A Comparison of Morphology among Four Termite Species with Different Moisture Requirements
Department of Sciences, John Jay College of Criminal Justice, City University of New York, 524 West 59th Street, New York, NY 10019, USA
Ft. Lauderdale Research and Education Center, Department of Entomology and Nematology, Institute of Food and Agricultural Sciences, University of Florida, 3205 College Ave., Ft. Lauderdale, FL 33314, USA
Author to whom correspondence should be addressed.
Insects 2020, 11(5), 262; https://doi.org/10.3390/insects11050262
Received: 3 April 2020 / Revised: 21 April 2020 / Accepted: 21 April 2020 / Published: 25 April 2020
(This article belongs to the Special Issue Insect Water Relations)
The thicknesses of the cuticle and rectal pads, and the spiracle morphology were compared for four termite species from different habitats, including one drywood termite, Cryptotermes brevis Walker, one “wetwood” termite, Cryptotermes cavifrons Banks, one subterranean termite, Coptotermes formosanus Shiraki, and one dampwood termite, Neotermes jouteli (Banks). Cuticle thicknesses were significantly different among all four termite species. Neotermes jouteli had the thickest cuticle, while Co. formosanus had the thinnest. The cuticle of C. brevis was thicker than that of C. cavifrons and Co. formosanus, which may reflect a comparably greater need to prevent water loss in drier habitats for C. brevis. Rectal pad widths were significantly different among all four termite species, except those of C. brevis with N. jouteli. The rectal pads of N. jouteli and C. brevis were thicker than those of C. cavifrons and Co. formosanus, and the rectal pads of C. cavifrons were thicker than those of Co. formosanus in turn. Larger rectal pads likely account for the water conservation mechanism of producing dry, pelleted frass in the kalotermitids (N. jouteli, C. brevis, and C. cavifrons). Morphological observations of the spiracles showed the presence of protuberances (atrial arms) in the three kalotermitids. The function of this protuberance is unclear, but it may serve as a sac-like structure, aiding in gas exchange, or a moisture trap aiding in the prevention of water loss through evaporation.