Flight Capacity Research Articles

Avaliação radiográfica e de função de vôo após fixação de osteotomias distais do úmero em pombas (Columba livia), com modelo de fixador externo articulado

O tratamento de fraturas umerais distais em aves impõe grande dificuldade para tratamento e cura, pois estes ossos são pneumáticos, sendo suas córtices muito finas. A anquilose da articulação úmero-rádio-ulnar com fixador externo, é inviável para aves que se pretende a reintrodução ao meio ambiente. Em todas as aves, o fixador experimental foi colocado sobre o úmero, com sua articulação sobre a articulação úmero-rádio-ulnar e a extensão do fixador sobre a ulna. As aves foram divididas em dois grupos: cirurgias bilaterais com anquilose de um lado (asa estática) e manutenção da articulação do outro (asa dinâmica) (Grupo 1), e cirurgia unilateral, com manutenção da articulação (asa dinâmica) (Grupo 2). O calo ósseo foi avaliado através de radiografias pós-cirúrgicas, às 3, 6 e 9 semanas. Os animais do Grupo 2 foram avaliados quanto à capacidade de vôo entre 11 e 15 semanas após a cirurgia. Todos os animais foram avaliados quanto à amplitude da asa e quanto ao comprimento do úmero, após a eutanásia. Às 6 semanas, todos os animais do Grupo 2 e quatro animais do Grupo 1, apresentavam fraturas consolidadas radiografica e clinicamente. Dois animais do Grupo 1 somente apresentaram consolidação das asas dinâmicas às 9 semanas e das estáticas às 12 semanas. Todos os animais do Grupo 2 apresentaram capacidade de vôo adequada, até 13 semanas após a cirurgia. Devido a poucos trabalhos na literatura mundial, o presente trabalho visou o estudo da utilização inédita de fixador externo articulado para a estabilização de fraturas distais de úmero, evitando a anquilose da articulação do cotovelo, e portanto mantendo viável a função de vôo; usando como modelo experimental, pombas (Columba lívia). O método proposto de técnica para fixação de fraturas umerais distais, sem a anquilose da articulação úmero-rádio-ulnar, demonstrou ser efetivo em manter o comprimento ósseo, a amplitude da asa bem como a viabilidade de músculos e tendões, e assim, garantindo a capacidade de vôo das aves tratadas, sendo um método adequado para a reparação de fraturas distais de úmero em aves quando se pretende a reabilitação destes animais.

Flight potential of Microplitis mediator, a parasitoid of various lepidopteran pests

The efficacy of using natural enemies to control pests under field conditions largely depends on their mobility and, more specifically, on their capacity to quickly locate pest infestation. For many natural enemies, for example parasitoids, mobility is directly related to flight aptitude, which is determined by the capacity and inclination of a species to engage in flight. In this study, we determined the various factors that affected flight performance of Microplitis mediator (Haliday) (Hymenoptera: Braconidae), using a computer-monitored flight mill. No differences were found in flight performance (i.e., flight distance, duration, speed) between both sexes of M. mediator, and flight capacity increased up to an age of 5–7 days followed by a gradual decline afterwards. For one-day-old female parasitoids, mean (±SE) flight distance and duration were 6.23 ± 0.88 km and 85.15 ± 14.44 min, respectively, with a maximum flight distance of 18.0 km. For male parasitoids, mean flight distance and duration were 5.27 ± 0.51 km and 85.74 ± 7.63 min, respectively. Mating status did not affect flight performance of males, while flight distance of four-day-old ovipositing M. mediator females was much lower than that of un-mated females of the same age. Un-mated adults flew most actively at 22–24°C and inclination to fly gradually declined with decreasing temperature. Temperatures above 26°C considerably reduced flight activity of M. mediator. Wasps engaged in normal flight under a broad range of relative humidity (RH) conditions, with an optimum RH range identified as 75–90%. Our research shows that M. mediator is a highly active parasitoid, because both sexes show great inclination to fly under a range of environmental conditions and flight capacity at different ages. Our results can help explain parasitoid performance in the field and provide baseline information to help guide augmentative releases.

Energetic trade‐off between maintenance costs and flight capacity in the sand cricket (Gryllus firmus)

Summary 1Energetic trade-offs are those compromises that appear when the energy budget of an individual's life history closely matches or exceeds the net available energy in the environment in a given moment. In these situations, two or more functions can compete and organisms face physiological decisions in order to survive and reproduce. 2In insects, one of the most costly investments is flight capacity, which increases dispersal capacity but is energetically expensive. Adult sand crickets (Gryllus firmus) can vary drastically in this capacity, being macropterous or micropterous depending on whether they exhibit flight-capable wings. However, this binary phenotype has a continuous subjacent determinant in the macropterous morph which is the mass of the muscles that power flight, the dorso-longitudinal muscles (DLM). 3Using respirometric measurements, we studied a potential trade-off between body parts, the mass of the DLM and energy metabolism (including both maximum and average metabolism). By recording the metabolic rate of c. 180 crickets and then dissecting and weighing their body parts, we took advantage of the correlational structure to infer associations between energetic and morphological variables. We found that the residual mass of the DLM shows a quadratic relationship with residual resting and average metabolism: at low DLM mass there is a negative relationship, which becomes positive at higher DLM mass. 4We suggest that this pattern of covariance is a consequence of the negative correlation between DLM mass and gonad mass, and the relative contribution of functional vs. non-functional DLM. Then, by using energetics and a combination of multivariate and correlational statistics we were able to show how two important life-history functions (i.e. Dispersal and fecundity) compete for the same resources in an insect species.

Nectar-foraging behavior of Euglossine bees (Hymenoptera: Apidae) in urban areas

Euglossine bees have been described as long-distance pollinators because of their great flight capacities although flight capacity is not necessarily correlated to home range. Here we report the nectar-foraging behavior of two euglossine species (Euglossa cordata and Eulaema nigrita) in urban areas and the predictive power of wing wear as an age estimator of these bees, using mark-recapture techniques at Thevetia peruviana trees. A total of 870 bees were marked. Recapture rates were 33% (± 19.2) for E. cordata and 25% (± 2.5) for E. nigrita. Only 7 bees were sighted at a different site from where they were first captured. More than 75% of the individuals showed site-constancy at trees for at least 30 days. Wing wear accumulation rate was variable among individuals and it was a poor predictor of age for E. cordata. Our data show that euglossine bees may have small foraging ranges in urban areas, indicating that home ranges greatly differ from their flight capacity and homing ability.

Variability and genetic basis for migratory behaviour in a spring population of the aphid,Aphis gossypiiGlover in the Yangtze River Valley of China

The population dynamics, development of gonads, takeoff and flight behaviour of Aphis gossypii Glover were investigated in order to test whether there was variation of migratory ability in the spring population. Field surveys showed that not all the aphids overwintering on hibiscus migrated to the secondary host plants, and the host-alternating and host-specific life-cycle forms coexisted in Nanjing, China. Substantial variation in flight capacity of winged individuals, development of gonads and takeoff behaviour were found within the spring population. The frequency distribution of flight duration and the number of ovarioles per individual alatae exhibited two peaks, representing the migratory and sedentary genotypes, respectively. Significant response to directional selection on takeoff behaviour demonstrated the additive genetic component of this variation. Selection for 'takeoff' individuals caused a significant increase in takeoff angle from 39.8 degrees in the first selection to 68.7 degrees in the fifth; and, hence, screened out the migratory genotype (M), while selection for the sedentary individuals increased the rate of non-takeoffs significantly, and screened out the sedentary genotype (S). The reciprocal cross, M(female) x S(male), produced hybrid offspring performing significantly steeper takeoff angles compared with those from the cross S(female) x M(male), suggesting the presence of a maternal effect. On the other hand, takeoff rate was ranked as M(female) x S(male)=S(female) x M(male)>M>S, involving no sex-linkage and maternal effect. The coexistence of host-alternating and host-specific life-cycle forms of A. gossypii on the primary host has, as deduced from the present studies, a genetic basis.

A estratégia de overbooking e sua aplicação no mercado de transporte aéreo brasileiro

A key issue regarding airline management is related to the balance between demand and supply. It is a common situation to observe flights departing with a significant amount of empty seats, mainly due to no-show passengers and the very late canceling of reservations. In Brazil, airline passengers do not usually cancel reservations; on the contrary, they usually wait for the deadline to buy it or, if the ticket is already bought, they simply do not show-up. These practices, "allowed" by airlines due the flexibility offer in some fare-classes, impede the airline to sell those empty seats on time for flight departure. Therefore it becomes economically rational for the firms to protect from the losses by recurring to mechanisms such as the virtual increase in flight capacity, that is, overbooking. The present paper aims at developing an analysis of the efficiency of overbooking, discussing its advantages and disadvantages, risks, economic viability, and issues regarding responsibilities and regulation.

Reproduction–Flight Relationship in the Beet Armyworm, <I>Spodoptera exigua</I> (Lepidoptera: Noctuidae)

To evaluate the relationship between reproduction and migratory flight, we examined ovaries, tethered flight, and egg laying in the beet armyworm, Spodoptera exigua (Hübner). Ovarian development in female S. exigua was classified into five stages in relation to the postemergence age of the moths. Oviposition peaked at ovarian stages III and IV. Mating accelerated ovarian development in this species, and thus the mated females developed faster than the virgin moths in ovaries. In virgin adults, flight capacity increased from the first day to the third day after emergence and remained at a high level until the moths were 7 d old. In contrast, the mated moths reached the maximum flight capacity in 2 d after emergence and maintained a high level until the age of 7 d. However, mating status could not influence the flight capacity of the beet armyworm, although there were general differences in flight capacity between virgin and mated adults at the same age. Moreover, significant correlations between the number of eggs laid and the flight capacity were not performed by the mated moths. These results showed that mating status and ovarian development did not seem to influence flight capacity in the beet armyworm, which was not in agreement with the definitions of the oogenesis-flight syndrome observed in many other migratory insects.

Optimising airline overbooking using a hybrid gradient approach and statistical modelling

We develop an overbooking approach for airline revenue management. We estimate a revenue function by employing a statistical modelling approach, specifically a multivariate adaptive regression splines approximation of a stochastic network model. We develop an overbooking cost function using a binomial distribution to model the number of customers that show up for the flight. We implement a hybrid gradient algorithm that combines Newton's and a steepest ascent method to optimise profit. Finally, we compare our method to one that overbooks based on the probability that the number of customers that show up for a flight exceeds the flight capacity.

Pricing strategies for perishable products: the case of Vienna and the hotel reservation system hrs.com

Consider a retailer who sells perishable products for which there is uncertain demand. Yield management with dynamic pricing is a standard practice that firms use for revenue management. For perishable products, recent analysis has focused on the distribution of flight capacity, referred to as ticket sales. Other non- storable, non-transportable, immaterial hospitality products include hotel capacity. The article discusses the extent to which hotel pricing strategies vary within the internet distribution system hrs.com. This study focuses on the distribution of hotel rooms available for booking on the internet for Vienna and gives an outlook to Euroland capitals. The main research interests are the underlying pricing models and the setting of the end price. Data was taken from hrs.com, which is the most important specialist for hotel room internet distribution in Germany according to recent studies by KMPG and others. The results include the identification of different pricing strategy clusters with regard to hotel category and hotel availability over a 22-day period for Vienna and one city from all Euroland countries (the capitals were studied for all cases except for the Netherlands, for which data was collected for Amsterdam). The study took the arrival days Mondays, Tuesdays, Wednesdays and Thursdays into account, and used data for all these days from the 11th of July, 2005, to the 10th of October, 2005, for Vienna, and the first and the last of these dates as a comparison base for the other Euroland cities.

Using financial options in airline booking process

This paper investigates the potential of using the financial options as a means of managing the ticket sales in an airline booking process. Call options are used to recall the tickets already sold, whereas put options are exercised to sell low-fare tickets in the last booking period whichever is favourable to the airline. By utilising the proposed approach, airlines can prevent the inherent drawback of overbooking, customer dissatisfaction due to denied boarding that occurs when the demand is higher than the flight capacity. Moreover, the proposed options approach can decrease the probability of a flight departing with vacant seats when the demand is lower than the capacity with consequent improvements in revenue for an airline company. In the paper, a mathematical model is introduced and a simulation study is conducted to explore the effectiveness and the potentials of the financial options in airline reservation systems for revenue improvement. Results obtained from the simulation study suggest that adoption of financial options creates significantly higher revenues in comparison to those by the traditional overbooking-based revenue management (RM) approach. It can be further conjectured that adoption and utilisation of the financial options in an airline booking process will reveal a seats’ true economic value in the long term. One potential and immediate application area of the suggested RM approach is the internet-based booking and bidding systems.

Red knots give up flight capacity and defend food processing capacity during winter starvation

Summary 1During the last phase of starvation, animals depend mainly on protein breakdown. All organs are a potential protein source. Do starving animals prevent particular organs from being catabolized in order to defend certain functions? In this study we investigated if starving birds maintain locomotion and digestion capacities, both essential for the recovery process. 2We compared body composition data of healthy wintering and winter-starved red knots (Calidris canutus islandica), a long-distance migrating shorebird that breeds on High Arctic tundra in Canada and Greenland, and winters in temperate coastal areas such as the Wadden Sea and the British estuaries. Throughout the wintering period they eat hard-shelled molluscs ingested whole. 3Our results showed that winter-starved knots had catabolized 60·5% of their pectoral muscles. This was much more than the decrease in overall body mass (32·5%). As a result, their flight capacities will have been reduced. 4Winter-starved knots defended the muscular gizzard, which lost only 21·2% of its mass. As knots crack the ingested shellfish with their gizzard, the organ is essential for food processing. The intestines and liver were not defended; their atrophy equalled that of the pectoral muscles (60·6% and 61·3%, respectively). 5Comparison with data from the literature led to the conclusion that starving birds only defend organs that are essential to either obtain or process food. These organs are maintained at the minimal level of normal capacity. Other organs decrease below this level and may lose much of their functional capacity. 6Even in near-death situations, with low fitness prospects, organisms show interpretably adaptive changes in organ size.

Note: Flight capacity, parasitism and emergence of fiveTrichogramma (Hymenoptera: Trichogrammatidae) species from forest areas in Brazil

The flight and parasitism capacities and emergence rate of fiveTrichogramma species [T. acacioi (Brun),T. bruni (Nagaraja),T. demoraesi (Nagaraja),T. maxacalii (Voegele & Pointel) andT. soaresi (Nagaraja)] were compared. The flight capacity of these parasitoids was assessed in test units. A tube was placed inside each test unit with a piece of card with 300Anagasta kuehniella (Zeller) (Lepidoptera: Pyralidae) eggs parasitized by one of theTrichogramma species. The emerged adults inside the test units were classified according to their position as flyers, non-flyers and walkers. Cards withA. kuehniella eggs, parasitized by one of theTrichogramma species, were assessed to determine the parasitism rate and emergence of these natural enemies. The data were submitted to analysis of variance and the means compared by the Scott-Knott test at 5% probability.Trichogramma maxacalii exhibited better flight capacity than the other species, in addition to good parasitism rate and high percentage of emergence.

Development of efficient combinatorial auction mechanism for airport slot allocation

The current allocation of slots in congested airports is fraught with deficiencies because of the liberalisation of air transportation undertaken all over the world. The existing grandfather rights rule is slowly being replaced with auctions. In the airport slot allocation problem, in order to effectively auction the slots, multiple-item auctions are employed. It is in this aspect that combinatorial auctions are employed, as they are the most efficacious in dealing with complimentarity. Since the existing mechanisms are more inclined towards maximising the auctioneer's profit with the monetary issue being the only concern they lead to biased allocations. Therefore, this paper develops a model and proposes a mechanism that could overcome the shortcomings of the existing auctioning procedures by incorporating the concepts of welfare issues with due consideration given to the flight capacity to effectively allot the slots.

Environmental physiology of the invasion of the Americas by Africanized honeybees

The expansion of Africanized honeybees (AHB) through the Americas has been one of the most spectacular and best-studied invasions by a biotype. African and European honeybees (EHB) hybridize, but with time, tropical and subtropical American environments have become dominated by AHB that exhibit only 20-35% genetic contribution from western European bees, and a predominance of African behavioral and physiological traits. EHB persist in temperate environments. Clines between AHB and EHB exist in ecotones of South and Central America, and are forming in North America. What individual-level genetic, behavioral and physiological traits determine the relative success of the AHB as an invader in the neotropics, and of the EHB in temperate areas? Preference for pollen versus nectar may be an important trait mediating these ecological trade-offs, as preference for pollen enhances nutrient intake and brood production for the AHB in the tropics, while a relative preference for nectar enhances honey stores and winter survival for EHB. AHB exhibit morphological (higher thorax-to-body mass ratios) and physiological (higher thorax-specific metabolic rates) traits that may improve flight capacity, dispersal, mating success and foraging intake. Enhanced winter longevity, linked with higher hemolymph vitellogenin levels, may be a key factor improving winter survival of EHB. Data from South America and distributions of AHB in the southwestern United States suggest that AHB-EHB hybrids will extend 200 km north of regions with a January maximal temperatures of 15-16°C. The formation of biotypic clines between AHB and EHB represents a unique opportunity to examine mechanisms responsible for the range limit of invaders.

Effect of Wind Speed on the Pheromone-Mediated Behavior of Sexual Morphs of the Potato Aphid, Macrosiphum euphorbiae (Thomas) Under Laboratory and Field Conditions

The effect of wind on the potato aphid, Macrosiphum euphorbiae, male responsiveness to the sex pheromone, and on the calling behavior of virgin oviparae, was studied under constant wind speeds in the laboratory and in the field. A significant proportion of females called at wind speeds up to 4 m/sec, whereas male flight behavior in clean air was inhibited at velocities > 2 m/sec. However, males continued to walk over the range of wind speeds at which females called. Under constant wind velocities in a wind tunnel, males downwind of calling females oriented on the upwind edge of the release stand, and fewer individuals took flight at low constant wind speeds than in a clean air plume. In all cases, whether calling females were present or not, the males that took flight moved downwind. However, when a bridge was available, a significant proportion of males walked upwind to the pheromone source. The same orientation and walking behaviors were observed when males were placed downwind of calling females under variable wind conditions in the field. However, contrary to the laboratory results, 30% of the males tested flew upwind and landed on the source. A more detailed examination found that males orienting toward a source would walk if wind speeds were high but initiated flight in an "upwind" direction if there was a lull in wind velocity. These findings suggest that for the potato aphid, and probably for many other insect species with weak flight capacity, walking behavior is a significant component of pheromone-mediated mate location. This would permit males to continue foraging for calling females in the vicinity when wind velocities inhibit flight.

A Drosophila model of oculopharyngeal muscular dystrophy reveals intrinsic toxicity of PABPN1

Oculopharyngeal muscular dystrophy (OPMD) is an adult-onset syndrome characterized by progressive degeneration of particular muscles. OPMD is caused by short GCG repeat expansions within the gene encoding the nuclear poly(A)-binding protein 1 (PABPN1) that extend an N-terminal polyalanine tract in the protein. Mutant PABPN1 aggregates as nuclear inclusions in OMPD patient muscles. We have created a Drosophila model of OPMD that recapitulates the features of the human disorder: progressive muscle degeneration, with muscle defects proportional to the number of alanines in the tract, and formation of PABPN1 nuclear inclusions. Strikingly, the polyalanine tract is not absolutely required for muscle degeneration, whereas another domain of PABPN1, the RNA-binding domain and its function in RNA binding are required. This demonstrates that OPMD does not result from polyalanine toxicity, but from an intrinsic property of PABPN1. We also identify several suppressors of the OPMD phenotype. This establishes our OPMD Drosophila model as a powerful in vivo test to understand the disease process and develop novel therapeutic strategies.

Soyuz in French Guiana: A strategic perspective

Abstract After a proposition from Russia to France, ESA agreed to see Soyuz rockets take off from French Guiana. From industry, to governments and agencies, many Russian and European actors were involved in this project and they all had different motives. It is therefore relevant to try to discern them so as to understand the rationale behind this cooperative endeavor. Soyuz's primary role is to consolidate Arianespace commercial position in the launching market and to bring activity and founding to a stagnating Russian space sector. With this decision Arianespace will have a full range of commercially available launchers with Soyuz completing the two European rockets Vega and Ariane V. But since Vega and Ariane must have the priority, there is a risk to see an insufficient launch rate for Soyuz, which would not satisfy the Russian partners. Commercial elements alone cannot justify the agreement. There is a larger strategic ambition behind. What is at stake is the future development of innovative launch systems. It is important for ESA to maintain an autonomous access to space and to maintain a dynamic and strong European propulsion industry. Cooperation with Russia can offer an increase of expandable rockets capabilities and can pave for the next generation of launch vehicles. Moreover, we can detect an interest in acquiring a system that has the potential for human space flight capacity. Finally, the decision to launch Soyuz from French Guiana was the conjunction of Russian and French national interests, which led to a complete redefinition of the relations between Europe and Russia. It is of strategic importance that we, Europeans, adapt to this evolution and understand the new place that Russia takes in our space sector.

Nutritional value of floral nectar sources for flight in the parasitoid wasp, Cotesia glomerata

Abstract. This study investigates the feeding of the parasitoid Cotesia glomerata on the floral nectar of Anethum graveolens and Origanum vulgare and evaluates the nutritional value of these food sources for increasing flight capacity. A significantly higher proportion of females are observed feeding on A. graveolens immediately after being released onto the floral nectar plants compared with those of the group released onto O. vulgare, although female wasps from both groups spent a similar period of time feeding on both nectar sources and there is no significant difference in their body weight increase. Laboratory tests on computer‐linked flight mills demonstrate that adult feeding significantly influences flight capacity, as defined by the number of flights, the longest single flight and the total distance flown during a given period of time, in female wasps but not in males, albeit the extent of influence varying with the type of food sources. After ad libitum feeding on the floral nectar of A. graveolens, female wasps perform flight activity as well as those feeding on honey, which is superior to those feeding on sucrose, in all the measured parameters. Feeding on the floral nectar of O. vulgare has a similar effect to feeding on the extrafloral nectar of Vicia faba and significantly increases the total distance flown but not the number of flights or the longest single flight. Feeding on sucrose does not increase flight capacity in the parasitoids beyond those having access to water only. The findings of this study suggest that judicious selection of floral nectar plants and habitat manipulation might play a key role in the biological control of pest insects.

Trade‐off between mobility and fitness inCydia pomonellaL. (Lepidoptera: Tortricidae)

Abstract. 1. The codling mothCydia pomonella, one of the most important pest insects of apple fruit orchards worldwide, is regarded as a ‘sedentary’ insect, but the natural populations consist of both mobile and sedentary genotypes that display different dispersal capacity in the field. The current study investigated whether there is a fitness consequence of being mobile in this species by comparing two strains with contrasting levels of mobility obtained through bi‐directional selection.2. Female moths of the sedentary strain were significantly larger, laid more eggs during their lifespan, and both male and female moths of this strain lived longer, when compared with the mobile strain.3. The age‐specific fecundity of female moths from the sedentary strain was significantly greater, in particular between 3 and 5 days after emergence when the peaks of both oviposition and flight capacity occur, relative to the mobile moths, thereby leading to a greater reproductive function.4. These differences resulted in different demographic parameters between the two strains. The sedentary strain had a significantly greater net reproductive rate (Ro) and a higher intrinsic rate of natural increase (rm), although the generation time (T) was similar, hence requiring a shorter time to double the population size, in comparison to the mobile strain.5. This study provides empirical evidence for the cost of being mobile inC. pomonella. Trade‐offs between mobility and fitness might have contributed to the existence of genetic variance for dispersal behaviour in the natural populations and the maintenance of relative sedentariness in the species.

Effects of the introduced ectoparasitePhilornis downsion haemoglobin level and nestling survival in Darwin's Small Ground Finch (Geospiza fuliginosa)

Abstract: The physiological impacts and fitness costs of parasitism by an introduced ectoparasitic fly,Philornis downsi(Muscidae), were studied in nestlings of Darwin's Small Ground Finch,Geospiza fuliginosa(Geospizinae), on the Galápagos Archipelago. Whole blood haemoglobin (Hb) concentration was used to measure host response to ectoparasitism due to its high repeatability and validity, as well as for its key role in aerobic activities that affect fitness, such as flight capacity and nestling begging intensity. Increased numbers of ectoparasitic larvae ofP. downsiwere strongly correlated with lower Hb levels in nestlings in the absence of blood parasites. Furthermore, immature red blood cell counts were negatively correlated with Hb level and positively correlated withP. downsiintensity. Nestlings with high levels of parasitism suffered higher mortality, which varied with clutch size. Our results provide evidence that endemic Galápagos bird populations are physiologically compromised byP. downsiand experience substantial fitness costs due to ectoparasitism.