Figure 1.

Experimental manipulation of wing stiffness in bumblebees. (a) Resilin structures mapped on the forewing of a bumblebee, Bombus impatiens, using fluorescent microscopy. (b) A piece of extra-fine polyester glitter (0.4 mm diameter, 20 µg) was affixed to the dorsal wing surface with cyanoacrylate, either splinting the 1 m-cu joint (experimental treatment, blue), or positioned adjacent to the joint (control treatment, red). (c) Method used to measure wing flexural stiffness. Each forewing was affixed at the leading edge to the tip of a syringe needle, and positioned above a pin attached to a micro force sensor. The wing was lowered a small distance (δ, 5% chord length) onto the pin head, applying a point force along the second branch of the cubitus vein at 85% chord length from the leading edge (L). The yellow dot marks the location of the 1 m-cu vein joint. (d) Percent increase in chordwise flexural stiffness (EI) caused by the control splint (Wilcoxon signed-rank test: p = 0.844) and joint splint (p = 0.031).