Olfactory orientation responses of the eucalyptus woodborer, Phoracantha semipunctata, to host plant in a wind tunnel

The 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.     

Costs of Refuge Use Affect Escape Decisions of Iberian Rock Lizards Lacerta monticola

Theoretical models of anti-predator escape behaviour suggest that prey may adjust their escape response such that the optimal flight distance is the point at which the costs of staying exceed the costs of fleeing. Anti-predatory decisions should be made based also on consequences for long-term expected fitness, such as the costs of refuge use. For example, in lizards, the maintenance of an optimal body temperature is essential to maximize physiological processes. However, if unfavourable thermal conditions of refuges can decrease the body temperature of lizards, their escape decision should be influenced by refuge conditions. Analyses of the variation in flight distances and emergence latency from a refuge for the lizard Lacerta monticola under two different predation risk levels, and their relationship with the thermal environment, supported these predictions. When risk increased, lizards had longer emergence latencies, and thus costs of refuge use increased (a greater loss of time and body temperature). In the low-risk situation, lizards that were farther from the refuge had longer flight distances, whereas thermal conditions were less important. When risk increased, lizards had longer flight distances when refuges were farther off, but also when the external heating rate and the refuge cooling rate were lower. The results suggest that, in addition to the risk of predation, expected long-term fitness costs of refuges can also affect escape decisions.     

Comparative morphology of the thorax musculature of adult Anisoptera (Insecta: Odonata): Functional aspects of the flight apparatus

Due to their unique flight mechanism including a direct flight musculature, Odonata show impressive flight skills. Several publications addressed the details of this flight apparatus like: sclerites, wings, musculature, and flight aerodynamics. However, 3D-analysis of the thorax musculature of adult dragonflies was not studied before and this paper allows for a detailed insight. We, therefore, focused on the thorax musculature of adult Anisoptera using micro-computed tomography. Herewith, we present a comparative morphological approach to identify differences within Anisoptera: Aeshnidae, Corduliidae, Gomphidae, and Libellulidae. In total, 54 muscles were identified: 16 prothoracic, 19 mesothoracic, and 19 metathoracic. Recorded differences were for example, the reduction of muscle Idlm4 and an additional muscle IIIdlm1 in Aeshna cyanea, previously described as rudimentary or missing. Muscle Iscm1, which was previously reported missing in all Odonata, was found in all investigated species. The attachment of muscle IIpcm2 in Pantala flavescens is interpreted as a probable adaption to its long-distance migration behaviour. Furthermore, we present a review of functions of the odonatan flight muscles, considering previous publications. The data herein set a basis for functional and biomechanical studies of the flight apparatus and will therefore lay the foundation for a better understanding of the odonatan flight.     

Investigation into mountain pine beetle above-canopy dispersion using weather radar and an atmospheric dispersion model

Above-canopy, wind-assisted mountain pine beetle (MPB) dispersion in British Columbia (BC) is examined during the summer 2005 beetle emergence period. Above-canopy dispersion is simulated by the HYSPLIT atmospheric dispersion model using back trajectories started from locations identified by clear-air returns from the Prince George BC weather radar station. The dispersion calculations are carried out over the 10 days showing the highest intensity of clear-air returns from the 2005 emergence season. The Weather Research and Forecast (WRF) model is used to simulate the meteorological conditions during each of the 10 emergence days. Cumulative clear-air returns throughout each emergence day are used to estimate the distribution of beetle emergence times and atmospheric residence times. Evaluation of the WRF model output is presented using both surface and upper air observations. Evaluation of the HYSPLIT model is performed through a comparison of the vertical distribution of MPB observed in a previous study. A secondary HYSPLIT evaluation is performed using aerial surveys taken during the following summer (2006), which identify the previous years’ beetle-infested regions. Beetle flight distances from the time of beetle emergence to the time of peak clear-air returns are calculated for each trajectory, and the distribution of all flight distances is presented. The mean back trajectory distance is 20.2 km with a standard deviation of 13.6 km. These values represent the MPB flight distance during half of the beetle atmospheric residence time, and typical daily wind-assisted dispersion distances would be expected to be roughly double this value. Mean beetle residence time in the atmosphere over the 10 emergence events is found to be 3.2 h.     

Using automated flight mills to manipulate fat reserves in Douglas-fir beetles (Coleoptera: Curculionidae)

Because current techniques for quantifying fat, the main fuel used for flight in insects, are destructive, researchers are limited to only one direct measure of fat per specimen. This limitation is problematic for studies aimed at assessing whether fat loss through flight influences subsequent behavioral activity. To overcome this problem, we used body volume, body mass, emergence day, and brood density as parameters in a multiple regression model to predict initial fat levels in female Douglas-fir beetles, Dendroctonus pseudotsugae Hopkins, on emergence from the host. The model explained 54% of the variation in fat reserves as determined by Soxhlet extraction with petroleum ether. Treatments of 30-1,380 min of flight on rotary flight mills were used to establish the relationship between flight and fat reserves. Using a model that incorporated estimated initial fat levels, as well as time spent in flight and time in nonflight activities on the flight mills, we found that 6 h of flight decreased fat by approximately 50%. Flight activity and nonflight activity did not differ significantly in terms of their effect on fat reserves. Individual beetles with high initial fat content flew longer and faster on flight mills than beetles with low initial fat reserves. Our study shows how researchers can manipulate fat levels in bark beetles and other insects through flight, thereby opening the door to using these manipulations in behavioral studies.     

Dispersal and influences on movement for Anoplophora glabripennis calculated from individual mark-recapture

We conducted an individual mark‐release‐recapture experiment on the beetle, Anoplophora glabripennis Motchulsky (Coleoptera: Cerambycidae). This invasive beetle has been introduced from Asia to Europe and North America and poses a serious threat to several important species of tree. Eradication efforts may benefit from knowledge of dispersal behaviour. Trees were cut and held to determine emergence rate of A. glabripennis. Unique marks were painted onto 912 beetles released into a group of 165 trees in Gansu, China. Data on subsequent sightings of beetles were used in a truncated diffusion model to calculate flight distances. Characteristics of the trees and climatic information were used in statistical tests for influence on movement. A total of 2245 sightings of beetles were observed and 29% of marked beetles were resighted. The scanning technique using binoculars was 90% effective in finding beetles and provided 81% accuracy for determining the sex of the beetles. Experimental manipulation of density quantified how A. glabripennis congregated on unoccupied trees and were repulsed from crowded hosts. The seasonal emergence rate of adults declined exponentially from July 20 to August 5. The results suggested A. glabripennis fly to nearby host trees at a rate of 34% per day. Median flight distance was estimated at 20 m per day. Statistical analysis with a generalized linear model tested the beetle's propensity to leave a tree and distance of flight. Generally, beetle movement showed a significant response to beetle density, weather conditions, beetle size, and tree size, in that order. The techniques developed here improve on previous recapture techniques to quantify dispersal and can be useful for analysing populations of other organisms.     

Relative flight responses of Rhagoletis indifferens as influenced by crowding, sex, and resources

Although flight is believed to be the primary mechanism for dispersal in the Western cherry fruit fly, Rhagoletis indifferens Curran (Diptera: Tephritidae), an orchard pest of both sweet (Prunus avium L.) and sour (Prunus cerasus L.) (Rosaceae) cherry crops, the movement of these flies between host patches is difficult to quantify in the field. A tethered flight mill system was used in the laboratory to examine the flight behaviour of sexually mature flies exposed to different levels of conspecific contact and resource availability. A complete 2 × 2 × 3 factorial design compared the relative influence of the factors ‘context’ (crowded, isolated), ‘sex’ (female, male), and ‘resources’ (low = food only; medium = food + leaf; high = food + leaf + cherries) on flight performance measures including distance flown, net trial time, and stopping patterns. Rather than using a minimum time or distance to determine trial length, flight observations were continued for each fly until a behavioural protocol based on stopping time was met. In this protocol each successful trial was composed of three consecutive flight intervals and included a minimum of three stops lasting a combined total of 5 min. Of the 160 flies tested, 86.9% flew <500 m on the flight mill. Individuals from both sexes were capable of maximum flights in the same order of magnitude, ca. 3 km on the flight mill. Distance flown was significantly influenced by ‘context’ such that crowded individuals flew >1.5-fold farther than isolated individuals. Sex influenced the frequency and duration of stops made, with females stopping more often and longer than males. Although females and males in high resource treatments had the shortest net trial times, the factor ‘resources’ did not produce any highly significant main effects, but did generate significant interaction terms with the factors ‘context’ and ‘sex’, suggesting that past experience with ‘resources’ modifies individual flight behaviour. We have shown for the first time using a tethered flight mill system that R. indifferens flight behaviour is context dependent and sensitive to adult crowding. The implications of this study for improved field experiments on dispersal are discussed.     

Ant attendance reduces flight muscle and wing size in the aphid Tuberculatus quercicola

In otherwise mutualistic relationships between aphids and ants, attendance by ants often has negative impacts on aphids. For example, in a previous study using traps in the field, the aphid Tuberculatus quercicola, which exhibits mutualistic interactions with ants, showed extremely low dispersal rates, despite having long wings. This study investigates whether components of the flight apparatus (mesonotum length, flight muscle and wings) differ between aphids attended by ants and not attended by ants. Randomized block analysis of variance, using body length as a covariate, showed that ant attendance has a negative influence on aphid flight apparatus. This result indicates that aphids produce honeydew at the expense of resource investment in flight apparatus. Since the dispersal of T. quercicola is limited under ant attendance, the reduction in flight apparatus could precede a decrease in body size. This study also showed that flight apparatus was more developed in aphids under ant-exclusion conditions. This may imply that T. quercicola fly when ants are not available. The maintenance of flight apparatus in T. quercicola might therefore be partly explained by gene flow on the rare occasions that this aphid species disperses.     

粘虫飞行对生殖及寿命的影响

该文报道了粘虫Mythimna separata（Walker）成虫飞行后产卵、交配及寿命的研究结果。1日龄成虫飞行6 h、12 h、18 h、24 h后的产卵前期均显著短于对照的,其中飞行6 h、12 h的比对照的短2天以上,产卵量均比对照的高。对1～5日龄成虫分别飞行23.5 h后的研究结果表明,1日龄飞行的产卵前期和上述结果相一致。2～4日龄飞行的与对照的没有显著差异,但产卵量则随飞行日龄的延迟而逐渐减少。5日龄飞行的产卵前期显著延长,产卵量已不到对照的一半。所有经过飞行的成虫产卵高峰日比对照的早1天。不同日龄成虫飞行时间、距离与成虫产卵量的关系为：1～3日龄飞行时间、距离长的个体产卵量也高;但4～5日龄的成虫飞行时间与距离越长,其产卵量越少,表现出明显的卵子发生飞行拮抗症(oogenesis-flight syndrome)。除了5日龄飞行的成虫交配率有所下降以外,所有经过飞行的成虫产卵历期、交配率及寿命与对照的没有显著差异。最后,根据这些结果,对粘虫迁飞的起飞时期,迁飞在粘虫生殖、种群动态及成灾规律中的作用进行了讨论。     

稻水象甲(Lissorhoptrus oryzophilus Kuschel)滞育征候群中的飞行行为

１９９４－１９９６年对浙江省双季稻区稻水象甲（ＬｉｓｓｏｒｈｏｐｔｒｕｓｏｒｙｚｏｐｈｉｌｕｓＫｕｓｃｈｅｌ）飞行行为的研究表明,稻水象甲飞行扩散的行为特征是：（１）长时间的起飞准备和不高的起飞成功率,每晚的迁出率只有三分之一左右,（２）卵巢,飞行肌呈季节性消长而无局地飞行（ｔｒｉｖｉａｌｆｌｉｇｈｔ）;（３）飞行速度不高,飞行能力不强,且风力稍大便无法起飞,一般情况下不会形成远距离自然扩散,因此     

STUDIES ON SOIL POPULATION OF CONTARINIA PISI WINN. IN 1957 IN YORKSHIRE AND LANCASHIRE

For studying the population of pea-midge cocoons, larvae and pupae in the soil, a new method of examining the 'float' obtained from washing soil through the wet-extraction apparatus is described.
Examination of soil samples in the summer of 1957 from fields which carried heavily attacked pea crops in 1956 indicated that pupae were present at depths of 0–3, 3–6, 6–9 in., respectively, from 18 June onwards, and that the peak emergence of midges was in the period 28 June-2 July; observations on adult activity in pea fields confirmed this. Small numbers of pupae were recovered throughout July.
Similar studies on pea fields in 1957 showed the build-up of the cocoon population and the rate of pupation of this generation of larvae. The first flight of 1957 was composed of individuals from the 1956 generation and was far larger than the second flight, which was composed of some 1956 generation and part of the first 1957 generation.
There were indications that increases of temperature might accelerate pupation with a resulting earlier emergence of adults.
The size of midge populations recorded from soil from green pea and dry-harvesting pea fields tended to be similar and appeared to be related to sowing date.     

Swarming and mating behaviour ofChironomus flaviplumus (Diptera: Chironomidae), compared with a sympatric congeneric species,C. yoshimatsui

The swarming and mating behaviour ofChironomus flaviplumus was observed and compared with a sympatric congeneric species,C. yoshimatsui. C. flaviplumus males swarmed around sunset near foliage or angles of buildings near the emergence site and copulated with females entering the swarm. Swarming and mating occurred under conditions of higher light intensity in cooler seasons than in warmer ones. Results suggested that temperature had an effect on the timing of flight to the swarming site in both sexes. TheC. flaviplumus swarm marker and swarming behaviour seemed very similar to that toC. yoshimatsui, and their respective daily swarming time zone greatly overlapped. No mixed swarm, however, was observed in the study area. This is probably due to the distance between the species' larval habitats. Possible premating isolation mechanisms between these 2 species are discussed.     

A songbird inhibits blinking behaviour in flight

Visual attention plays a fundamental role in avian flight but attention is likely limited whenever birds blink. Because blinks are necessary to maintaining proper vision, this study tested the hypothesis that birds strategically inhibit their blinks in flight. The blinks of captive great-tailed grackles (Quiscalus mexicanus) were recorded before, during and after they flew a short distance in an open environment. The grackles spent the least amount of time blinking in flight (take-off, during flight and landing) and the most amount of time blinking at impact. Their blinking behaviour was similar before and after flight. These results suggest that grackles strategically inhibit their blinking behaviour in flight, potentially because blinks impose costs to avian flight.     

Accelerated and Synchronized Oviposition Induced by Flight of Young Females May Intensify Larval Outbreaks of the Rice Leaf Roller

Physiological management of migration-reproduction trade-offs in energy allocation often includes a package of adaptions referred to as the oogenesis-flight syndrome. In some species, this trade-off may be overestimated, because factors like flight behavior and environmental conditions may mitigate it. In this study, we examined the reproductive consequences induced by different flight scenarios in an economically-important Asian migrant insect, Cnaphalocrocis medinalis. We found that the influences of flight on reproduction are not absolutely positive or negative, but instead depend on the age at which the moth begins flight, flight duration, and how many consecutive nights they are flown. Adult flight on the 1st or 2nd night after emergence, flight for 6 h or 12 h nightly, and flight on the first two consecutive nights after emergence significantly accelerated onset of oviposition or enhanced synchrony of egg-laying. The latter can contribute to subsequent larval outbreaks. However, flight after the 3rd night, flight for 18 h at any age, or flight on more than 3 consecutive nights after adult emergence did not promote reproductive development, and in some scenarios even constrained adult reproduction. These results indicate that there is a migration/reproduction trade-off in C.medinalis, but that it is mitigated or eliminated by flight under appropriate conditions. The strategy of advanced and synchronized oviposition triggered by migratory flight of young females may be common in other migratory insect pests.     

Laboratory evaluation of flight performance of the plum curculio (Coleoptera: Curculionidae)

Flight performance of laboratory-reared adults of the plum curculio, Conotrachelus nenuphar (Herbst) (Coleoptera: Curculionidae), was investigated under controlled conditions by using a flight mill system. Across all insects tested (n=198), median values of total distance traveled, total flight time, and maximum uninterrupted flight time were 122.7 m day(-1), 23.5 min day(-1), and 2.0 min, respectively. The latter result indicates that flight occurred primarily in short bursts. Although females had a significantly higher body mass than males, there were no significant differences in flight performance between the two sexes. Flight during the first 24-h test period (especially the first 6 h) was dominated by escape behavior, i.e., elevated levels of activity presumably associated with attempts by the insects to regain freedom of movement; during the second 24 h, flight activity was very limited throughout the late morning and afternoon, increased around sunset, and remained high during the night. All flight performance variables decreased linearly and significantly with insect age over the age range tested (2-16 d after emergence). Nutritional status also had a significant effect, whereby insects that had been provided with apples as a food source for 2 d after emergence showed considerably improved flight performance compared with those that had been given no food or only water during the same period. There was no significant effect of mating status on flight performance of male or female insects.     

Foraging behaviour of a leafminer parasitoid in the field

Abstract. 1. The searching behaviour of the parasitoid Sympiesis sericeicornis Nees (Hymenoptera, Eulophidae) is analysed under field conditions.
2. Females were tracked when flying around the canopy of apple trees infested with the tentiform leafminer Phyllonorycter cydoniella (D. & S.)(Lepidoptera, Gracillariidae) and their behaviour studied at the level of a single mine and at the level of several mines on the same leaf (patch level).
3. The presence of mines is detected during flight. The foraging behaviour at the patch level is efficient: the female is able to distinguish the suitable from the unsuitable hosts and handle the suitable hosts first. Not all mines are visited before departure from the leaf and those left unvisited are exclusively mines without suitable hosts. The patch leaving rule is discussed.
4. An ethogram of the behaviour on the mine is constructed. Selected behavioural categories are analysed for different combinations of mine content and outcome of the visit to the mine. The assessment of the mine content is done in a differential way, quickly and without mistakes.
5. The results are discussed in the context of two environmental factors, wind speed and temperature, which reduce the available time for searching. They are also related to the growing percentage of unsuitable hosts during each host generation. Tentiform mines remain attractive for a long period of time, even after parasitism or emergence of the adult, and their examination reduces the rate of host discovery.     

Ontogeny of flight initiation in the fly <Emphasis Type="Italic">Drosophila melanogaster</Emphasis>: implications for the giant fibre system

There are two modes of flight initiation in Drosophila melanogaster—escape and voluntary. Although the circuitry underlying escape is accounted for by the Giant fibre (GF) system, the system underlying voluntary flight initiation is unknown. The GF system is functionally complete before the adult fly ecloses, but immature adults initially fail to react to a stimulus known to reliably evoke escape in mature adults. This suggests that escape in early adulthood, ∼2-h post-eclosion, is not automatically triggered by the hard-wired GF system. Indeed, we reveal that escape behaviour displays a staged emergence during the first hour post-eclosion, suggesting that the GF system is subject to declining levels of suppression. Voluntary flight initiations are not observed at all during the period when the GF system is released from its suppression, nor indeed for some time after. We addressed the question whether voluntary flight initiation requires the GF system by observing take-off in Shak-B ² mutant flies, in which the GF system is defunct. While the escape response is severely impaired in these mutants, they displayed normal voluntary flight initiation. Thus, the escape mechanism is subject to developmental modulation following eclosion and the GF system does not underlie voluntary flight. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Antagonistic and reinforcing pleiotropy: a study of differences in development time in wing dimorphic insects

Morphological dimorphisms are found in many different taxa. Wing dimorphism in insects, in which some individuals possess wings and associated flight muscles and are thus volant while others lack a functional flight apparatus and are thus flightless, is a typical example of such types of dimorphisms. It has been extensively studied and such studies have demonstrated that the volant form, although possessing the advantage of flight capability, suffers a fitness cost in a delay in the onset of reproduction after emergence into the adult form and a reduced fecundity. Previous comparative analyses have suggested that there is no consistent trend for development time (hatching to adult) to differ between the two morphs. The present study analyses the phenotypic and genetic correlations between development time and wing morph in the cricket Gryllus firmus. It is shown that the macropterous (volant) morph develops faster than the micropterous (flightless morph). This trade-off is manifested at both thephenotypic and genetic level. Further, a comparative analysis shows that the same phenotypic trade-off is generally found in other Orthopteran species so far studied, but in other orders the micropterous morph develops faster. Provided that the phenotypic trade-off is genetically based, in the Orthoptera the fitness advantage of the earlier onset of reproduction in micropterous females is offset by the extended development time (antagonistic pleiotropy). However, in other orders there is reinforcing pleiotropy in that the micropterous females develop faster and reproduce sooner than the macropterous morph. These results highlight the complexity of fitness interactions and the need to study a phenomenon across several taxa.     

Sexual differences rather than flight performance underlie movement and exploration in a tropical butterfly

1. Individual movement behaviour governs several routine processes, and may scale up to important ecological processes, including dispersal. However, movement is affected by a wealth of factors, including abiotic conditions, flight performance, and behavioural traits. Although it has been historically assumed that insect flight is in the first place ruled by physiology and morphology, researchers have only recently begun to understand the potentially important role of behavioural traits. 2. This study aims to disentangle the relative importance of thermal conditions during development, and especially flight performance (capacity), versus behaviour (intrinsic motivation) in relation to movement attributes (i.e. time until take‐off, number of positions visited) under controlled laboratory conditions in the tropical butterfly Bicyclus anynana. 3. As predicted, links were found between flight performance (forced flight) and morphological traits (body size). However, this link was less pronounced for movement and exploratory behaviour, suggesting a more pronounced role of intrinsic motivation on the actual decision to move, or not. Thus, flight performance and movement may not be intimately associated. 4. Flight behaviour was mainly determined by sexual differences, with males showing better flight performance, higher mobility, and enhanced exploration than females. 5. Lower developmental temperatures increased thorax–abdomen ratio, thorax mass, and exploratory behaviour, and decreased wing loading. This may potentially aid flight capacity under thermally challenging conditions. 6. This study adds to the growing evidence that behavioural traits should not be neglected when investigating movement and dispersal, as they may well play a crucially important role.