FINE-STRUCTURE AND PHYSICOCHEMICAL ANALYSIS OF THE METATHORACIC SCENTGLANDS OF LINCUS-MALEVOLUS (ROLSTON) AND L-SPURCUS (ROLSTON) (HETEROPTERA, PENTATOMIDAE)

Bugs of the genus Lincus (Heteroptera : Pentatomidae) are attracted by volatile compounds emitted from the inflorescences of fertile palms. To define the basis of their chemical ecology, we have studied the met athoracic scent glands (MTG) of males and females of 2 species, L. spu rcus and L. malevolus. The metathoracic scent gland system belongs to the diastomien type. The 2 glandular pores located between the mesotho racic and metathoracic coxae are associated with ''crescent-like'' eva poration areas. The large median reservoir, which is composed of one t ype of flattened pigmented epithelial cells, is flanked by multitubula r lateral glands. These glands result from the apposition of 2 cell-ty pe glandular units. The strip-like accessory gland is embedded in the reservoir wall. At its level, the thinner cuticular intima forms finge r-like invaginations where a protein secretory product is secreted. Ex tracts of the volatile fraction of the metathoracic gland secretion we re analyzed by capillary gas chromatography (GC) and by GC-mass spectr ometry (GC-MS). These analyses exhibited a typical pentatomid MTG comp osition. The glands of L. spurcus and L. malevolus males and females c ontain 11 compounds: (E)-2-hexenal, 4-keto-(E)-2-hexenal, (E)-2-hexeno ic acid, decane, (E)-2-octenal, undecene, undecane, (E)-2-octenly acet ate, (E)-2-decenal, tridecane and (E)-2-decenyl acetate, including 3 m ajor compounds, which represent 60-85% of the secretion in the 2 speci es: (E)-2-hexenal, (E)-2-octenal, and n-undecane. The 4-keto-(E)-2-hex enal is present only in the L. malevolus MTG, and represents 26% of it s secretion. The female extracts of both species are characterized by the presence of (E)-2-hexenoic acid, which was detected in the male ex tracts as traces.