bluuebunny/crossref_metadata_2025 huggingface dataset:
The distribution in time and space of parasitism in Epinotia tedella (CI.) (Lepidoptera: Tortricidae)
Authors: MÜNSTER‐SWENDSEN M.
Published: March 2008

Abstract.

The temporal and spatial distribution of parasitism in Epinotia tedella was investigated within two spruce stands.

Most eggs were laid by the host female early in the season. The parasitoid, Pimplopterus dubius, was subjected to a temporal stress, and it also exhibited a greater oviposition rate early in its life. The temporal distribution of attack frequencies by P.dubius and Apanteles tedellae showed a good adaptation to the phenology of the host.

The spatial distribution of flight activity indicated a preference to exposed sub‐habitats by P.dubius and to dark and sheltered sub‐habitats by A.tedellae. The distribution of host larvae showed an aggregation in the lower and central parts of the canopy, and so did the attacks by A.tedellae— even more pronounced. The attacks by P.dubius showed a slightly inverse aggregation pattern. Apparently, the distribution of attacks was caused by preference to physical conditions, rather than local host densities.

The decreasing log. area of discovery on increasing log. parasitoid density is obviously a ‘pseudo‐interference’ phenomenon caused by the aggregation of A.tedellae, and temporal asynchrony in P.dubius.

P.dubius dominated in young stands and its importance decreased with increasing age of the stands. The importance of A.tedellae was greatest in stands between 20 and 40 years old, and it dominated in those stands that were especially dense and dark, due to absent thinnings.
Colour patterns of Syrphidae. III. Sexual dimorphism in Eristalis arbustorum
Authors: HEAL J. R.
Published: March 2008

Abstract. 1. The hoverfly Eristalis arbustorum L. (Diptera, Syrphidae) is a sexually dimorphic Batesian mimic of bees and wasps.

2. This dual mimicry entails good mimicry of several small, dark bees (mainly mining bees) by female E.arbustorum, and less specific mimicry of wasps and other yellow and black Hymenoptera by males.

3. There is also variability of colour pattern within both sexes of E.arbustorum.

4. Seasonal fluctuations in the pattern frequencies of males occur because the temperature during pupal development influences the coloration of the adult.

5. Temporal changes in the pattern frequencies of females are attributable to developmental darkening of the abdomen.

6. These effects can be explained by the fact that the phenotypic requirements for thermoregulation and protection against predation will be different for males and females, and will also vary with time.

7. Behavioural differences between males and females are a component of the sexual dimorphism in this species.
Habitat segregation among African treehole mosquitoes
Authors: LOUNIBOS L. P.
Published: March 2008

Abstract. 1. The division of macrohabitats, seasons and microhabitats among mosquitoes which inhabit water‐filled treeholes was investigated in a wet/dry seasonal environment near the coast of Kenya. Twenty‐two species from four genera (Aedes fourteen, Culex three, Eretmapodites three, Toxorhynchites two) were identified from treeholes and bamboo traps. These included five which were more abundant in other microhabitats: leaf axils, fruit husks, or abandoned snail shells.

2. Trapping in different vegetation zones or heights in forests revealed that all seventeen species examined showed opposition preferences for one or more macrohabitats. Segregation of related species by macrohabitat was particularly apparent among members of the subgenus Stegomyia of Aedes which accounted for 57% of individuals identified from one locality.

3. Seasonal overlap was low between Aedes, which tracked rainfall patterns, and Culex and Eretmapodites. Aedes bromeliae differed from other Aedes found in treeholes in that maximal larval numbers did not follow heavy rainfall.

4. Negative associations between Aedes fulgens and two congeners which co‐occur in the same forest and season were attributed to preferences for tree‐holes of different sizes. Positive associations between Aedes aegypti and several other Aedes were reduced when root buttresses, a subclass of larger treeholes containing more species, were removed.

5. Separation of species by growth stages may be accomplished by two schemes of egg hatching which desynchronize larval cohorts in the same tree‐hole: the early pattern of Stegomyia whereby 50–95% of all eggs hatch at first immersion, and the delayed pattern of other subgenera (Diceromyia, Finlaya, Pseudarmigeres) in which less than one‐third of all eggs hatch at first immersion.

6. The number of wet treeholes changed seasonally. During one year five or six periods occurred when 50% or more of the censused holes contained sufficient water for larval survival. The number of individuals and species of mosquitoes in treeholes were positively correlated with treehole volume. In a comparison of treeholes and their mosquito fauna from two forests, treehole volume and mean number of species per hole differed significantly, but mosquito density did not.

7. Ecotonal trapping sites of mixed grasses, trees, and scrub yielded the highest mean numbers of species per sample, and traps placed outside a village, the lowest. Specific dominance was significantly less in the ecotone than elsewhere. The predatory larvae of Toxorhynchites brevipalpis in ecotonal and forested traps were not correlated with species richness.
The sex ratio in ectoparasitic insects
Authors: MARSHALL ADRIAN G.
Published: March 2008

Abstract. 1. The sex ratio in 379 collections, each consisting of more than 100 individuals, of 250 different species of ectoparasite belonging to seven orders of insects is recorded. The data are gathered from a broad survey of published literature.

2. In general, ectoparasitic insects emerge as adults in equal numbers of each sex, although there are certain exceptions.

3. The sex ratio in natural populations may alter with numerous factors, but in general it is unbalanced, females usually predominating. Out of 359 collections from the host's body or home, the sex ratio of 30% showed no significant departure from unity, 63% contained significantly more females, and 7% significantly more males.

4. These imbalances could be due to sampling methods but this is rare. Generally they are due to one sex, usually the male, being shorter lived than the other. This may be because males are often more active and smaller than females, and thus more likely to be separated from the host's body or home, succumb to host predation, or be killed by adverse climatic or nutritional conditions.
Interaction between insect larvae and tadpoles in tropical rain pools
Authors: McLACHLAN ATHOL
Published: March 2008

Abstract. 1. Ephemeral rain pools on rock surfaces are common in Africa and are inhabited by dense populations of aquatic dipteran larvae. About 30% of the pools also support large numbers of tadpoles of the frog Ptychadena anchietae.

2. Experiments reveal that the presence of tadpoles suppress eclosion of the rock pool dwelling midge Chironomus imicola.

3. However, the presence of tadpoles also shortens the larval life‐span of C. imicola by speeding up growth rates. Since the larval stages must be completed before the pool dries tadpoles may help ‘fine‐tune’ the dipteran to the rock pool habitat.

4. A change in the diet of Cimicola larvae is associated with the accelerated development. Grazing by tadpoles results in algae, growing on the water surface, reaching the mud in tadpole faeces. These algae represent a high protein and energy food not otherwise accessible to mud dwelling dipteran larvae.

5. When pools dry tadpoles are killed, but a second species of dipteran Dasyhelea thompsoni have larvae able to survive to dry phase in situ. These larvae are scavengers so that on reflooding dead tadpoles are available as food. Experiments show that the presence of tadpoles again increase larval growth rates.

6. Both alive and dead tadpoles therefore are responsible for increasing the quality and quantity of food available to dipteran larvae and are thus among the mechanisms ensuring an abundance of food for rock pool dwelling insect larvae.
The distribution and biology of Sepsidae (Diptera) in upland regions of northern England
Authors: RANDALL M. , COULSON J. C. , BUTTERFIELD J.
Published: March 2008

Abstract. 1. A survey of the distribution of Sepsidae was made over 2 years at forty‐two sites in northern England. Material was collected by pitfall trapping and in sweep‐net samples.

2. With the exception of a single specimen taken in a pasture, only members of the genus Sepsis were found and three species, S.cynipsea, S.orthocnemis and S.neocynipsea, occurred at most sites. The numbers of S.cynipsea were greater than S.orthocnemis at the great majority of sites. S.neocynipsea was the least abundant of the three species but occurred over the whole altitudinal range and formed a greater proportion of the catch at higher sites.

3. It is suggested that the three commonest species use sheep dung as their main larval habitat in upland areas. Cow dung (the commonest reported larval habitat of Sepsis spp.) did not occur on any of the main sites studied. No sepsids were reared from red grouse droppings.

4. There was no difference in the species composition on peat and grassland sites but almost 4 times as many sepsids were caught on the peat moor than on the neighbouring grasslands.

5. There was a marked bimodal distribution of adults with a trough of captures in June and July. This is in contrast to data from other studies, at low altitudes, and is probably the result of there being only two generations per year in upland areas rather than four (or more) in warmer conditions.
The effect of temperature on the growth and reproduction of two closely related aphid species on sycamore
Authors: WELLINGS P. W.
Published: March 2008

Abstract. 1. Egg hatch in the two species of sycamore aphid was temporally separated: the median time to hatch was 30 days later in Drepanosiphum acerinum than in D.platanoidis.

2. D.platanoidis was larger at egg hatch than D.acerinum. Progeny of D.platanoidis adults were also larger than those of D.acerinum.

3. D.platanoidis was the larger of the two species as an adult, as a consequence of its greater birth weight.

4. Over a range of temperatures, development rates in the two species were the same, while the growth rate in D.acerinum was significantly higher at high temperatures.

5. The reproductive rate of the two species was significantly different at 6d̀C and 20d̀C.
Foraging ecology of hoverflies: morphology of the mouthparts in relation to feeding on nectar and pollen in some common urban species
Authors: GILBERT FRANCIS S.
Published: March 2008

Abstract.1. Previous accounts of the feeding behaviour of hoverflies (Diptera: Syrphidae) are contradictory and in many cases do not correspond with field observations.

2. Patterns of feeding on nectar and pollen differ between species: these patterns are correlated with morphological differences.

3. The data indicate that there are two correlates of increasing tongue length: first, the proportion of pollen in the diet decreases; and second, the flies concentrate on visiting flowers with longer corollae, which contain more nectar sugar.

4. Reasons for these effects are discussed.
The life cycles and age of Carabus glabratus Paykull and C.problematicus Herbst (Col.: Carabidae) on moorland in northern England
Authors: HOUSTON W. W. K.
Published: March 2008

Abstract. 1. The life cycles of C.glabratus and C.problematicus on moorland in northern England were studied in 1967. C.glabratus was a spring/summer breeder whilst C.problematicus was a late summer/autumn breeder and both had biennial life cycles.

2. Mandible wear and reproductive condition were used to indicate the age of the adults; some females lived for at least 2 years and probably three, with a distinct regression of their ovaries between each breeding season.

3. Mandible wear affected their ability to feed and thus build up fat reserves or develop eggs. Individuals with extreme mandible wear may die of starvation.
Patterns of abundance, distribution, and alary polymorphism among the salt marsh Delphacidae (Homoptera: Fulgoroidea) of Northwest Florida
Authors: McCOY EARL D. , REY JORGE R.
Published: March 2008

Abstract. 1. The species of Delphacidae captured in nearly 16000 sweeps of salt marsh vegetation in Northwest Florida, U.S.A., are examined. Individuals belonging to fourteen species were captured during the 15‐month study, a somewhat larger number than is found in most locations.

2. Abundances ranged from one to 1064 individuals per species. The abundances, habitat preferences, and patterns in wing‐polymorphism among the species collected were similar to those reported previously from other locations, but important differences were found which reflect the vegetational composition typical of our study area.

3. Wing‐morph ratio differences between delphacid populations may reflect strategies for dealing with differences in stability and distribution of their respective habitats. The ratio of macropter/brachypter individuals in various populations of delphacids investigated correlates with the probability that a dispersing individual will find a more suitable habitat patch. The phenomenon is illustrated with a comparison of wing‐morph ratios in populations of Prokelisia marginata (Van Duzee) from locations which differ in the extent, distribution, and stability of their stands of Spartina alterniflora Loisl. (smooth cordgrass), the common host of P.marginata.

4. Macroptery is favoured in Atlantic Coast marshes, where habitat patches are differentially suitable, but extensive and predictable. The probability of finding a better patch by dispersing is therefore high.

5. Brachyptery predominates at Cedar Key, Florida, where habitat patches are extensive, stable, and equally suitable during most of the year; and at St Marks, Florida, where resource patches are small, infrequent, isolated, and regularly disturbed. Under these conditions, the probability of finding a better patch by dispersal is low.

6. The conditions at St Marks may have promoted a local host expansion by P.marginata at this location.
Some aspects of the rate of increase of a coccinellid
Authors: MILLS N. J.
Published: March 2008

Abstract. 1. Fecundity, growth and development were determined at a range of feeding levels and temperatures and compared with the component models for the predator rate of increase.

2. Fecundity and growth rate show a linear dependence on rate of consumption, while development rate conforms to an alternative non‐linear model. The non‐linearity of development rate is due to a dependence of weight gain during an instar on rate of consumption.

3. The primary influence of temperature is on the rate of consumption, limiting fecundity and growth rate at temperatures below the optimum for the stage, while higher temperatures have a deleterious effect. Temperature has a more direct influence on development rates, allowing comparable growth despite the variation in rates of consumption.
Intraspecific variability in herbivore performance and host quality: a field study of Uroleucon caligatum (Homoptera: Aphididae) and its Solidago hosts (Asteraceae)
Authors: MORAN NANCY
Published: March 2008

Abstract. 1. Performances of two clones of Uroleucon caligatum on eleven clones of Solidago were measured by caging aphids on plants in the field.

2. Several measures were obtained, including developmental time from birth to adulthood, size of first instar nymphs, adult weight, and total colony weight.

3. All measures of performance were strongly affected by plant clone.

4. Effect of aphid clone‐plant clone interaction was significant only for first instar size.

5. In a subsequent screenhouse experiment, plant clones were subjected to uniform conditions and still exhibited large differences in host quality.
An ecological interaction between citrus fruit, Penicillium moulds and Drosophila immigrans Sturtevant (Diptera: Drosophilidae)
Authors: ATKINSON W. D.
Published: March 2008

Abstract. 1. Potential Drosophila breeding sites were collected from a fruit market, and the adults allowed to emerge from them.

2. D.immigrans and D.melanogaster were the species with the highest frequency of emergences from citrus fruit.

3. D.immigrans was especially associated with citrus fruits infected with Penicillium italicum or P.digitatum, two specialist moulds of citrus. D.melanogaster was more often found in uninfected fruit.

4. In the laboratory D.immigrans larvae survived better than D.melanogaster larvae on Penicillium‐infected citrus fruit.

5. These adaptations suggest that D.immigrans may have originally evolved as a citrus specialist, becoming a domestic species as these fruits were exploited commercially.
Wind as a factor influencing flower‐visiting by Hadena bicruris (Noctuidae) and Deilephila elpenor (Sphingidae)
Authors: BRANTJES N. B. M.
Published: March 2008

Abstract. 1. In a low‐speed wind tunnel, male as well as female moths of Hadena bicruris responded to floral odours with positive anemotaxis. Hitherto, such orientation has only been demonstrated for male moths in response to pheromones.

2. H.bicruris had a maximum flight speed of 4.5–5.4ms‐1 and stopped its flower visiting at a wind speed of 2.5–2.8 m s‐1.

3. Deilephila elpenor had a similar maximum flight speed (4.5— 5.1 ms‐1), but it continued visiting flowers up to wind speeds of 3.0–5.0 ms‐1.

4. Apart from mechanical resistance during flight and flower visits, wind might have adverse effects on the energy budget and on evaporative water loss.
The variation in population densities of fleas in house martin nests in Leicestershire
Authors: CLARK FRANK , McNEIL D. A. C.
Published: March 2008

Abstract. 1. Five species of flea were recorded from 150 nests taken from house eaves in Leicestershire. Three species, C.hirundinis, C.farreniand C.rusticus, were associated with nests used for breeding by martins in the year of collection whilst C.gallinae and C.fringillae were associated with nests used by sparrows.

2. Analysis of the three species of martin fleas with various characteristics of the structure and location of the nest revealed that all three species favoured the presence of nest lining consisting of feathers or grass (or the two combined) in preference to straw or to no nest lining.

3. Both C.hirundinis and C.rusticus showed a preference for the texture of the surface to which the nest was attached, the former preferring nests attached to plain brick, or pebble‐dashed surfaces, whilst the latter preferred pebble‐dash to stone. Both also showed a relation with the height of the nest above ground level.

4. The numbers of C.hirundinus showed a strong positive correlation with those of C.farreni and C.rusticus, which were not correlated with each other.

5. Lastly, the number of nests collected that had been used by house sparrows and contained C.gallinae and C.fringillae was too small to allow us to reach any conclusion about their preferences.
A modification of the Lincoln Index for estimating the population densities of mobile insects
Authors: FLETCHER B. S. , KAPATOS E. , SOUTHWOOD T. R. E.
Published: March 2008

Abstract. 1. To estimate populations of D.oleae in olive groves on Corfu by mark—recapture techniques, McPhail traps had to be used for sampling.

2. The prolonged sampling period (24 h) resulted in a differential loss of marked flies from the area and this biased the population estimates obtained from the standard Lincoln Index.

3. A modification was devised which enabled the rate of loss of marked flies to be calculated and incorporated into the Index as a correction factor.

4. Field comparisons indicated that the modified Index gave more accurate population estimates than the standard Lincoln Index and therefore it may be applicable to other situations when ‘instantaneous’ sampling of populations is not practicable.
The function of turret building behaviour in the larval tiger beetle, Cicindela willistoni (Coleoptera: Cicindelidae)
Authors: KNISLEY C. BARRY , PEARSON DAVID L.
Published: March 2008

Abstract. 1. Cicindela willistoni LeConte (Coleoptera: Cicindelidae) adults and larvae occur only on saline and alkali flats with little or no vegetation in southwestern U.S.A. Unlike other larval tiger beetle species, C.willistoni constructs a chimney‐like extension (turret) 1–4 cm above its burrow.

2. The function of these unique turrets was tested in relation to several biotic and abiotic factors in the Sulphur Springs Valley, Arizona, U.S.A.

3. The turrets did not prevent flooding of the larval burrows.

4. They did not prevent or reduce the frequency of parasitoids (mainly bombyliid flies of the genus Anthrax).

5. The turrets did not make it possible for the adult and larval beetles to feed on obviously different types or sizes of prey.

6. However, larvae with turrets were raised sufficiently above the substrate surface and boundary layer to allow them to thermoregulate in the lower temperatures at these heights and remain active throughout the day.

7. The shade produced by the turrets attracted significantly more potential prey items than were available to turretless larvae in the same habitat.
Host tree influences on the dispersal of first instar gypsy moths, Lymantria dispar (L.)
Authors: LANCE DAVID , BARBOSA P.
Published: March 2008

Abstract. 1. In laboratory tests, first instar gypsy moths attempted dispersal more frequency when exposed to less acceptable foliage.

2. First instars from small eggs attempted dispersal less frequently than larvae from large eggs when exposed to foliage from highly acceptable or marginally acceptable hosts. Dispersal rates of larvae from medium sized eggs were intermediate.

3. These results (1–2) confirm and expand upon the findings of Capinera & Barbosa (1976).

4. In the field, data on the relative densities of larvae on different host species support the conclusion that the frequency of dispersal attempts is inversely related to host acceptability.

5. The implications of these findings for the population dynamics of the gypsy moth are discussed.
The inheritance and maintenance of the melanic form nigrescens of Pachycnemia hippocastanaria (Lepidoptera: Ennominae)
Authors: MAJERUS M. E. N.
Published: March 2008

Abstract. 1. A New Forest population of P.hippocastanaria with both typical and nigrescens forms was studied over 6 years. The nigrescens form constituted between 10% and 17% of the population.

2. Breeding experiments showed that the nigrescens form is inherited as a unifactorial recessive; however, rearing at low temperatures induces a phenotype similar to nigrescens to result from insects with a genotype which normally produces typical imagines.

3. Old collections of P.hippocastanaria suggest that the frequency of the nigrescens form in the New Forest area has increased over the last 100 years.

4. Samples collected from other areas, within and outside the New Forest, indicated that the distribution of nigrescens is limited to heaths within the New Forest and on the extreme eastern border of Dorset.

5. A number of speculative reasons for the increase in the frequency of the nigrescens form in this area are suggested.
Butterfly migration: are synoptic‐scale wind systems important?
Authors: WALKER THOMAS J. , RIORDAN ALLEN J.
Published: March 2008

Abstract. 1. If synoptic‐scale wind systems are important in determining long‐distance movements of butterflies, a portion of the variation in daily counts of migrants at a site should be explainable by prior winds.

2. Using special flight traps near Gainesville, Florida, U.S.A., from 29 August until 12 November 1978, we made replicated, continuous counts of four migrant species: Phoebis sennae, Urbanus proteus, Agraulis vanillae and Precis coenia.

3. Significant SSE‐ward flights occurred for one or more of the four species on 47 days between 5 September and 6 November (Fig. 1).

4. Seasonal changes in numbers of migrants were similar for the four species (Fig. 1). Median fall migrants were trapped between 22 September (A.vanillae) and 1 October (U.proteus and P.sennae).

5. Daily fluctuations in total numbers of migrants were largely attributable to local weather, viz temperature, wind speed and cloud cover (Fig. 2).

6. Neither local wind direction (Fig. 3) nor back‐tracking the positions of air parcels (Fig. 4) helped explain the daily fluctuations.

7. The characteristic autumn weather patterns of south‐eastern U.S.A. and the day‐to‐day steadiness of the numbers of migrants are incompatible with the hypothesis that synoptic‐scale wind systems are important in determining butterfly migrations through Gainesville, Florida, in the autumn.
The role of cereal growth stages and crowding in the induction of alatae in Sitobion avenae and its consequences for population growth
Authors: WATT A. D. , DIXON A. F. G.
Published: March 2008

Abstract. 1. Alatiform nymphs of Sitobion avenae were first recorded on wheat in 1977 and 1978 when there were 0.6 aphids per tiller and reached a maximum proportion of 0.9 of the population despite a seventeen‐fold difference in aphid density between years.

2. At the same aphid density per tiller there was a higher proportion of alatiform nymphs on the tillers at an advanced than at an earlier stage of plant growth.

3. Both pre‐ and post‐natal crowding, and late stages of plant growth, were important in inducing the development of alatae in the laboratory.

4. Changes in the quality of the host plant through its previously reported effect on reproductive and survival rates, and its effect on alate induction and emigration was important in shaping the population dynamics of S.avenae on cereals.
Nest construction and larval behaviour of Bubas bison (L.) and Bubas bubalus (01.) (Coleoptera, Scarabaeidae)
Authors: KLEMPERER H. G.
Published: March 2008

Abstract.

Female beetles working alone or in cooperation with a male excavated vertical, tunnel‐shaped brood chambers. Each chamber was filled with dung to form a cylindrical brood mass which contained two eggs, one near each pole.

To examine the possible relationship with other Onitini (which lay either one or several eggs per brood mass) factors that influence the two‐egg programme were studied. Brood masses with only a single egg were formed if excavation was resumed prematurely. Conversely, when excavation was suppressed several oviposition programmes fused to produce a multi‐egg brood mass.

The larvae repaired their chambers in the typical Scarabaeine manner by building a self‐supporting wall formed from their own excrement. This behaviour also prevented direct contact and fighting between adjacent larvae in the same brood mass, and it allowed the larvae to survive inside artificial brood balls. Similar behaviour was observed in larvae of Onthophagus taunts and Ontho‐phagus vacca (which develop in one‐egg brood masses). The evolution of nesting habits that involve multi‐egg brood masses or free‐standing brood balls may depend on the pre‐existence of this larval repair behaviour.
Spatial variations in egg density and the intensity of parasitism in a neotropical chrysomelid (Cephaloleia consanguinea)
Authors: MORRISON GEROLD , STRONG DONALD R.
Published: March 2008

Abstract.

The chrysomelid beetle, Cephaloleia consanguinea (Hispinae), is a monophagous herbivore of Heliconia imbricata (Zingiberales: Heliconiaceae) in wet lowland forests of eastern Costa Rica.

Within the study area parasitism by eulophids and trichogrammatids (Hymenoptera: Chalcidoidea), the most common source of C. consanguinea egg mortality, varied in intensity from 35% to 50% during 1974–77.

Spatial relationships between the probability of parasitism and egg density per leaf were the net result of two opposing trends. The probability of at least one egg on an egg‐bearing H. imbricata leaf being encountered and parasitized (here termed a ‘discovery’ of that leaf by parasitoids) increased significantly as egg density per leaf increased. The conditional probability of parasitism for other eggs present, given an attack on one egg, decreased with increasing egg density.

The net result was a decrease in the overall probability of parasitism as egg density per leaf increased. Host aggregation appears beneficial in reducing the intensity of parasitoid attacks.

Despite this inverse relationship between the overall probability of parasitism and egg density per leaf, a model based on the binomial distribution provides a good description of the spatial aspects of this host—parasitoid interaction.
Physiological correlates of the availability of Glossina morsitans centralis Machado to different sampling methods
Authors: RANDOLPH SARAH E. , ROGERS D. J.
Published: March 2008

Abstract.

The feeding cycle for male tsetse flies and the pregnancy cycle for females are used as frameworks for investigating the field behaviour of Glossina morsitans centralis Machado in Zambia, and hence the sampling biases of different capture devices.

Flies were collected in the field using hand nets and an electric back pack on foot patrols, and hand nets, hand‐catching and an electric screen on landrover patrols. They were analysed for wing‐fray, vein‐length, chloroform‐extractable fat and haematin. In addition, samples of laboratory‐bred females killed daily during their second pregnancy cycle were analysed for the last two parameters.

The daily flying time of males is estimated from the fat—haematin curve to be about 32 min/day, which is identical to previous estimates for G. morsitans from Tanzania.

From the varying numbers and fat content of male flies caught by the different sampling methods during the course of the feeding cycle it is concluded that both haematin levels and fat reserves influence fly behaviour.

Comparison of the frequency distribution of wild‐caught and laboratory‐bred females along the corrected residual dry weight axis of the pregnancy cycle suggests that the results of combined electric‐trap and hand‐net sampling reflect the actual frequency distribution in the wild population at least for the first 7 days of the pregnancy cycle; but females in the last 2 days of their pregnancy cycle are apparently unavailable to sampling devices, perhaps because of their reduced flight activity.

The very variable percentage female catch (10.9–43.4%) returned by the different sampling methods is discussed in the light of the detailed analysis of the differential availability of male and female flies to each capture device.
Host searching and oviposition behaviour of some parasitoids of aphidophagous Syrphidae
Authors: ROTHERAY G. E.
Published: March 2008

Abstract.

An analysis of host searching behaviour suggests that female parasitoids respond to aphid odours bringing them to the region of an aphid colony.

Syrphid hosts are located within the aphid colony by response to contact chemicals on the larval integument.

The behavioural mechanisms used by syrphid larvae to resist attacks and the subsequent responses made by parasitoids are described.

Oviposition behaviour and host size preferences of parasitoids are described.
The adaptive and evolutionary significance of wing polymorphism and parthenogenesis in Ptinella Motschulsky (Coleoptera: Ptiliidae)
Authors: TAYLOR VICTORIA A.
Published: March 2008

Abstract.

The incidence of wing polymorphism varies seasonally in field populations of Ptinella aptera and Ptinella errabunda with alatae increasing in abundance in summer.

In laboratory cultures of P. aptera alate development varies with temperature. This implies that morph determination is based on a physiological switch sensitive to temperature and possibly other adaptively relevant environmental factors.

Alate P. aptera produce a higher proportion of alate offspring than do apterous parents suggesting an inherited component in polymorphism control, or some form of maternal effect.

The female biased sex ratio expected of a regularly inbreeding species was found only in the alate morph. Apterous beetles show a 1:1 sex ratio which is explained by the females' limited capacity to store sperm, the enormous size of the sperm, and the consequent need for multiple insemination.

Ptinella errabunda is thelytokous but fails to realize the potentially doubled fecundity associated with parthenogenesis. Both the number of eggs produced and their viability is lower than in bisexual congeners.

Enhanced colonizing ability, rather than energy economy, is considered to be the most important selective advantage of parthenogenesis to Ptinella in the subcortical habitat.

The spatial and temporal heterogeneity of the subcortical habitat is considered to have favoured the evolution and maintenance of parthenogenesis and wing polymorphism in Ptinella.
Supercooling points of insects and mites on the Antarctic Peninsula
Authors: BLOCK WILLIAM
Published: March 2008

Abstract. 1. Mean supercooling points of eleven species of arthropods (three Collembola, seven Acari and one Diptera) ranged from ‐6.2 to ‐9.4°C (high group), and from ‐17.7 to ‐31.0°C (low group). The majority of individuals in the high group had food in their gut systems.

2. Freezing was lethal to all species examined except larval Belgica antarctica Jacobs (Chironomidae).

3. Glucose, glycerol and mannitol were found in low concentrations in extracts of Ctyptopygus antarcticus Willem (Collembola) and larvae of B. antarcrica; it is udikely that these substances had a major effect on the supercooling of either species.

4. Two Collembola species possessed significantly (P< 0.05) lower supercooling points at locations on the Antarctic Pensinsula than at Signy Island, South Orkney Islands. The converse was observed for two species of Acari.

5. It is suggested that whilst gross climatic and also micro‐habitat conditions may influence the cold hardiness of such arthropods, especially seasonally, their full supercooling ability is rarely tested.
Biosystematics of the Muellerianella complex (Homoptera, Delphacidae): host‐plants, habitats and phenology
Authors: BOOIJ C. J. H.
Published: March 2008

Abstract. 1. Ecological differences between closely related species and forms of the planthopper genus MueIlerianella (Delphacidae) were studied.

2. In the field M.brevipennis and M.faimairei are restricted to Deschampsia cespitosa and Holcus lanahis/H.mollis. respectively. M.extrusa is mainly found on Molinia caerulea, but has also been recorded from other grass‐species. Triploid all‐female forms which reproduce by gynogenesis usually live on Holcus together with M.fairmairei. Other gynogenetic populations were found on Bromus ramosus, Deschampsia flexuosa and Calamagrostis canescens.

3. Breeding experiments showed that the diploid species cannot be maintained on each other's host‐plants, but accept other grass‐species.

4. Due to overlapping habitat requirements of the host‐plants, ecological isolation between the Muellerianella species is incomplete.

5. M.extrusa lives in bogs, moors and forests on poor acid soil. M.brevipennis is found in forests, carr, fens and in extensively managed grasslands. M.faimairei and associated triploid forms occur mainly in grasslands and other man‐made habitats. The habitats of all three species are usually wet.

6. In most parts of Europe M.brevipennis and M.extrusa are monovoltine and M.fairmairei is mostly bi‐or polyvoltine.
Phytophagous insects associated with cadang‐cadang infected and healthy coconut palms in South‐eastern Luzon, Philippines
Authors: ZELAZNY B. , PCA E. PACUMBABA
Published: March 2008

Abstract. 1. The most common phytophagous insects associated (as adults) with the leaves of coconut palms in the Southeastern part of Luzon have been identified as part of a study on the natural method of spread of cadangcadang disease. Sixty‐three species, of which at least twenty individuals were caught alive or with sticky boards, and five colony‐forming Homoptera are listed. The sixty‐three species belonged to the orders of Orthoptera (two species), Coleoptera (eight species), Hemiptera (one species) and Homoptera (fifty‐two species, mainly Cicadellidae and Derbidae).

2. Three beetles (Oryctes rhinoceros, Plesispa reichei and Hemipeplus sp.) and a lace bug (Stephanitis typicus) were found to be significantly more abundant in areas with a high incidence of cadangcadang disease. O.rhinoceros and P.reichei were also significantly more common on old palms (which are predisposed to the disease), and more abundant on cadang‐cadang infected than on neighbouring healthy palms. Hemipeplus sp. apparently feeds by scraping the cuticle layer of the youngest fronds.
Effects of inundation and salt on the survival of ants in a sandy coastal plain
Authors: BOOMSMA J. J. , ISAAKS J. A.
Published: March 2008

Abstract. 1. Survival of four species of ants, Myrmica rubra, Myrmica scabrinodis, Lasius niger and Lasius flavus, exposed to prolonged inundation and the drinking of brackish water, was experimentally determined.

2. In most of the experiments, survival of Lasius flavus workers was much worse than either Lasius niger or Myrmica scabrinodis.

3. After inundation with brackish water, and drinking of brackish water for more than 3 weeks, survival of workers of Myrmica rubra was also more affected than that of Lasius niger and Myrmica scabrinodis.

4. As a rule, survival of dealated queens after inundation appeared to be better in Lasius flavus and Lasius niger, but worse in Myrmica rubra, compared with worker survival.

5. After surviving inundation, the capacity to produce eggs and workers was only slightly affected in queens of both Lusius species.

6. The conclusions based on the experimental mortality rates seem to be consistent both with ant species distribution and with frequency of inundation and salt stress in different parts of the coastal plain and surrounding sand‐dunes on the Dutch Wadden island Schiermonnikoog.
The ‘edgeeffect’ in butterfly oviposition: causality in Anthocharis cardarnines and related species
Authors: COURTNEY STEVEN P. , COURTNEY SARAH
Published: March 2008

Abstract. 1. An ‘edge‐effect’, where outlying host plants receive proportionately most attention from insect herbivores, is described from the literature, and from data on Anthochoris cardamines (L.), in northern England.

2. Six hypotheses are examined as explanations for the effect in A.curdamines. Four are shown to be refuted by studies on female behaviour and the survival of larvae.

3. It is argued that the ‘edge‐effect’ comes about due to two or more aspects of the searching behaviour of females. The effect may be seen as an outcome of behaviour adapted to searching for host plants of low density.
Temperature effects in relation to the patterns of distribution and abundance of three species in the Drosophila affinis subgroup
Authors: FOGLEMAN JAMES C.
Published: March 2008

Abstract. 1. The effect of temperature on several aspects of the biology of Drosophila affinis, D.algonquin and D.athabasca were investigated in order to gain insight as to why these closely related species differ in their spatial and temporal patterns of occurrence.

2. No differences exist between the three species in the effect of temperature on egg hatchability.

3. Productivities of the three species were measured in a temperature gradient device. These measurements indicated that D.athabasca has an advantage in productivity over D.affinis at cooler temperatures (below 25°C). At warmer temperatures (above 25°C) the greater productivity of D.affinis makes it the better species. Drosophila algonquin, like D.athabasca, was characterized by its productivity curve as a species more adapted to cooler climates.

4. The competitive abilities of the three species were measured at 25°C, at 18°C, and in an environment which fluctuated between 18 and 25°C on a daily cycle. Competitive ability was estimated on the basis of the performance of the species in two‐ and three‐species populations.

5. In general, D.affinis exhibited its highest competitive ability relative to the other two species at the highest experimental temperature. D.athabasca had its highest competitive ability at the lowest temperature. The competitive ability of Ddgonquin was intermediate; less than that of D.affinis but greater than D.athabasca.

6. The dependence of competitive ability and productivity on temperature is thought to be partly responsible for the differences between the species with respect to their geographic distributions and their spatial and temporal patterns in natural populations.
Seasonal patterns in species richness of herbivores: Macrolepidopteran larvae on Finnish deciduous trees
Authors: NIEMELÄ PEKKA
Published: March 2008

Abstract. 1. The seasonal distribution of macrolepidopteran species richness on Finnish deciduous trees vaned from positively skewed (peak in spring) to negatively skewed (peak in autumn).

2. The skewness values of species richness had a significant negative correlation (r = ‐ 0.98) with the duration of the seasonal shoot‐growth period of the tree species.

3. Trees which complete their shoot growth early in the season (Quercus type) produce new leaves only during spring, while trees whose shoot growth continues to autumn (Populus type) do so throughout the summer.

4. Consequently, there is a difference in the number of available resources in the late summer foliage of different tree species, Trees ceasing leaf production early such as oak (Quercus robur) and bird cherry (Prunus padus) have one major resource type (mature leaves) in late‐season foliage while trees like birches and alders have two Ooung and mature leaves).

5. Because young leaves formed late in the season are preferred to mature ones by some species of herbivores and because other species prefer mature leaves at the same time, the species richness of Populus‐type trees is higher later in the season than the species richness of Quercus‐type of trees, which have just one type of resource available.
Hygrothermal determinants of insect activity patterns: the Diptera of water‐lily leaves
Authors: WILLMER P. G.
Published: March 2008

Abstract. 1. The numbers and types of flies resting on water‐lily leaves varied through the diurnal cycle. The different patterns of occupancy were recorded in relation to time of day and to microclimatic conditions at the leaf surface.

2. Overall fly activity on the leaves varied according to gross climatic patterns on particular days. The timing of activity differed according to species.

3. Smaller, darker flies (especially ernpids and Notiphila) were common on the leaves early and late in the day, with the more reflective dolichopodids occurring only towards midday and in full sun. Hence there were clearcut correlations between both the size and reflectance properties of flies, and the climate (in particular radiation received at the leaf surface); though this pattern was superimposed on a diurnal activity effect.

4. The timing of insect activity on the leaves could therefore be related to hygrothermal considerations, particularly the raising and maintenance of body temperature and avoidance of heat stress. Different types of fly used the favourable microclimate around the leaves as a resting site at times appropriate to their own biological requirements.
Adaptative significance of a temperature induced diapause in a cosmopolitan parasitoid of Drosophila
Authors: CARTON Y. , CLARET J.
Published: March 2008

Abstract. 1. We have previously demonstrated pre‐pupal diapause in a tropical population of Leptopilima boulardi Barbotin, Carton and Kelner‐Pillault (Cynipidae, Hymenoptera), a larval parasitoid of Drosophila melanogaster Meigen. Prepupal diapause was induced by low temperature (17.5°C) but absent at 25°C; it was independent of photoperiod.

2. Four populations which originated from different latitudes (4°S to 44°N) exhibit the same response to temperature without any major genetic geographical variation.

3. In temperate areas, this diapause may permit a phenological and temporal coincidence between the parasitoid and its host whose larval growth is only possible for temperatures above 13°C.

4. The significance of the persistence of this diapause in tropical areas is discussed.
Cold‐hardiness and development of eggs of Rhopalosiphum insertum
Authors: JAMES B. D. , LUFF M. L.
Published: March 2008

Abstract. 1. The eggs of Rhopalosiphum insertum (Walker) showed a seasonal increase in cold‐hardiness under field conditions. Their supercooling point fell from ‐35°C in November to below ‐40°C in January, then rose to‐35°C or above by March.

2. Laboratory experiments demonstrated that both temperature and date affected cold‐hardiness of the eggs. The supercooling points of eggs kept at 16 h photoperiod or in darkness did not, however, differ significantly.

3. Eggs brought from the field into warm, long‐day conditions would not hatch until after mid‐January. After this date, per cent hatch was significantly greater in 16 h photoperiod than in darkness; it did not differ between eggs kept at 5 or 0°C, but was reduced at ‐5°C.

4. It is concluded that eggs of Rinserturn are in diapause until mid‐January, and that hatching rate and cold‐hardiness are determined by separate environmental factors.
The basis of an apparent preference for isolated host plants by ovipositing Euptychia libye butterflies
Authors: MACKAY DUNCAN A. , SINGER MICHAEL C.
Published: March 2008

Abstract. 1. The tendency of Euptychia libye butterflies to oviposit with greater likelihood on isolated plants than on members of clumps is evident in the field and can be duplicated under controlled conditions in the laboratory.

2. The causes and effects of this behaviour and the difficulties inherent in inferring preference from egg distributions in the field are discussed.
Satiation and the functional response: a test of a new model
Authors: MILLS N. J.
Published: March 2008

Abstract.1. A model of the functional response to prey density is derived to include the reduction in time available for search,Ts, resulting from predator satiation.

2. For larger prey items predator satiation occurs at each prey capture andTsis reduced by the attack time and digestive pause of a series of attack cycles. For small prey items predator foraging is continuous at low densities withTsreduced solely by attack time. At higher densities predator satiation occurs after the capture of several small prey items andTsis reduced by the attack time and digestive pause of a series of foraging cycles.

3. A comparison of the predicted asymptotic level of prey capture using experimentally estimated parameter values, with the maximum consumption of aphids by larval and adult coccinellids provides a test of the satiation model.

4. The limitation of prey capture by predator satiation is discussed with reference to handling time and the success of coccinellids in biological control.
Strategies in energy consumption and partitioning in Collembola
Authors: TESTERINK G. J.
Published: March 2008

Abstract. 1. Consumption (in Joules), partitioning of assimilated energy between maintenance (standard metabolism and locomotory activity) and prcduction (growth and reproduction) and assimilation efficiency were studied in the laboratory using adults of the coexisting species Orchesella cincta (L.) and Tomocents minor Lubbock (Collembola, Entomobryidae).

2. A higher energy demand for maintenance was established in O.cincta, compared with T.minor, caused by a higher mobility and a higher live weight‐specific oxygen consumption (metabolic rate).

3. The energy required for higher maintenance in O.cincta, compared with T.minor, was derived from production, both from growth and reproduction.

4. The increase in live weight (in mg) during a moulting interval (feeding instar plus reproductive instar) was less in O.cincta than in T.minor, and was less in males than in females.

5. Reproduction (in Joules) was less in O.cincta than in T.ninor. The numbers of eggs produced were equal, but their energetic content was less in O.cincta. Survival of the eggs was similar.

6. Consumption (in Joules) and assimilation efficiency (on an energetic basis) during a moulting interval (feeding instar plus reproductive instar) were similar in both species.