摘要:

Abstract.1. Regular samples of flies swarming around cattle in Northumberland, England, were collected from late May to early October 1980–82, during weather judged to be suitable for fly activity.2. Results were grouped into weekly periods and averaged to reduce variation caused by the weather.3. For all species of Muscidae that were caught in reasonable numbers, the changes in abundance through the season are described.4. The proportion of each species in the total sample is discussed; biting species were not sampled as efficiently as were non‐biting species.Hydrotaea trritansandMorellia simplexwere the most numerous species forming 49% and 32% of the catch respectively.5. The total numbers of flies were low at the beginning of the sampling period, rose to a maximum in mid‐July, stayed high until mid‐September and then declined by

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00692.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Consumption, production and assimilation rates were determined for two age groups ofCrypropygus antarcticusto give an estimate of energy utilization, and to investigate low temperature adaptation in its energy partitioning.2. Feeding selectivity shown in laboratory preference tests was supported by gut analysis of field animals from contrasting sites. Although moulting rate was not significantly affected by food type, rates of growth were slowest and mortality highest when fed on a non‐preferred substrate.3. Both a radio labelling and a more direct method for measuring dry weight consumed gave similar results forCvpropygusfeeding on algae. The consuniption rate for animals when feeding on algae was lower than that on moss peat. The assimilation efficiency for immature animals feeding on algae was 46% and for mature animals was 19%; the values when feeding on moss peat were 7% and lo%, respectively, The net production efficiency ranged from 35%(inimatures) to 13% (matures) and was similar on both substrates.4. Food consumption exceeded assimilation over the range 2.5–10°C, but the two converged from 2.5 to 0°C. ImmatureCryptopygusmaintained a net positive energy balance over 0–10°C, whilst below 1S°C respiration exceeded assimilation for mature individuals.5. An estimate of the annual dry matter consumption (7 g m‐1y‐1) byCtypropygusin a moss turf at Signy Island agrees with one based on respiration data alone (Davis, 1981). The consumption at an alga‐dominated site wasc. 26 g m‐2y‐l, andCrypropygusmay have a locally limiting effect on net priniary produ

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00693.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. An experiment was performed to examine the relationship between overwintering mortality rates and physical conditions in the leaf litter forPhyllonorycterspp. onQuercus robur.2. Analyses also were performed to determine if survival and mortality rates vary with leaf size and the position of a leaf mine within a leaf.3. The results indicate that survival rates are independent of variation in physical conditions in the leaf litter, as well as leaf size and the position of a mine on a leaf.4. Mortality from leaf decomposition was higher at the bottom of the litter pack, and it may compensate for reduced mortality from predation, crushing, desiccation, and fungal attack at the level.5. Rates of parasitism were significantly higher on small than on large leaves.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00694.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Evidence used to support the theory that mixed function oxidases (MFOs) are important in the survival of polyphagous herbivores is briefly reviewed. This evidence includes data on patterns of variation in MFO activity among species and among developmental stages within species. It also includes data on induction of MFO activity by plant compounds and metabolism of plant cornpounds by MFOs.2. It is argued that the evidence presently available does not offer strong support of the theory because key pieces of information are lacking. Evidence which tends to refute the theory is reviewed and discussed.3. Experiments are proposed which could more rigorously test the theory.

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00695.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. This paper analyses catches of flower thrips, grass thrips and predatory flies in water‐traps of seven colours.2. A correlation is demonstrated between type of host‐plant of thrips and the relative numbers caught by traps of different colours.3. The literature is reviewed and some general relationships with the effectiveness of different trap colours are hypothesized for: non‐grass foliage insects and their predators and parasites; grass foliage insects; flower‐dwelling insects; predators and parasites not associated with foliage; biting insects; and wood‐borers.4. This may permit trap colours to be chosen, in particular circumstances, that are ecologically selective for different types

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00696.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. The mycophagous Drosophilidae flies in eastern North America display a range of ecological responses to their fungal trophic resources. Some (Drosophilu duncaniSturtevant, and two species labelled asMycodrosophila cluytonaeWheeler and Takada) specialize on the bracket fungi of the family Polyporaceae. Other species (Drosophila falleniWheeler,D.recensWheeler,D.putriduSturtevant andD.tripunctutaLoew) are broad generalists, non‐selectively consuming a diverse array of Basidioniycete mushrooms.D.restaceuvon Roser andD.ordinuriaCoquillett utilize a broad subset of the Basidio‐mycetes, whileM.dimidiatahew feeds on some Basidioniycetes, including a variety of Clavariaceae (coral fungi) and Heterobasidiomycetes (jelly fungi) not commonly used by other flies, and Ascomycetes (cup fungi).2. Unlike some phytophagous insects, host chemistry seems to have little effect on host preferences. The mycophagous drosophilids do not avoid fungi thought to be toxic or undigestible to other Diptera.3. Resource predictability appears to delimit trophic niches in the mycophagous guild. The average duration of individual host mushroom caps is negatively correlated with three measures of trophic niche breadth. Specialist fly species utilize long‐lasting resources, while more generalized mycophagous species include progressively ephemeral fungi in their

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00697.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Observations were made on the biologyof Anthocoris gallarumulmiDe Geer (Hemiptera ‐ Heteroptera: Anthocoridae) in West Central Scotland from 1973 until 1975. The life cycle was intimately linked with those of its principal prey speciesSchizoneura ulmiandS.patchae, leaf roll‐gall aphids, and elm, their primary host (Ulmussp.).2. Overwintered adults emerged in late April/May and could be found on a number of early flowering tree species, before congregating on elm in late May/June. This population was univoltine and exhibited obligatory female reproductive diapause.3. Overwintered females emerged already mated but the subsequent pre‐oviposition period was 25 days and oviposition period 27 days. Ova were deposited only in close association with galls ofS.ulmiandSpatchae, and behavioural variations were shown between sites. Fecundity wasc. 16 ova per female.4. The incubation period wasc. 8 days with the subsequent period of larval development 38–53 days, during which time the diet was almost exclusively eitherS.ulmiorS.patchae. Intergall migration was characteristic of post second instar larvae, which resulted in the concentration of fifth instar larvae and adults in a limited number of galls. It was during this period of local high population density that mating occurred.5. Adults left elm within 14 days of imaginal ecdysis and thereafter, until overwintering, were recorded in only very low numbers from a range of tree, shrub and herb species.6. Overwintering adults selected as hibernacula the bark of four tree species but principallyAcer pseudoplatanusandQuercus robor. Females required a period of at least 75 days of cold ‘shock’ to terminate reproductive diapause.7. Mortality among males surviving to spring emerge

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00698.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. The relationship between cyanogenesis in bracken fern and the insect fauna feeding on the plant was investigated over a 3 year period. The most common insects between May and July, while cyanide levels were high, were the sawfliesStrongylogaster impressataProvancher,S.multicinctaNorton,Aneug‐menus fzavipes(Norton), the aphidMacrosiphum euphorbiae(Thomas) and a microlepidopteran species ofMonochroa.2. Collections of insects from cyanogenic and acyanogenic fronds showed significantly fewer sawflies on the cyanogenic fronds. The aphid and the microlepidopteran were randomly distributed with respect to cyanogenicity.3. Feeding tests for two of the sawfly species (SimpressataandSmulticincta) showed that larvae grew more slowly and had a higher mortality when raised on cyanogenic fronds than on acyanogenic ones.4. Field collected cyanogenic bracken fronds were found to have sustained less damage from chewing herbivores compared with acyanogenic frond

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00699.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Laboratory experiments with yellow dung fly larvae,Scatophaga sfercorariaL. were carried out in the hope of clarifying the causal relationship underlying the extreme variation in body size in wild populations.2. First, parents were collected in the field and newly hatched larvae exposed to different density levels under two temperature regimes (15°C and 20°C). Second, heritability experiments were done.3. The results showed that density during the larval stage has a very significant effect on adult size. Male size is more affected than female size and the male larvae spend more time feeding than the female larvae with the result that the males are on average larger. Also, the additive genetic component is of little or no significance, supporting the notion that body size is positively related to fitness.4. Finally, the results are discussed in relation to field data on the effects of size on both male and female reproductive succes

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00700.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Abstract.1. Quantitative collections were made of arthropod predators from larch trees at Ranmore Common, Surrey, from August 1977 to September 1978.2. Spiders were numerically the most important predators accounting for 64% of the total.3. Antisera of the main larch dwelling, epiphyte herbivore orders, Collembola and Psocoptera, and the other common arboreal herbivore group at Ranmore, the Honioptera (principally Psyllidae) were prepared in rabbits.4. Serological determinations of predator diets indicated that, with a few exceptions, the predators were taking approximately equal proportions of the three prey groups.5. This apparent non‐specificity of the predators is analysed in relation to both the numerical abundance and biomass of the three prey types during the study period.6. These arboreal arthropod predators are selecting for large but rare prey items in preference to small and common ones.7. These findings are discussed in relation to the population dynamics of arboreal epiphytic herbivore

ISSN:0307-6946    

DOI:10.1111/j.1365-2311.1984.tb00701.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY