Fungal Feeding Research Articles

Beetles feeding on bugs (Coleoptera, Hemiptera): repeated shifts from mycophagous ancestors

A review of the literature shows that predation on Hemiptera (mainly Sternorrhyncha) by Coleoptera is widespread in the order, but little understood, even from a biocontrol perspective. Phylogenetic information indicates that feeding on hemipterans evolved predominantly in lineages containing fungus feeders (Derodontidae, Silvanidae, Laemophloeidae, Nitidulidae, Endomychidae, Anthribidae) and whose ancestors were fungus feeders (Coccinellidae) or were sap feeders (cetoniine Scarabaeidae). Other predators on Hemiptera whose ancestry could not be determined unequivocally (predatory/phytophagy or phytophagy/mycophagy) are included in families that contain a large number of species that are mycophagous (Trogossitidae, Mycetophagidae, and Salpingidae). Because changes in diet to feeding on hemipterans have repeatedly occurred in mycophagous taxa, and this shift is not present in other largely predatory groups of beetles, it is presumed that certain preconditions, which have promoted this specialised behaviour, only exist in these lineages. Ancestral associations with sooty moulds that grow on honeydew may have mediated shifts from mycophagy to predation, rather than having ancestors that were predatory and attracted to a novel prey type. Natural history data show that species that prey on Hemiptera also feed on honeydew and sooty moulds and a model is presented for the host shift from mycophagy to feeding on Hemiptera. An annotated list of Hemiptera prey for beetles (exclusive of Coccinellidae) includes records for species in the families Adelgidae, Aleyrodidae, Aphididae, Coccidae, Diaspididae, Kermesidae, Kerriidae, Margarodidae, Membracidae, Phoenicococcidae, and Pseudococcidae.

Simulated climate change affecting microorganisms, nematode density and biodiversity in subarctic soils

Arctic terrestrial ecosystems are strongly dominated by temperature, and global warming is expected to have a particularly strong impact in high latitudes. The Arctic will therefore be an important region for early detection of global change. In the present study the effects of environmental manipulations simulating climate change on soil microorganisms and nematode populations were investigated. Study sites were a dwarf shrub dominated tree-line heath (450 m a.s.l.) and a high altitude fellfield (1150 m a.s.l.) at Abisko, Swedish Lapland. Soil temperature was enhanced by using passive greenhouses and the impact on soil organisms with and without NPK fertilizer addition was assessed. The nematode community was strongly affected by warming and nutrient application. Population density was twice as high for all treatments at the fellfield as compared to controls. At the heath temperature enhancement with or without fertilizer application also led to a doubling of the population density, whereas fertilization alone caused an increase of about one third. The environmental manipulations resulted in a greater microbial biomass C and active fungal biomass in the heath soil. Increased density was also recorded for bacterial and fungal feeding nematodes at both sites. The results suggest that nematodes have an important impact on microbial biomass and turnover rates in the two subarctic systems. Elevated soil temperature apparently will lead to increased grazing on microorganisms, contributing to enhanced net N and P mineralization rates and plant nutrient availability. However, biodiversity was generally affected negatively by the environmental manipulations. The effects were more severe at the high altitude fellfield indicating that the influence of elevated temperature will be more pronounced in systems already stressed by extreme climatic conditions.

Effects of Klebsiella planticola SDF20 on soil biota and wheat growth in sandy soil

The potential for ecological effects to occur after the release of genetically engineered microorganisms is a global concern and the release of biotechnology products must be assessed on a case-by-case basis. In this research, a genetically engineered strain of Klebsiella planticola (SDF20) bacteria was added to microcosms containing sandy soil and wheat plants to assess the potential for effects on soil biota and plant growth. One half of the soil treatments in this study contained wheat plants to compare some effects on growing rhizosphere communities in the experimental system. When SDF20 was added to soil with plants, the numbers of bacterial and fungal feeding nematodes increased significantly, coinciding with death of the plants. In contrast, when the parental strain, SDF15 was added to soil with plants, only the number of bacterial feeding nematodes increased, but the plants did not die. The introduction of either SDF15 or SDF20 strains to soil without plants did not alter the nematode community. No effects were observed on the activity of native bacterial and fungal communities by either SDF15 or SDF20. This study is evidence that SDF20 can persist under conditions found in some soil ecosystems and for long enough periods of time to stimulate change in soil biota that could affect nutrient cycling processes. Further investigation is needed to determine the extent these observations may occur in situ but this study using soil microcosms was the first step in assessing potential for the release of genetically engineered microorganisms to result in ecological effects.

Nematodes in a coastal dune succession: Indicators of soil properties?

The nematode fauna of coastal sand dunes in the Slowinski National Park (Poland) were studied. Within the wet parts of dune hollows, vegetational succession starts from bare wet sand gradually colonized by grasses and mosses, and changes to plant communities dominated by sundew and heath. The aim of the study was to determine whether vegetation succession was accompanied by a parallel succession of the nematode fauna. Samples were taken from 12 subsequent stages of vegetational succession. The extracted nematodes were determined up to genus level after Bongers (1987). The percentage of nematodes of different feeding types (bacteriophagous, fungivorous, predators, plant-parasitic and omnivorous) was calculated for every site. Soil moisture (average water table and actual water content), the existence of an upper organic soil layer and pH seem to be the key environmental factors influencing nematode community structure. Multivariate analysis techniques were used to classify the nematode samples into four groups: A – the nematode community in sites at early succession stages without permanent colonization by plants. B – the nematode community in sites at stages with permanent plant cover (grasses and higher plants). C and D – the nematode communities in sites with a developing permanent and stable soil organic layer, but differing in water regime. Changes in the incidence of nematodes of different feeding types in relation to vegetational succession support this classification. Nematode community structure changed from a high percentage of predators to a dominance of bacterial feeders. Fungal feeding nematodes only occur in abundance in sites with a developed organic layer and higher moisture content (group D), and the nematode community may be a good indicator of the progress of ecological succession in the deflation hollows.

Response of the soil nematode community in a shortgrass steppe to long-term and short-term grazing

Nematode abundance and community structure were used to determine if grazing by cattle was a disturbance to soil. Soil samples were collected in bare ground, interplant spaces and under Bouteloua gracilis (H.B.K.) Lag. ex Griffiths (blue grama) in the arid shortgrass steppe of Colorado. Grazing treatments were long-term grazed (GG), long-term ungrazed (UU), short-term grazed (UG) and short-term ungrazed (GU). Long-term treatments were fifty-five years old. The short-term treatments were either grazed (GU) or ungrazed (UG) from 1939–1991, and then ungrazed or grazed for 2 years, from 1992–1994. Bacterial feeding nematodes and plant parasitic nematodes were the dominant nematode trophic groups. Grazing treatments had no effect on nematode absolute abundances, but did influence the percent contribution of fungal feeding nematodes. Total nematodes were higher in the under-plant locations, as were all trophic groups except omnivores and predators which had similiar densities in both locations. However, on a percentage basis, community composition was similar except for omnivores which were higher in the interplant location. These results suggest that grazing has no effect on belowground biota in the shortgrass steppe, with the exception of fungal feeding nematodes.

Oribatid mites enhance the recovery of the microbial community after a strong disturbance

The effects of panphytophagous oribatid mites on the recovery of the microbial community in F-layer materials from beech, spruce and mixed (beech and spruce) stands after strong disturbance (freezing and heating) were investigated in a laboratory microcosm experiment. Generally, oribatid mites enhanced the recovery of the disturbed systems by accelerating (1) the recolonization of litter materials by fungal species, (2) the restoration of the microbial biomass and basal respiration and (3) the stabilization of nutrient pools in the litter, i.e. minimizing nutrient leaching. It is concluded that the accelerated recovery of the microbial metabolism was caused by dispersal of spores by oribatid mites and by grazing on microbial populations. The stimulation of the microbial metabolism enabled microorganisms to grow, thereby immobilizing nutrients in microbial biomass. However, the duration of the experiment was too short for complete recovery of the microbial community and at the end of the experiment microbial biomass was only one third of its initial size, and heat-resistant or opportunistic fungi still dominated. Overall, it is concluded that fungal feeding microarthropods are of significant importance for the resilience of forest soil systems.

Dynamics and stratification of functional groups of micro- and mesoarthropods in the organic layer of a Scots pine forest

This paper addresses the abundance, biomass and microstratification of functional groups of micro- and mesoarthropods inhabiting the organic layers of a Scots pine forest (Pinus sylvestris L.). An experiment using stratified litterbags, containing organic material of four degradation stages, i.e., freshly fallen litter, litter, fragmented litter and humus, was performed over a period of 2.5 years. Statistical data analysis revealed that each organic layer had a different, characteristic species composition that changed with time following successive degradation stages. Species of Acari, Araneae and Collembola were assigned to different functional groups based on taxonomy, microstratification, food type or feeding mode. The abundance and biomass carbon of functional groups were dependent on the organic layer and most functional groups showed a particular preference for one of the upper organic layers. Temporal and spatial differences in density and biomass carbon of functional groups could partly be related to fluctuations in the soil climate, although effects of trophic interactions could not be ruled out. A general decline in abundance and biomass, especially in populations of fungal feeders, during the last year of the study could not be explained by a reduction in litterbag volume, changed litter chemistry or soil climate, but was attributed to an indirect effect of a remarkable increase in soil coverage by wavy hair grass, Deschampsia flexuosa (L.). The analysis demonstrated that species diversity, microhabitat specification, soil fauna succession, and degradation stages of organic material are interrelated. The results obtained indicate that both the chemistry of organic matter and decomposition rates have an important effect on trophic relationships and community structure.

Composition and Trophic Structure of Detrital Food Web in Ant Nest Mounds of Formica aquilonia and in the Surrounding Forest Soil

Community composition and food web structure of soil decomposer biota in relation to various habitat properties were compared between upper parts of red wood ant (Formica aquilonia) nest mounds and the adjacent forest soil. For a description of trophic structure of the decomposer community in the two habitats, soil decomposers were classified into 14 trophic groups. Classification of the taxa into three habitat preference categories resulted in a clear division of the fauna into either soil or nest specialists, relatively few taxa falling between these two groups. A large majority of the nest specialists belonged to a non-myrmecophilous soil decomposer fauna so far largely overlooked in studies on ant-invertebrate associations. Trophic organisation of the nest mound community differed clearly from that in the soil by having considerably larger biomass at the base of the food web, and less large predators -other than ants - at the top of the web. Contrary to forest soils. the clear dominance of bacterial feeding microfauna over the fungal feeding microfauna in the nest mounds suggests that most of the energy passing through the food web is channelled through a bacterial-based food-web compartment in the nest mounds. Relatively constant temperature and moisture in the nest surface, continuous energy input by the ants to the nests, and ant-induced reduction in predation pressure on macropredators are suggested to be responsible for the development of the typical decomposer community structure in the nest mounds. Thus, the food-web dynamics in ant nest mounds represent an interesting case in which the behaviour of an invertebrate species (i.e. the ant) has a potential to control the development of a system-level organisation. The high biomass of microbi-detritivorous animals, especially earthworms, in the nest mounds suggests that the activities of the decomposer fauna may feed back to the structure of nest mound and indirectly alter the performance of the ant colony.

COMPARISON OF NEMATODE COMMUNITIES IN AGRICULTURAL SOILS OF NORTH CAROLINA AND NEBRASKA

Samples of agricultural soils were collected across North Carolina in 1992 and Nebraska in 1993 to determine which indices of nematode communities could be applied to distinguish ecological pattern at regional geographic scales. Sampling density was proportional to the area of agriculture in each region of each state. Maturity indices (based on life-history characteristics) were calculated to determine the successional status of nematode communities, and diversity indices were calculated to estimate relative abundance of nematode trophic groups. Population densities of nematode families were also compared between states and among regions within states. The range of maturity-index values for free-living and plant-parasitic nematodes was greater for soils in North Carolina than in Nebraska. The relative distribution of nematode trophic groups (bacterial feeders, fungal feeders, plant parasites, omnivores, and predators) was similar in the two states. Significant differences in maturity-index values for free...

Decomposition of Genetically Engineered Tobacco Under Field Conditions: Persistence of the Proteinase Inhibitor I Product and Effects on Soil Microbial Respiration and Protozoa, Nematode and Microarthropod Populations

To evaluate the potential effects of genetically engineered (transgenic) plants on soil ecosystems, litterbags containing leaves of non-engineered (parental) and transgenic tobacco plants were buried in field plots. The transgenic tobacco plants were genetically engineered to constitutively produce proteinase inhibitor I, a protein with insecticidal activity. The litterbag contents and surrounding soil, as well as soil from control plots without litterbags, were sampled over a 5-month period at 2- to 4-week intervals and assayed for proteinase inhibitor concentration, litter decomposition rates, carbon and nitrogen content, microbial respiration rates and population levels of nematodes, protozoa and microarthropods. The proteinase inhibitor concentration in the transgenic plant litter after 57 days was 0.05% of the sample day 0-value and was not detectable on subsequent sample days. Although the carbon content of the transgenic plant litter was comparable to that of the parental plant litter on sample day 0, it became significantly lower over the course of the experiment. Nematode populations in the soil surrounding the transgenic plant litterbags were greater than those in the soil surrounding parental plant litterbags and had a different trophic group composition, including a significantly higher ratio of fungal feeding nematodes to bacterial feeding nematodes on sample day 57. In contrast, Collembola populations in the soil surrounding the transgenic plant litterbags were significantly lower than in the soil surrounding parental plant litterbags. Our results demonstrated that under field conditions proteinase inhibitor remained immunologically active in buried transgenic plant litter for at least 57 days and that decomposing parental and transgenic plant litter differed in quality (carbon content) and in the response of exposed soil organisms (Collembola and nematodes).

Tolerance to the fungal pathogen Rhizoctonia solani AG4 of transgenic tobacco expressing the maize ribosome-inactivating protein b-32

The maize b-32 protein is a functional ribosome-inactivating protein (RIP), inhibiting in vitro translation in the cell-free reticulocyte-derived system and having specific N-glycosidase activity on 28S rRNA. Previous results indicated that opaque-2 (o2) mutant kernels, lacking b-32, show an increased susceptibility to fungal attack and insect feeding and that ectopic expression in plants of a barley and a pokeweed RIP leads to increased tolerance to fungal and viral infection. This prompted us to test whether b-32 might functi on as a protectant against pathogens. The b32.66 cDNA clone under the control of the potato wun1 gene promoter was introduced into tobacco by Agrobacterium tumefaciens-mediated transformation. Out of 23 kanamycin resistant regenerated shoots, 16 contained a PCR fragment of the corrrect size spanning the boundary between the promoter used and the coding region of the b-32 gene. Eight independently transformed tobacco lines were randomly chosen for protein analysis: all of them expressed b-32 protein. The data presented indicate that transgenic tobacco plants expressing b-32 show an increased tolerance against infection by the soil-borne fungal pathogen Rhizoctonia solani Kuhn

Effects of management practices on nematode community structure in tallgrass prairie

The effects of burning, mowing, and nitrogen (N) and phosphorus (P) fertilization on the trophic structure of a tallgrass prairie nematode community were examined in a long-term field experiment established in 1986. Nematode densities and trophic composition were determined in October of 1987, 1989, and 1994 following 2, 4, and 9 years of treatment, respectively. Total populations of obligate herbivores tended to increase with annual burning and N fertilization but responses by individual taxa were relative to the structure and composition of vegetation as determined by management practice. In contrast, mowing resulted in consistent reductions in herbivore densities. The family Tylenchidae, with species classified as both root and fungal feeders, exhibited short-term decreases in numbers due to burning and long-term increases in numbers due to mowing. Treatment responses by this group were more consistent with the behavior of known fungal-feeding than root-feeding nematodes. Microbivore densities increased with burning and N fertilization, while numbers of omnivores and predators declined with chronic N additions. The effects of P fertilization on nematode population densities varied with management practice, primarily N fertilization. Canonical discriminant analysis differentiated trophic groups based on their responses to mowing and P-fertilization. Measurements of the trophic composition of the nematode community, particularly the relative abundance of individual herbivore taxa and the proportion of fungivores to microbivores, were good indicators of ecosystem responses to management practices.

Seasonality of canopy invertebrate communities in eucalypt forests of eastern and western Australia

Abstract Chemical knockdown procedures were used to sample canopy arthropods at 3 month intervals over 1 year at two sites, one in eastern Australia and the other in western Australia. Samples were taken from narrow‐leaved ironbark, Eucalyptus crebra, and grey box, Eucalyptus moluccana, in the east and from jarrah, Eucalyptus marginata, and marri, Eucalyptus calophylla, in the west. Arthropods were more abundant on trees in eastern Australia and exhibited different seasonal patterns from those in the west. Members of different functional groups exhibited different seasonal patterns, with some herbivorous groups responding to times of leaf production, decomposers and fungus feeders responding to high moisture availability, and predators/parasites responding to the abundance of food items. Seasonal variability was slightly higher in the west, possibly reflecting the greater seasonal amplitude in rainfall. In the eastern forest, proportionately more taxa peaked in spring or summer and declined to minimum numbers in winter. In the western forest several taxa attained peak numbers in autumn, winter or spring, while others declined to minimum values in winter or summer. The phenological patterns of canopy arthropods appear to be linked to the condition of the host plant and/or to climatic factors. Comparison of the western Australian data to those from a second year of sampling at a time when rainfall was greater and fell later into the season indicated that variability in arthropod numbers between years can be as great as that between seasons. Implications of the variability in seasonal and annual patterns of canopy invertebrate communities are discussed in relation to the need for long‐term sampling and in relation to evaluating the impact of disturbance on forest communities.

Cultural Studies On Soil Nematodes and Their Fungal Hosts

In laboratory experiments survival, feeding and reproduction of nematodes in cultures with mycorrhizal and saprophytic fungi were investigated. Nematodes extracted from the organic layer of a spruce forest soil were inoculated to fungal plates. The fungal feeder Aphelenchoides saprophilus was the most successful species to multiply. With mycorrhizal fungi as a food source its population developed faster and to a greater extent than it did with saprophytic fungal species. The grazing of A. saprophilus reduced mycelial weight and fungal growth rate. Similar effects are likely to occur in the field, and can influence mycorrhizal development or affect competition between soil fungi. Besides A. saprophilus, the saprophagous nematode Acrobeloides nanus reproduced well in cultures with mycorrhizal fungi. There may be an element of substrate ingestion or grazing on fungal hyphae for some bacterial feeding nematodes.

Nematode Fauna in Spruce Forest Soils: a Qualitative/ Quantitative Comparison

Nematode species composition, population density and trophic structure were investigated in 60 to 100 yr old spruce stands. Most of the 106 species observed were found at the least acidified sites with a thick organic layer, fewer species were found at the sites with acidified soils and extremely thin organic layers. Population density varied between 250 and 1900 individuals per g dry weight, or between 1.4 and 5.1 x 10 6 individuals per m 2 , respectively. The numbers decreased with depth. All sites were dominated by bacterial feeders, followed by root and fungal feeders. Obligate plant parasites, omnivores and predators were scarce. Commonly the bacterial feeders with their dominant taxa Plectus, Wilsonema schuurmansstekhoveni, Teratocephalus stratumus and Metateratocephalus crassidens were found in the upper soil horizons. Only Acrobeloides buetschlii and A. nanus preferred deeper soil layers. Root and fungal feeders were mainly species of Filenchus and Aphelenchoides. In general they increased with depth. The Maturity Index at most sites was low, suggesting a dominance of r-strategists among the nematode population. Only at the less acidified sites with an organic layer of 10 cm were higher proportions of Κ-strategists and consequently higher MI values observed.

Assessing nematode communities in agroecosystems of varying human intervention

The effect of disturbance on soil nematode communities was studied in eight treatments varying in intensity of human intervention at the Kellogg Biological Station Long Term Ecological Research site, Hickory Corners, MI. The agricultural treatments ranged from those manipulated with high chemical inputs and heavily impacted by human management to successional treatments that had no chemicals and little human impact. A canonical discriminant analysis of the nematode data separated the treatments into four systems: high chemical input (the conventional tillage and no tillage treatments, both corn/soybean rotations); organic (the low input and zero input treatments, both wheat/corn/soybean rotations); perennial (poplar and alfalfa treatments); successional (abandoned after tillage and never tilled treatments). Nematode abundance was highest in the high input and organic systems and lowest in the poplar treatment. Overall, bacterial feeding, plant parasitic and fungal feeding nematodes dominated the treatments. Species diversity was greatest in the successional treatments. The bacterial feeding trophic group and the modified Shannon index described differences at both the treatment and system levels, while the Shannon index demonstrated diversity at the system and annual and perennial crop level of analysis. Measures that detected differences ( P < 0.05) consistently across all treatments, systems, and annual vs. perennial crops were total abundance, the predator trophic group, the maturity index (MI) and the plant parasite index. The minimum analyses needed to detect disturbance reliably were a multivariate analysis and the MI. However, understanding and predicting the impact of the disturbance on the food web and ecosystem functioning would be increased with results from diversity indices and nematode functional groups.

Relationships between nematodes, soil microbial biomass and weed-management strategies in maize and asparagus cropping systems

Five weed-management strategies (sawdust mulching, repeated spring-summer cultivation, hand-hoeing, two herbicide treatments) were applied to asparagus and maize cropping systems near Hamilton, New Zealand. Assessments of 27 nematode populations on four sampling occasions over an entire cropping cycle are related to published microbial, arthropod and environmental data. Under asparagus cropping abundance of 11 nematode populations (at genus or family level) in 0–5 cm soil showed significant treatment effects on at least two sampling occasions; under maize 6 populations showed treatment effects. Overall, the most obvious trends were for some taxa of bacterial feeding nematodes to have their greatest abundances under different treatments. The ratio of bacterial feeding to fungal feeding nematodes varied significantly with time and treatment, and indicates shifts in trophic structure of the nematode fauna. Canonical correspondence analysis demonstrated that nematode populations were more strongly related to environmental factors at the prior sampling than those at the contemporary sampling time. Under asparagus cropping the sawdust mulch was the predominant factor affecting ordinations; bacterial and fungal feeding nematodes were most abundant or showed greatest treatment responses, but the increase in populations of predacious nematodes ( Nygolaimus, Mononchidae, Aporcelaimidae) may be responsible for absence of marked increases in these other groups. Under maize, effects were similar but less significant. Helicotylenchus and Pratylenchus were present under the maize crop but not under the asparagus crop. The responses of nematode taxa to weed management practices were very variable but, given the range of life history strategies within trophic groups, responses follow a predictable pattern. Detailed correlation of management-induced changes in nematode populations and biological environmental factors is confounded by the effect of nematode feeding activity on the microbial populations. Overall, the results confirm the important influence of microfaunal grazing on microfloral populations and the cycling of plant nutrients in the soil.

Fruit Rot, Antifungal Defense, and Palatability of Fleshy Fruits for Frugivorous Birds

We tested several predictions concerning fungal rot and antifungal defense of vertebrate—dispersed fruit. (1) Fungal fruit to should be generally deterrent to frugivores. But because fungi may vary in their negative effects, antifungal defenses should be allocated in relationship to net effects of particular species on dispersal. (2) Defenses of fruits under selection for high palatability should be directed primarily toward microbes ("microbespecific" defenses). Lower quality fruits, for which high palatability is not crucial to dispersal, may be defended by more general defenses. (3) Preferred fruits should be defended to a lower degree than less preferred fruits, as a result of consistently high dispersal rates (Removal Rate model). We tested our hypotheses using real fruits and artificial—pulp media of six temperate ericaceous plants in feeding trials with captive birds and in fungal growth trials. Plants had been assigned to two temperature fruiting classes (Summer Small—seeded, SS, Fall—Low—quality, FL), and differed in ripening phenology, persistence times, and fungal resistance in the field. We compared feeding rates on fruits rotted by members of a suite of fruit rot fungi. We also determined feeding rates on artifical—pulp media that either contained ripe fruit extracts or did not, and we determined fungal growth rates on identical media. We found that: (1) fungal species depressed feeding rates in general accordance with their reported vertebrate toxicity. Relative to nontoxic fungi, toxic fungi were inhibited more strongly by secondary fruit pulp extracts. (2) Artificial—pulp media of SS fruits were preferred in feeding trials, due both to basic nutritional composition and nondeterrent (microbe—specific) secondary defense. (3) In accordance with the Removal—Rate model, artificial—pulp media of the preferred SS fruits showed significant antifungal activity, but at a much lower level than that of FL fruits. Our results suggest that a primary function of secondary chemicals in ripe fruits may be to defend against destructive fungi that compete with seed dispersers for the pulp. Our results generally support the hypothesis that selective pressures may result in ripe fruit defenses that are directed primarily against organisms having strong negative effects upon dispersal. As such, factors influencing risk of pulp consumption by nondispersers may be useful predictors of fruit defense patterns.

Vitellogenin protein diversity in the HawaiianDrosophila

Egg and female hemolymph proteins were resolved via SDS-polyacrylamide gel electrophoresis in a diverse array of 33 endemic Hawaiian drosophilids, encompassing 17 picture-winged species, 3 of the antopocerus species group, 9 fungus feeders, 1 species from each of the modified mouthparts, crassifemur and ciliated tarsus groups, and 1 Scaptomyza species. Molecular weights of the two (10 species) or three vitellogenin bands (22 species) were highly variable, spanning a 7-kD range. The largest vitellogenin, V1, was the most variable, showing a change of some 10% in its mean size of 47.6 kD. The smallest V3 vitellogenin, mean size 44.1 kD, was evolutionarily the most conservative in size. The species Drosophila hawaiiensis was found to be polymorphic for two/three vitellogenin bands and, also, polymorphic with respect to the size of the V1 protein. No inter- or intrapopulation variability in vitellogenin size was detected in 10 other species examined. The major features of vitellogenin protein evolution in the Hawaiian Drosophila are change in molecular weight and regulatory differences that result in quantitative differences between species in patterns of vitellogenin protein production.

Destruction ofGnomonia LeptostylaPerithecia onJuglans NigraLeaves by Microarthropods Associated withElaeagnus UmbellataLitter

Companion planting of the woody shrub autumn olive, Elaeagnus umbellata Thunb., with black walnut, Juglans nigra L., in plantations resulted in control of Mycosphaerella leaf spot (4, 5) and walnut anthracnose (3), important defoliating diseases of black walnut. One of the principal beneficial effects ofthe autumn olive was to reduce ascospore primary inoculum ofthe two disease causal agents, Mycosphaerella juglandis Kessler and Gnomonia leptostyla (Fr.) Ces. & de Not. in the spring. A major cause of the reduced ascospore production of M. juglandis and G. leptostyla was microarthropod feeding upon perithecia within infected fallen walnut leaves (4). The purpose of this study is (1) to describe the type and extent of microarthropod perithecial feeding occuning in the leaf litters and (2) investigate the possible role of Collembola and oribatid mites as probable main fungal feeders involved.