bluuebunny/crossref_metadata_2025_split huggingface dataset:
Host‐handling behaviours in parasitoids of the black scale: a case for ant‐mediated evolution
Authors: Marco S. Barzman , Kent M. Daane 
Published: September 2010

Summary

We hypothesize that differences in host‐handling times among three closely related encyrtid parasitoids (Metaphycus anneckei Guerrieri & Noyes, Metaphycus hageni Daane & Caltagirone and Metaphycus lounsburyi[Howard]) are influenced by the defences of their host, black scale (Saissetia oleae[Olivier]). Two forms of host defence were examined: (i) the scale’s possession of a hard integument, and (ii) the effect of ants tending S. oleae.
Duration of host assessment, host rejection, drilling/oviposition and the presence or absence of host feeding were measured for M. anneckei, M. hageni and M. lounsburyi. Results show that M. anneckei oviposits through the soft ventral integument while M. hageni and M. lounsburyi oviposit through the harder dorsal integument. M. anneckei was never observed to host feed while both M. hageni and M. lounsburyi use hosts for either oviposition or host feeding. The ventral drilling location and absence of non‐concurrent host feeding significantly reduced the overall host‐handling time of M. anneckei, relative to M. lounsburyi and M. hageni.
Oviposition success of M. anneckei and M. hageni in the presence of ants was compared. An observation arena was established with the numbers of Argentine ants, Linepithema humile (Mayr) and S. oleae manipulated on potted oleanders. M. hageni and M. anneckei were placed, individually, onto the observation arena and their interaction with ants and S. oleae recorded. While 55·3% of M. anneckei successfully oviposited, M. hageni was unable to oviposit or host feed in the presence of foraging ants.
Field tests were conducted using potted oleander plants, infested with S. oleae, to determine the effect of L. humile on scale density, parasitism levels and parasitoid species composition. Ant‐tended plants had significantly more scale, lower scale parasitism and lower levels of host feeding (as indicated by unknown scale mortality levels). There were also significant differences in parasitoid species composition between ant‐tended and ant‐excluded treatments, with the relative frequency of parasitoid species with faster host‐handling times more common in the ant‐tended treatment.
Absolute foraging rate and susceptibility to interference competition in blackbirds varies with patch conditions
Authors: Cresswell Will , Smith Rik D. , Ruxton Graeme D. 
Published: September 2010

Summary Individual variation in feeding rate in the absence of competitors (absolute feeding rate) and change in feeding rate in the presence of competitors (susceptibility to interference) are crucial parameters used in individual‐based population models that predict the distribution of animals across patches. There are, however, few data on how these parameters are dependent on local foraging conditions, which will vary widely in natural systems. We tested the hypotheses that absolute feeding rate and change in feeding rate with group size were independent of patch conditions. We observed 27 European blackbirdsTurdus merulafeeding in seminatural experimental patches that were either open (where prey was easily visible) or covered with leaves (where prey was invisible until the leaves had been moved aside by the bird). Absolute feeding rate and susceptibility to interference were measured by recording feeding rates of blackbirds alone and in the presence of increasing numbers of competitors, respectively. There was significant individual variation in absolute feeding rate dependent on patch type, with some birds showing relatively large increases in open patches. There was no significant correlation between absolute feeding rate in open and leaf patches. There was significant variation in individual susceptibility to interference dependent on patch type. There was no correlation between an individual’s susceptibility to interference in open and leaf patches. Mathematical models that seek to make predictions of the distribution of animals across heterogeneous patches should incorporate measures of competitive ability over a wide range of patch conditions, or use more complex parameters that incorporate individual changes in density dependent pay‐offs dependent on patch conditions.
Queuing for preferred territories: delayed dispersal of Siberian jays
Authors: Ekman Jan , Eggers SÖnke , Griesser Michael , Tegelström HÅkan 
Published: September 2010

Summary

Siberian jays (Perisoreus infaustus) can acquire breeding status along two routes. Some offspring dispersed in their first summer of life, but one‐third of birds ringed as nestlings (39 of 117; 40 broods) postponed dispersal beyond their first winter and up to 3 years of age.
Birds dispersing in their first summer were able to settle in flocks outside their natal territory, while retained offspring appeared to be queuing for territorial vacancies in high‐quality habitat rather than claiming one of the currently available vacancies of low quality.
Males dispersing in their first year acquired territories close to human settlements, and with few low spruces. Reproductive success was low in those territories. Males with delayed dispersal acquired territories further away from human settlements and with a high density of low spruces (< 15 m). Reproductive success was high in such territories.
A preference of all birds for territories characterized by high reproductive success, regardless of their timing of dispersal, suggests a causal relationship to habitat characteristics. A non‐breeding surplus of retained offspring had priority to vacancies at high densities and these birds claimed territories where reproductive success was high. At low densities and without a non‐breeding surplus it was possible for birds dispersing as yearlings to shift territory, and acquire vacant sites of higher quality. It was birds settled in the territories with lowest reproductive success which shifted, and at low population density their territories remained vacant.
Siberian jays postponed dispersal as a strategic trade‐off, where they forego dispersal options of low quality while queuing for high‐quality habitat. However, a nepotistic parental behaviour towards retained offspring implies that fitness gains of delayed dispersal is not only a question of habitat quality.
Invasion and dynamics of covert infection strategies in structured insect–pathogen populations
Authors: BONSALL M. B. , SAIT S. M. , HAILS R. S. 
Published: September 2010

Summary

Pathogens are known to cause horizontally transmitted overt (fully symptomatic) and vertically transmitted covert (asymptomatic) infections. Here, we explore a range of different covert infection strategies on the persistence and dynamics of insect host–pathogen interactions.
The three strategies we explore are (i) sublethal infections in which hosts survive initial infection but suffer costs on fecundity or development, (ii) persistent infections, which are transmitted vertically with minimal costs on fecundity and development and which also confer immunity against superinfection and (iii) persistent infections without immunity against superinfection.
We examine the conditions that allow these three strategies to invade. We find that sublethal infections can act to modulate the population dynamics (i.e. cause changes in amplitude and periodicity of cycles) as well as inducing different dynamics (stable and unstable states). This is in line with empirical findings.
Covert infection strategies are also able to generate novel dynamics. In particular, over a wide range of parameter space the predicted dynamics of the covert infections without immunity are of a persistent stable interaction solely between the covertly infected hosts and the pathogen, with the exclusion of clean susceptible hosts.
Our results suggest that, in general, host–pathogen interactions may be maintained in low‐level persistent endemic states without the propensity to show the cyclic oscillations characteristic of enemy–victim interactions. Understanding host–pathogen dynamics requires a knowledge of the factors involved, such as covert infections, that may compensate for the destabilizing effects of time‐lags.
The effect of bovine tuberculosis and brucellosis on reproduction and survival of wood bison in Wood Buffalo National Park
Authors: JOLY DAMIEN O. , MESSIER FRANÇOIS 
Published: September 2010

SummaryWood bison (Bison bison athabascaeL.) abundance in Wood Buffalo National Park, Canada, declined from an excess of 10 000 bison in the late 1960s to a low of 2200 bison in the late 1990s.Bovine tuberculosis (Mycobacterium bovis) and brucellosis (Brucella abortus), were introduced to Wood Buffalo National Park in the late 1920s. As each of these pathogens has the potential to reduce survival and reproduction in bison, they are suspected to have played a role in the decline in bison abundance.We live‐captured bison in the winters of 1997–2000, tested for tuberculosis, brucellosis and pregnancy and released animals with radio transmitters to evaluate survival.We found that bison that were positive for both diseases were less likely to be pregnant or to survive the winter than bison positive for one or neither disease. Further, in one population, bison that were tuberculosis‐positive had a substantially lower pregnancy probability.Demonstrating a negative effect of diseases on survival and reproduction is a necessary, but not sufficient, test of the role of diseases in bison population decline.
Liver involvement in post‐smolt Atlantic salmon, Salmo salar L., infected with infectious pancreatic necrosis virus (IPNV): a retrospective histopathological study
Authors: Noguera P A , Bruno D W 
Published: September 2010

AbstractHistological changes associated with infectious pancreatic necrosis virus (IPNV) infection have historically been described for the pancreas and gut, but any involvement of the liver was poorly acknowledged or described. The aims of this study were to find robust evidence that the reported increase in liver pathology in Atlantic salmon post‐smolts in natural outbreaks was effectively related to IPNV infection and retrospectively to report when such a shift in the involvement of the liver had taken place, supported by a histopathological description for a differential diagnosis. The study reports new findings concerning the dynamics of liver pathology development, with apoptosis, demonstrated by histological and immunological techniques, described as the most relevant and particular feature. Immunohistochemical examination of affected liver suggests apoptosis is not only the result of the virus infection itself but triggered through the action of the host’s innate immune response. Liver involvement contributes to the nature of infection and becomes an important factor in the disease process. Additionally, it was established that the increase in infectious pancreatic necrosis prevalence is correlated with a new distinct pattern of outbreak distribution throughout the year. The role of smolt category (i.e. S1, S1/2 or S0), hence timing of seawater transfer as a strong correlating factor, is discussed.
Environmental and physiological factors influencing phototactic flight of Bemisia tabaci
Authors: BLACKMER J. L. , BYRNE D. N. 
Published: September 2010

Abstract. Experiments were conducted in a glasshouse and in the laboratory to determine the environmental and physiological parameters that affect flight behaviour of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). The number of whiteflies taking off and exhibiting a positive response to sky light in the glasshouse was greatest from 08.30 to 10.00 hours. During peak flight activity less than 5% of the population engaged in phototactic orientation. Temperature was the best single predictor for the phototactic response, accounting for 75% of the variability in whitefly ascent.Sex ratios were determined for individuals remaining on poinsettia, Euphorbia pulcherrima (Willd.), and for individuals that exhibited phototactic orientation; both groups deviated from an expected 1:1 ratio. Males were more prevalent on the plants (1:0.76), whereas females were much more prevalent (1:3.02) among the whiteflies responding to sky light. A higher percentage of the females displaying a phototactic response contained eggs when compared to females remaining on poinsettia (87 v 65%). The two groups of females did not differ significantly in their weights, but males that remained on the plants were heavier than males that responded to sky light. Mark–recapture studies and experiments where phototactic individuals were removed from the population established that the response was short‐lived.Whiteflies exhibiting a phototactic response in the glasshouse were more likely to exhibit long‐duration, phototactic flights in a vertical flight chamber when compared to individuals that remained on poinsettia (80.7 ± 6.7 v 36.0 ± 5.8% phototactic response; 7.0 ±3.2 v 0.7±0.2min flights). There was also less deviation in flight across the horizontal plane among the individuals that exhibited a positive response to sky light in the glasshouse in comparison to individuals that remained on their host. However, initial rates of climb were not significantly different between the two groups of whiteflies.
Impact of (Z)‐7‐dodecenol and turbulence on pheromone‐mediated flight manoeuvres of male Trichoplusia ni
Authors: LIU YONG‐BIAO , HAYNES KENNETH F. 
Published: September 2010

Abstract. Turbulence and chemical noise are two factors which may influence pheromone‐mediated flight manoeuvres of a moth in natural habitats. In this study, the effects of turbulence and the behavioural antagonist (Z)‐7‐dodecenol on flight manoeuvres of male Trichoplusia ni (Hübner) were evaluated in a wind tunnel. Male moths increase airspeed and course angles when turbulence is increased. This leads to significant increases in the length of flight tracks, but significant reductions in the time taken to reach a pheromone source. In less disturbed pheromone plumes, distributions of course angles and track angles of male T.ni show a prominent peak centred about 0° relative to the upwind direction, indicating that moths can temporarily steer directly upwind toward a pheromone source.When (Z)‐7‐dodecenol is released 10 cm upwind of a pheromone source to form an overlapping plume downwind, course angles, airspeeds and ground‐speeds of male T.ni are reduced significantly compared with those in uncon‐taminated pheromone plumes. This results in a longer flight time to reach a pheromone source. The decrease in flight speed would decrease the rate of contact with filaments, and thereby perhaps allow the moth to detect uncon‐taminated pheromone filaments independently from filaments containing the behavioural antagonist.
Discontinuous gas exchange and water loss in the keratin beetle Omorgus radula: further evidence against the water conservation hypothesis?
Authors: Bosch Mareza , Chown Steven L. , Scholtz Clarke H. 
Published: September 2010

SummaryDiscontinuous gas exchange cycles are demonstrated in Omorgus radula (Erichson) (Coleoptera, Trogidae) for the first time, thus extending evidence for such cycles to another family of beetles. The closed, flutter and open phases of the cycle were clearly distinguishable in this species, and the duration of these phases was 221 ± 28, 1403 ± 148 and 755 ± 43 s (mean ± SE), respectively. No evidence for significant intraspecific mass scaling of VCO2 or any of the components of the cycle was found. Although the prolonged F‐phase recorded here is unusual for many insects, it has previously been found in other scarabaeoid beetles, especially those from xeric environments. It has been suggested that such modulation of the discontinuous gas exchange cycle may result in a reduced VCO2 and, consequently, reduced water loss. In O. radula VCO2 (15.25 ± 1.49 μl/h) was considerably lower than that predicted from its body mass (0.207 ± 0.006 g). However, the small relative contribution of respiratory transpiration (6.5%) to total water loss indicated that reduced VCO2 has little to do with water economy. Rather, it may be a consequence of generally low activity levels of these beetles. The low respiratory water loss, but distinct subterranean component in the adult life of O. radula, lend some credence to the hypothesis suggesting that regular use of subterranean habitats might have been responsible for the evolution of discontinuous gas exchange cycles. However, non‐adaptive hypotheses can still not be discounted.
Thermotolerance and rapid cold hardening ameliorate the negative effects of brief exposures to high or low temperatures on fecundity in the flesh fly, Sarcophaga crassipalpis
Authors: Rinehart Joseph P. , Yocum George D. , Denlinger David L. 
Published: September 2010

SummaryAlthough the immediate effects of temperature stress are well documented, the longer‐term effects of such stresses are more poorly known. In these experiments, we investigate the effects of suboptimal and supraoptimal temperatures during pharate adult development on fecundity in the flesh fly, Sarcophaga crassipalpis Macquart. A 1 h cold shock at −10°C during the red‐eye pharate adult stage decreases the fecundity of both sexes. Induction of rapid cold hardening by pre‐treatment at 0°C for 2 h partially prevents reproductive impairment. Heat shock of pharate adults for 1 h at 45°C also reduces fecundity in both sexes, but inducing thermotolerance by pre‐treatment at 40°C for 2 h affords protection only to females. Males heat shocked at 45°C or first pre‐treated at 40°C consistently fail to transfer sperm to the females. The injury inflicted on males by heat shock is most pronounced when the stress is administered to pharate adults or adults; wandering larvae and true pupae are unaffected. The implications of these data for naturally occurring populations are discussed.
Hearing and evasive behaviour in the greater wax moth, Galleria mellonella (Pyralidae)
Authors: Skals Niels , Surlykke Annemarie 
Published: September 2010

SummaryGreater wax moths (Galleria mellonella L., Pyraloidea) use ultrasound sensitive ears to detect clicking conspecifics and echolocating bats. Pyralid ears have four sensory cells, A1−4. The audiogram of G. mellonella has best frequency at 60 kHz with a threshold around 47 dB sound pressure level. A1 and A2 have almost equal thresholds in contrast to noctuids and geometrids. A3 responds at + 12 to + 16 dB relative to the A1 threshold. The threshold data from the A‐cells give no indication of frequency discrimination in greater wax moths.Tethered greater wax moths respond to ultrasound with short‐latency cessation of flight at + 20 to + 25 dB relative to the A1 threshold. The behavioural threshold curve parallels the audiogram, thus further corroborating the lack of frequency discrimination. Hence, the distinction between bats and conspecifics is probably based on temporal cues.At a constant duty cycle (percentage of time where sound is on) the pulse repetition rate has no effect on the threshold for flight cessation, but stimulus duration affects both sensory and behavioural thresholds.The maximum integration time is essentially the same: 45 ms for the A1‐cell and 50–60 ms for the flight cessation response. However, the slopes of the time‐intensity trade‐off functions are very different: − 2.1 dB per doubling of sound duration for the A1‐cell threshold, and − 7.2 dB per doubling of sound duration for the behavioural threshold.The significance of the results for sexual acoustic communication as well as for bat defence is discussed.
Developmental changes in the patterns of feeding in fourth‐ and fifth‐instar Helicoverpa armigera caterpillars
Authors: Raubenheimer D. , Browne L. Barton 
Published: September 2010

SummaryData are presented for developmental changes in feeding behaviour within and across the fourth and fifth stadium of Helicoverpa armigera (Lepidoptera, Noctuidae) caterpillars fed nutritionally homogeneous semi‐synthetic foods. We recorded the microstructure of feeding over continuous 12‐h periods on consecutive days throughout the two stadia, and in one experiment recorded continuously for 21 h. Larvae in the two stadia showed the same general pattern of macro‐events in feeding, including a similar duration of post‐ecdysis fast, which was usually broken by consumption of the exuviae, and then a sustained period in which discrete meals on the experimental food were taken regularly. There were, however, some distinct differences in the patterns of meal‐taking both between stadia and across different one‐third time segments within stadia. Considering between‐stadium differences, the proportion of time spent feeding differed significantly only in the last segment of the feeding period of the two stadia, with the value for the fourth‐instar larvae being substantially greater than for fifth‐instar larvae. As regards within stadium changes, the proportion of time feeding increased from the first to the second segment of both stadia. However, whereas the proportion of time feeding increased from the second to the final segment of the fourth stadium, it decreased across the same period in the fifth stadium. These patterns of changes in the proportion of time feeding within and between stadia, and their behavioural mechanisms (combination of meal durations and meal frequencies), can be explained only partially with reference to increasing food requirements with development. Three areas are identified where further study might help elucidate the reasons for the observed developmental changes in the microstructure of feeding: allometric constraint, the dynamic links between ingestion and post‐ingestive processing, and ecological factors such as predation.
Olfactory orientation responses of the eucalyptus woodborer, Phoracantha semipunctata, to host plant in a wind tunnel
Authors: Barata E. N. , Araújo J. 
Published: September 2010

SummaryThe eucalyptus woodborer, Phoracantha semipunctata Fabricius (Coleoptera: Cerambycidae), attacks mainly species of Eucalyptus (Myrtaceae). This study investigated walking and flight behaviour of P. semipunctata males and females exposed to an odour plume originating from a log of E. globulus placed vertically in the upwind end of a wind tunnel. In control experiments, beetles were exposed to a PVC drainpipe in the same position as the log, providing a visual stimulus without host‐tree odour. No statistical differences were found between behavioural responses of either sex when exposed to the log or PVC pipe. No beetles landed on the PVC pipe, whereas 49% of the beetles exposed to host‐tree odour plume landed on the log. Beetles aged over 24 days after emergence from the host tree were more responsive than beetles aged 20–24 days, and accounted vor 86% of the beetles that landed on the log. While walking, host‐tree odour affected the behaviour of the beetles that landed on the log as follows: upwind movement and path linearity increased, whereas turning rate, stopping frequency, mean stopping time and time to take‐off flight decreased. During flight, host‐tree odour affected the behaviour of the beetles that landed on the log as follows: increased upwind flight, turning rate, flight time, flight distance, and decreased flight speed. For beetles that never lost contact with the odour plume, flight progressed upwind with narrow zigzags, and showed higher directedness upwind, path linearity, faster flight speed and lower turning rate than for beetles that lost contact with the odour plume. After loosing contact with the plume, beetles tended to decrease their upwind progression, exhibiting a sharp turn or quick counterturns followed by crosswind or downwind excursions. This led to regaining contact with the odour plume and resumed upwind progression at higher speed provided they flew within the boundaries of the plume. The results showed that host‐tree odour affects both walking and flight behaviour of P. semipunctata beetles, inducing a more directed upwind movement and landing on the visual stimulus of a tree trunk.