Biophysical properties of yellow granules in the Oriental (Vespa orientalis) cuticle

By Marian Plotkin Tel-Aviv University, Sackler Faculty of Medicine Department of Physiology Digging activity Correlation between insolation and hornet flight activity Model of a cuticle segment of a yellow stripe Yellow colored cuticle Brown colored cuticle Yellow pigment granules structure

Absorption of brown cuticle Absorption of yellow cuticle Exo- Yellow Endocuticle Pigment Layer Granules Reflectance of hornet cuticle liver functions in the Oriental hornet Xanthopterin identified in the pigment granules Dye Sensitized Solar Cell (DSSC) model

Exo-endocuticle Transparent Electrode & Antireflective coating - Light absorbing pigment in Photochemical? barrel shape housing that increase the effective I3- 3I- surface area available for Hemolymph? absorption + Voltage buildup across a yellow Stripe Dye Sensitized Solar Cell (DSSC) Dye = Xanthoptherin

0.335% < ~11% Discussion 1) The oriental hornet brown/yellow pattern serves the obvious purpose of warning other that the are venomous.

2) The yellow stripes protect the hornet from the harmful solar radiation similar to the role of in the brown cuticle.

3) The Oriental hornet cuticle bears yellow-colored stripes composed of yellow granules. The yellow granule contains xanthopterin. This array of yellow granules maximizes the ability of the extensively conjugated xanthopterin to absorb a wide range of visible light extending up to UV light.

4) The hornets leave the silk cap 3 days prior to its full maturation. The ontogenesis from ovum to pupa requires about 25–30 days. So this would mean that the reproductive rate of the can be increased by 10% or more if the hornets leave the silk cap 3 days prior to its full maturation (since the empty cell can be oviposited again more quickly).

5) Liver-like functions are present in the pigment layer those functions are UV dependent. Discussion

4) The exocuticle serves as an antireflective coating allowing the absorbance of almost 99% of the solar radiation throughout most of the visible range.

5) This work suggests that hornet cuticle may act as an organic solar cell. This process helps the hornets harness the solar radiation in order to conduct its rigorous digging activity.