Morpho peleides

Abstract: A male Morpho peleides butterfly wing is decorated by two types of scales, cover and ground scales. We have studied the optical properties of each type of scales in conjunction with the structural information provided by cross-sectional transmission electron microscopy and computer simulation. The shining blue color is mainly from the Bragg reflection of the one-dimensional photonic structure, e.g., the shelf structure packed regularly in each ridges on cover scales. A thin-film-like interference effect from the base plate of the cover scale enhances such blue color and further gives extra reflection peaks in the infrared and ultraviolet regions. The analogy in the spectra acquired from the original wing and that from the cover scales suggests that the cover scales take a dominant role in its structural color. This study provides insight of using the biotemplates for fabricating smart photonic structures.

Abstract: We have described the feeding behavior of the frugivorous butterfly Morpho peleides (Butler 1872) under various conditions and tested its ability to take up fluid from selected natural and artificial food sources in comparison with the nectarvorous Vanessa cardui (Linnaeus 1758). Both nymphalids showed similar probing behavior except for one particular proboscis movement and the fact that M. peleides was unable to feed from Lantana flowers. In 2-min feeding trials, M. peleides imbibed a greater amount of fluid from the food sources, with the most conspicuous difference on rotting banana. Without time restriction, M. peleides gained a significantly greater percentage of body weight from soaked plotting paper, whereas no significant difference occurred from tubular artificial flowers. The ability of M. peleides to feed more efficiently from wet surfaces than V. cardui is discussed in context with proboscis morphology.

Abstract: Butterflies use visual and chemical cues when interacting with their environment, but the role of hearing is poorly understood in these insects. Nymphalidae (brush-footed) butterflies occur worldwide in almost all habitats and continents, and comprise more than 6,000 species. In many species a unique forewing structure--Vogel's organ--is thought to function as an ear. At present, however, there is little experimental evidence to support this hypothesis. We studied the functional organization of Vogel's organ in the common blue morpho butterfly, Morpho peleides, which represents the majority of Nymphalidae in that it is diurnal and does not produce sounds. Our results confirm that Vogel's organ possesses the morphological and physiological characteristics of a typical insect tympanal ear. The tympanum has an oval-shaped outer membrane and a convex inner membrane. Associated with the inner surface of the tympanum are three chordotonal organs, each containing 10-20 scolopidia. Extracellular recordings from the auditory nerve show that Vogel's organ is most sensitive to sounds between 2-4 kHz at median thresholds of 58 dB SPL. Most butterfly species that possess Vogel's organ are diurnal, and mute, so bat detection and conspecific communication can be ruled out as roles for hearing. We hypothesize that Vogel's organs in butterflies such as M. peleides have evolved to detect flight sounds of predatory birds. The evolution and taxonomic distribution of butterfly hearing organs are discussed.

Abstract: The ears of insects exhibit a broad functional diversity with the ability to detect sounds across a wide range of frequencies and intensities. In tympanal ears, the membrane is a crucial step in the transduction of the acoustic stimulus into a neural signal. The tropical butterfly Morpho peleides has an oval-shaped membrane at the base of the forewing with an unusual dome in the middle of the structure. We are testing the hypothesis that this unconventional anatomical arrangement determines the mechanical tuning properties of this butterfly ear. Using microscanning laser Doppler vibrometry to measure the vibrational characteristics of this novel tympanum, the membrane was found to vibrate in two distinct modes, depending on the frequency range: at lower frequencies (1-5 kHz) the vibration was focused at the proximal half of the posterior side of the outer membrane, while at higher frequencies (5-20 kHz) the entire membrane contributed to the vibration. The maximum deflection points of the two vibrational modes correspond to the locations of the associated chordotonal organs, suggesting that M. peleides has the capacity for frequency partitioning because of the different vibrational properties of the two membrane components. Extracellular nerve recordings confirm that the innervating chordotonal organs respond to the same frequency range of 1-20 kHz, and are most sensitive between 2 and 4 kHz, although distinct frequency discrimination was not observed. We suggest that this remarkable variation in structure is associated with function that provides a selective advantage, particularly in predator detection.