Sciarid Larvae Research Articles

Succession of fungi and fauna during decomposition of needles in a small area of Scots pine litter

During micromorphological investigations on Scots pine litter, several decomposition stages have been recognized on fallen pine needles, each being associated with the activity of animal and microbial organisms, both. To well-known fungal successions that have been so far described by mycologists we must add succession of animal groups such as nematodes, amoebae, enchytraeids, sciarid larvae, oribatid mites and earthworms. A bacterial development was observed in the L2 layer, following penetration by microfauna (nematodes, amoebae). After that stage pine needles were actively tunnelled by enchytraeids, sciarid larvae and oribatid mites and at the same time were nibbled on by epigeic earthworms (L2 and F1 layers). When the fine root system of pine developed through accumulated old needles (F1 layer), mycorrhizal fungi penetrated the needles and seemed to impede any further bacterial development. Pine foliar tissues were progressively incorporated into the fecal material of earthworms and other members of the soil fauna. A more realistic scheme was suggested for plant litter decomposition in moder humus.

Food resources and diets of soil animals in a small area of Scots pine litter

The fauna inhabiting a small area (ca. 5 cm × 5 cm) were investigated in a Scots pine stand. After microstratification of the litter layers in the field and fixation in 95% ethyl alcohol, invertebrates, mainly mesofauna, were sorted under a dissecting microscope and mounted or dissected in order to study their intestinal guts. Faeces were mounted or sectioned to obtain information about the activity of other invertebrate groups not represented in the sample and to follow the fate of plant and microbial material after defaecation occurred. Plant material, mainly from moss, bracken, pine needles and bark, was extensively consumed by enchytraeid and lumbricid worms, sciarid larvae and phthiracarid mites. Fungal material was ingested by all groups, either in combination with plant material or alone (camisiid and oppiid mites, some species of Collembola, sciarid and chironomid larvae). Isotomid springtails and chironomid larvae appeared to consume faecal material. The choice and the degree of comminution and digestion of the material differed greatly from one group to another, but without any indication of resource sharing.

Fluctuations of diptera larvae in soil from a spruce forest in relation to climatic factors

Diptera larvae were extracted by the wash and flotation method according to Healey and Russell-Smith (1970) as modified by Altmuller (1979). The larvae had been kept in alcohol for at least 2 months. After this time their specific gravity changed, and an additional flotation with MgSO4-water solution of SG = 1.26 g/cm3 was very effective. This new method is described. The working procedure can be reduced to about 50%–70% of the time Altmuller (1979) and Hovemeyer (1984) needed. Many tests have shown that some small sciarid larvae settle out with the needle and humus particles in solution of SG = 1.26 and cannot be found, so that it is necessary to apply a correction factor. Samples taken each August from 1979 to 1984 were extracted and floated off by the methods described. Larvae from seven families of Diptera nematocera and from six families of Diptera brachycera were found. Numbers of sciarid larvae varied between 2500 (1979) and 100/m2 (1981), of the cecidomyid larvae between 6700 (1983) and 400/m2 (1980) and of the brachyceran larvae between 650 (1979) and 50/m2 (1984). The correlation coefficient (= r) of larval population size with temperature and precipitation, respectively, was calculated and hence the coefficient of determination as a percentage (r2 x 100), which represents the proportion of the fluctuations in population size that is accounted for by weather factors. All families were influenced negatively by the temperature and positively by the precipitation in August, i.e., the higher the precipitation and the lower the temperature in August the higher the larval abundance in August. The development of the larvae begins in the previous year, and the influence of monthly climatic factors during the whole period of development was tested. It was shown that: Precipitation is correlated with the abundance of (1) sciarid larvae in June and August of the previous year (positively); (2) brachyceran larvae in June (August) of the previous year and in (February), March, April and August of the same year (positively); and (3) cecidomyid larvae in July of the same year (negatively). Temperature is correlated with the abundance of (1) sciarid larvae in August of the previous year (negatively); (2) brachyceran larvae in August of the previous year (negatively); and (3) cecidomyid larvae in September of the previous year, in January and July of the same year (positively). Monthly data for precipitation and temperature, taken together, showed maximum positive correlations with abundance as follows: (1) for sciarid larvae, with data for August of the previous year; (2) for brachyceran larvae, with data for August of the previous year; (3) for cecidomyid larvae, with data for July of the same year.

Decomposition in five woodland soils: relationships with some invertebrate populations and with weather

In two alluvial forests, a beech forest, an oakhazel-wood and a spruce forest, correlations between abiotic factors and the different groups of soil animals on the one hand and the decomposition rate (mean rate of disappearance) on the other hand have been the subject of investigation. There is a positive correlation between Lumbricidae and Brachycera imagines and the pH and the decomposition rate, but a negative one with Enchytraeidae and Nematocera imagines. Varying weather conditions are of great importance for decomposition processes. The influence of temperature seems to be insignificant. In the deciduous forests fluctuations of precipitation correlate fairly well with fluctuations in rates of decomposition, because of the high abundance of lumbricids. The spruce forest has very few lumbricids and the influence of weather on the course of decomposition is insignificant. Yet there is only a very loose relationship with the annual fluctuations of weather conditions. Only a major event such as the relatively low temperature and precipitation of 1980 is capable of inhibiting the development of sciarid larvae and enchytraeids and hence reducing the ensuing decomposition rate in 1981 and possibly even in 1982. The reason for this is that sciarid larvae and imagines, for example, go through critical periods during their development, which are influenced by the weather, frequently with a time lag of 1 year. Long-term investigations in the spruce forest have established a high correlation between sciarid larvae and enchytraeids and the decomposition rate.

The effect of sciarid larvae (Lycoriella auripila) on cropping of the cultivated mushroom (Agaricus bisporus)

SUMMARYSignificant linear relationships between the mean number of sciarid, Lycoriella auripila, larvae/125 g‐sample of casing and yield, numbers of mushrooms and weight/mushroom were demonstrated at all stages of a mushroom crop. Negative relationships were obtained for yield throughout the cropping period. There was no injury threshold for this pest, although an economic threshold of one larva/sample was deduced. Loss in yield was mostly due to the destruction of mushroom primordia and presumed interruption of nutrient supply to the developing sporophores.Numbers of mushrooms were severely reduced in the first, second and third flushes, more so than yield, although a large increase in numbers was demonstrated in the fourth flush. The size of mushroom was inversely related to numbers, although the increases in size in the first three flushes were insufficient to compensate for the reduction in numbers. A reduction in size was evident in the fourth flush.

MONITORING FUNGUS GNATS (DIPTERA: SCIARIDAE) IN CUCUMBER GREENHOUSES

AbstractSimple, sticky traps were used to monitor adult sciarid populations, and soil cores were used to monitor larval sciarid populations in commercial cucumber greenhouses. Four methods of sticky-trap placement were compared and it was found that 5 traps in a “W” formation correlated closely with more intensive 12- and 30-trap random placements. All 4 of the greenhouses studied exhibited similar sciarid population patterns in 1983 but only 2 showed large sciarid populations in 1984 and the other 2, using different overwinter sanitation methods, had no detectable sciarid populations. Moth-flies (Psychodidae) were often the most numerous form of small dipteran found on the traps. Larval sciarids occurred in the upper 5 cm of each 10-cucumber bag, and weekly 50-mL core samples showed a range of 0.0 to 1.1 larvae/mL which corresponded to estimated larval populations of up to 2500 per bag. Plants that had succumbed to fungal pathogens and then been sampled immediately for sciarid larvae were found to have fewer larvae per bag than apparently healthy plants. Insect monitoring in cucumber greenhouses has enabled growers to reduce and/or eliminate the need for insecticide applications against sciarids during the growing season.

Mushroom Sciarid Control with Diflurenzuron (DIMILIN), 1984

Abstract Twenty-four mushroom growing trays (0.37m2 X 0.15m), each containing 22.6 kg (72% water) of deammoniated and pasteurized Phase II wheat-straw-bedded horse manure, were individually spawned with llOg of light cream mushroom spawn (MGA #801) and placed into a single mushroom production room. During the spawn run 480 female sciarids were released into the production room and an additional 1000 females 26 days alter spawning. For the test, Dimilin 25W at a formulation rate of 412 g/100m2 was applied as a drench to the casing surface in the first casing water application. Three pasteurized casing materials were used: (1) Canadian Sphagnum Peat Moss, (2) mineral soil, and (3) mixture of weathered spent compost and Canadian Sphagnum Peat Moss (1:1, by volume). Evaluation of diflubenzuron to control sciarid larvae in each casing type was measured through yield assessment and larval sampling in the casing.

Mushroom Sciarid Control with Cyromazine (ARMOR), 1984

Abstract Twenty-four mushroom trays (0.37m2 x 0.15m), each containing 20.4 kg of deammoniated and pasteurized Phase II wheat-straw-bedded horse manure compost (72% water), were individually spawned with 110 g of light cream mushroom spawn (PSU #324) and placed into a single mushroom production room. Four days after spawning 500 female sciarids were released into the production room. Two casing materials were used: (1) Canadian Sphagnum Peat Moss and (2) mineral soil. Cyromazine (8.75 g (AI)/100m2 of production surface was either drenched onto the casing surface in the first casing watering or incorporated at the same a.i. into the casing material (2628 kg soil and 452 kg peat moss, dry wt. basis). Three trays were used for each treatment and check. In addition, cyromazine was incorporated into 3 trays of compost at 5.72 g (AI)/1000 kg compost (72% moisture) to serve as standard comparison. Evaluation of cyromazine to control sciarid larvae in both casing materials and application methods was through larval sampling and yield assessment.

The Feulgen reaction: Importance of the wash after hydrolysis

Washing in absolute ethanol after FEULGEN hydrolysis minimizes losses of DNA. The hydrolysis in HCl diluted in tetrahydrofuran is not superior in this respect to conventional hydrolysis if this is followed by an ethanol wash. These conclusions are based on cytophotometric and radiometric experiments made on salivary glands of sciarid larvae.

A Migrating Army of Sciarid Larvae in the Philippines

This article has no abstract.