Wings in insects with complete metamorphosis develop internally from clusters of undifferentiated cells called imaginal disks. The disks start to divide and differentiate during the feeding and non-feeding stages of the last larval instars. It is possible to remove the imaginal disks from the larvae and study their characteristics. A group of scientists* recently compared wing development in the Buckeye Butterfly, Junonia coenia and the Tobacco Hornworm, Manduca sexta. The wing is produced by cells that must grow and divide into the appropriate shape. The division is controlled by the hormones ecdysone and insulin and the density of hormone receptors on the cells. Wings are mostly two dimensional, a factor that makes the study of wing formation easier to observe than dense three dimensional structures. The imaginal disks have different patterns of elongation that lead to different final wing patterns.
Wing development in the Tobacco Hornworm (Top) and Common Buckeye (Bottom)
The earliest stage is on the left and images to the right are from increasingly later times.
Image: Nijhout and colleagues
*Nijhout, H. Frederik; Cinderella, Margaret & Grunert, Laura W. 2014. The development of wing shape in Lepidoptera: mitotic density, not orientation, is the primary determinant of shape. Evolution & Development. 16: 68-77.
http://dx.doi.org/10.1111/ede.12065
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