Auditory sensitivity of Hawaiian moths (Lepidoptera: Noctuidae) and selective predation by the Hawaiian hoary bat (Chiroptera: Lasiurus cinereus semotus).

The islands of Hawai'i offer a unique opportunity for studying the auditory ecology of moths and bats since this habitat has a single species of bat, the Hawaiian hoary bat (Lasiurus cinereus semotus), which exerts the entire predatory selection pressure on the ears of sympatric moths. I compared the moth wings discarded by foraging bats with the number of surviving moths on the island of Kaua'i and concluded that the endemic noctuid Haliophyle euclidias is more heavily preyed upon than similar-sized endemic (e.g. Agrotis diplosticta) and adventive (Agrotis ipsilon and Pseudaletia unipuncta) species. Electrophysiological examinations indicated that, compared with species less preyed upon, H. euclidias has lower auditory sensitivities to the bat's social and echolocation calls, which will result in shorter detection distances of the bat. The poor ears of H. euclidias suggest that this moth coevolved with the bat using non-auditory defences that resulted in auditory degeneration. This moth now suffers higher predation because it is drawn away from its normal habitat by the man-made lights that are exploited by the bat.     

Otoacoustic emissions from insect ears: evidence of active hearing?

Sensitive hearing organs often employ nonlinear mechanical sound processing which generates distortion-product otoacoustic emissions (DPOAE). Such emissions are also recordable from tympanal organs of insects. In vertebrates (including humans), otoacoustic emissions are considered by-products of active sound amplification through specialized sensory receptor cells in the inner ear. Force generated by these cells primarily augments the displacement amplitude of the basilar membrane and thus increases auditory sensitivity. As in vertebrates, the emissions from insect ears are based on nonlinear mechanical properties of the sense organ. Apparently, to achieve maximum sensitivity, convergent evolutionary principles have been realized in the micromechanics of these hearing organs-although vertebrates and insects possess quite different types of receptor cells in their ears. Just as in vertebrates, otoacoustic emissions from insects ears are vulnerable and depend on an intact metabolism, but so far in tympanal organs, it is not clear if auditory nonlinearity is achieved by active motility of the sensory neurons or if passive cellular characteristics cause the nonlinear behavior. In the antennal ears of flies and mosquitoes, however, active vibrations of the flagellum have been demonstrated. Our review concentrates on experiments studying the tympanal organs of grasshoppers and moths; we show that their otoacoustic emissions are produced in a frequency-specific way and can be modified by electrical stimulation of the sensory cells. Even the simple ears of notodontid moths produce distinct emissions, although they have just one auditory neuron. At present it is still uncertain, both in vertebrates and in insects, if the nonlinear amplification so essential for sensitive sound processing is primarily due to motility of the somata of specialized sensory cells or to active movement of their (stereo-)cilia. We anticipate that further experiments with the relatively simple ears of insects will help answer these questions.     

Moth hearing on the Faeroe Islands, an area without bats

ABSTRACT. The ultrasound-sensitive ears found in several families of moths are believed to be part of a predator (bat) specific defence strategy; the moth's evasive responses, elicited by the calls of bats, reduce its chances of being caught. Bats have never been found on the Faeroe Islands, whereas moths migrated there before the last Ice Age, and have since been isolated from areas with bats. For this reason, the hearing characteristics of moths from the Faeroes are investigated in this study. All noctuid moths caught there have functional ears sensitive to ultrasound. Audiograms are determined for thirty-two individuals of four noctuid species: Cerapteryx gramminis L., Apamea crenata Hūfn., Apamea maillardi Gey. and Diarsia mendica F. The auditory characteristics of the moths from the Faeroes resemble those of moths from other temperate zones where bats are abundant. The audiograms revealed best frequencies between 20 and 45 kHz, relatively broad turnings (Q_10dB around 1), and thresholds of 35–50 dB SPL at the best frequency. The fact that the moths on the Faeroes possess such sensitive ears is explained by the large time spans which might be required for reduction of a character which is not directly opposed by a selection pressure.     

Observations on the blood of a tropical bat, Otomops martiensseni

Observations are reported on the composition of the blood of a tropical, cave-dwelling bat, Otomops martiensseni. The most remarkable feature of the blood was the very high numbers of erythrocytes, with mean values of 14–42 times 10⁶ and 12–46 times 10⁶ cells per mm³ of blood, for female and male bats respectively. The red cells were spherical, biconcave discs with a mean diameter of 5-3 um, a mean thickness of 1–8 urn and a mean volume of 40-7 μm³. High haemoglobin values were obtained, with means of 20–70 and 18-15 g per 100 ml of blood, for female and male bats respectively. The leucocyte count varied from 1360 to 5200 cells per mm³ of blood and was rather lower than in other mammals. Electrophoresis of serum gave six protein fractions which were identified as albumin and α₁α₂, β₁β₂ and γ globulins.     

Moth wing scales slightly increase the absorbance of bat echolocation calls

Coevolutionary arms races between predators and prey can lead to a diverse range of foraging and defense strategies, such as countermeasures between nocturnal insects and echolocating bats. Here, we show how the fine structure of wing scales may help moths by slightly increasing sound absorbance at frequencies typically used in bat echolocation. Using four widespread species of moths and butterflies, we found that moth scales are composed of honeycomb-like hollows similar to sound-absorbing material, but these were absent from butterfly scales. Micro-reverberation chamber experiments revealed that moth wings were more absorbent at the frequencies emitted by many echolocating bats (40-60 kHz) than butterfly wings. Furthermore, moth wings lost absorbance at these frequencies when scales were removed, which suggests that some moths have evolved stealth tactics to reduce their conspicuousness to echolocating bats. Although the benefits to moths are relatively small in terms of reducing their target strengths, scales may nonetheless confer survival advantages by reducing the detection distances of moths by bats by 5-6%.     

Behaviors of Western Spruce Budworm Moths (Choristoneura occidentalis) as Defences Against Bat Predation

We investigated potential defense behaviors of adult western spruce budworm (Choristoneura occidentalis), a non-auditive lepidopteran, against bat predation. Although western spruce budworm moths started to fly before sunset, earlier than many species of moths, temporal isolation of flying moths from foraging bats was incomplete as moths were most active after sunset once bats were foraging. Flying C. occidentalis were most active close to their host trees, and thus were isolated from some bat activity because vegetation limits foraging by some bats. Moths mostly flew near the tops of trees, an area that may have a high predation pressure from bats. Resting western spruce budworm spent little time fluttering their wings or crawling, behaviors that are used as cues by gleaning bats. The outbreak nature of this species, in which large numbers of moths are active at one time, may allow dilution effects to reduce predation risk.     

High mortality and female‐biased operational sex ratio result in low encounter rates and moderate polyandry in a spider

The taxonomy of the Old World bat genus Otomops (Chiroptera: Molossidae) has been the subject of considerable debate. The failure of classical morphological studies to provide consistent patterns regarding interspecific relationships within Otomops has limited any understanding of the evolutionary history of the genus. We used traditional and geometric morphometric approaches to establish the species limits of taxa from sub‐Saharan Africa, the Arabian Peninsula, and Madagascar. Morphometric data supported the recent recognition of three distinct Afrotropical taxa: Otomops madagascariensis from Madagascar; Otomops martiensseni s.s. from southern, eastern, central, and western Africa; and an undescribed taxon from north‐east Africa and the Arabian Peninsula. Analyses of craniodental measurements and landmark‐based data showed significant cranial size and shape divergence between the three taxa. Cranial size and shape variation within Afro‐Arabian Otomops were strongly influenced by altitude, seasonality of precipitation, and precipitation in the driest month. Based on morphometric patterns and molecular divergence estimates, we suggest that morphological evolution within Afro‐Arabian Otomops occurred in response to the fluctuating climate during the Pleistocene on the one hand, and the increasing aridity and seasonality over north‐eastern Africa on the other. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, •• , ••–••.     

Fearful symmetry? Intra-individual comparisons of asymmetry in cryptic vs. signalling colour patterns in butterflies

The signalling role of asymmetry has attracted considerable recent interest among evolutionary biologists. Although it has been studied primarily within the context of sexual selection, symmetry of signals may play a role also in inter-specific communication, such as predator–prey interactions. Both theory and experimental evidence suggest that asymmetry may impair the efficacy of visual warning signals used to deter potential predators, but increase the protective value of non-signalling, cryptic colour patterns used to decrease the risk of detection. Here we tested the prediction from this hypothesis by means of intra-individual comparisons of asymmetry in colour pattern elements in three species of moths (Arctia caja (L.), Noctua orbona (L.), Smerinthus ocellata (L.)) that possess cryptic fore wing patterns and signalling hind wing patterns. Mean asymmetries constituted 4.3% (range 2.1–7.0%) of trait size for colour pattern elements, whereas individual asymmetry levels reached as high as 26%. Asymmetry tended to be somewhat larger in cryptic patterns on fore wings than in signalling patterns on hind wings in five of six comparisons, but in only one case was the difference statistically significant. In addition, pattern elements were somewhat more asymmetric on fore wings also in Saturnia pavonia (L.), which possesses identical signalling eyespots on both fore and hind wings. The relatively low levels of asymmetry also in cryptic patterns imply either that selection does not favour increased asymmetry in cryptic patterns, or that the evolution of pronounced asymmetry is developmentally or genetically constrained.     

On the selective forces acting in the industrial melanism of Biston and Oligia moths (Lepidoptera: Geometridae and Noctuidae)

Melanic and typical morphs of Biston betularius (L.), Oligia latruncula (D. & S.) and 0. strigilis (L.) made choices between vertical trunks and horizontal branches, sprayed with white and black paints, in a transparent plastic cylinder in natural illumination. The moths settled in exposed positions. In neither Biston nor Oligia did the choice for white/black backgrounds differ between the morphs. Biston moths settle on narrow branches (not on twigs) with the body at right angles to the longitudinal axis of the branch. The Oligias showed an asymmetrical light reaction: one eye is kept in shadow so that they settle as a continuation of an irregularity of the surface, often of a lichen.
In nature, Biston betularius probably rests high up in the canopies, on the under surfaces of horizontal branches. The visual selection acting on the morphs is expected to be less intensive than that measured on tree trunks. The mark-release-recapture results of Kettlewell (1955a, 1956) do not show any qualitative change during the self-determination of the moths but the material is too limited for firm conclusions.
Newly-hatched Biston males take off straight from the trunk where they have expanded their wings but the females may climb higher in the tree. A hypothesis is presented to explain the black-and-white coloration of f. carbonaria : the short-winged moths climbing up the trunks might deter bird predation.     

福建省三明市发现南长翼蝠

2013年7月在福建省三明市尤溪县梅仙镇峰岩村峰岩3号洞(26°15'15″N,118°16'55″E,海拔536 m)用雾网采集到4只蝙蝠(1♀、3♂)。利用数显电子秤和数显游标卡尺测量了外形17项及头骨25项指标,并与文献记载的海南、爪哇岛、斯兰岛标本进行了比对。体型较小,耳短而宽,毛短而密,毛被扩展到鼻子后方,背毛黑褐色,腹毛深棕色,头颈部毛色与腹部毛色较一致;翼膜狭长,第Ⅲ指第二指节的长度约为第一指节的3倍;头骨的吻突低而略宽,脑颅高、大而圆;体重7.1~9.8 g,前臂长41.7~43.7 mm,颅全长13.87~14.17 mm,颅高6.21~6.73 mm。经鉴定为南长翼蝠(Miniopterus pusillus),为福建省翼手类新纪录。标本保存在河南师范大学生命科学学院。     

Bat-deafness in day-flying moths (Lepidoptera, Notodontidae, Dioptinae)

Assuming that bat-detection is the primary function of moth ears, the ears of moths that are no longer exposed to bats should be deaf to echolocation call frequencies. To test this, we compared the auditory threshold curves of 7 species of Venezuelan day-flying moths (Notodontidae: Dioptinae) to those of 12 sympatric species of nocturnal moths (Notodontidae: Dudusinae, Noctuidae and Arctiidae). Whereas 2 dioptines (Josia turgida, Zunacetha annulata) revealed normal ears, 2 (J. radians, J. gopala) had reduced hearing at bat-specific frequencies (20–80 kHz) and the remaining 3 (Thirmida discinota, Polypoetes circumfumata and Xenorma cytheris) revealed pronounced to complete levels of high-frequency deafness. Although the bat-deaf ears of dioptines could function in other purposes (e.g., social communication), the poor sensitivities of these species even at their best frequencies suggest that these moths represent a state of advanced auditory degeneration brought about by their diurnal life history. The phylogeny of the Notodontidae further suggests that this deafness is a derived (apomorphic) condition and not a retention of a primitive (pleisiomorphic), insensitive state. Accepted: 1 May 1997     

Tympanal and atympanal 'mouth-ears' in hawkmoths (Sphingidae).

The labral pilifers and the labial palps form ultrasound-sensitive hearing organs in species of two distantly related hawkmoth subtribes, the Choerocampina and the Acherontiina. Biomechanical examination now reveals that their ears represent different types of hearing organs. In hearing species of both subtribes, the labral pilifer picks up vibrations from specialized sound-receiving structures of the labial palp that are absent in non-hearing species. In Choerocampina, a thin area of cuticle serves as an auditory tympanum, whereas overlapping scales functionally replace a tympanum in Acherontiina that can hear. The tympanum of Choerocampina and the scale-plate of Acherontiina both vibrate maximally in response to ultrasonic, behaviourally relevant sounds, with the vibrations of the tympanum exceeding those of the scale plate by ca. 15 dB. This amplitude difference, however, is not reflected in the vibrations of the pilifers and the neural auditory sensitivity is similar in hearing species of both subtribes. Accordingly, morphologically different - tympanal and atympanal - but functionally equivalent hearing organs evolved independently and in parallel within a single family of moths.     

The zoogeography, ecology and taxonomy of the genus Labeotropheus Ahl, 1927, of Lake Malawi (Pisces: Gichlidae)

Two species of Labeotropheus are currently recognized, but an earlier study of aquarium specimens caused doubt to be cast upon their specific distinctness. This doubt was removed by a field and laboratory study which showed that L. fuelleborni differed from L. trewavasae morphologically, in coloration, in geographic distribution, preferred habitat and ability to penetrate depth. The two species practise assortative mating.
Labeotropheus fuelleborni feeds predominantly from upper surfaces of rocks while L. trewavasae favours under surfaces. Although both species are specialized to crop epilithic algae they also feed secondarily on other food resources (e.g. plankton, insects) when these are available.
Gene flow between many populations of rock-frequenting cichlids is restricted by their sedentary nature and apparent inability to cross open water between rocky areas. Consequently, numerous geographic races, incipient species and species are found in the lake. This suggests that intralacustrine allopatric speciation may account for much of the species diversity of cichlids of rocky zones.
It is recommended that biologists working on cichlids from Lake Malawi should ascertain the precise location at which their specimens were caught and avoid using aquarium reared fish.     

Auditory changes in noctuid moths endemic to a bat-free habitat

If the ears of moths exist primarily to detect the echolocation calls of hunting bats, endemic moths in bat-free areas (i.e., species that have evolved in the absence of the selection pressure maintaining ears) should exhibit signs of deafness. Noctuid moths from the Pacific islands of French Polynesia, a site that has never possessed bats, were sampled and electrophysiologically analysed to test this hypothesis. The auditory sensitivities of seven endemic and twelve immigrant species, captured from the islands of Tahiti, Moorea, and Hiva Oa, were compared. Both classes possess neurally responsive ears, but endemics are significantly deafer than immigrants at frequencies above 35 kHz. This form of deafness is similar to other moths presumably released from the selection pressure of bat predation. I conclude that endemic moths at this site exhibit preliminary stages of deafness and that, considering their small cellular investment, ears in moths will be lost at a slower rate than more complex sensory organs.     

The effect of adult feeding on lipid and protein reserves in African armyworm, Spodoptera exempta, moths before and during reproduction

ABSTRACT. Newly-emerged Spodoptera exempta (Walker) (Lepidoptera: Noctuidae) moths contain high levels of lipid held largely in the abdominal fat body, the quantity depending on the larval feeding conditions. There is a positive relationship between weight-related lipid content and moth weight, which is consistent for female but not for male moths, suggesting that larval feeding conditions producing large individuals allow the accumulation of quantitatively disproportionate lipid reserves. Male and female moths have comparable levels of abdominal protein.
Changes in the water content in starved moths or ones provided with distilled water or sucrose solution show that while starved individuals die rapidly from desiccation, water-fed moths regulate their water contents between narrow limits which are higher for females than for males. Sucrose-fed moths maintain higher, more variable water contents probably due to the phagostimulatory effect of the sugar.
Reproducing and unmated moths are able to supplement their lipid and, to a lesser extent, their protein reserves following carbohydrate uptake.
During both larval and early adult stages, the capacity to accumulate lipid reserves in excess of those apparently required for reproduction, suggests that these reserves also provide the main fuel for the prolonged flights of which migratory individuals are known to be capable.     

Nestling obesity in procellariiform seabirds: temporal and stochastic variation in provisioning and growth of short-tailed shearwaters Puffinus tenuirostris

Procellariiform seabirds such as short-tailed shearwaters Puffinus tenuirostris accumulate large quantities of lipid during the nestling period. The functional significance of this pattern of development remains unclear, but has been related both to temporal variation in feeding conditions around the colony and to stochastic variation in the foraging success of individual parents. This paper examines temporal and age-specific variation in the pattern of food delivery to nestling short-tailed shearwaters, which have one of the lowest provisioning rates of any procellariiforms and are known to experience occasional long intervals between feeds. We assess whether variation in the provisioning rates of chicks was associated primarily with temporal variation in food delivery at the level of the colony or with stochastic variation in food delivery at the level of the individual. We then discuss this variability in the context of nestling obesity. For all but the youngest chick age-classes, individual meals delivered by adults averaged 141 g, which was 25% of adult body mass. The proportion of chicks fed each night was low (49%) and highly variable (coefficient of variation = 82%), which means that occasional long intervals between feeds would be expected to arise simply by chance. In keeping with this, intervals between feeding events for individual chicks followed a negative exponential distribution with a mean of 2 nights and a maximum interval of 13 nights. There was significant temporal variation in food delivery, but deviations from expected values for both feeding frequency and meal size were restricted to a small number of nights, included values both higher and lower than expected and did not persist for more than 2 nights in succession. These data suggest that even among those species with very low feeding frequencies and occasional long intervals between feeds, nestling obesity in Procellariiformes should be regarded as a response to chronic stochastic variability in food delivery at the level of the individual chick rather than as insurance against sporadic temporal variation at the level of the colony. Received: 3 March 1997 / Accepted: 10 May 1997     

Reduced antennal sensitivity, behavioural response, and attraction of male codling moths, Cydia pomonella, to their pheromone (E,E)-8,10-dodecadien-1-ol following various pre-exposure regimes

The effects of pre‐exposing male codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), to their pheromone (E,E)‐8,10‐dodecadien‐1‐ol (codlemone), in static and moving air, under laboratory and field conditions, on subsequent antennal sensitivity, behavioural responsiveness, and attraction to codlemone were investigated. In flight tunnel experiments, the percentage of moths wing fanning and taking flight were mostly unaffected, but upwind flight to, and contact with, pheromone sources known to elicit responses of both were shown to depend on the intensity and duration of previous exposure to codlemone and recovery time between exposure and assessment. Ten to 30‐min pre‐exposures to codlemone in static air (≈ 35 µg l^?1) not only caused a 99% reduction in attraction, but also significantly reduced electroantennogram response to codlemone. Recovery of full antennal sensitivity to codlemone took more than 1 h, but recovery of attraction took over 4 h, suggesting that habituation is also partially involved in reduced behavioural responsiveness following pre‐exposure. Seventy‐five min exposures to codlemone in moving air (5–10 cm s^?1) at rates of 0.9, 4.5, and 18 µg h^?1 from Celcon fibres caused 75, 86, and 99% disruption, respectively. However, 30–34‐h exposure of caged moths to air moving through an orchard treated with 1000 Isomate‐C® dispensers ha^?1 releasing approximately 20 µg h^?1 per dispenser during tests, had no impact on moth response in flight‐tunnel assays 30 min after removal from the orchard. In this treated orchard, catches of free‐flying moths in pheromone‐baited traps were completely inhibited. If observed mechanisms such as long‐lasting antennal adaptation or habituation of the central nervous system contribute to the disruption of pheromone communication among codling moths under field conditions, it seems unlikely that they occur following exposure to the average atmospheric concentrations of codlemone. For these effects to be important, codling moths may require close contact with pheromone sources for extended periods, or repeated close encounters.     

Fine nanostructural variation in the wing pattern of a moth <Emphasis Type="Italic">Chiasmia eleonora</Emphasis> Cramer (1780)

Butterflies and moths possess diverse patterns on their wings. Butterflies employ miscellaneous colour in the wings whereas moths use a combination of dull colours like white, grey, brown and black for the patterning of their wings. The exception is some of the toxic diurnal moths which possess bright wing colouration. Moths possess an obscure pattern in the dorsal part of the wings which may be a line, zigzag or swirl. Such patterns help in camouflage during resting period. Thus, the dorsal wing pattern of the moth is used for both intra- as well as inter-specific signal communication. Chiasmia eleonora is a nocturnal moth of greyish black colouration. The dorsal hindwing possesses yellow and black colour patches. A white-coloured oblique line crosses both left and right fore- and hindwings to form a V-shaped pattern across the dorsal wing. This V-shaped pattern possesses a UV signal. Closer to the body, the colour appears darker, which fades towards the margin. The fine nanostructural variation is observed throughout the wings. This study elucidates the wing pattern of the geometrid moth C. eleonora using high-resolution microscopy techniques that has not been described in previous studies.     

Comparison of stimulus-response (V-log I) functions in five types of lepidopteran compound eyes (46 species)

Summary Stimulus intensity-response relations (V-log I curves) were electrophysiologically (ERG) determined for the compound eyes of 46 lepidopteran species belonging to five different groups: butterflies (22 species), hesperids (3 species), diurnal sphingids (2 species), diurnal moths (3 species) and nocturnal moths (16 species). The V-log I curves were fitted to the Naka and Rushton equation, in whichn represents the slope of the linear part of each curve. The slopes so determined range fromn=0.35 (the shallowest slope) in nocturnal moths with the greatest dynamic range ton=0.54 (the steepest slope) in diurnal moths andn=0.53 in butterflies both of which have narrow dynamic range. Hesperids (n=0.41) and diurnal sphingids (n=0.38) have intermediate values between butterflies and nocturnal moths.The ratio of rhabdom to retinula volume is significantly higher in nocturnal moths (70–75%), however, those of butterflies and of diurnal moths are very small (2–5%), and hesperids and diurnal sphingids show intermediate ratio (ca. 25%).The slopes of V-log I curves are inversely proportional to the ratio of rhabdom to retinula volume in the various eye types. In all groups except diurnal moths, the light intensities which produce maximal and saturated responses are nearly the same, therefore the nocturnal moths which have the lowest threshold to light increase their sensitivity to dim light mainly by decreasing the slopes of V-log I curves.