The metathoracic scent gland system in Hydrocorisae (Heteroptera: Nepomorpha)

Abstract. The metathoracic scent gland system is a basic feature of the order Heteroptera. It occurs widely not only in the terrestrial forms (Geocorisae) and water‐surface bugs (Amphibicorisae) but also in the totally aquatic bugs (Hydrocorisae) and their littoral relatives (Ochteridae, Gelastocoridae). In Hydrocorisae the metathoracic scent gland conforms to Carayon's (1971) omphalian type (orifice median and undivided or, if divided, orifices close together towards the mid‐ventral line) but shows marked differences in structure and physiological function between species from different families. There is taxonomic interest in the distribution of the three distinctly different types of metathoracic occlusion apparatus. Naucoridae and Belostomatidae have a median lip‐valve, Notonectidae and Gelastocoridae a pair of stop‐valves, Corixidae a median flap‐valve. The valve opener muscles are usually dorso‐ventral but are ventral in Corixidae; the cuticular microsculpture in the metathoracic efferent system specifically in Hydrocorisae with stop‐valves (Notonectidae, Gelastocoridae) is similar to that widely present in Geocorisae. Groupings of Hydrocorisae from variations in the metathoracic occlusion apparatus differ from others based upon variations in the chemical constitution of the secretions. It is considered that the facts now known on metathoracic scent gland structure and function accord well with the hypothesis that Hydrocorisae constitute a polyphyletic assemblage. Copyrigh

The scent glands and their chemicals in the aposematic cotton harlequin bug, tectocoris-diophthalmus (Heteroptera: Scutelleridae)

In describing differences in morphology, developmental fate and secretion composition in the scent glands of the cotton harlequin bug Tectocoris diophthalmus we have sought to extend comparative knowledge of the scent gland system in the pentatomoid families within the Hemiptera-Heteroptera. Chemical investigation of the secretions was undertaken by coupled gas chromatography-mass spectrometry (GC-MS). The following volatiles were detected: 2-hexenal, 2-hexenyl acetate and 2- octenyl acetate from the metathoracic scent gland (an adult gland); nonanal from the abdominal dorsal first gland (the divided dorsal gland) in the adults; 2-hexenal, 2-octenal, 4-oxohex-2-enal, dodecane and tridecane from the abdominal dorsal second and third glands (the undivided dorsal glands) in fifth-instar nymphs. Secretory units are sparse, opener muscles absent, and secretion scarcely, if at all, present in the second and third dorsal abdominal scent glands in the adults. T. diophthalmus is an addition to the small but growing list of pentatomoids in which biochemical divergence of the abdominal dorsal first gland from the abdominal dorsal second and third glands has been reported. The metathoracic scent gland in T. diophthalmus is comparatively small, as it is in many other aposematic species within the Hemiptera-Heteroptera

Antennal glands in Psylliodes chrysocephala, and their possible role in reproductive behaviour

The antennal morphology of Psylliodes chrysocephala L. (Coleoptera: Chrysomelidae), an important pest of oilseed rape (Brassica napus), was studied. Two types of tricellular, integumentary glands were found. The common antennal glands are distributed under all sensilla-bearing parts of male and female antennae. The male-specific antennal glands are only located under a glabrous area found on antennomeres 6-10 of male beetles. The common antennal glands are synthetically active in both pre- and post-diapause adults, but the male specific antennal glands are only active in post-diapause (reproductively active) males. During studies of mating behaviour, the antennae of the males were highly active at the beginning and end of copulation, and in response to increased female activity. The male specific antennal glands may secrete a sex pheromone, and the glabrous area on the male antennae could be the release site for such a pheromone