Sphingid Moths Research Articles

The significance of pollination time and frequency and of purity of pollen loads for seed set in Rhinanthus angustifolius (Scrophulariaceae) and Viscaria vulgaris (Caryophyllaceae).

The effects of time of the day and frequency of application and of purity of artificially deposited pollen loads on fruiting and seed set were studied in Rhinanthus angustifolius (diurnally visited by bumblebees) and Viscaria vulgaris (diurnally visited by bumblebees, nocturnally by sphingid moths).Time of the day did not influence pollination success in either species. Increase of pollination frequency increased fruiting and seed set in Rhinanthus but had no affect on Viscaria. Five successive artificial pollinations were needed to achieve seed set equal to that observed naturally in Rhinanthus while a single artificial pollination was sufficient in Viscaria. Mixing Lupinus and Viscaria pollen did not reduce fruiting and seed set in Viscaria. The results are discussed in relation to observed seed sets in early and late flowers, and small and large patches of Viscaria vulgaris and among Rhinanthus flowers in populations of different densities.

Flight Energetics of Euglossine Bees in Relation to Morphology and Wing Stroke Frequency

ABSTRACT Mass-specific oxygen consumption of euglossine bees during free hovering flight is inversely related to body mass, varying from 66mlO2g−1h−1 in a 1−0·10 bee to 154mlO2g−1h−1 in a 0·10-g bee. Individuals of Eulaema and Eufreisea spp. have smaller wings and higher wing stroke frequency and energy metabolism at any given mass than bees of Euglossa spp. or Exaerete frontalis. Calculated aerodynamic power requirements represent only a small fraction of the energy metabolism, and apparent flight efficiency [aerodynamic power (= induced + profile power)/power input] decreases as size declines. If efficiency of flight muscle = 0·2, the mechanical power output of hovering bees varies inversely with body mass from about 480 to 1130 W kg−1 of muscle. These values are 1·9 to 4·5 times greater than previous predictions of maximum mechanical power output (Weis-Fogh & Alexander, 1977; see also Ellington, 1984c). Mass-specific energy expenditure per wing stroke is independent of body mass and essentially the same for all euglossines. Differences in energy metabolism among bees having similar body mass is primarily related to differences in wing stroke frequency. Scaling of energy metabolism in relation to mass is generally similar to the relationship for sphingid moths despite the fact that bees have asynchronous flight muscle whereas moths have synchronous muscle.

Chromosomes of Seven Species of Indian Sphingid Moths

Chromosomes of Seven Species of Indian Sphingid Moths

Pollination of Leuhea (Tiliaceae) In Costa Rican Deciduous Forest

Studies of the reproductive biology of three species of Luehea (Tiliaceae) conducted in Costa Rican deciduous forest demonstrated that all species produce hermaphroditic flowers exhib- iting nocturnal anthesis, anther dehiscence, nectar secretion, and fragrances consistent with adapta- tion for nocturnal moth pollination. Luehea candida, flowering during the wet season, has self- incompatible flowers pollinated primarily by sphingid moths. Generalist diurnal visitors, including stingless bees, flies, and butterflies, were also common flower visitors, but experiments showed that they were ineffective pollinators. Luehea candida apparently rejects pollen from nearby conspecifics as a means of limiting inbreeding resulting from pollination by poor outcrossers such as stingless bees. The principal pollinators of L. seemannii, which flowers during the dry season, were determined to be the same types of diurnal visitors that contributed nothing to pollination success of L. candida. Nocturnal moths were low in abundance during the dry season and pollinated few flowers. Individuals of the deciduous forest population of L. seemannii ranged from partially to fully self-compatible, though an evergreen forest population was self-incompatible. The partial breakdown of incompati- bility, diurnal pollinators, and nectar analysis of L. seemannii suggest an ongoing evolutionary shift to diurnal pollination resulting from the scarcity of nocturnal pollinators and selection by diurnal in- sects, especially stingless bees, in the deciduous forest. Luehea speciosa, with floral morphology and behavior nearly identical to L. candida, rarely attracted sphingids during its blooming period in the early dry season even though these moths were present in the habitat. Chemical analysis showed that nectar of L. speciosa is of a type preferred by bats rather than sphingids, but no evidence for bat pollination could be found. This species may also be pollinated largely by opportunistic diurnal visitors.

Retinular fine structure in compound eyes of diurnal and nocturnal sphingid moths

Retinular fine structure has been compared in the superposition compound eyes of three sphingid moths, one nocturnal, Cechenena, and two diurnal, Cephonodes and Macroglossum. Cechenena and Cephonodes have tiered retinas with three kinds of retinular cells: two distal, six regular and one basal. The distal retinular cells in Cechenena are special in having a complex partially intracellular rhabdomere not present in Cephonodes. Macroglossum lacks the distal retinular cell. In Cephonodes a unique rhabdom type, formed by the six regular retinular cells in the middle region of the retinula, is divided into three separate longitudinal plates arranged closely parallel to one another. Their constituent microvilli are consequently all nearly unidirectional. The ratio of rhabdom volume to retinular cell volume in the two diurnal sphingids is 10-27%; this is about the same as that (25%) of skipper butterflies, but significantly smaller than in the nocturnal Cechenena (60%). In the diurnal sphingids retinular cell membranes show elongate meandering profiles with septate junctions between adjacent retinular cells. From the comparative fine structure of their eyes the diurnal sphingids and the skippers would appear to be phylogenetically closely related.

A comparison of electrophysiologically determined spectral responses in 35 species of Lepidoptera

Spectral responses from the compound eyes of 35 lepidopteran species representing 14 families were investigated electrophysiologically using ERG recordings. The light-stimuli used overed the range of 383–700 nm wavelengths. All species show three or four maxima in their spectral sensitivity curves. Two of these peaks were usually associated with ultraviolet and blue light (383 and 460 nm, respectively). The other maxima occurred in the 500–620 nm region. In Nymphalidae the highest peak was found in response to 560–580 nm stimuli. Of all wavelengths tested, these are the longest wavelengths to produce principal peak sensitivities. Pieridae and Lycaenidae have maxima in the UV region which represent significantly higher sensitivities than the secondary peaks to stimuli of longer wavelengths. Satyridae, Danaidae, Hesperiidae and diurnal moths except Epicopeia (Epicopeidae) generally have similar sensitivity curves with principal peaks between 500 and 520 nm. In Papilionid species except Graphium (max = 560 nm) high maxima occur in the UV and blue (460 nm) region. Noctural Sphingid moths possess the highest peak sensitivity at 540 nm. All other noctural moths tested have three or four maxima.

The altitudinal and geographical distributions of flower types in Rhododendron section Vireya, especially in the Papuasian species, and their significance

Most species of Rhododendron section Vireya from Papuasia can be assigned to well-marked flower types, 127 species being placed in five of these types. It is suggested that two of the main types may be pollinated mainly by birds, one by sphingid moths and one by butterflies. Above 3000 m red-flowered species greatly predominate over those with other colours in Papuasia, and also through much of Malesia; the relationship between ornithophily and this correlation is discussed. The distribution of flower types within supraspecific taxa suggests that some rearrangement of the latter may be necessary; some flower types are demonstrably polyphyletic. It is shown that in west Malesia species with flower colour other than red, not or slightly zygomorphic flowers and relatively longer corolla lobes are commoner than within Papuasia; it appears that section Viveya is, florally at least, most specialized in this latter area. Flower type and pollinators in section Vireya are related to those in the rest of the genus, and it is suggested that the adoption of ornithophily has been an important factor in the success of the Ericaceae as a whole in tropical montane areas.

Quick Estimates of Flight Fitness in Hovering Animals, Including Novel Mechanisms for Lift Production

ABSTRACT On the assumption that steady-state aerodynamics applies, simple analytical expressions are derived for the average lift coefficient, Reynolds number, the aerodynamic power, the moment of inertia of the wing mass and the dynamic efficiency in animals which perform normal hovering with horizontally beating wings. The majority of hovering animals, including large lamellicom beetles and sphin-gid moths, depend mainly on normal aerofoil action. However, in some groups with wing loading less than 10 N m−2 (1 kgf m−2), non-steady aerodynamics must play a major role, namely in very small insects at low Reynolds number, in true hover-flies (Syrphinae), in large dragonflies (Odonata) and in many butterflies (Lepidoptera Rhopalocera). The specific aerodynamic power ranges between 1·3 and 4·7 WN−1 (11–40 cal h−1 gf−1) but power output does not vary systematically with size, inter alia because the lift/drag ratio deteriorates at low Reynolds number. Comparisons between metabolic rate, aerodynamic power and dynamic efficiency show that the majority of insects require and depend upon an effective elastic system in the thorax which counteracts the bending moments caused by wing inertia. The free flight of a very small chalcid wasp Encarsia formosa has been analysed by means of slow-motion films. At this low Reynolds number (10–20), the high lift coefficient of 2 or 3 is not possible with steady-state aerodynamics and the wasp must depend almost entirely on non-steady flow patterns. The wings of Encarsia are moved almost horizontally during hovering, the body being vertical, and there are three unusual phases in the wing stroke: the clap, the fling and the flip. In the clap the wings are brought together at the top of the morphological upstroke. In the fling, which is a pronation at the beginning of the morphological downstroke, the opposed wings are flung open like a book, hinging about their posterior margins. In the flip, which is a supination at the beginning of the morphological upstroke, the wings are rapidly twisted through about 180°. The fling is a hitherto undescribed mechanism for creating lift and for setting up the appropriate circulation over the wing in anticipation of the downstroke. In the case of Encarsia the calculated and observed wing velocities at which lift equals body weight are in agreement, and lift is produced almost instantaneously from the beginning of the downstroke and without any Wagner effect. The fling mechanism seems to be involved in the normal flight of butterflies and possibly of Drosophila and other small insects. Dimensional and other considerations show that it could be a useful mechanism in birds and bats during take-off and in emergencies. The flip is also believed to be a means of setting up an appropriate circulation around the wing, which has hitherto escaped attention; but its operation is less well understood. It is not confined to Encarsia but operates in other insects, not only at the beginning of the upstroke (supination) but also at the beginning of the downstroke where a flip (pronation) replaces the clap and fling of Encarsia. A study of freely flying hover-flies strongly indicates that the Syrphinae (and Odonata) depend almost entirely upon the flip mechanism when hovering. In the case of these insects a transient circulation is presumed to be set up before the translation of the wing through the air, by the rapid pronation (or supination) which affects the stiff anterior margin before the soft posterior portions of the wing. In the flip mechanism vortices of opposite sense must be shed, and a Wagner effect must be present. In some hovering insects the wing twistings occur so rapidly that the speed of propagation of the elastic torsional wave from base to tip plays a significant role and appears to introduce beneficial effects. Non-steady periods, particularly flip effects, are present in all flapping animals and they will modify and become superimposed upon the steady-state pattern as described by the mathematical model presented here. However, the accumulated evidence indicates that the majority of hovering animals conform reasonably well with that model. Many new types of analysis are indicated in the text and are now open for future theoretical and experimental research.

The Suppression of Isolated Populations of Sphingids1 by Blacklight Traps

When blacklight traps were operated at a density of 3/mile2 for 43 months on St. Croix, U. S. Virgin Islands, the collections of sphingid moths were found to be associated with the seasonal pattern of rainfall. The 12-month collection of Hyles lineata (F.) was 17.5% of the 1st 12 months collection after 43 months. The collcction of Callionima ramsdeni (Clark) had dropped 50% after 33 months of trapping but increased to 64% of the 1st 12 months after 43 months. The collection of Agrius cingulatus (F.) was 32% that of the 1st year after 36 months but increased to 81% after 43 months. The collection of Manduca rustica harterti (Rothschild) was 14% that of the base year after 39 months but increased to 21% after 43 months. The collection of Eumorpha vitis (L.) was 15% that of the base year after 39 months but increased to 19% after 43 months. The collection of Xylophanes pluto (F.) was 36% that of the initial year after 36 months but increased to 70% after 43 months. The collection of Xylophanes tersa (L.) was 59% that of the base year after 37 months but increased to 80% after 43 months. The increased collections the last year of trapping were attributed to the absence of a dry season that year. If the collection trends prior to that unusual rainfall pattern had continued, several species would have been eradicated by an additional year of trapping pressure.

TWO NEW SPECIES OF OTOPHEIDOMENIS (ACARINA: PHYTOSEIIDAE) ECTOPARASITIC ON SPHINGID MOTHS, WITH A NOTE ON NOCTUISEIUS

AbstractThe genus Noctuiseius Prasad is synonymized with Otopheidomenis Treat. Two new species, Otopheidomenis kayosiekeri and Otopheidomenis pholusis, are described and illustrated. O. kayosiekeri is known from Honduras, Panama Canal Zone, and Peru from the sphingid moths Pachylia darceta, P. resumens, and Triptogon lugubris. O. pholusis is known from Bolivia and Honduras from the sphingid moths Pholus sp., P. anchemolis, and P. obliquus. A key to the known species of Otopheidomenis is included.

Vitamin A deficiency: effect on retinal structure of the moth Manduca sexta.

Sphingid moths (Manduca sexta) were reared for several generations on an artificial diet deficient in vitamin A and its precursors. Retinal tissue from depleted moths was removed for histological examination. There was extensive histolysis in the retinal epithelium and underlying nervous and connective tissues. This pathology correlated with severe visual impairment, even though normal growth, metamorphosis, and reproduction occurred. In the adult this pathology could be reversed when the larvae were reared only on tobacco (its usual host) or on the artificial diet supplemented with beta-carotene or vitamin A palmitate.

The control of the rocking response in hemileucine moths by sensory stimulation

The control by precurrent sensory stimulation of the side to which Automeris first swings its head at the beginning of a rocking response (the bias of the response) was examined. The responses of some moths are always biased to the same side whatever stimuli are presented. The direction of the bias of other moths can be controlled by bilaterally asymmetric stimuli which themselves do not release a response. When rocking is elicited after unequal, sustained illumination of the eyes, the response is biased to the more brightly lit side. The response is also biased to the same side as a unilateral ‘on’ stimulus and less consistently to the opposite side from a unilateral ‘off’ stimulus. The following results imply that the action of light and of ‘on’ stimuli on rocking are excitatory, whereas the action of ‘off’ stimuli is inhibitory: (1) Intense ‘on’ stimuli evoke the rocking response more frequently than intense ‘off’ stimuli; (2) the number of oscillations in a response (rocking score) is greater if moths are kept under bright illumination than if they are kept under dimmer illumination; and (3) an ‘off’ stimulus delivered during the course of a response will cut it short. The opposite actions of ‘on’ and ‘off’ stimuli can also be seen in the bias of the response after flashes of different lengths. After a long flash (500 msec) the response is biased to the same side as the flash, but after a short flash (5 msec) the response is more commonly biased to the opposite side from the flash. The flash length at which the direction of the bias switches is related to the excitability of the system emdiating rocking. Thus the responses of moths with high rocking scores are biased ipsilaterally by flashes which impose a contralateral bias on the response of moths with lower rocking scores. Stimulation with identical, overlapping flashes to both eyes showed that an ‘on’ stimulus to one eye inhibits the effects of a slightly later ‘on’ stimulus to the other eye. Proprioceptive stimuli also control the direction of the bias. The after-effects of visual and proprioceptive stimuli probably decay at different rates and may be stored simultaneously. The results are discussed with reference to the electrical activity of visually sensitive units recorded in the medial protocerebrum of saturniid and sphingid moths.