MORPHOLOGY AND DISTRIBUTION OF ANTENNAL SENSE-ORGANS AND DIVERSITY OFMOUTHPART STRUCTURES IN ODONTOPUS-NIGRICORNIS (STALL) AND NEZARA-VIRIDULA L (HEMIPTERA)

Sensilla on the antennae and labial tip of the adult hemipteran bugs, Odontopus nigricornis Stall (Pyrrhocoridae) and Nezara viridula L. (Pe ntatomidae) (Hemiptera) were examined with an electron microscope in o rder to study their morphology, distribution, and possible chemo- and mechanoreceptive functions for food detection. The antenna contains 2 types of sensilla trichodea and 3 types of sensilla basiconica on the flagellar segments. S. trichodea are most abundant in both insects. Lo ng slender hairs with elevated bases, and slightly shorter hairs with flexible sockets at the bases are common in both species. However, on each antennal segment of O. nigricornis, 1 or 2 rows of very long tric hodeal hairs with longitudinal grooves and blunt tips are visible. At the periphery, S. busiconica with bulbous bases were also observed in addition to sensilla chaetica. The tripartite apex of the labium in bo th species consists of 2 lateral lobes and an apical plate. Each later al lobe possesses a field of 11 thick-walled uniporous peg sensilla an d long non-porous hair sensilla. Mandibular stylets of O. nigricornis have barbs, which may help in penetrating the hard seed coat. These in sects made circular holes while feeding on the seed. A possible mechan ism of feeding is discussed.