Eugene Miliczky

Trophic hierarchies illuminated via amino acid isotopic analysis.

Food web ecologists have long sought to characterize the trophic niches of animals using stable isotopic analysis. However, distilling trophic position from isotopic composition has been difficult, largely because of the variability associated with trophic discrimination factors (inter-trophic isotopic fractionation and routing). We circumvented much of this variability using compound-specific isotopic analysis (CSIA). We examined the 15N signatures of amino acids extracted from organisms reared in pure culture at four discrete trophic levels, across two model communities. We calculated the degree of enrichment at each trophic level and found there was a consistent trophic discrimination factor (~7.6‰). The constancy of the CSIA-derived discrimination factor permitted unprecedented accuracy in the measurement of animal trophic position. Conversely, trophic position estimates generated via bulk-15N analysis significantly underestimated trophic position, particularly among higher-order consumers. We then examined the trophic hierarchy of a free-roaming arthropod community, revealing the highest trophic position (5.07) and longest food chain ever reported using CSIA. High accuracy in trophic position estimation brings trophic function into sharper focus, providing greater resolution to the analysis of food webs.

Spider abundance and diversity in apple orchards under three insect pest management programmes in Washington State, U.S.A.

1 Many apple growers in Washington State, U.S.A. use mating disruption (MD) for control of codling moth, Cydia pomonella (Linnaeus). Fewer applications of synthetic, broad‐spectrum insecticides are made in MD orchards than in orchards under conventional (C) management. Spider abundance and diversity in MD, C and certified organic (O) orchards were compared. Spiders inhabiting the trees (arboreal), the understory vegetation, and the ground surface were studied.

Diversity and Phenology of Predatory Arthropods Overwintering in Cardboard Bands Placed in Pear and Apple Orchards of Central Washington State

Abstract Overwintering shelters composed of cardboard bands were placed on pear and apple trees located in central Washington state to monitor overwintering by predatory arthropods and by two pest taxa. A subset of bands was sampled at regular intervals between late summer and mid-December to determine when taxa began to enter bands. The remaining bands were left undisturbed until collection in mid-December to determine the numbers and types of arthropods overwintering on tree trunks in these orchards. More than 8,000 predatory arthropods were collected from bands left undisturbed until mid-December, dominated numerically by Acari (Phytoseiidae) [Galendromus occidentalis (Nesbitt), Typhlodromus spp.], Araneae, and Neuroptera (Hemerobiidae, Chrysopidae). Predatory mite numbers were higher in bands placed in apple orchards than bands placed in pear orchards. The Araneae were particularly diverse, including >3,000 spiders representing nine families. Less abundant were Heteroptera, including a mirid [Deraeocoris brevis (Uhler)] and three species of Anthocoridae [Anthocoris spp., Orius tristicolor (White)]. Coleoptera included Coccinellidae, dominated by Stethorus picipes Casey, and unidentified Staphylinidae and Carabidae. The bands that were collected at regular intervals to monitor phenology provided >15,000 predatory arthropods, dominated numerically by spiders, Dermaptera [Forficula auricularia (F.)], lacewings, and predatory mites. Some well-defined phenological patterns were apparent for some taxa. Brown lacewing adults (Hemerobius) began appearing in bands in late October, coinciding with leaf fall in orchards. Cocooned larvae of green lacewings (Chrysopa nigricornis Burmeister), conversely, were most abundant in bands in September, which was well before leaf fall. Predatory mites began to appear in bands in late September before onset of leaf fall. Patterns for predatory Heteroptera were less clear, but results showed that D. brevis and O. tristicolor were active in the orchards well into the period of leaf fall. Two pest taxa, spider mites (Tetranychus spp.) and pear psylla [Cacopsylla pyricola (Foerster)], were also monitored. Spider mites entered bands beginning in September and finished movement at the beginning of leaf fall, similar to patterns shown by Phytoseiidae. Pear psylla moved into bands very late in the season (November and December). Our results suggest that postharvest applications of chemicals, as made by some growers, would occur before most predatory taxa have entered overwintering quarters.

Numbers, Diversity, and Phenology of Spiders (Araneae) Overwintering in Cardboard Bands Placed in Pear and Apple Orchards of Central Washington

Abstract Cardboard bands were placed on pear and apple trees at each of three sites to act as overwintering shelters for spiders. Bands were placed on the trees in late August, at three heights on the tree. One-third of the bands was collected in January to determine what taxa of spiders overwintered in the shelters. The remaining bands at each site were collected and replaced at weekly intervals between late August and early December to monitor phenology of movement into the shelters. More than 2,900 spiders in 10 families were recovered from the winter-collected set of bands. Spiders were collected from all three sampling heights in the trees. The majority of spiders were juveniles, although adults of some Salticidae [especially Pelegrina aeneola (Curtis) and Phanias sp.] were fairly common. The dominant families were Philodromidae (primarily Philodromus spp.) and Salticidae (primarily P. aeneola), comprising 66 and 28%, respectively, of the total specimens. In the weekly collections, >5,600 bands were sampled during the study producing >6,000 spiders represented by 12 families and 30 identified genera. Dominant taxa in the weekly collected bands included Philodromus cespitum (Walckenaer), P. aeneola, Xysticus spp. (Thomisidae), Sassacus papenhoei Peckham and Peckham (Salticidae), Phidippus spp. (Salticidae), and Anyphaena pacifica Banks (Anyphaenidae). Of these taxa, Xysticus spp., S. papenhoei, and A. pacifica were very uncommon in the winter-collected bands, and we infer from these results that these spiders used the bands as temporary refuges only, and overwintered elsewhere. Data obtained from the weekly collected bands suggested that Philodromus spp., Dictyna spp., P. aeneola, and Cheiracanthium mildei L. Koch entered overwintering shelters during the interval between mid-October and mid- to late November. Pear and apple blocks at the same site were more similar in community composition than a common crop species at two different sites. More spiders were recovered from bands placed in the unmanaged and organically managed orchards than from apple and pear blocks that received insecticides during the growing season.

Observations on phenology and overwintering of spiders associated with apple and pear orchards in south-central Washington

Abstract Beating tray and sweep net samples from apple and pear orchards in south-central Washington State were used to obtain information on life history and phenology of orchard-associated spiders. Cardboard shelters placed in the orchards in the fall and collected during the winter yielded information on spider overwintering. Data were obtained for 43 species in 28 genera and 12 families. The eight most abundant species were Pelegrina aeneola (Curtis 1892), Meioneta fillmorana (Chamberlin 1919), Oxyopes scalaris Hentz 1845, Theridion neomexicanum Banks 1901, Misumenops lepidus (Thorell 1877), Xysticus cunctator Thorell 1877, Philodromus cespitum (Walckenaer 1802), and Sassacus papenhoei Peckham & Peckham 1895. Each was represented by more than 690 specimens. Salticidae, Philodromidae, and Linyphiidae were represented by the largest number of species. Most species appear to have univoltine life cycles in the study area. Species matured at different times during the season between spring and fall. Twenty-seven species utilized cardboard shelters for overwintering, but some common spiders failed to do so and apparently use alternative locations. Some species overwintered in a broad range of developmental stages, whereas other species overwintered in only one or two instars.

Natural enemy fauna (Insecta, Araneae) found on native sagebrush steppe plants in eastern Washington with reference to species also found in adjacent apple and pear orchards

Seven native plants (four shrubs, two perennial herbs, and a woody vine) common in sagebrush steppe habitats of eastern Washington were sampled for predatory and parasitic arthropods. Sagebrush steppe is a common natural habitat adjacent to apple and pear orchards in that part of the state. Many predatory arthropod species found on the native plants also occur in adjacent orchards; some of these species were particularly abundant on the plants when they were flowering. Other species found on the native plants rarely occur in adjacent orchards. Orius tristicolor (White, 1879) was the most abundant of the natural enemies that also occur in orchards. Other predatory Hemiptera also found in adjacent orchards included Deraeocoris brevis (Uhler, 1904), Nabis alternatus Parshley, 1922, and Geocoris spp. Coccinellidae, Chrysopidae, and Hemerobiidae were not common on the native plants, but one or more species in each family that commonly occur in orchards were collected. Spiders found on the native plants that also occur in orchards included Misumenops lepidus (Thorell, 1877), Xysticus cunctator Thorell, 1877, Sassacus papenhoei Peckham & Peckham, 1895, Phidippus spp., Oxyopes scalaris Hentz, 1845, and Meioneta fillmorana (Chamberlin, 1919). Parasitoids, almost all of which were Hymenoptera, were collected on all plants, but species of known importance in orchard biocontrol were not found.

Observations on the Nesting Biology of Andrena (Plastandrena) Prunorum Cockerell in Washington State (Hymenoptera: Andrenidae)

Abstract Nesting and associated behaviors of Andrena (Plastandrena) prunorum Cockerell were studied at two sites in western Washington: a suburban lawn and a vacant lot. A maximum of five nests, usually well separated from one another, was found at a given site and year. Nest and cell structure at both sites were similar, but cell depth differed markedly between sites, and between years at one site. All nests were multi-cellular. Provision masses were flattened spheres of pollen moistened to a doughy consistency. The curved egg was placed atop the provision mass with both ends contacting it. A brief description of larval feeding is provided. Andrena prunorum and its Nomada parasite overwinter as adults. Nests, cell, provision mass, egg placement, and a feeding larva are illustrated. Information on mating, female foraging behavior, and local pollen sources are given. Adult phenology and the possibility of two generations per year are discussed. Nomada sp. nr. calloxantha Ckll. parasitized A. prunorum at one site and larval feeding by the cleptoparasite is described.

New Geographic Records for the Nearctic Psyllid Bactericera maculipennis (Crawford) with Biological Notes and Descriptions of the Egg and Fifth-Instar Nymph (Hemiptera: Psylloidea: Triozidae)

Abstract. The Nearctic psyllid Bactericera maculipennis (Crawford) (Hemiptera: Psylloidea: Triozidae) is one of only five known species of Psylloidea worldwide whose host plants include species of Convolvulaceae (Solanales). Current checklists of North American Psylloidea report B. maculipennis only from California and Utah. Our surveys of field bindweed, Convolvulus arvensis L. (Convolvulaceae), an Old World plant introduced into North America, show that B. maculipennis is considerably more widespread than indicated by historical accounts. We update the psyllids geographic range to include four states (Washington, Idaho, Oregon, Montana) not previously included in contemporary checklists. The egg and fifth instar nymph are described. We provide characters of the egg and nymph that distinguish this species from a congeneric species, Bactericera cockerelli (Šulc), occasionally found on field bindweed. Photographs of the male and female terminalia are provided. Bactericera maculipennis developed successfully on field bindweed and on several species of Ipomoea (Convolvulaceae) in laboratory assays. Overwintering females collected from leaf litter and dead or dormant stems of C. arvensis at locations in Central Washington mated and began to oviposit within 7 days of removal from the field, suggesting that B. maculipennis overwinters in a temperature-controlled quiescence rather than in a true reproductive diapause. Eggs and nymphs of B. maculipennis were found on stems of C. arvensis well into November in Central Washington, suggesting that this psyllid also may overwinter in pre-adult stages, as indicated by literature accounts from the 1940s and 1950s. Lastly, we propose that successful colonization of the invasive and exotic weed C. arvensis by B. maculipennis has allowed the psyllid to expand its geographic range well beyond historical boundaries. This conclusion is based upon the scarcity of native Convolvulaceae within regions in which the psyllid is newly recorded, combined with the now extensive distribution of the invasive C. arvensis in North America.

New North American Records for the Old World Psyllid Heterotrioza chenopodii (Reuter) (Hemiptera: Psylloidea: Triozidae) with Biological Observations

Abstract. The Palearctic psyllid Heterotrioza chenopodii (Reuter) (Hemiptera: Psylloidea: Triozidae) belongs to a complex of psyllids having plants in the Amaranthaceae (including the former Chenopodiaceae) as hosts. Geographic records for this introduced species in North America date from 1988, and include a number of coastal regions in eastern Canada, the Northeastern U.S., inland Virginia, coastal British Columbia, California, and wetland habitats near Lincoln, Nebraska. We updated North American records for H. chenopodii to include inland Washington and Oregon, southwestern Idaho, northcentral California, western Colorado, and southern and central Alberta. Psyllids were collected from Atriplex micrantha (Amaranthaceae) and unidentified Atriplex species, and from yellow sticky cards that had been placed in potato fields to monitor arthropod pests of potatoes. Traits of the adult psyllid, fifth-instar nymph, and egg used in identifying specimens are summarized.We provide the first photographs of the egg, fifthinstar nymph, and terminalia of the adult male psyllid. Rearing trials showed that H. chenopodii developed on A. micrantha, A. hortensis, Chenopodium album, C. berlandieri, and garden beet, Beta vulgaris, but failed to develop on Amaranthus tricolor. Development was most rapid on the two Atriplex species. Heterotrioza chenopodii has been shown in Europe to exhibit photoperiod-controlled dimorphism in wing size, producing a long-winged form in spring and summer, and a short-winged form in autumn. We confirmed in rearing trials and by field collections that populations of H. chenopodii from central Washington State also exhibit this dimorphism. Short-winged forms began replacing long-winged forms in field populations between late August and early October.