Larvae Coleoptera Research Articles

Enclosing decomposer food web: implications for community structure and function

We designed a field experiment to evaluate how restriction of soil faunal movements affects decomposer community structure, food web architecture, and decomposition of organic matter. Intact soil cores (3cm thick, diameter 16cm) were placed either in “open” (mesh size 1mm, allowing all meso- and microfauna to move through) or “closed” (27μm, animal movement prevented except for the smallest microfauna) mesh bags in early May. Before being buried in the forest floor of a mixed spruce stand, hay litter was placed in the mesh bags in separate litter bags. The samplings took place 2 and 6 months after establishing the experiment. Additional “field samples” were taken from the adjacent soil to determine possible side effects of the mesh-bags. Physicochemical conditions, decomposition rate of hay litter, and total respiration of soil cores were identical in the two bag treatments. Enchytraeids increased significantly in the closed treatment, while macrofauna, such Coleoptera larvae and dipteran larvae, went close to extinction in the closed bags. The elevated enchytraeid number is in accordance with the findings of closed microcosm studies, and is best explained by reduced predation by macrofauna. Although a set of 14 mite taxa was found to distinctively reflect the degree of isolation, neither the total number of individuals nor the number of microarthropod taxa differed between the bag treatments, or between the bags and the field samples. It is concluded that in the time-span of one growing season, reduction in the spatial scale does not necessarily reduce the diversity of fauna but can significantly change the decomposer food-web architecture.

The diet of insectivorous ducklings and the acidification of small Ontario lakes

We examined the diet of insectivorous ducklings of four species of waterfowl, Common Goldeneye (Bucephala clangula), Ring-necked Duck (Aythya collaris), Hooded Merganser (Lophodytes cucullatus), and American Black Duck (Anas rubripes), collected from small lakes covering a range of acidity in northeastern Ontario. The numbers of Odonata larvae, aquatic Hemiptera, aquatic Coleoptera, and Trichoptera larvae eaten by the ducklings were estimated from combined esophageal and gizzard contents and analysed with respect to differences in lake acidity and fish presence. Ducklings of all species, especially Common Goldeneye and Hooded Merganser, ate significantly more nektonic prey, especially Notonectidae (Hemiptera) and Dytiscidae (Coleoptera), from lakes without fish than from lakes with fish. Ducklings of species other than American Black Duck ate more Anisoptera larvae on acidic lakes. American Black Duck ducklings ate more teneral Odonata on acidic lakes. There was a tendency for more Trichoptera larvae to be eaten on non-acidic lakes than on acidic lakes. All four species adjusted, to some extent, for the absence of acid-sensitive prey in acidified lakes by feeding on prey that are most abundant under acidic, Ashless conditions. Differences in diet among species were related to differences in diving and foraging behaviour, and to hatch date.

Domain organization of Bacillus thuringiensis CryIIIA delta-endotoxin studied by denaturation in guanidine hydrochloride solutions and limited proteolysis.

Denaturation of Bacillus thuringiensis CryIIIA delta-endotoxin--an insecticidal protein, active against Coleoptera larvae--in concentrated guanidine hydrochloride solutions was pursued by fluorescence and circular dichroism spectroscopy and limited proteolysis. It was found that the protein consists of two fragments that differ by their stability to denaturation by guanidine hydrochloride at pH 3. The less stable fragment corresponds to the N-terminal alpha-helical domain limited by Leu-279; the more stable one starts with Ile-280, contains about 330 amino acid residues, and corresponds to the molecule C-terminal moiety that consist of its two beta-structural domains forming a superdomain.

Colonization and Degradation of Cattle Dung: Aspects of Sampling, Fecal Composition, and Artificially Formed Pats

Many biotic and abiotic factors influence colonization and degradation of cattle dung pats. Thus, studies using the pat as an experimental unit require precise methodology to prevent misinterpretation of results. This paper reports trials in which impact of methodological procedures on dung fauna and dung degradation was investigated. Factors investigated were pat position on pasture, sampling techniques, influence of various diets, and a comparison between naturally voided versus artificially formed pats. Parameters used to measure these factors included quantitative and qualitative monitoring of dung fauna, including Coleoptera, Diptera, bacteria, nematodes, and Lumbricidae, and assays of pH, moisture content, and organic matter content of dung. An influence of pat position on colonization was seen, with Staphylinidae occurring more frequently in pats located toward the center of a pasture compared with pats located close to a road. Coleoptera larvae preferred the northern parts of the pats. Pat composition influenced colonization of Coleoptera. Staphylinidae and Scarabaeidae preferred pats from cattle fed with grass, but Hydrophilidae preferred pats from cattle fed corn silage. More Coleoptera larvae were collected from pats produced by grazing cattle compared with pats from cattle fed hay or corn silage. There were no significant differences between artificial and natural pats as to the total number of Coleoptera, Diptera, or bacteria collected. However, development of Diptera larvae was accelerated in the artificial pats. Degradation of pats measured by content of organic substance and pat area was similar in artificial and natural pats.

The degradation of dung produced by cattle treated with an ivermectin slow-release bolus

Eight female calves of the Deutsches Fleckvieh breed, weighing 161–207 kg, were each treated at turnout on 16 May 1989 with one ivermectin sustained-release intraruminal bolus designed to release ivermectin at 12 mg day −1 for approximately 120 days. Eight animals remained as untreated controls. A third group of eight unmedicated tracer calves was not considered as part of this evaluation. All 24 animals grazed together on a single pasture throughout the study. On Days 21/22, 70 and 119, 15 faecal pats were selected from each treatment group and ranked according to surface area; within each group of three consecutively ranked pairs of pats, two pairs were randomly allocated as observation pats and the third as a sampling pat. The surface area of observation pats was measured, photographs taken, and dry matter, crude ash and organic matter determined at various intervals following deposition. A 1 4 sample collected from sampling pats 3, 7, 14 and 28 days after deposition was weighed and examined for Coleoptera (adults and larvae), Diptera larvae and nematodes. No differences between groups were seen in respect of organic matter content, numbers of frequency of adult Coleoptera species and soil nematodes. A decrease in numbers of Coleoptera larvae, Diptera larvae and dung-specific nematodes was observed in pats from ivermectin-treated cattle. Based on the evaluation of the surface area, a delay in the degradation rate of pats from treated compared with those from untreated animals was seen; however, the difference was statistically not significant ( P>0.05).

Survey of some granivorous and non-granivorous insects and mites of stores in Saudi Arabia

Insects and mites infesting wheat, maize, wheat bran and dust samples, stored in or collected from Riyadh and Dammam Provinces, Saudi Arabia, during two seasons, 1987 and 1988, were identified. Of these pests, 16 species of insects were mainly granivorous. Another 26 insect species and 7 mite species were mainly non-granivorous, being either predators, parasites, scavengers or incidentals. The relative abundance of the different species was discussed, and found to be dependent on factors of season, province and type of commodity. “Common” species found in both seasons and provinces, included 9 granivorous (4 Trogoderma spp, Tribolium castaneum, Latheticus oryzae, Rhyzopertha dominica, Liposcelis sp. and one Thysanoptera species beside Coleoptera larvae) and 2 non-granivorous (one Cecidomyiidae sp. and Acaropsis sollers) species.

Diet of bat-eared foxes <i>Otocyon megalotis </i>in the Karoo

The diet of bat-eared foxes Otocyon megalotis was studied from March 1988 to September 1989 at two sites near Beaufort West in the central Karoo. In a near-natural habitat (Karoo National Park), insects and wild fruit contributed almost equally to the diet, while more insects than plant material were consumed on a sheep farm (Saucyskuil). Adult and larval Coleoptera (KNP) and Orthoptera (Saucyskuil) were predominantly preyed upon in an opportunistic manner, influenced by food availability. A higher volume of Isoptera was consumed at Saucyskuil, suggesting higher availability in the farming area.

Reactions of the Macrofauna of a Forest Mull to Experimental Perturbations of Litter Supply

Jean-Fransois David, Jean-Fransois Ponge, Pierre Arpin, and Guy Vannier David J.-F., Ponge, J.-F., Arpin, P. and Vannier, G. 1991. Reactions of the macro- fauna of a forest mull to experimental perturbations of litter supply. - Oikos 61: 316-326. The effects on forest soil macrofauna of two treatments, viz. litter interception and twofold litter supply, were studied for five yr in the field. Results concern five saprophagous groups (Lumbricidae, Diplopoda, Isopoda, Coleoptera larvae, Diptera larvae) and five zoophagous groups (Geophilomorpha, Lithobiomorpha, Pseudo- scorpionida, Coleoptera larvae, Diptera larvae). The litter interception had a nega- tive effect on the abundance of most taxa, but was rather slow; there was no significant decrease in abundance before at least 1 yr in Lumbricidae, 2 yr in Isopoda and zoophagous Diptera larvae, 2.5 yr in Diplopoda, saprophagous Diptera larvae, Geophilomorpha and Lithobiomorpha. The twofold litter supply had no significant effect on the abundance of most taxa; on the other hand, it initiated a process of dead leaf accumulation in relation to control, with an annual decomposition rate (k') higher on the control plot than on the plot with an increased litter supply. The results do not support the assumption that saprophagous soil macrofauna are food-limited in acid mull conditions.

Tobacco Plants Transformed with the Bean αai Gene Express an Inhibitor of Insect α-Amylase in Their Seeds

Bean (Phaseolus vulgaris L.) seeds contain a putative plant defense protein that inhibits insect and mammalian but not plant alpha-amylases. We recently (J Moreno, MJ Chrispeels [1989] Proc Natl Acad Sci USA 86:7885-7889) presented strong circumstantial evidence that this alpha-amylase inhibitor (alphaAI) is encoded by an already-identified lectin gene whose product is referred to as lectin-like-protein (LLP). We have now made a chimeric gene consisting of the coding sequence of the lectin gene that encodes LLP and the 5' and 3' flanking sequences of the lectin gene that encodes phytohemagglutinin-L. When this chimeric gene was expressed in transgenic tobacco (Nicotiana tabacum), we observed in the seeds a series of polypeptides (M(r) 10,000-18,000) that cross-react with antibodies to the bean alpha-amylase inhibitor. Most of these polypeptides bind to a pig pancreas alpha-amylase affinity column. An extract of the seeds of the transformed tobacco plants inhibits pig pancreas alpha-amylase activity as well as the alpha-amylase present in the midgut of Tenebrio molitor. We suggest that introduction of this lectin gene (to be called alphaai) into other leguminous plants may be a strategy to protect the seeds from the seed-eating larvae of Coleoptera.

Biochemical Ecology of Canavanine‐Eating Seed Predators

L—canavanine, a nonprotien amino acid structurally similar to L—arginine, is potentially toxic to many insects. In northwestern Guanacaste Province in Costa Rica, most insect seed predators do not feed on seeds that contain canavanine. However, several larval Coleoptera have become specialists on canavanine—containing seeds. Three of these beetles were compared with a number of other insects with regard to their biochemical ability to deal with and utilize L—canavanine. Our analysis revealed that certain biochemical capacities required by canavanine—feeding insects may have existed prior to their exposure to dietary canavanine.

Cloning of an insecticidal toxin gene ofBacillus thuringiensissubsp.tenebrionisand its expression inEscherichia colicells

A structural gene of a crystal protein toxic for coleoptera larvae was cloned from plasmid DNA of Bacillus thuringiensis subsp. tenebrionis (BTT). The DNA was partially digested with restriction enzyme BamHI and fragments were inserted into cosmid pHC79. In Western blot analysis extracts from infected Escherichia coli cells revealed expression of the BTT crystal protein in antibiotic-resistant cells. Cell lysates from a selected E. coli clone were toxic for larvae of the Colorado potato beetle (Leptinotarsa decemlineata). The electrophoretic mobility in SDS gels of crystal protein from E. coli cells was 68 kDa and 74 kDa as observed for BTT-toxin in B. thuringiensis extracts. The cosmids obtained were unstable during cellular propagation. The deletion product still carried the δ-endotoxin gene.

EFFECT OF PHORATE ON SOIL ARTHROPODS AND SOYBEAN PRODUCTIVITY IN A NORTH CAROLINA COASTAL PLAIN CROPPING SYSTEM

Soil arthropods were sampled from untreated and phorate-treated conventionally tilled soybean (Forrest cv) systems at the Tidewater Research Station, Plymouth, NC. Arthropods larger than 420 microns (U.S. Std. 40 mesh) were collected in 10-cm diameter by 15-cm depth soil cores and extracted through an elutriation process. Microarthropods larger than 149 microns (U.S. Std. 100 mesh) were collected in 5-cm diameter by 5 cm-depth soil cores and extracted using a salt flotation technique. Soybean root weight, root damage, nodulation, and yield were also quantified. Coleopteran larval number in early-planted soybean was positively correlated with root weight (r = 0.404, P < 0.01) and nodulation, yet soybean yields were higher (P < 0.05) in phorate-treated than in untreated plots. Adult Ataenius spp. number was higher (P < 0.05) in phorate-treated than in untreated plots in 1984 and 1985, suggesting higher arthropod decomposer activity in phorate- than in untreated soil. Predaceous centipede number was positively correlated with the number of Chrysomelidae larvae (r = 0.478, P < 0.001) and other Coleoptera larvae (r = 0.357, P < 0.01) in late-planted soybean. Similar nodulation levels between phorate-treated and untreated plants suggests compensatory or possibly stimulatory growth in response to low levels of soil arthropod feeding.

Ambiguous Relations between Bruchus affinis and the Lathyrus Group

The relationship between plants and insects is generally considered from a Manichean point of view. So, phytophagous insects are separated from pollinating insects. The seeds of many Leguminosae (Fabaceae) are consumed by larvae of specialist Coleoptera (Bruchidae) which are considered pests of these plants. But some data show that adults visit the flowers before ovipositing on (or inside) the pods. The mature seeds of many Lathyrus spp. are consumed by larvae of Bruchus affinis. The flowers of some populations of L. latifolius, L. sylvestris and L. tuberosus are frequently visited by the adults of this insect whose mouth parts become abundantly contaminated with pollen. Such contaminated adults are not discovered on flowers of other species. In addition, though Fabaceae are essentially autogamous, the frequency of aborted flowers is very high in these three species. For these reasons: the specificity of the adult Bruchus-Lathyrus relationship, and the variability of abortion of their ovules, we suggest that the pollination activity of Bruchus affinis balances for these perennial plants the negative effect of the reduction of mature seeds by the larvae. The selective pressure of this destruction is debatable in perennial plants where propagation occurs by vegetative hypogeal parts. This is probably an example of the ambiguous nature of the relation between plants and insects.

Changes in the abundance and activity of certain soil and litter fauna in the jarrah forest of Western Australia after a moderate intensity fire

Soil coring and pitfall trapping in high quality jarrah forest from December 1979 until November 1982 evaluated the effect of a moderate intensity fire on the abundance and activity of the larger invertebrates inhabiting soil and litter. A burnt plot subject to a moderate intensity fire (780 kW m-1) in January 1980 was compared with an adjacent unburned control plot. Differences between the plots in the invertebrate fauna collected on 17 sampling dates after the fire were assessed by the Wilcoxon non-parametric test. Ten taxa in the soil cores showed no significant difference in density between plots from February 1980 to November 1982: Megascolecidae (earthworms), Araneae (spiders), Isopoda (daters), Isoptera (termites), Dermaptera (earwigs), Orthoptera part (crickets), Coleoptera (beetle) larvae, Coleoptera adults, Diptera (fly) larvae and Formicidae (ants). Diplopoda (millipedes) occurred at significantly greater densities in the burnt plot, and Chilopoda (centipedes), Thysanura (silverfish) and Blattodea (cockroaches) at significantly lower densities in the burnt plot. The total number of taxa and the density and biomass of that part of the invertebrate fauna studied did not differ significantly between plots. Similar numbers of 12 taxa were captured in pitfall traps in both plots: earthworms, spiders, Pseudoscorpionida (pseudoscorpions), centipedes, termites, cockroaches, earwigs, adult beetles, fly larvae, Hemiptera (bugs), Lepidoptera larvae (caterpillars) and Orthoptera part (grasshoppers). Crickets, beetle larvae and ants were captured in greater numbers in the unburnt plot. Similar numbers of taxa and of individuals (of all taxa combined) were captured in the plots. Therefore, all but three taxa recovered in density within three years of a moderate intensity fire in the jarrah forest. The relative abundance and/or activity of three other taxa remained depressed on the burned plot during the same period.

Dietary Overlap of Sorex longirostris and S. cinereus in Hardwood Floodplain Habitats in Vigo County, Indiana

Stomach contents were examined from 90 individuals of Sorex longirostris and 167 individuals of S. cinereus from hardwood floodplain habitats in Vigo Co., Indiana. The five most important foods of S. longirostris were spiders, Lepidoptera larvae, Gryllidae, Coleoptera adults and harvestmen. The five most important foods of S. cinereus were the same except that Coleoptera larvae replaced Gryllidae. Maintenance of a contiguously allopatric pattern of distribution within the relatively small geographic area of range overlap is probably important in minimizing competition between these two morphologically similar species. INTRODUCTION The southeastern shrew (Sorex longirostris) occurs throughout the southeastern U.S. ranging as far W as Louisiana and Arkansas, and N to Missouri, Illinois and Indiana (French, 1980a). The masked shrew (S. cinereus) is the most widespread North American Sorex, with a range extending across North America (Hall, 1981). Ranges of the two species overlap in portions of Illinois and Indiana, and in Indiana both species occur in Knox, Spencer, Tippecanoe and Vigo counties (Mumford and Rippy, 1962; French, 1980b; Rose, 1980). In Vigo County, these shrews are allopatric, however (French, 1980b). Sorex cinereus is found within the boundaries of the glacial floodplain of the Wabash River. Sorex longirostris is found in similar habitats and on some of the same soil series as S. cinereus but only outside the boundaries of the glacial floodplain of the Wabash River. The purpose of this study was to determine the degree of similarity in diets of Sorex cinereus and S. longirostris that occupy the same type of habitat but do not overlap in distribution in Vigo Co., Indiana. It was hypothesized that morphological similarities between these two shrews reflect similar diets that contribute to allopatric distribution patterns in Vigo County. MATERIALS AND METHODS Sorex longirostris and S. cinereus were trapped with no. 10 cans set as pitfalls from 1976 to 1979 in Vigo Co., Indiana. Each can contained ca. 10 cm of water and shrews drowned quickly after entering the cans. Most specimens of both species were trapped in floodplain hardwoods along the Wabash River and its tributaries. Specimens of S. longirostris and S. cinereus were collected during all seasons as follows: January (1,0); February (1,0); March (9,2); April (11,72); May (9,12); June (13,3); July (6,23); August (14,3); September (3,1); October (18,21); November (3,21), and December (3,10). Stomach contents were preserved in 70 % isopropyl alcohol and examined in shallow petri dishes using a binocular dissecting microscope. The percent of total volume for each food item was estimated by visual inspection (Whitaker and Mumford, 1972). Items were identified by comparison with materials collected in the field. For aid in identification, microscope slides were made of all questionable food items; these were studied in detail at a later time. Shrews with empty stomachs were not included in the analysis. A similarity coefficient (Whittaker, 1970) was used to compare the results of this 1 Present address: Eastern Regional Heritage Program, The Nature Conservancy, 294 Washington Street, Boston, Mass. 02108.

REVISION OF THE HOLARCTIC GENUS PYRACMON (HYMENOPTERA: ICHNEUMONIDAE)

AbstractThe species of the holarctic genus Pyracmon Holmgren are revised. These are presumably all parasites of soil dwelling larvae of Coleoptera. Pyracmon sepiellum (Holmgren) is a parasite of Macropygon piceus LeConte (Dascillidae) and P. ctenicerae n. sp. is a parasite of Ctenicera destructor (Brown) (Elateridae). Seven species are recognized of which two are described as new, namely bucculentum (Holmgren), fumipenne (Zetterstedt), truncicola Thomson, and heteropus (Thomson), all from Europe, nigrifemur n. sp. from Japan, sepiellum (Holmgren), Holarctic, and ctenicerae n. sp. from western North America. The species are described, keyed, and figured based on characters of the adults. The final instar cephalic structures of larvae of sepiellum and ctenicerae are described and figured, these being the first descriptions representing the genus. Relationships of the genus Pyracmon with other members of the subfamily Campopleginae are discussed.

The distribution of foraging workers of the wood-ant formica lugubris zetterstedt (hymenoptera: formicidae) and their effect on the numbers and diversity of other arthropoda

The surface-running arthropods of a plantation (9·3 ha) of pine were sampled over two years. The activity of Formica lugubris was concentrated in an ‘ant-rich’ area within 40 m of its nests. There were fewer Araneae, Coleoptera, Collembola Arthropleona, Myriapoda and larval Diptera, but more Hymenoptera (ants apart), Symphypleona and Acarina in the ant-rich area than outside it. The numbers of Opiliones, Diptera, Chelonethi and larval Coleoptera did not differ. Some individual species of Araneae and Opiliones showed other differences in numbers in the two areas and were not consistent in the two years. Faunal diversity (Shannon-Wiener Index) was not less in the ant-rich area. This suggests that the encouragement or introduction of F. rufa-group ants to control forest pests would not have an adverse effect on the fauna in general.

Summer food of the golden plover Pluvialis apricaria at Hardangervidda, southern Norway

Golden plover stomachs were examined through the breeding season al Hardangervidda, southern Norway. The main foods were Diptera larvae (in particular Tipula excisa), adult Coleoptera (notably Otiorrhynchus dubius and Carabidae), and in May and August berries of Empetrum hermaphroditum. Also some larvae of Coleoptera and Lepidoptera were taken. Adult Coleoptera were considerably more common in the diet than expected from abundance data, while Araneae were unimportant as food in spite of a high abundance. The males take the major parental duties after hatching, allowing the females a more undisturbed feeding, supposed to be strongly advantageous for them due to close proximity of egg‐laying and the start of the postnuptial moult. This is reflected in the diet: in July males showed a larger tropic diversity, and ate more adult insects and less insect larvae than the females.

Status of the Barred Bandicoot, Perameles Gunnii, in Victoria: With a Note on Husbandry of a Captive Colony.

Barred or Gunn's bandicoot (Perameles gunnii), formerly widely distributed in Victoria, Australia, is now restricted to the western basalt plains around the city of Hamilton. A small captive colony was begun in 1972 near Geelong. The bandicoots were fed on commercial dog food [dried pellets?] with some sunflower seed or chopped apple occasionally and they obtained other food from the soil. They required fairly large outdoor enclosures and only 1 pair could be kept in a 0.07-ha pen. Notes are given on frequency of litters. Bandicoots in Tasmania are known to eat crickets (Gryllus servellei), moths and larvae of coleoptera and lepidoptera; crickets, pasture grubs and moths were mostly available in autumn and the abundance of food then may stimulate winter breeding. Breeding bandicoots for release to the wild would require money and effort, and it was doubtful whether a wild population could be established. It might be possible to develop methods of land management to provide suitable habitat for bandicoots, but there was little public interest; community education in Hamilton was needed.

A revision of the Anomaloninae (Hymenoptera: Ichneumonidae) Melanesia. I. The genera Anomalon Panzer to Aphanistes Foerster

AbstractA key is provided to the eight genera of Anomaloninae occurring in Melanesia. The Anomaloninae are endophagous parasites of Lepidoptera and Coleoptera larvae. The Melanesian species of Anomalon Panzer, Trichomma Wesmael,Heteropelma Wesmael, Therion Curtis, Pseudanomalon Szépligeti, and Aphanistes Foerster are keyed and discussed. A total of 21 species is recognised of which 11, Trichomma cheesmanae sp. n., T. pacificum sp. n., Heteropelma hirsutum sp. n., Therion unguiculum sp. n., A phanistes nexus sp. n., A. luscus sp. n., A. limulus sp. n., A. dnopherus sp. n., A. paupus sp. n., A. sedlaceki sp. n. and A. anaxeussp. n., are described. An Australian species, Anomalon, morleyiGauld, is recorded from Melanesia for the first time. Trichomma elegantulum Turner is placed as a junior synonym of T. clavipes Krieger.