A Comparison of Morphology among Four Termite Species with Different Moisture Requirements

Abstract

<jats:p>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.</jats:p>

Entomopathogenic Potential of <em>Bacillus velezensis</em> CE 100 for the Biological Control of Termite Damage in Wooden Architectural Buildings of Korean Cultural Heritage

“…Thus, the degradation of cuticular protein fibers and chitin polymers by protease and chitinase enzymes produced by bacterial entomopathogens causes the disintegration of insects' cuticle, which is a vital structural and functional organ in the insects' life [31][32][33][34]37]. Cuticle disintegration causes loss of moisture and leads to a rapid rate of termite mortality due to poor desiccation tolerance [35,36].…”

“…The faster degradation rate of the cuticular glycoproteins and chin polymers by bacterial proteases and chitinase enzymes could be vital to achieve rapid termite mortality with less chances of survival by escaping termites. Once the cuticle is degraded, the termite death is inevitable due to their extremely low tolerance to desiccation [35,36]. Moon et al (2023) reported a mortality rate of more the 80% in subterranean termites treated with B. licheniformis PR2 entomopathogen.…”

The Anti-Termite Activity of Bacillus licheniformis PR2 against the Subterranean Termite, Reticulitermes speratus kyushuensis Morimoto (Isoptera: Rhinotermitidae)

“…Thus, the observed termite mortality in both the crude enzymes and bacterial broth culture treatments could be a direct result of the activity of cuticle-degrading enzymes such as chitinase and protease. Unlike in other insects such as the Coleoptera, the nature of termite cuticles could have unique weaknesses that may contribute to the susceptibility to cuticle degradation [60,61]. For instance, wet wood termites are extremely prone to desiccation and require high relative humidity to survive, which indicates a potential deficiency in the development of a waterproof waxy layer on the surface of the epicuticle [60,61].…”

“…Unlike in other insects such as the Coleoptera, the nature of termite cuticles could have unique weaknesses that may contribute to the susceptibility to cuticle degradation [60,61]. For instance, wet wood termites are extremely prone to desiccation and require high relative humidity to survive, which indicates a potential deficiency in the development of a waterproof waxy layer on the surface of the epicuticle [60,61]. This could also reduce the barrier and allows the contact of treatments with the epicuticle, which consists of a cuticulin bilayer of chitin, lipoproteins, and protein-polyphenol sandwiching fatty acid polymers [34,40,62].…”

Morphological and Structural Observation on the Rectum of Bolua turkiyae Ünal, 1999 (Orthoptera, Tettigoniidae)

“…There is no rectal pad in rectum in some insect species such as Pylaemenes mitratus (Phasmid: Basillidae) [10] and Karenia caelatata (Hemiptera: Cicadidae) [11]. On the contrary, there is found the rectal pad in the rectum of Streltzoviella insularis (Lepidoptera: Cossidae) [12], Cryptotermes brevis (Blattodea, Kalotermitidae), Cryptotermes cavifrons (Blattodea, Kalotermitidae), Coptotermes formosanus (Blattodea, Rhinotermitidae), Neotermes jouteli (Blattodea, Kalotermitidae) [13], Gryllus pennsylvanicus (Orthoptera, Gryllidae) [14], and Poecilimon cervus (Orthoptera, Tettigoniidae) [15] similar to the rectum of B. turkiyae. The presence or not of rectal pads may be related to the insect's diet.…”