Dr. Papp Jenő szerk.: Folia Entomologica Hungarica 24/1-23. (Budapest, 1971)
the salivary gland. In insects with gnawing mouthparts, the salivary canal - emptying near the pharynx - secretes saliva automatically due to activation by certain muscular movements during gnawing. In insects with other types of oral organs, several kinds of other effectB, e.g. vacuum (suctorial) action triggers saliva production. The main nerve trunk nervus labialis contains typically 16 motoric and sensory nerves (Pig. 2). The main nerve trunk may contain in many insect species one or two further nerve centres (ganglion labiale) which harmonize the work of certain muscles of the lower lip. The muscular motor mechanism of the several parts of the labium is extremely simple.The joints and lamellae of the submentum,mentum, and glossa also enjoy autunomous movements to a certain extent,and the relaxation and contraction of the appropriate muscles assure their coordinated motion.One may except the palpus labialis, since its role consists of mainly the holding of the food, its lifting to the oral aperture, and its placing into the direction of the operative action of the mandible, or its pushing into the mouth, and not of the gnawing process proper. A comparative study of the labial muscles reveals that the primary role of the labium is the formation of a reliable foundation supporting the motion of the other oral organs. The main nerve trunk emits, adjacent to the nervus postmenti I and generally in a common sheath,the first motoric nerve branch, the n. postmento-praementalis (n = 26), while the nervus postmenti II separates from the main trunk beyond an intercalary nerve centre. Between these two nerves 5 motoric nerves may be considered typical, 4 of which (n - 27-30) are the nerves of the muscles of the mentum, while the fifth (n - 31), together with another nerve originating_further away (n - 32), represent the motoric nerves of the muscles of the salivary gland. The palpus labialis receives generally 3 nerves,of which two may be designated motoric (n - 36-37) and one as sensory (nervus palpi labialis). These latter execute the activating of
