Elaterid Larvae Research Articles

Flexible trophic position of polyphagous wireworms (Coleoptera, Elateridae): A stable isotope study in the steppe belt of Russia

Larvae of Elateridae beetles, known as wireworms, are widespread pest species damaging various crop plants. In spite of a general morphological similarity, wireworms demonstrate a wide spectrum of trophic modes ranging from phytophagy to predation. In many wireworm species, facultative carnivory ensures the acquisition of proteins necessary for metamorphosis, whereas feeding on living plant tissues (especially juicy roots and tubers) can be stimulated by water deficiency. We therefore hypothesized that polyphagous wireworm species inhabiting three types of steppe (grassland) ecosystems should be more phytophagous in dry conditions. To assess the trophic position of wireworms, we compared their isotopic signatures with those of plants and the soil, as well as of reference species including carnivorous centipedes and Diptera larvae, herbivorous weevils and saprophagous earthworms. Larvae of Agriotes obscurus, Agriotes lineatus, Selatosomus aeneus and Selatosomus latus inhabiting well-drained soils were 3–4‰ enriched in 15N compared to larvae inhabiting wet floodplains, suggesting a difference in at least one trophic level. A comparison with soil animals with known trophic positions indicates that omnivorous wireworms tend to be phytophagous and saprophagous in floodplain, but carnivorous in well-drained habitats. The capability of changing the diet is confirmed by the age-related shift in the trophic position of some species. Elder A. obscurus larvae are significantly depleted in 13C and enriched in 15N, likely indicating a switch from saprophagy to carnivory. Overall, our data suggest a considerable flexibility in the feeding behavior of elaterid larvae in steppe habitats.

Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root herbivores with large, fast growing plants may counteract dominance of those species, thus promoting plant diversity.

Food of the ArmadilloDasypus novemcinctusL. from Cumberland Island, GA

We provide a review of Dasypus novemcinctus (Nine-banded Armadillo) food studies and report on the diet on Cumberland Island, GA. Major invertebrate foods eaten by Armadillos on Cumberland Island were ants (19.3%); beetles, adults and larvae (27.4 %); centipedes (6.5%); lepidopterans, mostly larvae (caterpillars, 13.2%); millipedes (5.7%); spiders (2.1%); and sowbugs (2.2%). Vertebrates eaten (1.9% volume) were mostly frogs and lizards. Plant material comprised about 12% of the volume, including much fruit such as Melia azedarach (China Berry), Vitis (grapes), Ampelopsis arborea (Pepper Vine), and Serenoa repens (Saw Palmetto). The subterranean fungi, Endogonaceae, were eaten by 23.9% of the Armadillos, comprising 1.6% of the volume of their diet. The millipede Narceus sp. appears to have been greatly reduced, based on the significant reduction of this species as a component of the gut content over three decades. This reduction could be due to Armadillo predation. Ants, scarabaeid adults and larvae, and spiders also showed significant decreases during the period of study, which could be a result of Armadillo predation. A number of items—elaterid larvae, crickets, caterpillars, centipedes, sowbugs, and Endogonaceae—showed significant increases as components of Armadillo stomachs, but it is not known whether these changes might be related to Armadillo predation. The increases could have been due to other causes such as habitat or climatic changes.

Multilocus sequence analysis (MLSA) of ‘Rickettsiella costelytrae' and ‘Rickettsiella pyronotae’, intracellular bacterial entomopathogens from New Zealand

Larvae of scarab beetles live in the soil and are frequently hosts for microbial pathogens. In New Zealand, larvae of the grass grub, Costelytrae zealandica (Coleoptera: Scarabaeidae), and manuka beetles, Pyronota spp. (Coleoptera: Scarabaeidae), have been collected from field populations showing loss of vigour and a whitened appearance. Diagnosis indicated an intracellular infection of fat body tissues by Rickettsiella-like micro-organisms. Rickettsiella bacteria are under evaluation as a possible new source of insect bio-control agents for important agricultural pests as, e.g. scarabaeid and elaterid larvae. The present study aimed at the unequivocal molecular taxonomic identification and comparison of the bacteria associated with Costelytra and Pyronota. Electron microscopy and phylogenetic reconstruction using a multilocus sequence analysis approach based on the 16S ribosomal RNA gene together with four protein-encoding markers (ftsY, gidA, rpsA, and sucB) demonstrated that both bacteria from New Zealand are phylogenetically closely related, but not identical, and belong to the taxonomic genus Rickettsiella. The bacteria under study should be referred to as pathotypes 'Rickettsiella costelytrae' and 'Rickettsiella pyronotae', respectively. Moreover, on the basis of the currently accepted systematic organization of the genus Rickettsiella, both pathotypes should be considered synonyms of the nomenclatural type species, Rickettsiella popilliae. The study demonstrates that Rickettsiella bacteria are geographically widespread pathogens of scarabaeid larvae. Implications of the phylogenetic findings presented for the stability of host adaptation by Rickettsiella bacteria are critically discussed.

Stable isotope analysis reveals whether soil-living elaterid larvae move between agricultural crops

Tracking the movement of soil-living herbivores is difficult, albeit important for understanding their spatial ecology as well as for pest management. In this study the movement of Agriotes obscurus larvae between plots harbouring isotopically different plants was examined. Neither between maize and wheat nor between maize and grassland movement could be detected. These data suggest that Agriotes larvae rarely disperse between crops as long as local food supply is sufficient. Moreover, the current approach provides a new means to study the dispersal of soil invertebrates in situ.

Does scavenging extend the host range of entomopathogenic nematodes (Nematoda: Steinernematidae)?

Living and freeze-killed natural and laboratory hosts, with different susceptibility to entomopathogenic nematodes, were exposed to the larvae of Steinernema affine and Steinernema kraussei in two different experimental arenas (Eppendorf tubes, Petri dishes), and the success of the colonisation and eventual progeny production were observed. Both nematodes were able to colonise both living and dead larvae of Galleria mellonella (Lepidoptera) and adult Blatella germanica (Blattodea) even though the progeny production in dead hosts was lower on average. Living carabid beetles, Poecilus cupreus, and elaterid larvae (Coleoptera) were resistant to the infection, however, both nematodes were able to colonise and multiply in several dead P. cupreus and in a majority of dead elaterid larvae. By scavenging, EPNs can utilise cadavers of insects that are naturally resistant to EPN infection, and so broaden their host range.

Spatial avoidance of patches of polluted chernozem soils by soil invertebrates

AbstractSoil invertebrates and heavy metal concentrations are heterogeneously distributed in the soil of steppe plots surrounding an iron mining enterprise in southern Russia. This study assesses whether patches of high soil invertebrate abundance coincide with patches of low concentrations of pollutants. For this aim, spatial analysis by distance indices (SADIE) was applied. Three valleys in Belogorye Nature Reserve were chosen. One valley faced the tailing pond to the north and the other two faced south‐east or south‐west. Two sampling plots were chosen in each valley, 60 m apart from each other. On every plot 16 soil cores were collected from a grid of 4 × 4 units with a 5‐m distance between each sample unit. Each soil core had an area of 76 cm2 and was 12–15 cm deep. All macroinvertebrates were hand‐sorted and identified to family. Abundance of soil invertebrates was not controlled by patches of metal concentration in the soil. Epigaeic groups, like insects and other invertebrates inhabiting the litter layer, were not directly associated with local parameters of the soil. On the contrary, belowground invertebrate abundance (elaterid larvae and earthworms) showed significant dissociation with some heavy metal (Fe, Pb, Zn) concentrations in the soil. The patchiness of soil pollution may act as a leading factor of belowground soil invertebrate distribution. The spatial structure of animal populations in industrially transformed soils needs further research.

The feeding ecology of elaterid larvae in central European arable land: New perspectives based on naturally occurring stable isotopes

To understand soil food webs, empirically generated data on the trophic connections and the feeding ecology of the major below-ground animal taxa are needed. Here we used stable isotope analysis to assess the trophic ecology of wireworms, the larvae of click beetles, in Central European arable land. Wireworms are amongst the major soil macroinvertebrates and are of practical importance in arable soils. Besides feeding on crops, they are thought to feed on weeds, soil organic matter (SOM), and even animal prey, but their feeding ecology is poorly studied under natural conditions. Elaterid larvae and their putative feeding substrates—plant roots, SOM, and litter—were sampled at 17 locations in Austria, Germany, and Italy and their isotope ratios of carbon ( 12C/ 13C) and nitrogen ( 14N/ 15N) measured to determine the wireworms’ trophic level, the importance of SOM and weeds within the diet of Agriotes larvae, as well as the individual diet variation in Agriotes obscurus larvae. δ 15N signatures suggested that Agriotes larvae are predominately herbivorous, whereas the other wireworm species primarily fed on animal prey. In contrast to SOM, weeds were readily eaten by Agriotes larvae: their dietary contribution ranged between 28% and 67% in weedy maize fields. Most A. obscurus larvae fed on a mixed diet of weeds and maize, although ∼15% of the larvae fed primarily on one of the two food sources only. δ 15N signatures indicated that ∼10% of the “herbivorous” A. obscurus larvae fed primarily on animal prey, revealing high intraspecific trophic plasticity in these soil insects. Wireworm feeding behaviour is apparently complex at the individual level: the population consists of types A and B generalists, a phenomenon which needs further assessment.

Chemical, biological and evolutionary aspects of beetle bioluminescence

This work is dedicated to Prof. Waldemar Adam, an esteemed friend and eminent scientist who, for decades, generously shared knowledge, enthusiasm, and laboratory supplies with many Brazilian investigators, among them G. Cilento and myself. In 1980, Prof. Adam was elected Foreign Member of the Brazilian Academy of Sciences in recognition for his substantial contributions towards the development of Chemistry in Brazil. Abstract The hypothesis that luciferases evolved from ligases that acquired oxygenase and luminogenic activities, thereby contributing to the antioxidant machinery of bioluminescent organisms, is revisited here. Larvae of click beetle Pyrearinus termitilluminans (Coleoptera: Elateridae) live under conditions close to normoxia into tunnels dug into termite mounds, whereas other elaterid larvae inhabit tunnels in decaying logs, where pO2 is ~ 2-5%. Interestingly, the catalase and superoxide dismutase (SOD) activities in click beetle larvae were found to respond to the habitat pO2 and are significantly lower in non-luminescent elaterids. Exposure of larval P. termitilluminans larvae to hyperoxia induced SOD and catalase activities concomitantly with increments in luciferase and luciferin levels mainly in the prothorax, the brightest larval segment. Thoracic luciferase activity is 1000-fold higher than in the abdomen, while SOD activity is 2- fold higher. With larval development, an expected decline in antioxidant enzyme activities was apparently compensated by an increase in luciferase activity (2-3 fold) and in urate (40-fold), a major insect antioxidant. Finally, we found that the ligase-rich fat body of larval Tenebrio molitor, a non-luminescent beetle, contains a primal luciferase-like activity. Altogether, these data strengthen the hypothesis that various bioluminescent systems may have developed from potentially chemiluminescent metabolites and ligases that acquired a dioxygenase and luminogenic function over the course of evolution.

Population dynamics of wireworms (Coleoptera, Elateridae) in arable land after abandonment

The community of elaterid larvae of three sites (field and two fallows), representing different stages of secondary succession, were studied using soil sampling from 1986 to 1993. All three sites were abandoned arable land: a field cultivated until 1991, a fallow I abandoned in 1986, and a fallow II abandoned about 1976. The fallow II was used as a meadow after abandonment and was regularly mown until 1985, when cultivation stopped. Six species of Elateridae larvae were found at all three study sites. In the field, Agriotes obscurus, Athous niger, Athous subsuscus, Dalopius marginatus and Athous vittatus were found, A. niger and A. obscurus being the most abundant species. During cultivation, larval densities were very low, however, larval abundance increased up to 8.8 ± 8.3 ind. m-2 when cultivation stopped. Only small A. obscurus larvae were found during cultivation, whereas larval size increased after abandonment. In fallow I A. obscurus, A. niger, A. subsuscus, D. marginatus, and Agrypnus murinus were found and the average annual abundance fluctuated between 0.8 ± 1.4 to 40.8 ± 10.9 ind. m-2 with A. obscurus being the most abundant species. Fallow II supported the highest densities of wireworms from all plots studied (71.2±35.2 to 280.0±24.8 ind. m-2). A. obscurus, A. niger, A. subsuscus and D. marginatus were found in fallow II. The abundance of all larval Elateridae as well as the dominant species A. obscurus decreased during the study period, while simultaneously the occurrence of small sized A. obscurus larvae decreased. The frequency of cultivation and time elapsed since last cultivation appeared to be the most important factors affecting elaterid occurrence in the field and fallow I. In fallow II, the decrease in abundance correlates with the accumulation of a dense litter layer, which may correspond with soil surface structure, plant community changes or predator pressure.

Evaluating 15N/ 14N and 13C/ 12C isotope ratio analysis to investigate trophic relationships of elaterid larvae (Coleoptera: Elateridae)

Carbon and nitrogen isotope ratios in consumer tissues can be used to analyse the diet and trophic level of soil animals. However, life history traits may significantly influence stable isotope patterns. We evaluated in a series of experiments how stable isotope ratios of carbon ( 13C/ 12C) and nitrogen ( 15N/ 14N) at natural abundance can be used to study the diet and trophic position of long-lived macro-invertebrates, elaterid larvae, which are major below-ground herbivores. Small, but significant differences in δ 13C signatures were found between the larvaes’ anterior and posterior body segments, whereas exuvia reflected the body's overall isotopic composition. The species-specific trophic shift (±SE) in δ 15N for Agriotes obscurus and Agriotes sputator (1.62±0.24‰ and 1.08±0.27‰, respectively) was significantly lower than “mean enrichment estimates” reported in the literature, showing the limited applicability of such generalised estimates in studies of invertebrate trophic ecology. To avoid false-positive assignments to two trophic levels due to variation in δ 15N values, a minimum sample size of three and five individuals for A. obscurus and A. sputator, respectively, was needed to reduce this risk to below α=5%. Keeping elaterid larvae for up to 128 days without food did not affect their isotopic signatures, in contrast to previous studies on starving animals. Switching wireworms to isotopically different diets induced changes in their isotopic signatures within 2 weeks. Changes, however, were significant only when the isotopic difference between diets was large. We conclude that experimental studies evaluating how specific life history traits affect stable isotope signatures in consumers have to precede any interpretation of stable isotope data gathered in the field.

Soil dwelling macro-invertebrates in intensively grazed dairy pastures in Pennsylvania, New York and Vermont

This study estimates the relative contributions of environment and farm management strategies in influencing soil faunal assemblages and attempts to identify the species with potential to affect sustainability of intensive grazing management systems in the north-eastern USA. It arises because of the change from confinement feeding of dairy cattle, consequent upon concerns about negative environmental effects, the rising costs for machinery and housing, and reduced profit margins, together with the absence of data from which the consequences of such change on the soil fauna may be predicted. Macro-invertebrates were sampled in soil from seventy-eight grazed pastures on twenty-one dairy farms in Pennsylvania, USA, in the spring of 1994. On five of these farms, macro-invertebrates were sampled (four pastures per farm) in the spring, summer and autumn seasons of 1994, 1995 and 1996. In 1997, macro-invertebrates were sampled in soil during spring, summer and autumn from (four pastures per farm) on three farms in New York, and during spring and summer on three farms in Vermont. Species richness ranged from two to twelve species (mean 6·4) per pasture site in Pennsylvania and five to eighteen species (mean 10·7) in New York and Vermont. The communities were dominated at most sites by earthworms. Earthworms were correlated with soil basal and substrate-induced respiration/carbon ratio, and soil moisture, but were negatively correlated with cows per hectare and herbage biomass in Pennsylvania. Sitona larvae were recorded at nineteen of the twenty-one farms during the spring of 1994 across Pennsylvania and occurred at populations >5 m−2 in 68% of the sampled pastures. Sitona larvae were less abundant in New York and Vermont. Elaterid larvae comprised a complex of seven species of which Aeolus melillus (Say) and Melanotus communis (Gyllenhal) comprised 35% and 39%, respectively, of the elaterids collected in Pennsylvania. Agriotes mancus (Say) and Ctenicera destructor (Brown) comprised 41% and 26%, respectively, of four species collected in New York and Vermont. Scarabaeid larvae, comprising a complex of eight species, were detected at only 27% of the seventy-eight pastures sampled in spring 1994 in Pennsylvania. Five species were collected in ten of the twelve New York pastures and four species in nine of the twelve Vermont pastures. Populations of scarabaeid larvae averaged <25 m−2 in all three states, except in three Pennsylvania pastures in spring 1994. Detrended canonical correspondence analysis (DCCA) showed pasture standing biomass, legume diversity, pre-winter stubble height, white clover pasture content, and soil phosphorus levels influenced numbers of invertebrate species more than climatic factors, such as temperature, rainfall, altitude, latitude and seasonal water table. DCCA also showed most pastures to be close to the average of environmental factors. The extremely low density of herbivorous macro-invertebrates in soil and the absence of pest outbreaks may indicate a stable soil ecosystem.

Bioluminescence as a Possible Auxiliary Oxygen Detoxifying Mechanism in Elaterid Larvae

This work examines the hypothesis that beetle bioluminescent reactions may primarily have evolved to provide an auxiliary O 2 detoxifying mechanism. The activities of antioxidant enzymes and of luciferase in the prothorax (bright) and abdomen (dim) of luminous larval Pyrearinus termitilluminans (Coleoptera: Elateridae) were measured after previous challenge with either hyperoxia, hypoxia, or the firefly luciferase inhibitor luciferin 6′-methyl ether (LME). Upon exposure to pure O 2 for 72 h, the prothorax activities of total superoxide dismutase (SOD) and catalase were found to increase by 85% and 50%, respectively. Concomitantly, levels of luciferase and luciferin increased 80% and 50%. Assays of thiobarbituric acid reactive substances (TBARS) showed significantly augmented lipid peroxidation only in the abdomen (30%) where levels of antioxidant enzymes and especially luciferase are low. In contrast, exposure to hypoxia (2% O 2) led to significant increases in prothorax citrate synthase (85%), succinate dehydrogenase (25%), and lactate dehydrogenase (30%) activities, but not in luciferase or antioxidant enzyme levels. LME administration alone decreased luciferase activities 20% but did not alter prothorax SOD activity. Prothorax SOD activity was increased by concomitant LME and hyperoxia treatments (30%), along with higher levels of TBARS (25%) and protein reactive carbonyl groups (50%). Altogether these data suggest that in elaterids, bioluminescence and reactions catalyzed by antioxidant enzymes may cooperate to minimize oxidative stress.

The effectiveness of helmeted guineafowl Numida meleagris (Linnaeus 1766) in controlling the banded fruit weevil Phlyctinus callosus (Schönherr 1826), and their impact on other invertebrates in apple orchards in the Western Cape Province, South Africa

The role of indigenous vertebrate predators, especially birds, in controlling pest insects is poorly known. This study quantifies the effectiveness of helmeted guineafowl Numida meleagris (Linnaeus 1766; Aves: Numididae) in controlling the banded fruit weevil Phlyctinus callosus (Schönherr 1826; Coleoptera: Curculionidae), a pest in apple and nectarine orchards in the Western Cape Province, South Africa. The impact of guineafowl on other invertebrates and on apple crops is also assessed. Periodic counts of weevils under trunk bands showed that guineafowl did not reduce weevil numbers significantly, but suction samples indicated that weevils were more abundant in plots without guineafowl. On average only 1.07 weevils were found in 30 guineafowl crops (range 0–14 weevils). The results suggest that although guineafowl consume weevils, they have a negligible impact on large weevil populations. Other invertebrates, especially molluscs and elaterid larvae (Coleoptera) were often eaten. Guineafowl reduced insect diversity in apple orchards either directly through predation or indirectly by altering the structure of the cover plants. The damage that guineafowl allegedly cause to apples was not confirmed.

The influence of omnivorous elaterid larvae on the microbial carbon cycle in different forest soils

Data are presented on the influence of Athous subfuscus larvae (Coleoptera, Elateridae) on the microbial carbon cycle in the biotically most active horizons of three contrasting beech forest soils: the Ah horizon of a mull soil on limestone (Göttinger Wald, FRG), the F/H horizon of a moder soil on new red sandstone (Solling area, FRG) and in the F/H horizon of a lime ameliorated area close to the second site. Gut content analyses demonstrated that the larvae of A. subfuscus are humiphagous and that this unspecific feeding behaviour is widely independent of soil conditions. Differences in 14C incorporation demonstrated that only the larvae in the F/H horizon of the limed moder soil directly affected primary decomposer organisms. However, the burrowing activity of the larvae in the topsoil indirectly modified the time course of beech leaf-litter decomposition in the litter layer of all three soils. The microflora of the mull soil contained 2.6%, that of the moder soil 0.7% and that of the limed moder soil 2.2% of total C. The metabolic quotient (qCO2, 10°C) of the soil microflora was 0.0010 (mgCO2-C·mg-1 biomass-C·h-1) in the mull soil, 0.0034 in the moder soil and 0.0012 in the limed moder soil. The A. subfuscus larvae generally reduced the size of the microbial C pool (<-30%) and increased the metabolic quotient of the microflora (>+50%). Considering these soil-independent effects of A. subfuscus on the C turnover of the soil microflora, the burrowing activity of humiphagous soil arthropods may generally increase nutrient availability to primary producers. The results of this study reveal that some of the micro- and mesoscale effects of humiphagous arthropods on the microbial carbon turnover in beech forest soils are surprisingly similar, even under very different soil conditions. The long-term modification of the time course of leaf litter decomposition, in contrast, indicates that the influence of humiphagous arthropods on the formation of the humus layer is soil-specific. There are profound differences in the role of humiphagous arthropods in limed moder soils and in naturally base-rich soils. It is concluded that liming increases competition within the microfloral population due to accelerated humification. The negative effect of A. subfuscus on 14C mineralization in the limed substrate could thus be explained by its effects on a microflora that was strongly limited by the availability of carbon.

IDENTIFICATION OF THE LARVA OF GLYPHONYX BIMARGINATUS SCHAEFFER (COLEOPTERA: ELATERIDAE)

Elaterid larvae of an unknown species were reared to adults and identified as Glyphonyx bimarginatus Schaeffer. The larva of G. bimarginatus is described and illustrated on the basis of cast larval skins and preserved specimens.

Brazilian species of luminescent Elateridae: Luciferin identification and bioluminescence spectra

In vivo and in vitro bioluminescence spectral data are presented for 12 species of Elateridae (two tribes, four genera) in distinct stages of their life cycle. In adults, the emission color from the abdominal light organ is always shifted (20–40 nm) towards the red relative to that from the prothoracic lanterns (525–560 nm). Thin layer chromatography in five different elution conditions revealed that the luciferin extracted from 13 elaterid species, at different stages of development and from either the thoracic or abdominal lanterns, is the same as that of firefly luciferin. The spectral data suggest the occurrence of luciferase isozymes in the abdominal and thoracic lanterns and in the four metamorphic stages. The bioluminescence intensity from Pyrearinus termitilluminans eggs and larvae increases sharply upon increasing the temperature, with an apparent activation energy of ca 25 kcal mol −1 ( in vitro E a ∼ 16 kcal mol −1 . Field and laboratory observations show that light emission by elaterid larvae serves hunting and defense purposes.

Oxygen toxicity aspects in luminescent and non-luminescent elaterid larvae

Superoxide dismutase (SOD) and catalase activities were determined in larvae of luminescent and non-luminescent click-beetles (Elateridae). Superoxide dismutase levels were found to be 5- ( Pyrophorus divergens and an unidentified Pyrophorinae) and 15- ( Pyrearinus termitilluminans) fold higher in the luminescent insects. Regarding catalase, the data show that P. divergens and the unidentified species are richer (1.7 and 3-fold, respectively), whereas P. termitilluminans is poorer (0.7-fold) in this enzyme than non-luminescent Elateridae. For luminescent larvae, a direct correlation between SOD activity and brightness from the segments of their body (thoracic or abdominal) was observed. The results are interpreted in terms of SOD protection against deleterious effects of active oxygen species arising from storage of molecular oxygen to sustain the bioluminescent reaction.

Insect and Mammal Predation of Yellowheaded Spruce Sawfly Cocoons (Hymenoptera: Tenthredinidae) 1

Predation by small mammals and insects on overwintering cocoons of the yellow headed spruce sawfly, Pikonema alaskensis (Rohwer), was measured using an exclusion cage technique. In exposed soil cores mammals preyed on a total of 45.2% of the “planted” cocoons and insects preyed on an additional 20.3%. Insects preyed on 38.8% of the cocoons in cores enclosed by mammal exclusion cages. Eight species of small mammals were trapped in the study areas. Elaterid and carabid larvae were the dominant insect predators. In the soil cores 95.2% of the sawfly cocoons were at a depth of 2 cm or less. Mammal and insect predation rate was slightly heavier on cocoons in the surface stratum than on cocoons deeper in the soil.

Seasonal Vertical Movement of Wireworm Larvae in Missouri: Influence of Soil Temperature on the Genera Melanotus Escholtz and Conoderus Escholtz1

The seasonal vertical movement and distribution of Elaterid larvae was observed in a cornfield near Columbia, MO during 1971–1972. The seasonal vertical movement of Melanotus may be cyclic whereas the seasonal vertical movement of Conoderus may not be cyclic but is coincident with soil temperature. The results also indicate that wireworm damage to corn seeds and seedlings in central Missouri may be primarily attributed to larvae of the genus Melanotus .