bluuebunny/crossref_metadata_2025 huggingface dataset:
Energy expenditure and food intake of territorial male Pachydiplax longipennis (Odonata: Libellulidae)
Authors: FRIED CAREN S. , MAY MICHAEL L.
Published: March 2008

ABSTRACT.

Field observations of males of the dragonfly, Pachydiplax longipennis (Burmeister), were used to determine how individuals of this species allocate energy to different activities during territory occupancy.

The effects of biological and physical factors on the species’daily activity pattern were examined. The proportion of time spent in flight was independent of temperature but increased asymptotically with increasing population density.

Measurements of assimilation efficiency and the quantity of faeces produced per day were used to calculate daily intake of food. An independent estimate of food consumption was derived from data on gut contents and clearance rate.

Food intake appears to exceed only slightly the energy required to maintain a territory, with little available for other activities. The activity pattern may be determined in part by the amount of energy available to individuals.
Auchenorrhyncha‐host plant interactions: leafhoppers and grasses
Authors: PRESTIDGE R. A. , McNEILL S.
Published: March 2008

ABSTRACT.

Grass nutrient levels differed considerably between the grass species and with time.

Most species of leafhopper (Homoptera, Auchenorrhyncha) were present on all the grasses sampled but each grass had a different dominant leaf‐hopper fauna.

The leafhopper—plant association varied depending on the leafhopper species. Species that were strongly associated with one host were rare. Other more oligophagous species were associated with a particular nitrogen level in the grass. These species were found on grasses that had nitrogen concentrations within a narrow range. As the plant nitrogen levels altered (associated with flowering, seed setting, and senescence) leafhoppers switched onto other food plants that had a suitable nitrogen level. An intermediate group of leafhoppers showed little specificity and little association with plant nitrogen levels.
Sugaring for moths: why are noctuids attracted more than geometrids?
Authors: UTRIO PIRKKA
Published: March 2008

ABSTRACT.

The attraction of nocturnal moths (Noctuidae and Geometridae) to fermenting sugar baits and to volatile organic compounds formed in these baits was studied by field trapping in South Finland.

In general, noctuids were attracted synergistically to these compounds (i.e. a mixture of compounds attracted more moths than the summed attraction of the components of the mixture predicted). Geometrids were not attracted synergistically. A similar pattern, with a few exceptions, was obtained by specific evaluation of forty‐one noctuid and fifteen geometrid species.

The degree of synergistic response was correlated with the general morphology of the moths. The robust species (proportionally large thorax and small wings; most of the Noctuidae) were attracted synergistically, while the slender species (proportionally small thorax and large wings; most of the Geometridae) were only weakly or not at all attracted synergistically.

The ecological background of the morphology‐related synergism is discussed. It is suggested that the energy demands of the robust species are substantially higher than those of the slender species, thus leading to different foraging strategies.
Aggregation in field parasitoid populations: foraging time allocation by a population of Diadegma (Hymenoptera, Ichneumonidae)
Authors: WAAGE JEFFREY K.
Published: March 2008

ABSTRACT.

A field study was made of foraging time allocation by a population of parasitic wasps, Diadegma spp. (Ichneumonidae), to plants containing different densities of their hosts, the caterpillars of Plutella xylostella (L.).

The parasitoid population exhibited a clear aggregative response, spending more total time on higher density patches, which probably resulted from wasps making more and longer visits to these densities.

Despite this aggregation, positive density dependent parasitism was not found. The functional response of the Diadegma population exhibited an upper asymptote at high host densities, probably due to an increase in the proportion of time spent handling hosts, which countered the effect of aggregation.

While Diadegma may select and forage preferentially on plants with higher host density, they do not exhibit the tendency, predicted by some optional foraging models, to exploit progressively less profitable plants during a foraging bout. Some factors affecting patterns of parasitoid foraging in the field are discussed.
Thermal constraints on activity patterns in nectar‐feeding insects
Authors: WILLMER P. G.
Published: March 2008

ABSTRACT.

All the insects visiting Tilia and Heracleum flowers showed diel patterns of activity, which could best be explained in terms of weather. Of the recorded parameters, solar radiation gave the best correlations with activity.

Correlations between activity and radiation depended on the size and colour of particular groups of insects; small bright species visited fully insolated flowers, (r high), while large dark forms visited early and late in the day (r low or negative).

Consequently mean reflectance and mean weight of foragers showed consistent trends through a day and predictable relations with radiation for both flowers, suggesting that thermal costs are a critical determinant of feeding times.

By contrast, the nectar reward (as sugar amounts) in flowers was poorly correlated with timing of insect visits, indicating that caloric reward is not limiting; although nectar concentration (only measurable for Tilia) did correlate reasonably well with total visitation.

The exception to this pattern was Bombus. This endothermic species visited early in the day when nectar was abundant. Thus visits correlated well with reward and negatively with radiation, showing a dependence on high rewards to offset thermoregulatory metabolic costs.

For most insects foraging appeared to be largely determined by the visitors thermal requirements and the restrictions imposed by avoidance of overheating. Nectar rewards were not critical, and nectar concentration, itself dependent upon climatic parameters, was probably only incidentally correlated with diel patterning for all but the largest (endothermic) insects.
Oviposition and egg brooding by the mosquito Trichoprosopon digitatum in cacao husks
Authors: LOUNIBOS L. P. , MACHADO‐ALLISON C. E.
Published: March 2008

Discarded fruit husks which catch rain water provide transitory yet nourishing habitats for larval mosquitoes. In this report we describe maternal care of eggs and how husk fluid and shape influence oviposition of a neotropical mosquito, Trichoprosopon digitatum (Ron‐dani), in cacao.
Seasonal abundance during the summer months of some cattle‐visiting Muscidae (Diptera) in northeast England
Authors: BALL STUART G.
Published: March 2008

Abstract. 1. Regular samples of flies swarming around cattle in Northumberland, England, were collected from late May to early October 1980–82, during weather judged to be suitable for fly activity.

2. Results were grouped into weekly periods and averaged to reduce variation caused by the weather.

3. For all species of Muscidae that were caught in reasonable numbers, the changes in abundance through the season are described.

4. The proportion of each species in the total sample is discussed; biting species were not sampled as efficiently as were non‐biting species. Hydrotaea trritans and Morellia simplex were the most numerous species forming 49% and 32% of the catch respectively.

5. The total numbers of flies were low at the beginning of the sampling period, rose to a maximum in mid‐July, stayed high until mid‐September and then declined by October.
The causes of over wintering mortality of Phyllonorycter on Quercus robur
Authors: CONNOR EDWARD F.
Published: March 2008

Abstract. 1. An experiment was performed to examine the relationship between overwintering mortality rates and physical conditions in the leaf litter for Phyllonorycter spp. on Quercus robur.

2. Analyses also were performed to determine if survival and mortality rates vary with leaf size and the position of a leaf mine within a leaf.

3. The results indicate that survival rates are independent of variation in physical conditions in the leaf litter, as well as leaf size and the position of a mine on a leaf.

4. Mortality from leaf decomposition was higher at the bottom of the litter pack, and it may compensate for reduced mortality from predation, crushing, desiccation, and fungal attack at the level.

5. Rates of parasitism were significantly higher on small than on large leaves.
Predictability, toxicity, and trophic niche breadth in fungus‐feeding Drosophilidae (Diptera)
Authors: LACY ROBERT C.
Published: March 2008

Abstract. 1. The mycophagous Drosophilidae flies in eastern North America display a range of ecological responses to their fungal trophic resources. Some (Drosophilu duncani Sturtevant, and two species labelled as Mycodrosophila cluytonae Wheeler and Takada) specialize on the bracket fungi of the family Polyporaceae. Other species (Drosophila falleni Wheeler, D.recens Wheeler, D.putridu Sturtevant and D.tripunctuta Loew) are broad generalists, non‐selectively consuming a diverse array of Basidioniycete mushrooms. D.restaceu von Roser and D.ordinuria Coquillett utilize a broad subset of the Basidio‐mycetes, while M.dimidiata hew feeds on some Basidioniycetes, including a variety of Clavariaceae (coral fungi) and Heterobasidiomycetes (jelly fungi) not commonly used by other flies, and Ascomycetes (cup fungi).

2. Unlike some phytophagous insects, host chemistry seems to have little effect on host preferences. The mycophagous drosophilids do not avoid fungi thought to be toxic or undigestible to other Diptera.

3. Resource predictability appears to delimit trophic niches in the mycophagous guild. The average duration of individual host mushroom caps is negatively correlated with three measures of trophic niche breadth. Specialist fly species utilize long‐lasting resources, while more generalized mycophagous species include progressively ephemeral fungi in their diets.
Predation pressure on the arboreal epiphytic herbivores of larch trees in southern England
Authors: TURNER B. D.
Published: March 2008

Abstract. 1. Quantitative collections were made of arthropod predators from larch trees at Ranmore Common, Surrey, from August 1977 to September 1978.

2. Spiders were numerically the most important predators accounting for 64% of the total.

3. Antisera of the main larch dwelling, epiphyte herbivore orders, Collembola and Psocoptera, and the other common arboreal herbivore group at Ranmore, the Honioptera (principally Psyllidae) were prepared in rabbits.

4. Serological determinations of predator diets indicated that, with a few exceptions, the predators were taking approximately equal proportions of the three prey groups.

5. This apparent non‐specificity of the predators is analysed in relation to both the numerical abundance and biomass of the three prey types during the study period.

6. These arboreal arthropod predators are selecting for large but rare prey items in preference to small and common ones.

7. These findings are discussed in relation to the population dynamics of arboreal epiphytic herbivores.
Density dependence and the augmentative release of egg parasitoids against graminaceous stalk borers
Authors: HAMBURG H. VAN , HASSELL M. P.
Published: March 2008

Abstract. 1. The augmentative release of Trichogranznza species for the biological control of graminaceous stalkborers is reviewed.

2. Previous experiments indicate strong density dependence acting on the early larval stages of the sorghum stalkborer (Chilo partellus). These data are described by a simple model for density dependence, whose properties are briefly described.

3. The effects upon the total mortality of different levels of egg parasitism are discussed when combined with density dependent larval losses that vary from under‐ to over‐compensating.
Latitudinal effects on treehopper species richness (Hornoptera: Membracidae)
Authors: WOOD THOMAS K. , OLMSTEAD KAREN L.
Published: March 2008

Abstract. 1. Membracid species richness declines with increasing latitude in the Western hemisphere but begins to increase again in temperate regions. In northern latitudes this transition occurs in the highlands of Mexico and is the result of the emergence of a new tribe and greater host specialization.

2. The relationship between number of species per genus and latitude is parabolic.

3. We suggest the low number of species per genus in tropical regions may be due to the lack of host specialization and reduced coordination of life history with host phenology.
The fecundity, development and host relationships ofCeratobaeusspp. (Hymenoptera: Scelionidae), parasites of spider eggs
Authors: AUSTIN A. D.
Published: March 2008

Abstract.1.Ceratobaeusspp. enter the nest of their host spider and oviposit into eggs through the thin silk eggsac.

2. Temperatures below 15° C limit oviposition by slowing parasites down.

3. Males emerge prior to females and mate with their sibs. Sex ratios of 6.6–6.0:1 in favour of females were observed in the field and laboratory for two species.

4. Even though females can oviposit almost immediately after emergence their full complement of eggs (x̄= 65) is not reached until several days later.

5. Superparasitism is low and appears to occur from subsequent accidental ovipositions. No marking of the external surface of hosts was observed.

6. Parasites overwinter as adults under bark. They do not feed as adults nor do they reabsorb their eggs, but rather oviposit as soon as host eggs become available in spring.

7. Successful oviposition occurs in later stages of host eggs reared at 15° C and 20° C than it does at 25°C. Different rates of development between host and parasite is proposed as an explanation for this phenomenon.

8. The species studied show varying degrees of specificity but each has a dominant host. Location of hosts involves cues from the habitat (bark), silk nests of spiders, and some factor associated with host eggs.
Bud burst and success of the beech weevil, Rhynchaenus fagi: feeding and oviposition
Authors: BALE J. S.
Published: March 2008

Abstract. 1. Overwintered and starved weevils fed on beech within 5 min of contacting the plant in spring, and oviposition occurred in less than 48 h after feeding.

2. Size of unlaid eggs was significantly reduced when feeding weevils were subsequently starved from beech for 3 days.

3. Date of bud burst did not affect the amounts of feeding or oviposition by weevils.

4. Weevils fed and oviposited preferentially among trees, and the same trees were preferred in two successive years. This preference was independent of bud burst date.
Predator gut state and prey detectability using electrophoretic analysis of gut contents
Authors: GILLER P. S.
Published: March 2008

Abstract. I. An investigation of the effects of position of food in the gut (gut state), time since feeding, meal size and environmental temperature on the detection of prey using the electrophoretic separation of proteins with esterase activity was undertaken. The waterbug Notonecta glauca Linn (Hemiptera/Heteroptera) was used as the model predator.

2. Seven easily recognizable gut states can be identified at different times since commencement of a meal.

3. Specific prey esterase ‘fingerprint’ bands can be detected whilst food remains in the foregut.

4. Meal size and environmental temperature (affecting digestion and assimilation rates) both affect the rate of filling and emptying of the foregut, and hence the time period over which prey proteins can be detected by electrophoresis following a meal. Small meals and high temperatures lead to quite rapid changes in gut state with time and thus reduce the time period over which prey can be identified from gut contents (20 h). Large meals and low temperatures extend this period (48 h).

5. Predator gut state is the most important parameter in prey detectability from gut contents, and from a visual examination of the gut state it is immediately evident whether or not prey detection by electrophoresis will be possible.

6. There is further evidence in support of a twocompartment food processing model for Nofoonecru, and the significance of this type of processing in relation to gut content analysis of sucking predators is discussed.
Host‐specific variation in Ieaf miner population dynamics: effects on density, natural enemies and behaviour of Stilbosis quadricustatella (Lepidoptera: Cosmopterigidae)
Authors: MOPPER SUSAN , FAETH STANLEY H. , BOECKLEN WILLIAM J. , SIMBERLOFF DANIEL S.
Published: March 2008

Abstract. 1. We compared high and low density populations of a leaf miner (Stilbosis quadricustatella (Cham.)) on two host oaks to ascertain mechanisms influencing abundance. High density miner populations occurred on sand live oak, Quercus geminata (Fagaceae), found in homogeneous stands at inland and coastal sites. Quercus nigra, water oak, a patchily distributed inland species, supported a low density leaf miner population.

2. Average foliar nitrogen of Q.geminata was significantly lower than that of Q.nigra, and lad mining period on Q.geminata was correspondingly longer than on Q.nigra.

3. The average leaf area of Q.nigra was significantly greater than that of Q.geminata.

4. Parasitism was significantly greater in Q.geminata miner populations and predation was significantly higher in Q.nigra populations. However, parasitism and predation rates were roughly reciprocal so that overall larval mortality did not differ significantly between hosts.

5. In a laboratory experiment, pupal overwintering survivorship did not differ significantly between moist and dry treatments of the sand and loam soil types that typify Qgeminata and Q.nipra habitats, respectively.

6. Within‐leaf miner density on Q.geminata significantly affected larval survivorship, parasitism and predation. Leaf area and within‐leaf miner density were positively correlated.

7. We detected no host‐patch area or isolation effect on miner densities on coastal Qgeminata and there was no significant gradient of local coastal conditions affecting larval survivorship or natural enemies.

8. Coastal leaf miner densities were significantly higher on oak patch edges than in interiors.
The chironomid larvae of a small chalk stream in Berkshire, England
Authors: WRIGHT J. F.
Published: March 2008

Abstract. 1. The longitudinal distributions of larval Chironomidae (Diptera) were examined for 1 year in the intermittent and perennial sections of the Winterbourne, a small chalk stream in Berkshire, England.

2. Forty‐nine chironomid taxa were recorded at ten major sites which were sampled on six occasions and four additional taxa were recorded at sites sampled only once.

3. Cluster analyses using data from the major sampling sites identified three groups of sites. A pond in the stream channel which had a distinct chironomid fauna was distinguished from all other sites before the remaining intermittent sites were separated from all perennial sites on the basis of the chironomid fauna.

4. In the perennial stream, a site heavily shaded by trees had low species richness compared with partially and unshaded sites further downstream. The lowest site, which was near to the confluence with a larger chalk stream, the River Lambourn, had the highest number of taxa (thirty‐five), including several which were frequent in the Lambourn.

5. By recording the occurrence of prepupae, an indication of emergence periods was obtained and many taxa were shown to have extended periods of emergence.
Facultative defences and specialist herbivores? Cinnabar moth (Tyria jacobaeae) on the re growth foliage of ragwort (Senecio jacobaea)
Authors: CRAWLEY M. J. , NACHAF'ONG M.
Published: March 2008

Abstract. 1. Ovipositing females of cinnabar moth lay just as many eggs on regrowth foliage as on normal rosette leaves of ragwort.

2. Larvae reared on regrowth tissues achieve the same weight at pupation as insects fed on primary leaves and capitula. Diet affected neither survival rate nor development time.

3. Larvae from eggs laid on normal foliage achieve lower pupal weights when fed regrowth tissues, and larvae from eggs laid on regrowth leaves perform less well on a diet of normal foliage.

4. The complex of changes associated with re growth following defoliation does not appear to reduce the fitness of this specialist herbivore, nor does it reduce the likelihood that the plant will be attacked by ovipositing adult moths.

5. A facultative response which consisted of an increase in ‘qualitative defences’ is unlikely to be effective against adapted herbivores.
Sex ratios of Spalangia endius (Hymenoptera: Pteromalidae), in relation to current theory
Authors: DONALDSON J. S. , WALTER G. H.
Published: March 2008

Abstract. 1. Spulungiu endius Walker is a solitary parasitoid of house fly puparia.

2. The sex and size of S.endius was not related to host size.

3. In the laboratory the mean sex ratio of all offspring of nine groups, each comprising twenty females, was consistently female‐biased (x = 83.5%, range 79–87%). The sex ratio in the field was less female‐biased and showed greater fluctuation (61–75%). This may be a consequence of females laying male eggs before mating, some females remaining unmated, possible shorter adult life expectancy in the field than in the laboratory, and, perhaps, the presence of conspecific females.

4. The sex ratio of offspring of individual females varied from 66% to 100% females, and males were deposited early in the oviposition sequence.

5. Although a large number of fly puparia died before adult flies or parasitoids emerged (64.5%; n= 5874), there was no differential mortality of either sex.

6. Our results fit no general sex ratio hypothesis and we conclude that (i) the genetic nature of sex ratios in these insects needs careful examination, and (ii) the prevalence of female‐biased sex ratios in solitary parasitoids needs investigation.
The complex hatching response of Aedes eggs to larval density
Authors: LIVDAHL TODD P. , KOENEKOOP ROBERT K. , FUTTERWEIT STEPHEN G.
Published: March 2008

Abstract. 1. We investigated the effects of hatching medium, larval density and larval instar on egg hatching in Aedes triseriutus (Say) (Diptera: Cuficidae).

2. In a nutrient broth medium, hatching rates, responded positively to low densities of large larvae, but were suppressed by high densities.

3. The magnitude of suppression was moderated through the use of a yeast hatching medium, which provides a food source for the large larvae. Small instars generally exerted positive effects on hatching, with the exception of first in star larvae in the yeast medium, which inhibited hatching at low and moderate densities.

4. The results demonstrate an ability of eggs to assess indirectly the potential risks of hatching through their responses to changes in dissolved oxygen concentration.
Manipulation of host plant development by the gall‐midge Rhabdophaga strobiloides
Authors: WEIS ARTHUR E. , KAPELINSKI AUDREY
Published: March 2008

Abstract. 1. The gall‐midge Rhabdophaga strobiloides (O.S.) forms a gall in the apical bud of actively growing willow twigs.

2. Galls were not randomly distributed among twigs. Twigs that arose towards the distal end of the branch were much more likely to be galled. Distally located twigs also grew to greater girth than more proximally located twigs.

3. Comparisons of galled twigs with normal twigs in similar locations along their branch showed that the gall causes even greater growth in twig girth than when no gall is present.

4. The hypothesis that galled twigs draw photosynthate produced elsewhere in the plant was tested in an experiment that measured the growth of galled and normal twigs. with their leaves intact, to galled and normal twigs that were manually defoliated. Defoliation caused reduced growth in normal twigs, but galled twigs grew equally well with or without their leaves. Leaf removal had no effect on gall growth.

5. Twig diameter was positively correlated with gall diameter. Call diameter was positively correlated with larval biomass.

6. Patterns of twig and gall growth suggest that the gall‐midge manipulates host plant growth and development to provide resources for growth and survival. Manipulation of the host may be an important phenomenon in the evolution of parasitic organisms.
The responses of polyphagous predators to prey spatial heterogeneity: aggregation by carabid and staphylinid beetles to their cereal aphid prey
Authors: BRYAN KEVIN M. , WRATTEN STEPHEN D.
Published: March 2008

Abstract. 1. Discrete patches of aphids were artificially created in winter wheat fields in 1982 and in 1983 using field cages.

2. Aggregation by polyphagous predators at these patches following cage removal was measured using pitfall traps in patch and control areas.

3. Several species of polyphagous beetle (Carabidae and Staphylinidae) aggregated in these patches while other species did not.

4. The consequences of aggregation by polyphagous predators to a single prey species are discussed.
Aide memoire mimicry*
Authors: ROTHSCHILD MIRIAM
Published: March 2008

Abstract. 1. Animals and plants may gain protection by reminding would‐be aggressors of failure, or an unpleasant experience following an attempt at capture and ingestion. Thus they need not be mistaken for noxious or dangerous prey; defence is adequate if the aggressor is forced to recall the attributes of such species, or the disagreeable sequela to a previous assault upon them.

2. Batesian mimics and mildly toxic Mullerian mimics can also add to their repertoire by such defensive strategies.

3. Several examples of this phenomenon, designated aide mémoire mimicry, are described.
The distribution of aphids in response to variation among individual host plants: Uroleucon rudbeckiae (Homoptera: Aphididae) andRudbeckia laciniata (Asteraceae)
Authors: SERVICE PHILIP
Published: March 2008

Abstract. 1. An investigation was conducted to determine the effects of variation among individual plants of Rudbeckia laciniata L. on the distribution and abundance of the aphid Uroleucon rudbeckiae (Fitch).

2. Wild plants were examined repeatedly for up to 21/2 years to obtain information about plant growth and flowering, and about aphid densities on individual plants.

3. Aphid densities on individual plants were positively associated with several measures of plant vigour, including height, growth since previous year, and occurrence of flowers.

4. The colonization of plants by alate aphids was more highly correlated with plant height than with plant exposure. Aphid densities on individual plants were more strongly associated with plant height than with number of colonists.

5. In all years there were many hosts which were never colonized by aphids. Some of these plants produced shoots but did not flower. Experimental infestation of these plants showed that they were unsuitable for aphid growth and reproduction. Some plants which did flower and which escaped aphid infestation were nevertheless suitable hosts. Previously unsuitable host individuals were able to support aphids when grown under glass‐house conditions.
Discrimination and release of unpalatable butterflies by Nephila clavipes, a neotropical orb‐weaving spider
Authors: VASCONCELLOS‐NETO JOÃO , LEWINSOHN THOMAS MICHAEL
Published: March 2008

Abstract. 1. Nephila clavipes (L.), a common spider in neotropical forests, discriminates some unpalatable prey and releases them unharmed from its web. Release is not accidental but results from a specific behavioural sequence.

2. Field trials with twenty‐seven butterfly species showed that spiders respond consistently to butterfly species and higher taxa. Ithomiinae and some Danainae are almost always released while Heliconiinae, Nymphalinae, Acraeinae, Pieridae and Papilionidae are usually eaten.

3. Paired tests showed that an immediately preceding experience with a different butterfly did not reveal any change in the spider's usual response to a particular butterfly.

4. Warning coloration is not involved in spider response. Spiders rejected the models but ate the mimics of two different butterfly species pairs. Distastefulness is probably signalled by chemical cues.

5. Some unpalatable butterflies stay motionless when entangled and while the spiders release them. Motionlessness in webs seems to be a requisite to allow recognition of their distastefulness without being bitten by the spider.

6. Spiders differ from vertebrates in the prey accepted and in rejection mechanics. Although there is no indication of learning, spiders may select butterflies for distastefulness, chemical signals and motionlessness, at the individual level.
The influence of food plant dispersion on caterpillar searching success
Authors: CAIN M. L. , ECCLESTON J. , KAREIVA P. M.
Published: March 2008

Abstract. 1. Collards (Brassica oleracea L.) grown in clumps were more difficult for unstarved, early instar cabbage white caterpillars (Pieris rapae L.) to find than collards spaced at regular intervals, although total plant densities were identical.

2. Early instar, unstarved larvae are less mobile than later instar larvae (our data) or starved larvae (Jones' 1977 data).

3. Starved larvae and late instar larvae tend to find plants more readily than do unstarved or younger larvae.

4. We contend that larval mobility governs the success of searching caterpillars and their sensitivity to variations in plant dispersion.

5. Our results show that the dispersion of targets can influence searching success even though target density is constant. This means that the degree of clumping in host plants is capable of influencing their availability to herbivores.
Survival of honeybees in cold climates: the critical timing of colony growth and reproduction
Authors: SEELEY THOMAS D. , VISSCHER P. KIRK
Published: March 2008

Abstract. 1. The adaptive significance of the timing of growth and reproduction by honeybee, Apis mellifera L., colonies in cold climates was studied by describing the seasonal patterns of food storage, brood rearing, and swarming, and then observing the consequences of experimentally perturbing the seasonal cycles of brood rearing and swarming.

2. Colonies consume large amounts of food over winter (20+ kg of honey), but have only a brief period (about 14 weeks) for food collection each year.

3. The honeybee's striking habits of starting brood rearing in midwinter and swarming in late spring evidently help colonies achieve maximum use of the short summer season. Colonies whose onset of‐brood rearing was experimentally postponed until early spring showed greatly retarded colony growth and swarming. Other experiments demonstrated that late swarms starve more often during winter than do early swarms.

4. We conclude that the timings of colony growth and reproduction are essential elements in the honeybee's suite of adaptations for winter survival.
Insect chemosensory responses: a chemical legacy hypothesis
Authors: CORBET SARAH A.
Published: March 2008

Abstract. 1. Changes in the chemosensory responses and physiological host tolerance of phytophagous insects and parasitoids may result in new host associations. This paper considers the origin of those changes in ecological and evolutionary time.

2. The chemical legacy hypothesis postulates that effects of larval chemosensory environment on adult chemosensory responsiveness depend not (or not only) on persistent neural changes (‘memory’), but on traces of chemical cues, inside or outside the insect's body, which influence adult behaviour, perhaps particularly during a ‘sensitive period’ associated with adult emergence or hatching of the egg.

3. Chemical cues bequeathed by earlier stages may affect adults or larvae by reducing peripheral sensitivity. Depending on the form of the dose–response curve, this change could decrease aversion or increase a positive response to a previously deterrent stimulus.

4. Attention is drawn to a possible link between this behavioural induction and the induction of detoxification enzymes. This link might be of practical importance if exposure to host allelochemicals were to influence insects' responses to insecticides, and vice versa.

5. An influence on the chemosensory responsiveness of an individual by chemical cues derived from its parents would be hard to distinguish from a genetic effect.

6. Some testable postulates of the chemical legacy hypothesis are identified.
Wound‐induced changes in the acceptability of tomato to larvae of Spodoptera littoralis: a laboratory bioassay
Authors: EDWARDS P. J. , WRATTEN S. D. , COX H.
Published: March 2008

Abstract. 1. Leaves of tomato (cv. Moneymaker) were artificially damaged and offered to Spodoptera larvae at a range of intervals following damage. Grazing levels on these leaves were compared with those on undamaged leaves on the same or different plants.

2. In separate experiments, three leaves in a middle position on the main stem were clipped and after 48 h grazing levels on undamaged leaves above and below those damaged were compared with similar leaves from control plants.

3. Within 8 h, grazing levels on damaged leaves were significantly lower than those on control leaves, and within 24 h, leaves adjacent to damaged ones were similarly affected. These effects persisted for at least 7 days and leaves above and below those damaged were affected. There was up to nine‐fold reduction in area consumed.

4. The possible ecological consequences of reduced palatability at these levels are discussed.
Plant structure and the foraging success of Aphidius rhopalosiphi (Hymenoptera: Aphidiidae)
Authors: GARDNER SARAH M. , DIXON A. F. G.
Published: March 2008

Abstract. 1. A study of searching behaviour on wheat and host preference of Aphidius rhopalosiphi (DeStefani‐Perez) is described.

2. Parasitoids divided their time equally between the leaves but spent very little time on the ear.

3. After contact with honeydew or an aphid host, parasitoids were arrested in a particular area and increased the time spent searching.

4. Aphids feeding on the ear were parasitized less successfully, since their position between the grains protected them from parasitoid attacks.

5. A.rhopalosiphi exhibited no preference for Metopolophium dirhodum (Walker) or Sitobion avenae (Fabricius), although the handling time for the latter was significantly longer; this resulted in fewer S.avenae being parasitized when it was abundant. Parasitoids did not switch between hosts in these experiments.

6. As a result of its searching behaviour, A.rhopalosiphi will encounter and parasitize M.dirhodum feeding on the leaves more frequently than S.avenae, which feeds on the ear. This will limit the parasitoid's ability to regulate populations of the cereal aphid S. avenae.
Egg weight variation in relation to egg mortality and starvation endurance of newly hatched larvae in some satyrid butterflies
Authors: KARLSSON BENGT , WIKLUND CHRISTER
Published: March 2008

Abstract. 1. Egg weights decrease over the oviposition period in all of the five satyrid butterflies that have been studied, viz Parage aegeria L., Lasiommata petropolitana F., L.maera L., L.megera L. and Lopingaachine Scop. However, within each species, no correlation was found between variation in egg weight and egg mortality in 30% relative humidity or the ability of newly hatched larvae to survive without food for 1–4 days.

2. Although egg weights of Papilio machaon L. were similar to the highest satyrid egg weights, newly hatched larvae of P.machaon showed significantly higher mortality after 1 day of starvation when compared to all of the satyrid larvae. This indicates that the capability of newly hatched larvae to endure starvation is not necessarily correlated with egg weight, and consequently that this character trait of satyrid larvae has been selected for (i.e. should be regarded as an adaptation). It is noteworthy that this ability of satyrid larvae to endure starvation is coupled with the habit of many satyrid butterflies not to deposit their eggs directly on the larval host plants.

3. In 30% relative humidity, egg mortality of L.achine was 100% and that of P.aegeria 29.2%, whereas that of the three Lasiommata spp. was significantly lower. At 100% relative humidity egg mortality in L.achine dropped to 8%. Since egg weights are higher in L.achine than in the other four satyrids this indicates that egg resistance to desiccation is not necessarily correlated with egg size (as might be expected due to the area to volume ratio which is negatively correlated with egg size). Thus the resistance to desiccation which is found in the three Lasiommata spp. should be regarded as an adaptation to the habit of these three butterflies to deposit their eggs in relatively dry microhabitats. This resistance to desiccation is not found in eggs of the two forest‐dwelling satyrids P.aegeria and L.achine which lay their eggs in microhabitats where the relative humidity is high.
Oviposition preferences in relation to larval growth rates and survival in the pine beauty moth, Panolis flammea
Authors: LEATHER SIMON R.
Published: March 2008

Abstract. 1. Adult female pine beauty moths, Panolis flammea (D & S), when given a choice of whole plants or needle pairs of four provenances of Lodgepole pine, Pinus contorta (Douglas), laid most eggs on that provenance on which the larvae attained their greatest growth rates.

2. When presented with a greater number of Lodgepole pine provenances and Pinus sylvestris L, P.flammea oviposition preferences reflected the trade‐off between growth rate and survival.

3. There is some evidence to suggest that the moths are responding to the monoterpene composition of the plants.

4. Adult moths showed no preference for Lodgepole pine needles of a range of ages (1–4 years), ovipositing uniformly on all age classes.
The use of fluorescent pigments to study insect behaviour: investigating mating patterns in a butterfly population
Authors: WHEYE DARRYL , EHRLICH PAUL R.
Published: March 2008

Abstract. 1. Mating patterns in a natural population of checkerspot butterflies, Euphydryas editha Boisduval, were investigated by dusting male external genitalia with fluorescent dyes and examining mated females under UV light.

2. These dyes may have diverse applications in studies of insect populations.
Geographical variation in food web structure in Nepenthes pitcher plants
Authors: BEAVER R. A.
Published: March 2008

Abstract. 1. Relative to Nepenthes species in West Malaysia near the evolutionary centre of the genus, outlying species of Nepenthes in the Seychelles, Sri Lanka and Madagascar have fewer species of both prey and predator living in them, fewer and smaller guilds of species, much apparently empty niche space, less complex food webs, and a greater connectance. The ratios of prey to predators, and of connectance (C1) to the total number of trophic types present remain approximately constant.

2. Differences between the food webs appear to be related in a complex way to the size of the country and its degree of spatial and temporal isolation, the size of the local species pool capable of colonizing the pitchers, and the number of Nepenthes species present. However, the maximal length of food chains in the richest and most complex food webs is probably limited by energetic constraints or environmental predictability.

3. The data may illustrate how food webs change to become more complex, both by the addition of new guilds of species and the addition of species to existing guilds, while at the same time certain properties of the food web are kept approximately constant.
Seasonal abundance of macropterous Nilaparvata lugens and Sogatella furcifera based on presumptive macroptery in fifth‐instar nymphs
Authors: COOK A. G. , PERFECT T. J.
Published: March 2008

Abstract. 1. The seasonal changes in abundance of macropterous N. lugens (Stal) and S. furcifera (Horvath) (Homoptera: Delphacidae) are described based on observed numbers of adults and presumptive macroptery in fifth‐instar nymphs occurring in rice crops in the Philippines.

2. Percentage presumptive macroptery in fifth‐instar nymphs was correlated with nymphal density over the range of 0–20 nymphs per hill for females of both species and 5–20 nymphs per hill for male N. lugens.

3. Lunar phase had no effect on wingmorph expression in either species.

4. Comparison of the percentage macroptery in fifth‐instar nymphs with subsequent percentage macroptery in N. lugens adults for one season showed net emigration occurred from 60 DAT (days after transplanting) to harvest except for a period of net immigration lasting 7–10 days at approximately 95 DAT for both sexes.
Radar observations of moths migrating in a nocturnal low‐level jet
Authors: DRAKE V. A.
Published: March 2008

Abstract. 1. Radar observations of insects migrating at night over central‐western New South Wales have detected an instance of migration in a low‐level wind jet.

2. From the characteristics of the radar echoes, and from the catches obtained in traps at ground level and at the altitude of migration, the migrants can be identified as noctuid and pyralid moths of a number of different species.

3. The migration, which was in a downwind direction, started at dusk and ended at about dawn. During the period immediately before first light, a large proportion of the migrants were concentrated into a 100m deep layer at an altitude of about 250m; this layer had not been present during the first half of the night.

4. The boundary layer wind profile at dawn exhibited a clear low‐level jet structure, with a wind maximum between 100 and 300m, and strong shear in the wind direction below 300m. A strong surface temperature inversion, but not a wind‐speed maximum, had been present the previous evening.

5. The formation of the layer concentration in the upper part of the jet may be accounted for in terms of previously described responses of nocturnally migrating insects to a surface temperature inversion. It is not therefore necessary to assume that the migrants were responding specifically to the presence of a wind‐speed maximum.
The effects of body size on mating and reproduction in Brachinus lateralis (Coleoptera: Carabidae)
Authors: JULIANO STEVEN A.
Published: March 2008

Abstract.1. The causes and reproductive consequences of body size variation of Brachinus lateralis Dejean, a parasitic carabid beetle, were investigated.

2. Body size variation occurs within and between sites. Host size has a major influence on body size of the adult.

3. Fecundity is positively correlated with body size. Egg size is not correlated with body size.

4. Mating males tend to be larger than non‐mating males. There is a positive correlation of body sizes in mating pairs.

5. Limited opportunity for host choice may maintain size variation despite the advantages of large size.

6. The non‐random patterns of mating for a species without obvious intrasexual aggression suggest that subtle means of male‐male competition or female choice may be important.
Pollen‐feeding and the host specificity and fecundity of flower thrips (Thysanoptera)
Authors: KIRK WILLIAM D. J.
Published: March 2008

Abstract. 1. Flower thrips could feed on pollen of a wide range of sizes and were unaffected by exine spines. One species of thrips was unable to feed on very adhesive grains.

2. The proportion of time spent feeding on each species of pollen (in seconds per minute of exposure) reflected the known host specificities. Host‐specific thrips could distinguish their host pollen, apparently without probing.

3. Kakothrips pisivorus (Westwood) appeared to have a higher rate of ingestion of a host pollen than of four non‐host pollens.

4. In cages in the laboratory, Thrips fuscipennis Haliday laid significantly more eggs over 48h when given pollen than when given other floral tissues or no food. K. pisivonis and Ceratothrips ericae (Haliday) also laid significantly more eggs over 48h in the presence of pollen than in its absence.

5. In comparisons between pollen diets, T. fuscipennis, a generalist, laid similar numbers of eggs with each species of pollen, but K. pisivorus and C. ericae laid significantly more eggs with their respective host pollens. The differences in oviposition rate between pollen diets reflected the differences in the proportion of time spent feeding.
Host plant toxins and unpalatability of Neacoryphus bicrucis (Hemiptera: Lygaeidae)
Authors: McLAIN DENSON K. , SHURE DONALD J.
Published: March 2008

Abstract. 1. Host plant choice of the seed bug, Neacoryphus bicrucis Say (Hemiritera, Lygaeidae), was evaluated in four different Georgia habitats. N. bicrucis utilized only species of Senecio as host plants at a granite outcrop and at old fields on the coastal plain, in the piedmont, and in the Blue Ridge Mountains.

2. In laboratory tests N. bicrucis is distasteful to the green anole lizard, Anolis carolinensis Voight. Only six of ninety field‐collected bugs were eaten in palatability trials while eighty‐four of the remaining ninety attacked bugs were rejected by lizards without apparent harm. However, the bugs were palatable to Fowler's toads, Bufo woodhousei fowleri Hinckley, which ate all thirty‐six bugs offered to them.

3. N. bicrucis selectively sequesters pyrrolizidine alkaloids from Senecio spp. These may cause the insects' distastefulness to green anoles. In palatability trials, lizards ate all twenty insects reared on sunflower seeds, Helianthus annus, but rejected all twenty reared on Senecio smallii.
Specializations and polyphagy of Plebejus argus (Lepidoptera: Lycaenidae) in North Wales
Authors: THOMAS C. D.
Published: March 2008

Abstract. 1. The polyphagous butterfly, Plebejus argus L., was found to have specialized requirements: eggs are laid along vegetation/bare ground margins, larvae specialize on tender meristematic and reproductive growth, larvae and pupae are tended by Lasius ants, and warm microclimates are favoured.

2. These requirements are met in early successional habitats within several bio topes. These habitats are locally distributed, as is P. argus.

3. Populations on limestone, heathland and mossland biotopes did not differ greatly in ecologies. Given a choice of foodplants in captivity, larvae from heathland and limestone did show slight differences in preference, selecting some of the hostplants they normally encounter in the wild. Regardless of biotope, all these larvae were plant taxa generalists (on three plant families), but specialists on plant parts.

4. The decline of P. argus in Britain is attributed to loss of biotopes and to declining traditional management of them. Fewer habitats are available, and the distances between them are greater than formerly. As some of these habitats are short lived, and P. argus rarely flies far, the butterfly's decline is a compound effect of reduced areas of habitat and inability to colonize them.
Ovariole number and fecundity for the two emigrating generations of the bird cherry‐oat aphid (Rhopalosiphum padi) in Sweden
Authors: WIKTELIUS S. , CHIVERTON P. A.
Published: March 2008

Abstract. 1. The number of ovarioles and the potential fecundity in first (fundatrigenia) and second generation emigrants of Rhopalosiphum padi (L.) was investigated.

2. The relationships between weight and host quality on ovariole number were investigated.

3. The first generation of emigrants had a greater number of ovarioles and a higher fecundity than the second.

4. There was a positive relationship between ovariole number and weight.

5. The number of ovarioles and weight decreased with decreasing host quality.

6. The results do not agree with a recently proposed reproductive strategy of aphids where the number of ovarioles are supposed to be independent of weight and host quality.

7. In years with a high initial population on bird cherry, the migration to grasses, e.g. cereals, will be earlier, probably larger and, to a greater extent, consists of aphids which have a higher reproductive rate than in years with a small initial number on bird cherry.