bluuebunny/crossref_metadata_2025 huggingface dataset:
The contribution of multiple mating and spermatophore consumption to the lifetime reproductive success of female field crickets (Gryllus bimaculatus)
Authors: SIMMONS L. W.
Published: March 2008

ABSTRACT.

The adaptive significance of multiple mating by female Gryllus bimaculatus (De Geer) was investigated.

Multiple mating prevented the depletion of sperm stores and, therefore, maintained high hatching success. This may not, however, explain the high frequency of remating in this species.

Male‐derived egg stimulants known to be passed with sperm at mating increased the number of eggs produced only when females mated throughout their lifespans.

Spermatophore consumption appeared to provide nutrients which, while they did not increase the quantity of eggs, increased egg quality as indicated by weight. Females who consumed spermatophores had a greater hatching success.

While females may derive non‐genetic benefits from mating, these are apparently long‐term benefits; females must mate throughout their lives in order to accrue them.

Since the benefits of mating may not be derived from individual males, the spermatophores and their contents in this species are best considered as mating effort.
Patterns of oviposition by Sandia xami (Lepidoptera, Lycaenidae) in relation to food plant apparency
Authors: JORGE SOBERÓN M. , CARLOS CORDERO M. , BETTY BENREY B. , PAULINA PARLANGE P. , GARCIA‐SÁEZ CARLOS , BERGES GERARDO
Published: March 2008

ABSTRACT.

The butterfly Sandia xami (Reakirt) has a very clumped yearly pattern of oviposition on its food plant Echeveria gibbiflora D.C., and the mean number of eggs per plant is always very low.

Three features of host plants are highly associated with the probability of being oviposited upon: height of plant; degree of conspicuousness; and degree of isolation from conspecific plants.

The relative importance of these factors as predictors of the probability of oviposition change according to the time scale considered: height and conspicuousness are more important over short (weekly) time intervals whilst isolation takes precedence over longer (yearly) periods.

It is hypothesized that the clumped pattern of oviposition is responsible for the low numbers of the butterflies relative to their very abundant food plant.
Predation by wasps on lepidopteran larvae in an Ozark forest canopy
Authors: STEWARD V. B. , SMITH K. G. , STEPHEN F. M.
Published: March 2008

ABSTRACT.

Predation by birds, crawling arthropods (ants, harvestmen, spiders), and social wasps (Vespula) spp. on introduced stocks of Heliothis virescens (Fabricius) larvae was investigated in a oak‐hickory forest canopy in northwestern Arkansas (U.S.A.).

Wasps, Vespula maculifrons (Buysson) and V.squamosa (Drury), removed over 90% of the larvae. Repeated visits to a feeding site by the same marked wasps accounted for removal of either a single larva or all larvae. Larvae pinned (punctured) to artificial leaves were selected over 70% of the time by wasps when compared to attachments that did not puncture larvae; however, unpunctured larvae were taken.

Crawling arthropods accounted for low levels of predation, and birds did not appear to prey on larvae. Apparently wasps removed larvae rapidly and efficiently, thereby depleting the feeding sites before other predators discovered the larvae.

Although attaching larvae to artifical hickory leaves provided an easy method for placing larvae into the forest canopy, a lower percentage of larvae were removed from these leaves compared to natural hickory leaves. Moving feeding sites did not influence the number of larvae taken.
Low temperature mortality of the peach‐potato aphid Myzus persicae
Authors: BALE J. S. , HARRINGTON R. , CLOUGH M. S.
Published: March 2008

ABSTRACT.

The mean supercooling points of first instar and adult Myzus persicae (Sulzer) maintained at 20°C and cooled at 1°C min−1 were −26.6 and −25.0°C respectively.

The LT50 (temperature) of the same age groups drawn from the same population and cooled at the same rate were −8.1 and −6.9°C, indicating extensive pre‐freeze mortality in M.persicae under laboratory conditions.

Acclimation at 10 and 5°C did not affect supercooling but depressed the LT50 of both first instars and adult aphids.

Freezing of leaves during feeding did not increase mortality above that expected from the direct effects of low temperature.

The level of cold in different winters can be expressed in terms of the total number of frost days, and the frequency of abnormally cold days. Winter temperatures differ markedly in a vertical profile from the soil to the soil or grass surface, and then to the air (and foliage) above.

The time of the first record of M.persicae in suction trap samples is correlated with January and February temperatures except in the west of England and Wales. Further north December and January temperatures are relatively more important.

Winter temperatures and the resultant aphid mortality is a primary determinant of the timing of the spring migration.
The relationship of provision weight to adult weight and sex ratio in the solitary bee, Ceratina calcarata
Authors: JOHNSON MICHAEL D.
Published: March 2008

ABSTRACT.

The female of the solitary bee Ceratina calcarata (Robertson) (Hymenoptera: Anthophoridae) excavates a tunnel in a pithy twig and then constructs and provisions a linear series of brood cells that make up her nest.

Adult females are, on the average, 1.3 times heavier than the males, a significant difference (P<0.001). There is no difference between the sexes in the amount of weight gained per unit of larval food.

Larger females occur because their provision masses are, on the average, 1.3 times heavier than male‐producing provision masses, a significant difference (P<0.001).

Because mothers invest more time and energy in their daughters, Fisher's theory predicts that they should produce more sons. When available resources are fewer in a given year as reflected in lighter provision masses, more males are produced during the year.

The observed sex ratio did not differ significantly from the expected, calculated as mean female weight/mean male weight and was male‐biased.

Unlike species which nest in pre‐formed tunnels, the sex of any brood cell except the innermost is random with respect to that cell's position in the nest and the tunnel's depth and diameter. The innermost position contained offspring with a female biased sex ratio (P<0.005).
Host and parasitoid recruitment for quantifying losses from parasitism, with reference to Pieris rapae and Cotesia glomerata
Authors: VAN DRIESCHE R. G. , BELLOWS T. S.
Published: March 2008

ABSTRACT.

A technique for quantifying mortality due to insect parasitoids in insect populations is presented. The method is based on the measurement of recruitment to both the host susceptible stage and the pool of parasitized hosts.

The technique provides estimates of generational mortality due to parasitism and, when combined with estimates of population density, provides estimates of other mortality rates acting on both host and parasitoid populations. Such estimates are available both for the generation as a whole and for separate sampling periods.

The method is illustrated by application to two generations of Pieris rapae L. (Lepidoptera: Pieridae) and its larval parasitoid Cotesia (Apanteles) glomerata (L.) (Hymenoptera: Braconidae).
Habitat use by bumble bees (Bombusspp.)
Authors: WILLIAMS PAUL H.
Published: March 2008

ABSTRACT.

Analysis of surveys of bumble bee distribution among 2 km grid‐squares in Kent revealed that some species are nearly ubiquitous among localities and abundant within each. For these ubiquitous species, Kent is near the middle of their latitudinal ranges.

The other species have very restricted distributions among localities and are less abundant where they occur. For each of these local species, Kent is near the margin of its latitudinal range.

The areas to which the local species are restricted are characterized by only a few of the many kinds of vegetation represented in Kent (shingle, sand dune, saltmarsh or old meadow). The ubiquitous species are also more abundant in areas with these kinds of vegetation.

A random model (Gause, 1936) and the core/satellite hypothesis (Hanski, 1982a) were proposed to explain similar patterns of distribution. I conclude that their assumptions are not well supported by the results of the present analysis.

A marginal mosaic model (after Andrewartha & Birch, 1954; Hengeveld & Haeck, 1981; Brown, 1984) is used to account for these patterns. This model depends on environmental factors (including resource levels and climate) affecting the economics of energy and, consequently, local persistence.

It follows from the marginal mosaic model that if the level of limiting resources in a habitat declines, then it is the species closest to their distribution limits that are most likely to face local extinction. These selective extinctions would result in a form of ‘community structure’.
Maternal behaviour of a webspinner (Order Embiidina): mother‐nymph associations
Authors: EDGERLY JANICE S.
Published: March 2008

ABSTRACT.

The life cycle of Antipaluria urichi (Saussure) (Embiidina: Clothodidae) was aseasonal and without overlap of generations within fifteen closely monitored colonies observed over a 9½ month field season. Adult females remained with their nymphs after hatch but disappeared prior to maturation of their offspring.

Time budgets of nymphs and their mothers differed significantly. Adult females spent significantly more time spinning silk than their offspring. After the nymphs hatched, the increase in area of the silk covering approximated an exponential curve, reflecting the increase in silk spinning behaviour exhibited by the adult female. These results indicate that silk may be a major contribution of the mother.

Observations suggest that silk protects embiids from some predators and from rainfall, which is often torrential in the rainforest.

In experimental field colonies, nymphs with their mothers developed significantly faster than those alone, indicating that maternal behaviours promote the development of their nymphs.
Virginity in haplodiploid populations: a study on fig wasps
Authors: GODFRAY H. C. J.
Published: March 2008

ABSTRACT.

The fig wasps inhabiting the figs of Ficus hispidioides S. Moore in New Guinea were investigated. The galls formed by the pollinating agaonid were also inhabited by two other non‐pollinating species of wasp; a third non‐pollinating wasp caused the production of a different type of gall, and was itself parasitized by a fourth species. In all species, males were wingless and all matings occurred within the fig.

It was estimated that 2% of the pollinating fig wasps left the fig unmated. The equivalent figures for three of the non‐pollinating wasps were 2%, 4% and 23%. The significance of oviposition by virgin females to the sex allocation strategy of mated females is discussed.

The absence of fighting and male wing dimorphism were studied in the context of the predictions of their occurrence by Hamilton (1979).
The efficiency of pitfall trapping for polyphagous predatory Carabidae
Authors: HALSALL NIGEL B. , WRATTEN STEPHEN D.
Published: March 2008

ABSTRACT.

The efficiency of pitfall trapping was investigated for seven carabid species, using time‐lapse video recording equipment, in the laboratory.

The effects of differing substrates, trap designs and seasons of collection on the capture rates of the carabids was also investigated.

Capture rate differed significantly between the species studied. The differences in capture rates between the species were unrelated to beetle size, speed of movement and diurnal behaviour.

Few differences arose in the capture rates when type of substrate or trap or season of capture were changed.
Foliar damage, parasitoids and indirect competition: a test using herbivores of birch
Authors: HAWKINS BRADFORD A.
Published: March 2008

ABSTRACT.

The hypothesis that leaf‐chewing caterpillars and leaf miners indirectly compete via the influence of foliar damage on parasitoids was experimentally tested using the leaf miner Coleophora serratella (L.) and a complex of folivorous caterpillars on birch.

Separate experiments tested the effects of manipulating artificial or caterpillar‐induced leaf damage on parasitism of leaf miners at several spatial scales.

Parasitism of C. serratella by specialist and generalist parasitoids was independent of the extent of either collateral or leaf‐miner damage, whether experimentally or naturally induced.

Support in the literature for the hypothesis is restricted to a single case, and only on a limited spatial scale; thus, the idea that collateral damage directs parasitoid‐mediated competition among herbivores remains highly speculative.
Patterns of parasitism by Trybliographa rapae, a cynipid parasitoid of the cabbage root fly, under laboratory and field conditions
Authors: JONES T. H. , HASSELL M. P.
Published: March 2008

ABSTRACT.

The spatial patterns of parasitism of the cabbage root fly caused by the cynipid parasitoid Trybliographa rapae (Westw.) have been studied in a laboratory system, within field cages and in a natural situation.

Continuous observations during the laboratory experiments showed the parasitoids to spend proportionately more time on the patches of high host density. This resulted in the per cent parasitism per patch being directly density dependent.

Similar patterns of parasitism were found from the field cage system, and also from experiments using the natural parasitoid population and either manipulated or natural host densities.

While mutual interference was marked in the laboratory experiments, there was little or no sign of it within the larger field cages.
Plant water deficits and insect responses: the preference of Corythucha arcuata (Heteroptera: Tingidae) for the foliage of white oak, Quercus alba
Authors: CONNOR EDWARD F.
Published: March 2008

ABSTRACT.

The preference of Corythucha arcuata (Say) (Heteroptera: Tingidae) for the foliage of Quercus alba L. (Fagaceae) grown under water deficit was examined. Potted Q.alba saplings were grown under controlled levels of water deficit in a glasshouse. Adult C.arcuata were exposed to excised Q.alba foliage under controlled conditions in a growth chamber, and feeding preference assessed by recording the percentage of individuals feeding on leaves from each level of water deficit.

Two experiments were performed. In the first, all foliage was supplemented with water (via the petiole) to alleviate physical changes in the leaves that accompany plant water deficits. In the second experiment, leaves were not supplemented with water.

C.arcuata had no preference when presented water supplemented leaves, but preferred leaves that were fully hydrated when presented leaves that were not supplemented with water.

These results suggest that plant water deficits are important in determining the feeding preference of C.arcuata because they lead to avoidance of drought grown foliage. This avoidance may be caused by an increase in the metabolic cost to the herbivore of maintaining water balance when ingesting drought grown foliage or to an increase in foliage toughness.
Robber‐like pollinators: overwintered queen bumblebees foraging on Corydalis ambigua
Authors: HIGASHI SEIGO , OHARA MASASHI , ARAI HIROHITO , MATSUO KAZUHITO
Published: March 2008

ABSTRACT.

The behaviour of nectar‐collecting Bombus hypocrita sapporensis Cockerell queens was observed on a population of a spring ephemeral plant Corydalis ambigua Cham, et Schlecht.

Daily patterns of activity and behaviour changed with the progress of flowering. Activity peaked shortly before sunset early in the flowering season but approximately at noon towards the end of flowering. In the peak flowering period the queens tended to visit nearby plants and to change direction often, whereas early or late in the flowering period they flew further between visits and were less likely to change direction.

Each plant was visited 0 to 24 times (mean 9.4 ±SD 5.2) by the queens during the whole flowering season.

The queens collected nectar, rarely through the front of the flowers but mostly through the spurs perforated by themselves or predecessors. At the beginning of the flowering season the illegitimate foragers often visited the front of the flowers before moving to the spurs; later, most queens quickly learned to land directly on the spurs.

Even the 59.7% of plants that were visited only by illegitimate foragers set seeds. Close observation confirmed that the illegitimate foragers opened the inner petals enclosing anthers and stigma frequently when visiting the front of the flowers before robbing, or occasionally when walking about on the flowers or collecting nectar through the perforated spurs.
Life history strategy and egg diapause in the intertidal collembolan Anurida maritima
Authors: WITTEVEEN J. , VERHOEF H. A. , HUIPEN T. E. A. M.
Published: March 2008

ABSTRACT.

In a field survey of 1 year the intertidal collembolan Anurida maritima (Guérin) was found to be a univoltine species. Every year in early May a new generation emerges from eggs that overwinter. The first animals become adult in July. Almost all eggs laid in summer do not hatch, but undergo a period of diapause. Diapause is terminated in autumn by temperatures below 5°C. However, due to the low temperatures in winter further egg development is suppressed until spring.

The adult animals die, mainly in autumn. One of the causes of mortality may be starvation. In late autumn body size decreases and glycogen and lipid content are lower.

It is argued that in autumn due to low temperatures A.maritima, which forages during low tide on the open shore and seeks refuge underground before the incoming tide, is too sluggish to find food in the limited period of low water. This probably explains why this cosmopolitan species has developed a strategy to survive the winter in the temperate zone in the egg stage.
The population characteristics of the brown plant hopper, Nilaparvata lugens, in the Philippines
Authors: COOK A. G. , PERFECT T. J.
Published: March 2008

Abstract. 1. Population characteristics of the brown planthopper, Nilaparvata lugens (Stål), were investigated over eight growing seasons on rainfed rice in the Philippines.

2. Three nymphal generation peaks were observed in most seasons. The third peak was not always the largest and peaks varied considerably in size from season to season.

3. Generation peaks were less distinct at a second sampling site within an irrigation system, possibly associated with increased asynchrony of planting and the consequent increased immigration potential.

4. Mortality was highest for eggs and first instar nymphs. Egg to adult survivorship was estimated as 1–12%.
Nesting of Afrotropical Oniticellus (Coleoptera, Scarabaeidae) and its evolutionary trend from soil to dung
Authors: DAVIS A. L. V.
Published: March 2008

Abstract. 1. Oniticellus egregius Klug constructs brood ovoids of dung in the soil immediately under the edge of animal droppings. Each successive brood ovoid is enveloped within a soil shell. After completion of brood construction, loose earth is cleared from around the broods to produce a brood chamber. The immatures are then abandoned as eggs or first instar larvae.

2. O.planatus Castelnau and O.formosus Chevrolat usually construct brood balls of dung within animal droppings. Each brood is progressively enlarged by the addition of further dung after egg‐laying. This enlargement is slight in O.planatus and marked in O.formosus. Parental females of both species remain in the brood chambers during development of the immatures which are abandoned principally as pupae.

3. Under very moist experimental conditions, O.planatus buries dung and constructs broods shallowly in the soil. Such nests are frequently connected to the pad by a short tunnel.

4. From a consideration of behavioural patterns it is suggested that the specialized nesting habits of these species have been derived from those of dung‐burying ancestors similar to the modern genus, Euoniticellus, through reduction and loss of tunnelling in the soil.
Population studies of the beech leaf mining weevil (Rhynchaenus fagi) in Ireland and Scotland
Authors: DAY KEITH R. , WATT ALLAN D.
Published: March 2008

Abstract. 1. Population budgets for Rhynchaenus fagi, based for the most part on samples of beech leaves taken in June, were constructed for a 10‐year period (Northern Ireland) and a 3‐year period (Scottish borders).

2. There were years of sustained population growth and sustained decline, but not enough evidence to suggest a cycle. Similar population levels were found at both sites in all but one year.

3. Key factors were associated with the adult stage, although egg mortality may also make a significant contribution to population change.

4. Unknown sources of mortality embodied in the residual mortality were also suspected of acting in a density dependent manner, compensating for variation in parasitism.

5. Death rate of larvae within mines was related to May temperature in Northern Ireland, but not so clearly in Scotland.
Reproductive cost of flight capability: a comparison of life history traits in wing dimorphic planthoppers
Authors: DENNO ROBERT F. , OLMSTEAD KAREN L. , McCLOUD ERIC S.
Published: March 2008

Abstract. 1. Reproductive costs associated with flight capability were evaluated in the wing dimorphic planthopper, Prokelisia dolus Wilson, by comparing the life history of traits of winged (macropterous) and flightless (brachypterous) females under controlled laboratory conditions.

2. Macropters with large thoraces and fully developed wings maintain a greater investment in flight apparatus than brachypters with small thoraces and reduced wings.

3. Associated with greater flight capability in the macropter of P.dolus are shorter adult life, decreased total fecundity, and delayed age at first reproduction compared to brachypterous females.

4. Under field conditions where mortality is high, the difference in realized fecundity between the two wing forms living on similar resources is further exaggerated with the brachypter having the greater advantage.

5. When the life history traits of the wing forms of P. dolus are compared with traits for nine other species of planthoppers, two similarities emerge. First, the preoviposition period of the macropterous wing form is always longer than that for the brachypter resulting in a reproductive delay. Second, most studies show that macropters are less fecund than brachypters.

6. There is no general tendency among planthopper species for macropterous adults to live fewer days or develop more slowly as nymphs compared to their flightless counterparts.

7. The reproductive delay and reduced fecundity of the volent wing form of planthoppers supports the notion that flight capability is costly and that phenotypic trade‐offs between flight and reproduction exist.
Nonlinear responses of spider mites to drought‐stressed host plants
Authors: ENGLISH‐LOEB GREGORY M.
Published: March 2008

Abstract. 1. This study examines the shape of the population response curve of the two‐spotted spider mite, Tetranychus urticae Koch, feeding on bean plants, Phaseolus vulgaris L., which have been subjected to one of a range of drought stresses.

2. Abundance of spider mites declined at slight drought stress, increased at intermediate intensities of stress, and declined again at severe stress.

3. Fecundity showed the same pattern found for total abundance. Developmental rates of immatures, on the other hand, generally increased with stress intensity. Survivorship of immatures and adult females appeared unrelated to stress intensity.

4. These results indicate that responses of mites to drought‐stressed beans are nonlinear. Such a pattern helps explain contradictory results obtained for spider mites and other arthropod herbivores.
Sex allocation and egg distribution of an autoparasitoid, Encarsia pergandiella (Hymenoptera: Aphelinidae)
Authors: HUNTER MARTHA S.
Published: March 2008

Abstract. 1. Encarsia pergandiella Howard females develop as primary parasitoids on immature whiteflies, and males develop as secondary parasitoids on females of their own or a related species. The hypothesis that the sex ratio reflects the relative abundance of the two host types was tested in the laboratory using petri dish arenas with varying proportions of early fourth instar greenhouse whitefly (Trialeurodes vaporariorum (West.)) (primary hosts) and pupal female E.pergandiella (secondary hosts). Egg distribution was analysed with respect to sex ratio, super‐parasitism and host discrimination.

2. The proportion of primary and secondary hosts parasitized in each treatment reflected the relative availability of each host type. Thus females presented with 75% primary hosts laid more female eggs than male. However, in all treatments, a greater proportion of secondary hosts were parasitized than would be expected from the proportion of secondary hosts available. This indicates that more male eggs were laid than expected.

3. More secondary hosts than primary hosts were superparasitized.

4. Host discrimination analysis using a new test statistic showed that females generally laid eggs at random with regard to previous parasitism of primary or secondary hosts. However, females in one treatment with 50% of each host type appeared to preferentially oviposit in secondary hosts which did not contain any eggs.
An alternative mating system in small male insects
Authors: McLACHLAN ATHOL , NEEMS RACHEL
Published: March 2008

Abstract. 1. Small males of all midge (Diptera: Chironomidae and Chaoboridae) species thus far examined (one chaoborid and six chironomids) are rare in mating swarms. They are found instead in vegetation adjacent to the swarm.

2. We show that it is here that females aggregate prior to embarking on mate acquisition flights. In the vegetation females appear to be accessible to males staying behind.

3. Such behaviour in small males may exploit the mate‐attracting activities of large males in the swarm and may, at the same time, reduce competition and conserve energy.

4. The evolution and maintenance of these size‐related types of mating behaviour are discussed.
Regulation of host diapause by an insect parasitoid
Authors: MOORE SANDRA D.
Published: March 2008

Abstract. 1. The interaction between larval development and parasitism by the braconid wasp Cotesia koebelei (Riley), was investigated in a population of the butterfly Euphydryas editha (Boisduval) (Nymphalidae). In this population, the butterfly host has an obligatory overwintering larval diapause.

2. It was found that E. editha larvae harbouring parasitoids were more likely to pass through an extra feeding instar before entering diapause than were non‐parasitized conspecifics.

3. In addition, some individuals that were experimentally exposed to multiple parasitoid attacks bypassed diapause completely; these larvae passed through five or six feeding instars, reaching sizes typical of final instar post‐diapause larvae.

4. The observed effect of superparasitism occurred regardless of whether the host larvae subsequently produced mature parasitoids, suggesting that parasitoid attack is sufficient to invoke the response.

5. It is proposed that the parasitoid C.koebelei regulates the number of pre‐diapause feeding instars of its insect host E. editha, and that some component of the female venom, injected at oviposition, is responsible for this regulation.
Variations in the life‐history parameters of Hemipyrellia ligurriens (Diptera: Calliphoridae) in response to larval competition for food
Authors: SO PING‐MAN , DUDGEON DAVID
Published: March 2008

Abstract. 1. Larval rearing densities of Hemipyrellia ligurriens (Wiedemann) (Diptera: Calliphoridae) in standardized carrion were manipulated in order to investigate changes in life‐history parameters in response to larval competition for food.

2. Competition was of the typical scramble type. Survivorship remained high at densities up to 32 larvae g liver‐1 but decreased rapidly as larval density increased further.

3. Emergent adults were undersized with reduced fecundity and longevity. Variations in adult body size apparently reduced the effects of competition on larval mortality.

4. Females of dry weight corresponding to only 10.4% of the potential maximum emerged at the highest rearing densities of 128 larvae g liver‐1. However, these females had a nearly four‐fold increase in reproductive investment (per unit weight) when compared to the largest individuals.

5. The duration of larval development declined when competition was intense (i.e. at high larval densities).

6. The short adult life of H.ligurriens, combined with the unpredictability of larval habitat availability, may reduce the value of long‐range dispersal so that females ‘do better’ by maintaining reproductive investment despite a concomitant decline in dispersal ability.
Predator‐mediated coexistence in laboratory communities of mycophagous Drosophila (Diptera: Drosophilidae)
Authors: WORTHEN WADE B.
Published: March 2008

Abstract. 1. This laboratory experiment examined the effects of interspecific competition and predation by Ontholestes cingulatus Gravenhorst (Coleoptera: Staphylinidae) on three species of mycophagous Drosophila (Diptera: Drosophilidae): D.tripunctata Loew, D.falleni Wheeler and D.putrida Sturtevant.

2. Single‐species and three‐species assemblages were exposed to single commercial mushrooms on wet pine shavings in 200 ml culture bottles. A predacious rove beetle (Ontholestes cingulatus) was present in half of the three‐species replicates. The stocked adult flies and beetles were removed after 4 days, and the number, biomass and mean mass of emerging progeny was recorded.

3. For all three species the abundance and biomass of the progeny emerging in the ‘no predator’ communities' was significantly less than for the progeny emerging in single‐species replicates, suggesting an interspecific competitive effect. D.tripunctata was the competitive dominant; it emerged in abundance from all seven three‐species ‘no predator’ communities while D.putrida and D.falleni were often excluded.

4. The decrease in production was attributed to strong interspecific competition among larva and not interference among ovipositing adults.

5. Predation on ovipositing adults significantly reduced the number and biomass of D.tripunctata progeny emerging, and indirectly facilitated the number and biomass of emerging D.falleni and D.putrida.Predation on adults reduced larval recruitment, relaxed larval competition, and released the inferior competitors.
Oviposition on host plants by a tropical forest grasshopper (Microtylopteryx hebardi: Acrididae)
Authors: BRAKER H. ELIZABETH
Published: March 2008

Abstract. 1. The tropical forest grasshopper Microtylopteryx hebardi Rehn (Orthoptera, Acrididae, Ommatolampinae) oviposits inside leaves or stems of its host plants. This is the first known instance of oviposition inside living plant tissue (rather than in the ground, on top of leaves, or in detritus) for a tropical forest acridid.

2. In understorey secondary forest at La Selva, Costa Rica, M.hebardi females fed on fifteen species of host plants, but oviposited in only four of these.

3. In laboratory choice tests, females showed selectivity for oviposition host plants similar to that inferred from field observations.

4. Plant volume was a better predictor of the number of eggs laid per stem than variables that indicated leaf or stem characteristics of individual plants.

5. Unlike the ovipositor of acridids laying eggs in the ground, that of M.hebardi is equipped with toothed, sclerotized edges, probably used to bore into plant tissue.

6. Endophytic oviposition in M.hebardi may be related to finding host plants in a habitat that is complex, heterogeneous, and rich in plant species.
Microhabitat specialization and similarity of scale‐insect assemblages on different fruit trees and in different countries
Authors: KOZÁR FERENC
Published: March 2008

Abstract. 1. Assemblages of scale‐insects on deciduous fruit trees were compared in a wide geographic range of Palaearctic subregions.

2. The parts of all host plant species in the whole geographic region were unsaturated with scale species. There was no clear niche expansion, nor any niche segregation between scale‐insect species.

3. These results show that even plants such as deciduous trees, rich in coccoid species, are not fully utilized by scale insects.

4. The similarity of the scale‐insect faunas on different plant species could be explained partly by the distribution patterns of the insects, and partly by phylogenetic connection between host plants.
The diversity of Hymenoptera in the tropics with special reference to Parasitica in Sulawesi
Authors: NOYES JOHN S.
Published: March 2008

Abstract. 1. The results of a recent faunistic survey of the Hymenoptera of northern Sulawesi, Indonesia, are compared with the known British fauna.

2. All families of Hymenoptera are probably more species rich in Sulawesi than in Britain, with the possible exception of Symphyta and gall‐forming Cynipidae.

3. The diversities of the samples obtained from Sulawesi are compared with those published from previous studies on the relationship between latitude, altitude and the diversity of parasitic Hymenoptera in tropical and temperate regions.

4. Despite its possibly greater species richness, the Ichneumonidae as a whole was no more diverse in the Sulawesi samples than in samples taken in temperate areas, including Britain.

5. The diversity of Parasitica as a whole appears to have been greater in the Sulawesi samples than those from either Britain or Michigan but lower than those from Costa Rica.

6. Parasitica as a whole was probably not more diverse inside the forest than at its edge, but the Aculeata was more diverse at its edge.

7. Both Parasitica and Aculeata were less diverse at 1765 m than at 220 m altitude.
Mating prior to overwintering in the imported willow leaf beetle, Plagiodera versicolora (Coleoptera: Chrysomelidae)
Authors: STEVENS LORI , McCAULEY DAVID E.
Published: March 2008

Abstract. 1. We report on the mating status of overwintering adults of the imported leaf beetle, Plagiodera versicolora Laicharting. This species overwinters as adults, under the bark of willow trees.

2. Individuals were collected both in the autumn, just after initiation of diapause, and in the spring, just before natural termination of diapause. From the autumn sample, we discovered that diapause can be terminated by husbanding the adults at 4°C for 4 weeks.

3. Most females lay fertile eggs upon the termination of diapause; however, a significant number of females lay non‐fertile eggs after overwintering in the field.

4. Many females mate with more than one male before entering diapause. Progeny analysis using allozyme genetic markers shows that, on average, females who are fertile upon termination of diapause utilize sperm from 1.2 males to fertilize their eggs.
The growth and survival of Panolis flammea larvae in the absence of predators on Scots pine and lodgepole pine
Authors: WATT A. D.
Published: March 2008

Abstract. 1. The survival, growth and development of larvae of the pine beauty moth, Panolis flammea (D & S) (Lepidoptera: Noctuidae) were examined as part of a study to determine (i) why damaging outbreaks of this insect in Scotland are frequent on lodgepole pine but do not occur on Scots pine, and (ii) why outbreaks are associated with areas of deep un‐flushed peat.

2. Larvae were studied inside predator exclusion cages on mature pine trees in Elchies forest where a major infestation occurred in 1978–79.

3. Surprisingly, larval survival was generally greatest on Scots pine and lowest on lodgepole growing in deep peat. Also, larval growth and development were greater on Scots than lodgepole pine and were unaffected by the type of soil in which the lodgepole pine was growing.

4. Larval performance was generally better on lodgepole pine that had been thinned and received fertilizer.

5. Larval survival was affected by pine shoot stage during egg hatch in one of the two years in which this was examined.

6. Observations on P.flammea pupae were confused by disease, parasitism and probably by differences in weight loss caused by differences in larval development. Parasitism by ichneumonid parasitoids was recorded on Scots pine but not on lodgepole pine.

7. It was concluded that (i) the absence of pine beauty moth outbreaks on Scots pine, and (ii) the occurrence of outbreaks on lodgepole pine growing in deep unflushed peat were not the result of lodgepole pine growing in deep peat being a more suitable host plant than lodgepole pine and Scots pine growing elsewhere. It seems more likely that the observed outbreak behaviour of P.flammea in Scotland is associated with differences in predation and parasitism in plantations of difference host plants and in plantations of lodgepole pine growing in different soils.
Regional diversity, local community structure and vacant niches: the herbivorous arthropods of bracken in South Africa
Authors: COMPTON S. G. , LAWTON J. H. , RASHBROOK V. K.
Published: March 2008

Abstract. 1. Seventeen species of phytophagous arthropods (sixteen insects and one gall‐forming eryiophyid mite) were found feeding on the above‐ground parts of bracken (Pteridium aquilinum (L.) Khun.) in surveys throughout the geographic range of the plant in South Africa. A further thirteen species of insects may possibly feed on the plant in this region.

2. Given the area over which bracken grows in South Africa, this is very close to the number of species expected on the plant, based on species‐area calculations and comparisons with bracken in other geographic regions.

3. The species‐richness of bracken‐feeding arthropods in local communities reflects the size of the regional pool of species in different geographic areas. Local richness in South Africa is intermediate between that in south‐western U.S.A. and Britain.

4. In both Britain and South Africa there is a weak tendency (0.05 < P < 0.07) for larger local patches of bracken to support more species of phytophages than small patches, with similar very shallow slopes (0.083 and 0.086) in plots of log species versus log area on both continents.

5. The taxonomic composition of bracken‐feeding arthropods in South Africa is markedly different from that in other pants of the world, suggesting very different and largely independent evolutionary histories in different regions.

6. There is no sign of convergence in the feeding niches of communities of bracken‐feeding arthropods in different parts of the world, and the pattern of feeding relationships is very different in South Africa to patterns observed elsewhere. Conspicuous vacant niches (ways of exploiting the plant that are observed in other geographic regions) are easily identified in the South African communities.
Patterns of locomotion of polyphagous arctiid caterpillars in relation to foraging
Authors: DETHIER V. G.
Published: March 2008

Abstract. 1. Patterns of locomotion of three species of arctiid caterpillars, Diacrisia virginica, Fabr., Pyrrharctia Isabella (J. E. Smith) and Estigmene congrua Walk, were studied in the field and laboratory in an attempt to understand factors determining foraging behaviour.

2. Tracks were recorded on artificial substrates indoors, in the open, and in the normal habitat under the following conditions: in darkness, in bright sunlight, under heavy overcast, under blue sky with the substrate intermittently rotated, with an overhead sheet of polaroid rotated, on a substrate with asperities, in natural field conditions with a variety of forbs in dispersed and clumped distributions.

3. Tortuosity and general directions of paths were analysed.

4. The effects of various levels of deprivation were also analysed.

5. In the absence of photic and chemical stimulation paths on smooth surfaces are straight and direction is random.

6. Obstacles perturb the paths and impart a meandering pattern. Patterns of locomotion induced by obstacles on a smooth substrate are indistinguishable from patterns of locomotion in the field. Unless food plants are closer than 1cm they have no effect on locomotion. Patterns of locomotion in dispersed and clumped foodplants are the same.

7. What appears to be food‐related search behaviour is primarily the result of physical features of the environment perturbing a central neuronal pattern of locomotion. Stimuli from foodplants appear to be irrelevant unless actually enountered.
Oviposition site selection by Mansonia mosquitoes on water lettuce
Authors: LOUNIBOS L. P. , DEWALD L. B.
Published: March 2008

Abstract. 1. Viable Mansonia egg masses occur in nature on both the upper and under surfaces of Pistia stratiotes (L.) leaves. Upper‐surface masses were from Mansonia dyari Belkin, Heinemann & Page, but lower‐surface oviposition was attributable to both M. dyari and M. titillans Walker.

2. Upper‐surface egg masses were often out of water but were concentrated near a wet‐dry stain line on the leaf. Lower‐surface masses were laid underwater within 3 mm of the leaf edge, except for those oviposited through fenestrations caused by insect damage.

3. Oviposition varied seasonally and masses were most numerous between August and December when water lettuce plants were large and crowded. Egg masses were clumped on plants and leaves and concentrated on mature or mature‐old leaves that subtended mean angles of 28–34° from the horizontal.

4. On intact plants in cages, M. dyari laid egg masses on both leaf surfaces in approximately the same proportions as observed in nature. On detached leaves floating flat on the water, M. dyari laid all masses on under surfaces.

5. At 20 and 25°C, egg development of M. dyari required 17.4 and 8.8 days (means), these being significantly longer than the mean times for M. titillans. Some larvae from eggs that hatched in the absence of water survived 72 h in the eggshell.

6. Upper‐surface oviposition by M. dyari may be an adaptation to the crowded growth of water lettuce, the mosquito's favoured host plant, whose leaves are largely out of water. Leaf ageing and subsidence cause submergence of most upper‐surface eggs by the time of hatching.
Foraging behaviour of a leafminer parasitoid in the field
Authors: CASAS J.
Published: March 2008

Abstract. 1. The searching behaviour of the parasitoid Sympiesis sericeicornis Nees (Hymenoptera, Eulophidae) is analysed under field conditions.

2. Females were tracked when flying around the canopy of apple trees infested with the tentiform leafminer Phyllonorycter cydoniella (D. & S.)(Lepidoptera, Gracillariidae) and their behaviour studied at the level of a single mine and at the level of several mines on the same leaf (patch level).

3. The presence of mines is detected during flight. The foraging behaviour at the patch level is efficient: the female is able to distinguish the suitable from the unsuitable hosts and handle the suitable hosts first. Not all mines are visited before departure from the leaf and those left unvisited are exclusively mines without suitable hosts. The patch leaving rule is discussed.

4. An ethogram of the behaviour on the mine is constructed. Selected behavioural categories are analysed for different combinations of mine content and outcome of the visit to the mine. The assessment of the mine content is done in a differential way, quickly and without mistakes.

5. The results are discussed in the context of two environmental factors, wind speed and temperature, which reduce the available time for searching. They are also related to the growing percentage of unsuitable hosts during each host generation. Tentiform mines remain attractive for a long period of time, even after parasitism or emergence of the adult, and their examination reduces the rate of host discovery.
The effects of temperature and body size on the mating pattern of a gregariously nesting bee, Colletes cunicularius (Hymenoptera: Colletidae)
Authors: LARSSON FOLKE K. , TENGÖ JAN
Published: March 2008

Abstract. 1. In a 3‐year study of the solitary bee Colletes cunicularius L. in Sweden, average body size and population density fluctuated greatly between years.

2. In this protandrous population, females mated just once and the sex ratio was slightly male biased. Males were smaller than females.

3. Size assortative mating (homogamy), associated with an increase in population density during the central days of female emergence and mating, was observed in two out of three years. Homogamy was also observed in pairs with remating males.

4. Most of the mating males had emerged the day they mated, but 42% were older. We found no support for a general large‐male mating advantage.

5. Weight of emerging females and mating males were negatively correlated with ground temperature, indicating thermoregulatory influence on the process of sexual selection in this species.
Size variation and reproductive success of female Aedes punctor (Diptera: Culicidae)
Authors: PACKER M. J. , CORBET PHILIP S.
Published: March 2008

Abstract. 1. Variation in size (wing length) of females and males within a population of Aedes punctor (Kirby) at emergence was recorded in northern Britain during 1984 and 1985.

2. Wing length correlated well with body dry weight, confirming its usefulness as a measure of body size. In 1984, but not in 1985, mean size decreased significantly as emergence progressed.

3. The size of host‐seeking females caught at human bait varied seasonally. This was partly accounted for by size variation during emergence.

4. Of females which fed to repletion, the largest spent least time in contact with the host.

5. In the laboratory, wing length correlated well with potential fecundity (number of ovarioles) and less well with actual fecundity (number of matured follicles) after feeding on human blood.

6. In the field, larger females were more successful at locating hosts, developed more egg clutches in a lifetime and generally lived longer than did smaller ones. Larger females appear to enjoy greater reproductive success than do smaller females.
Onset and spread of an African army worm upsurge
Authors: PEDGLEY D. E. , PAGE W. W. , MUSHI A. , ODIYO P. , AMISI J. , DEWHURST C. F. , DUNSTAN W. R. , FISHPOOL L. D. C. , HARVEY A. W. , MEGENASA T. , ROSE D. J. W.
Published: March 2008

Abstract. 1. Onset and spread of the severe outbreaks of African armyworm, Spodoptera exempta (Walk.), over Ethiopa, Kenya, Tanzania and Burundi in late 1984 have been analysed in relation to trap and weather records.

2. Although first outbreaks in each country appeared progressively further south, winds on the best estimated dates of moth concentration and egg laying blew from directions precluding moth movements between them.

3. Such independently developing outbreaks are called ‘primary’ to distinguish them from any ‘secondary’ outbreaks that may develop from them.

4. Parent moths giving rise to all seven areas of primary outbreaks were derived from low‐density populations that had persisted through the dry season, probably near the coast of East Africa.

5. Primary outbreaks developed on the south‐eastern sides of individual rainstorms over the highlands, most likely because windborne moths were concentrated there by convergent winds.

6. Of the secondary outbreaks within Kenya, Tanzania and Burundi, most were derived from only one area of primary outbreaks in Kenya, which were therefore critical for effective control of spread; the paucity of other secondaries was presumably due to a lack of timely rainstorms or other concentrating mechanisms.