was used to estimate population dynamics, as well as possible consequences of climatic changes to the life cycle of forest cockchafer. Additionally, seedlings of two distant oak provenances were exposed to forest cockchafer larvae in a greenhouse experiment and their population genetic and root-based VOC profiles were studied. Larvae preferences for the different plants/populations were estimated and terpene synthase gene expression of the plants was measured.Chloroplast haplotypes showed patterns of migration from different refugial regions. However, no clear association between genetic constitution of the different provenances and the abundance of cockchafer populations on site was observed. TPS gene expression patterns in response to larval feeding revealed geographic variation rather than genotypic variation. Our results support the assumption that root-released VOC are influencing the perception of roots by herbivores.

A plant's offspring may escape unfavourable local conditions through seed dispersal. Whether plants use this strategy to escape insect herbivores is not well understood. Here, we explore how different dandelion ( Taraxacum officinale agg.) populations, including diploid outcrossers and triploid apomicts, modify seed dispersal in response to root herbivore attack by their main root-feeding natural enemy, the larvae of the common cockchafer Melolontha melolontha. In a manipulative field experiment, root herbivore attack increased seed dispersal potential through a reduction in seed weight in populations that evolved under high root herbivore pressure, but not in populations that evolved under low pressure. This increase in dispersal potential was independent of plant cytotype, but associated with a reduction in germination rate, suggesting that adapted dandelions trade dispersal for establishment upon attack by root herbivores. Analysis of vegetative growth parameters suggested that the increased dispersal capacity was not the result of stress flowering. In summary, these results suggest that root herbivory selects for an induced increase in dispersal ability in response to herbivore attack. Induced seed dispersal may be a strategy that allows adapted plants to escape from herbivores.

Between 2012 and 2014, we tested the efficacy of different synthetic attractants for the purpose of massive trapping of common European cockchafer adults (Melolontha melolontha). The research took place in three different locations in Slovenia (Otlica, Crni Vrh nad Idrijo, Cesta nad Ajdovscino) during flight periods of adult beetles. In the period 2013–2014, we used, on the basis of the preliminary test results (2012), the following chemicals: toluquinone, cis–3–hexen–1-ol, ethyl acetate, toluquinone + cis–3 hexen–1-ol, and ethanol as a control. M. melolontha adults were most abundant in the location Crni Vrh nad Idrijo; the traps in this location caught 18 times more of them than those in the first location and more than six times more than those in the third location. Male insects accounted for 73 to 87% of the trapped specimens. We confirmed the highest efficiency of cis–3–hexen–1-ol in 2013 (43.25 ± 0.08 males/trap), as well as in 2014 (15.00 ± 0.14 males/trap). On the basis of the trapped adu...

Rapid adaptation of insect species to environmental changes can be advantageous for their development. Forest cockchafer (Melolontha hippocastani) is herbivorous insect species with high food intake that has been widely studied within European conditions. It can cause huge economic and ecological losses especially in oak-dominated forest stands. Food preference of this species is mainly comprised of trees with a potential to accumulate manganese in their assimilation apparatus. In order to determine cockchafer's reactions to increased Mn concentration in its food, the adults were reared in laboratory conditions controlled for temperature, humidity, and light on a natural diet of oak (Quercus petraea) leaves. Food was contaminated by soaking in solutions of MnCl2·4H2O in concentrations from 0.5 to 10 mg ml−1. Food consumption, activity period of adults, quantity of eggs laid, body weights of individuals, as well as Mn concentrations in unconsumed food, excrement, and the bodies of cockchafers were determined to indicate how these change in reaction to food quality altered in terms of Mn content. The results showed that very high Mn content in the diet significantly influenced food consumption by M. hippocastani adults and thereby their development. This was in spite of the tendency of individuals to expel Mn through the faeces and incorporate it into undetermined parts of their bodies. Negative reactions of the experimental population were determined in treatments fed leaves with Mn concentration of 1800 ppm and more. Our experiment proved that Mn can greatly influence the phytophagous cockchafer (decreased feeding time, food consumption, and fertility).

Cockchafers of the genus Melolontha (Coleoptera, Scarabaeidae) seem to have a strong effect on forest management by inducing significant losses in the forest stands. Monitoring of the occurrence of Melolontha is carried out in many European countries, and the detailed data are available. But there is still a lack of data of the genetic population structure of Melolontha species as well as appropriate genetic markers. Amplification of microsatellite loci, developed for Melolontha melolontha, was performed in the closely related species Melolontha hippocastani. We successfully amplified the same eight polymorphic markers in both species of Melolontha. Generally, more alleles (from 5 to 15) were obtained for M. melolontha markers, and considerably fewer alleles (from 2 to 7) were observed for M. hippocastani. The mean observed heterozygosities were 0.676 and 0.192 respectively. The microsatellite markers tested in this study could be successfully used to study the population genetics of M. hippocastani.

Current meta-analysis has identified the shortage of information on responses of woody plants to root damage as the most critical gap in studies of belowground insect herbivory. We explored the impacts of natural and simulated root herbivory on seedlings of three boreal forest-forming trees, Pinus sylvestris , Picea abies and Betula pendula . We compared the effects of natural herbivory and mechanical damage by placing one larva of the common cockchafer, Melolontha melolontha, of different instars (to manipulate root loss) into a pot with a one-year-old seedling or we excised a portion of the roots by inserting a 13-mm diameter cork borer into the soil. During the experiment, which lasted from 2 to 8 weeks, the larvae consumed 53–73% of root biomass, whereas the mechanical damage treatment removed 30–40% of roots. Seedling mortality was low (5%) across all treatments, but the aboveground biomass decreased by 3–43% due to natural herbivory and by 6–30% due to mechanical damage. The M. melolontha larvae consumed a larger amount of roots from B. pendula than from either P. sylvestris or P. abies, but the larvae showed similar relative growth rates and mass gains, indicating a different efficiency of conversion of ingested food (ECI). The values of ECI calculated for larvae of M. melolontha (2.3–3.5%) appeared much lower than the 17% reported earlier for larvae of foliage-feeding beetles, presumably due to the high energetic cost of locomotion in the soil. Consequently, root-feeding insects consume much more plant biomass than leaf-feeding insects do to gain similar body mass, and therefore they inflict relatively more damage to plants per unit of mass gained. Based on the biomass of insect herbivores in European forests, we estimate that they consume 0.5% of the available fine root biomass. The effects of low levels of root damage on growth and reproduction of woody plants remain virtually unknown, emphasising the need for studies of plant- and ecosystem-level effects of minor but chronic root herbivory.

Five non-spore-forming bacteria were isolated from the European cockchafer, Melolontha melolontha ( Linnaeus , 1758 ) (Coleoptera: Scarabaeidae). Their potential was tested against the three economic insect pests, the great spruce bark beetle, Dendroctonus micans Kugelann (Coleoptera: Curculionidae); the pine processionary, Thaumetopoea pityocampa (Lepidoptera: Thaumetopoeidae); and the gypsy moth, Lymantria dispar (Linn.) (Lepidoptera: Erebidae), to find an effective biological control agent. All isolated bacteria were cultured and identified using VITEK bacterial identification systems and 16S rRNA gene sequence analysis. The bacteria were identified as Enterobacter cloacae complex (isolate 1M), Serratia marcescens (isolate 3M), Pseudomonas aeruginosa (isolate 4M), Kocuria kristinae (isolate 5M), and Serratia liquefaciens (isolate 8M). Laboratory experiments, carried out to evaluate the virulence of these isolates, showed that all isolated bacteria had a pathogenic effect on the tested pests. E. cloacae had 35, 56.7, and 84%; S. marcescens 50, 60.9, and 47.8%; P. aeruginosa 55, 69.6, and 48%; K. kristinae 40, 43.5, and 16%; and S. liquefaciens 45, 65.2, and 36% mortality rates on the larvae of D. micans, T. pityocampa, and L. dispar, respectively. The isolated bacteria can be considered in integrated pest control programs.

Root-feeding Scarabaeidae larvae can pose a serious threat to agricultural and forest ecosystems, but many details of larval ecology are still unknown. We developed an acoustic data analysis method based on active sound production by larvae (i.e. stridulations) for gaining new insights into larval ecology. In a laboratory study, third instar larvae of the Common Cockchafer (Melolontha melolontha) (n = 38) and the Forest Cockchafer (M. hippocastani) (n = 15) kept in soil-filled containers were acoustically monitored for 5 min each, resulting in the first known stridulation recordings for each species. Subsequent continuous monitoring of three M. hippocastani larvae over several hours showed that a single larva could stridulate more than 70 times per hour, and stridulation rates increased drastically with increasing larval abundance. The new fractal dimension-based data analysis method automatically detected audio sections with stridulations and provided a semi-quantitative estimate of stridulation activity. It is the first data analysis method specifically targeting Scarabaeidae larvae stridulations in soils, enabling for the first time non-invasive species-specific pest monitoring.

Root-feeding Melolonthinae larvae are a forest pest species in Europe that can exert serious damage. In Poland, they are classified as the most dangerous pest on land dedicated to afforestation and the most serious threat to natural regeneration in the stands. This study was performed in three forest districts in east Poland (Lubart&oacute, w, Marcule, and Wyszk&oacute, w forest districts) in mixed conifer forests, where the presence of Melolontha spp. grubs was evaluated in autumn and spring of 2012 to 2017, respectively. In spring 2012, 2014, and 2016, consecutively &lsquo, small sawdust pits&rsquo, in rows between seedlings were prepared, and in adjacent inter-rows similar control pits without sawdust were marked. In spring and autumn of the following year, sawdust and soil from both types of pits were sieved and Melolonthinae larvae were counted and compared. More grubs were found in sawdust pits in spring than in autumn. In Marcule Forest District (FD) (2014), more grubs were found in inter-rows than in rows with seedlings, when compared to grubs detected using the traditional method of &ldquo, autumn large pits assessment&rdquo, recommended by Polish forest rules. The Melolonthinae population size and location of grubs were related to the weather conditions in the evaluated periods, as well. We conclude that to properly assess the cockchafer threat, it is necessary to perform spring assessment and to search in inter-rows. This could be recommended for decisions on control.

Volatiles are often released upon herbivory as plant defense compounds. While the formation of volatiles above-ground has been intensively studied, little is known about herbivore-induced root volatiles. Here, we show that cockchafer larvae-damaged roots of Populus trichocarpa and P. nigra release a mixture of monoterpenes, including (−)-α-pinene, (−)-camphene, (−)-β-pinene, p-cymene, and 1,8-cineole. Three terpene synthases, PtTPS16 and PtTPS21 from P. trichocarpa and PnTPS4 from P. nigra, could be identified and characterized in vitro. PnTPS4 was found to produce 1,8-cineole as sole product. PtTPS16 and PtTPS21, although highly similar to each other, showed different product specificities and produced γ-terpinene and a mixture of (−)-camphene, (−)-α-pinene, (−)-β-pinene, and (−)-limonene, respectively. Four active site residues were found to determine the different product specificities of the two enzymes. The expression profiles of PtTPS16, PtTPS21, and PnTPS4 in undamaged and herbivore-damaged poplar roots generally matched the emission pattern of monoterpenes, indicating that monoterpene emission in roots is mainly determined at the gene transcript level. Bioassays with Phytophtora cactorum (Oomycetes) revealed inhibitory effects of vapor-phase 1,8-cineole and (−)-β-pinene on the growth of this important plant pathogen. Thus herbivore-induced volatile monoterpenes may have a role in defense against pathogens that cause secondary infections after root wounding.

In 2011, the General Directorate of State Forests in Poland managed 669 forest nurseries on the total area of 2411 ha that produced forest tree seedlings bare root systems, hence vulnerable to Melolontha spp. white grubs. Up to date, no chemical or biological plant protection product for control of cockchafer grubs in forests has been registered in Poland. The study was carried out with the aim to evaluate the efficacy of a biocontrol product Bovecol with BP strain of Beauveria brongniartii on sterilized wheat grain in control of Melolontha spp. white grubs in forest nurseries, established on acidic soils (with pH analogous to that of forest soils) as well as on those alkaline. The active substance of Bovecol was 108 fungal conidia per 1g of the product. Study plots were established in 3 bareroot nurseries, situated in the areas with different soil reaction values and abundant populations of Melolontha spp. white grubs (assessed before Bovecol treatments). The product was applied against L1 larvae (rates in the Czerniawka and Bałtów nurseries: 120 kg/ha and 240 kg/ha) and against L2 larvae (the Iłki nursery: 240 kg/ha). Grub population numbers were assessed 2, 3 and 4 months after the treatments. Application of Bovecol against L1 into the soil with neutral reaction (pH 6.8) caused the reduction of white grub numbers in 2 months, down to the threshold recommended by the Instruction of the protection of forests (mandatory guidelines for the protection of Poland’s State Forests), i.e. less than 1 grub/sampling pit. Bovecol treatment against L1 cockchafer larvae into acidic soil (pH 4.8) had no statistically significant effect on the reduction of grub population numbers, even 4 months after product application. Bovecol treatment against L2 larvae applied into the soil with medium pH value (5.3) gave poorer results when compared to the soil with pH 6.8, but considerably better – when compared to the soil with pH 4.8. The selection of a fungal strain with insecticidal properties against soil insect pests should include the evaluation of strain requirements with regard to soil pH range – optimal for germination, development and growth of a given strain.

The forest cockchafer Melolontha hippocastani is a serious forest pest whose infestation levels have been increasing in South-West Germany since the mid-1980 s. During the past 25 years several control measures have been taken to manage its populations. In 2007 and 2008, 122 and 73 hectares of forest stands comprising of deciduous trees were sprayed with NeemAzal®-T/S (1% azadirachtin A) by helicopter, respectively. Here we summarize the results of the accompanying research with the aim to evaluate the efficacy of NeemAzal®-T/S in the control of M. hippocastani populations under field conditions. As expected from azadirachtin’s mode of action, no immediate mortality occurred but maturation feeding and oogenesis was interrupted. It appeared that precise timing of the application is a crucial issue regarding the level of its effect on the population density. In 2007, the first application was performed in good synchrony with the climax of female emergence from the soil, resulting in a remarkable decline of the population density in the next generation of beetles in 2011. In 2008, our data suggest that maturation feeding and oogenesis had already been completed when the agent was sprayed. Hence, no significant decline of the population density could be registered in 2012. Practicability of the use of NeemAzal®-T/S against M. hippocastani in forests is discussed.

Volatile organic compounds (VOCs) mediate communication between plants and insects. Plants under insect herbivore attack release VOCs either at the site of attack or systemically, indicating within-plant communication. Some of these VOCs, which may be induced only upon herbivore attack, recruit parasitoids and predatory insects to feed on the attacking insects. Moreover, some plants are able to ‘eavesdrop’ on herbivore-induced plant volatiles (HIPVs) to prime themselves against impending attack; such eavesdropping exemplifies plant–plant communication. In apple orchards, the beetle Melolontha melolontha L. (Coleoptera: Scarabaeidae) is an important insect pest whose larvae live and feed on roots for about 4 years. In this study, we investigated whether the feeding activity of M. melolontha larvae (1) alters the volatile profile of apple roots, (2) induces the release of HIPVs systemically in the leaves, and (3) whether infested plants communicate to neighbouring non-infested conspecifics through HIPVs. To answer these questions, we collected constitutive VOCs from intact M9 roots as well as M. melolontha larvae-damaged roots using a newly designed ‘rhizobox’, to collect root-released volatiles in situ, without damaging the plant root system. We also collected VOCs from the leaf-bearing shoots of M9 whose roots were under attack by M. melolontha larvae and from shoots of neighbouring non-infested conspecifics. Gas chromatography-mass spectrometry analysis showed that feeding activity of M. melolontha larvae induces the release of specific HIPVs; for instance, camphor was found in the roots only after larvae caused root damage. Melolontha melolontha also induced the systemic release of methyl salicylate and (E,E)-α-farnesene from the leaf-bearing shoots. Methyl salicylate and (E,E)-α-farnesene were also released by the shoots of non-infested neighbouring conspecifics. These phenomena indicate the induction of specific VOCs below- and above-ground upon M. melolontha larvae feeding on apple roots as well as plant–plant communication in apple plants.

The ability to identify areas of pasture that are more likely to support damaging levels of the soil-borne, redheaded cockchafer (Adoryphorus couloni) (Burmeister) (RHC) would allow farmers to target expensive control measures. This study explored soil properties, measured via electromagnetic surveys (EM38), pasture biomass via active optical sensors (CropCircle™) and topography via GPS elevation survey as potential indicators of RHC population density. A combination of these variables was used to produce risk maps with an accuracy of 88 % at predicting likely RHC density-categories on a dairy property in the Gippsland region of Victoria, Australia. This risk mapping protocol could be used to improve sampling programs and direct site-specific pest management.

Melocont® Pilzgerste, a commercial product based on the entomopathogenic fungus Beauveria brongniartii (Sacc.) Petch (Ascomycota: Hypocreales) strain BIPESCO 2, was applied at different rates and time points over a period of 24 years in East-, North- and South Tyrol (Austria and Italy) to control the European cockchafer (Melolontha melolontha L. and M. hippocastani F.). Beauveria spp. density was assessed and Beauveria spp. isolates were characterized at species and genotype level using Bloc intergenic region sequence and simple sequence repeat marker analyses. BIPESCO 2 was detected at 41 % of the treated sites, predominantly at sites where the fungus was applied at least once during the four years prior to sampling. At one site BIPESCO 2 was detected 15 years after the last treatment. Results showed that applications should be repeated to achieve good persistence of the biological control agent, and it indicated that despite intensive applications diverse populations of B. brongniartii or Beauveria spp. consortia can coexist in these habitats.

Plants are constantly exposed to the influence of biotic and abiotic stress factors that significantly affect the induction of resistance responses. Biotic factors include bacteria, fungi and insects such as the common cockchafer (Melolontha melolontha) that harm many tree species, including pine and larch. The adult beetles damage needles, while the larvae (grubs) feed on roots. The aim of the experiment was to determine how plants cope with the damage caused by these insects. The activity of antioxidant enzymes such as peroxidase (POD) and superoxide dismutase (SOD) were determined three and six weeks after the insect-induced damage and the results show that the peroxidase activity, as measured with guaiacol (GPOD), was higher in the damaged roots of larch. The POD activity measured with syringaldazine (SPOD) was slightly higher in damaged pine needles as well as pine roots. SOD activity was higher in the damaged roots of both species as compared to the needles. It is believed that changes in the activity of POD and SOD as well as the presence of another form of SOD in the roots of larch, indicate direct involvement of these enzymes in the plants’ response to damage caused by M. melolontha.

Insects are among nature’s most nimble flyers. In this paper we present the functional and structural analysis of wing joint mechanism. Detailed action of the axillary plates and their mutual interaction was also described. Because of the small dimensions of the wing joint elements and the limited resolution of the light microscope, the authors used a scanning electron microscope. Based upon the knowledge of working principles of beetle flight apparatus a wing joint mechanism kinematics model has been developed.

Cockchafers are among the most dreaded insect pests in many European countries, causing economic losses in agriculture, horticulture and forestry. In forests of south-western Germany, populations of the forest cockchafer ( Melolontha hippocastani ) and also the field cockchafer ( M. melolontha ) have been increasing during the past three decades and, therefore, monitoring of these populations has been intensified. In the present field study, data on adult emergence from the soil, male swarming flights and female oogenesis, collected at three infestation sites by visual inspection, with soil eclectors and with light traps in early spring 2009-2011, are presented and discussed in the context of the current knowledge of cockchafer biology. Furthermore, three air temperature sum models for the prediction of the onset of the swarming flight period in spring, published in the early/mid 20 th century, were validated in view of their applicability in forestry practice.

In Europe the mature stage in the life cycles of cockchafers, 3–4 years for Melolontha melolontha L. and 4 years for Melolontha hippocastani Fabr., often causes foliage damage in deciduous forests. Within the scope of dendrochronology, secondary effects on wood production have been generally observed in tree-ring series of rather old oak trees. Flight years were detected by eye and/or sign-test (Gleichlaufigkeit) principally with reference to a 50-year long schematic model representing the cockchafer's reproduction cycles. In the SW German dendroarchaeological record, the detection of cockchafer effects in short oak tree-ring series from different periods has led to a reconsideration of the mode of calculation, which now takes into account a shorter time span which is in better agreement with the development of the cockchafer populations (∼30 years) and paying particular attention to the calendar distribution of the cockchafer flight systems known in the region North of the Alps. In the case of th...

The redheaded pasture cockchafer, Adoryphorus couloni (Burmeister) (Scarabaeidae: Dynastinae: Pentodontini) is a pest of semi-improved and improved pastures in south-eastern Australia. It is a native species that has adapted to managed pastures, and despite many years of research in attempts to control it, this species still causes major economic damage, especially to perennial dairy pastures in south-eastern Australia. This is a review of available information on A. couloni and identifies some basic information gaps that require addressing: correct identification of the main pasture beetles, more accurate detection and monitoring methods, and better information on its biology and ecology, especially its feeding behaviour in soil.

Feeding plots often contribute to the spread of micro- and macroparasites. We compared cockchafer grub density, the prevalence and mean intensity of Macracanthorhynchus hirudinaceus infection in cockchafer grubs between wild boar feeding plots and other habitat patches in the southwestern Hungary. Grub density was higher, although not significantly, in feeding plots (6.57 specimen/m2, N = 125) than in the other habitats (4.77 specimen/m2, N = 148). There was significant difference in the prevalence and mean intensity of parasite infestation of the grubs between the two habitat patches. This indicates that the temporary aggregation of wild boar could mildly affect grub density and M. hirudinaceus infestation in its intermediate host.

In times of mass occurrence, massive numbers of the outbreaking species serve as food sources not only to predators and parasitoids but also to scavengers and decomposers. One example benefiting from this process is the necrophagous guild, which depends on a carcass for nutrition and reproduction. A well-known outbreaking insect is the forest cockchafer Melolontha hippocastani F. It inhabits woodlands on sandy soils, the same habitat as Nicrophorus vespilloides Herbst—a common burying beetle feeding on a variety of animal carcass. In this regard, N. vespilloides may come in contact with plant protective agents applied to control M. hippocastani populations. In a laboratory trial, we studied sublethal effects of NeemAzal®-T/S on the reproductive output of female N. vespilloides. They were previously fed with cockchafers, which in turn had been fed with neem-treated leaves. It was shown that female beetles fed with ‘treated’ cockchafers were negatively affected in carcass burying behavior and egg-laying. Furthermore, reduction in larval hatching and survival during the parental feeding phase caused further diminution of the reproductive output. On the other hand, neither impacts on mean larval weights nor morphological malformations in N. vespilloides were observed. Transferability of the results into the field is discussed.

In dendrochronological dating, we encounter the trouble that some samples cannot be dated due to the occurrence of anomalies in the tree-ring series. When dating subfossil wood for the extension of existing master chronologies, this may be an especially unwanted circumstance as subfossil wood is scarce and each sample is valuable. In Moravia (Czech Republic) outbreaks of the cockchafer ( Melolontha sp.) used to appear with a disastrous effect on agricultural crops, and, for a dendrochronologist, on samples of wood to be dated. Oak ring width reduction caused by cockchafer induced defoliation can superimpose climate induced growth variations and may complicate dating of historical or subfossil samples. For this study, 33 samples of sub-fossil trunks were assessed; 19 of which were attacked by cockchafer. For comparison, we analysed a total of nine living oak trees from the forest district Stražnice-Vracov, recently attacked by the cockchafer. Occurrence of the cockchafer was reported there in 1999, 2003 and 2007. We found clear growth patterns with cyclic narrow rings every 4 years. This allowed us to create an artificial curve expressing the recurring cycles of cockchafer outbreaks which assisted us in the detection of the same pattern in subfossil tree growth. The tree-ring series of the attacked living oak stand as well as the 19 individual tree-ring series from subfossil oak trunks could not be dated using standard chronologies and showed a high resemblance to the cockchafer life cycle. Additionally, we found out that the living oak stand was attacked in 1983, 1987, 1991 and 1995 as well. The results support the hypothesis that the periodical reduction observed in tree-rings at regular increments is caused by cockchafer infestation. This evidence is further supported by characteristic anatomical features in early wood. A mean tree-ring series was created from the individual tree-ring series of subfossil oaks even though radiocarbon dating showed completely different ages of samples. This means that the affected tree-ring series cannot be used for dendrochronological dating and dendroclimatological analyses. These series cannot be used without preceding mathematical and statistical modification.

A culture independent method based on qPCR was developed for the detection and quantification of two fungal inoculants in soil. The aim was to adapt a genotyping approach based on SSR (Simple Sequence Repeat) marker to a discriminating tracing of two different species of bioinoculants in soil, after their in-field release. Two entomopathogenic fungi, Beauveria bassiana and B. brongniartii, were traced and quantified in soil samples obtained from field trials. These two fungal species were used as biological agents in Poland to control Melolontha melolontha (European cockchafer), whose larvae live in soil menacing horticultural crops. Specificity of SSR markers was verified using controls consisting of: i) soil samples containing fungal spores of B. bassiana and B. brongniartii in known dilutions; ii) the DNA of the fungal microorganisms; iii) soil samples singly inoculated with each fungus species. An initial evaluation of the protocol was performed with analyses of soil DNA and mycelial DNA. Further, the simultaneous detection and quantification of B. bassiana and B. brongniartii in soil was achieved in field samples after application of the bio-inoculants. The protocol can be considered as a relatively low cost solution for the detection, identification and traceability of fungal bio-inoculants in soil.

The role of soil characteristics for cue-directed behaviour of rhizophagous insects remains largely unexplored to date. Here, we studied behavioural responses of polyphagous cockchafer larvae (Melolontha melolontha; Scarabaeidae) to roots of one of its preferred host plants, dandelion (Taraxacum sectio ruderalia; Asteraceae). Plants were grown in substrates with different adsorptive capacities, i.e. in vermiculite or sand. A behavioural assay was developed which allowed both monitoring the release of attractive CO2 from roots and observation of larval behaviour at the same time. In sand, larvae got closer to the roots than in vermiculite where they eventually stopped orienting towards the roots: However, their total locomotory activity and the number of turning events/stationary points were higher in vermiculite. Larval behaviour was not correlated with CO2 concentrations in both vermiculite and sand. On average, larvae kept a greater distance to vermiculite-grown roots. However, a feeding bioassay revealed that the larvae consumed more of vermiculite-grown roots than of sand-grown ones. This result showed that the weaker orientation of larvae towards vermiculite-grown roots was not due to the lower palatability of these roots. Vermiculite might adsorb foraging-relevant cues of dandelion roots, alter composition of root exudates, and/or physically impair oriented movements of soil-dwelling insects. Our study shows that the type of substrate affects responses of rhizophagous larvae to host roots at multiple levels independently of root-derived CO2 gradients.

To take full advantage of the natural hazel resources and improve its yield and quality in Great Xing’an Ridge region, we carried out an initial investigation. The result showed that: there are two species in this area: Corylus heterophlla and Corylus mandshurica. They mainly distribute from south of XinLin town, HuMa county, Heilongjiang province to south boundary of Great Xing’ an Ridge in mountain and hilly areas. Most of hazel in this area was under the state of natural growth with no scientific man-management. Soil where Corylus heterophlla grew was about 40 cm to 50 cm and Corylus mandshurica was 30 cm to 45 cm. The main plant disease was powdery mildew and insect pest were Curculio dieckmani, Zeuzera sp. and Faust Cockchafer. 100-seed weight of Corylus heterophylla was more than twice of Corylus mandshuria. However, Corylus mandshuria was plumper, had much more kernel and much less empty shell than Corylus heterophylla, and what’s more, shell sickness of it turned to be significantly thinner than Corylus heterophylla, all of which showed great cultivation value and economic commodity value.

In the period between 2003 and 2009 we evaluated the abundance of adults of Melolontha hippocastani Fabr. and Melolontha melolontha (L.) cockchafers in four forest regions of the Czech Republic. During this period each of the evaluated localities was hit twice by heavy swarming. The course of swarming, species composition, abundance of the respective tribe, sex ratio during swarming and the correlation between the course of swarming and average daily temperature were monitored by means of a light trap, an automatic meteorological station and observations in the open space; the data were represented in the form of graphs. We evaluated how the trend of the abundance of the particular species developed in the respective localities in order to work out a more specific prediction of the occurrence of the cockchafer in subsequent years and the extent of damage caused by the grubs to forest plantations. Research will continue in 2010–2011.

SUMMARYActuation of the closing of the elytra was previously ascribed to intrinsic muscles in the mesothorax. We investigated closing (1) by loading or arrest of some thoracic segments in a tethered flying beetle, (2) by animation, i.e. passive motion of preparations of the thorax simulating the action of some muscle, and (3) by excision of some parts of sclerites or cuts across certain muscles. We found out that depression of the prothorax, necessary to unlock the elytra, precedes their opening but elevation of the prothorax is synchronous with the closing. The closing is retarded if the elevation is retarded by loading; if the elevating prothorax is clamped, then the closing is also arrested or hindered; animation of the elevation of the prothorax in the dead animal is enough for the closing of the previously spread elytra; the closing is prevented if a piece at the hind edge of the pronotum, positioned in front of the root of an elytron, is excised. This excision also prevents closing in the in vivo experiments. Mechanical interaction between the elytron and the prothorax is limited to the contact point between the posterior edge of the pronotum and the lateral apophysis of the root. Thus, the elevation of the prothorax is the indirect and main mechanism of the closing in Melolontha.

Studies on the oviposition of the cockchafer (Melolontha melolontha L.) in dependence on the host plants used by their larvae In experiments concerning the host plants for white grubs (Melolontha melolontha L.) roots of dandelion (Taraxacum officinale) proved to be the best source of nutrition. Therefore, it was necessary to test whether the cockchafers preferred places for oviposition with T. officinale, which was the preferential food for the larvae. The experiments were conducted in a cage with plots grown with various plants. The cockchafers had the possibility to choose between the plots. The number of oviposition holes and the number of larvae per plot served as an indication, which plants were preferred by the beetles. The T. officinale plots had 19 %, those with Rumex acetosa 9 % und those without plants only 3 % of the oviposition holes. In correspondence with these results, the percentage of larvae was significantly highest in the T. officinale plots (18 %). There is a conformity when comparing the survival rate of larvae during the feeding experiments and the number of the oviposition holes (T. officinale plot: 77 oviposition holes and 80 % survival rate; Festuca pratensis plot: 24 oviposition holes and 13 % survival rate). These results point to a good adaption of the beetles for the choice of the oviposition places and has to be interpreted as a case of breeding care. Zusammenfassung In Untersuchungen zum Wirtspflanzenkreis der Engerlinge von Melolontha melolontha L. erwiesen sich die Wurzeln von Taraxacum officinale als die fur die Larven am besten geeignete Nahrung. Es war zu prufen, ob die Maikafer sich der Abhangigkeit ihrer Larven von T. officinale angepast haben und ihre Eier bevorzugt auf Flachen mit dieser Pflanze ablegen; dazu wurden Versuche in Flugraumen durchgefuhrt, in denen die Kafer bei der Eiablage zwischen Platzen mit unterschiedlichem Pflanzenbewuchs frei wahlen konnten. Sowohl durch die Anzahl der Eiablagelocher als auch durch die Engerlingsdichte in den Parzellen lies sich dabei gesichert nachweisen, das die Kafer bei der Eiablage Flachen mit T. officinale bevorzugt hatten. So wurden z. B. bei T. officinale 19 %, bei Rumex acetosa 9 % und in der Parzelle ohne Pflanzenbestand 3 % der Eiablagelocher gefunden. In Ubereinstimmung mit den Ergebnissen zu den Eiablagelochern war die Engerlingsdichte in der T. officinale-Parzelle mit 18 % aller Larven gesichert am hochsten. Bei dem Vergleich der Zahl der Eiablagelocher mit der Uberlebensrate der Engerlinge in den fruheren Futterungs- und Praferenzversuchen ergaben sich Ubereinstimmungen, die belegen, das die Kafer bei der Eiablage Pflanzen aussuchen konnen, deren Wurzeln fur die Engerlinge am besten geeignet sind (T. officinale: 77 Eiablagelocher und eine Uberlebensrate von 80 %; Festuca pratensis: 24 Eiablagelocher und eine Uberlebensrate von 13 %). Die Ergebnisse weisen auf die gute Anpassung der Kafer bei der Auswahl der Eiablageorte hin, die vermutlich auf eine angeborene Assoziationshandlung beruht und als Brutfursorge anzusprechen ist.