PARABIOSIS AND ITS PROXIMATE MECHANISMS IN 4 KALAHARI DESERT TENEBRIONID BEETLES

Four nocturnal desert tenebrionids with complete ecological niche over lap as adults form daytime aggregations in burrows in species pairs, E remostibes with Parastizopus and Herpiscius with Gonopus. Parastizopus and Gonopus were the primary burrowers, the associations being initia ted by the smaller partners. Association was not dependent on differen ces in temperature preference between species nor only on the ecologic al conditions the larger beetles provided. Partner species were prefer red over other tenebrionids of the same size. The proximate segregatin g mechanism was avoidance of the non-partner by the smaller species. A voidance was odour-mediated in Eremostibes, which also showed an equal odour-based preference for conspecifics and Parastizopus. Odour profi le similarity between the two was hypothesized as the mechanism permit ting coexistence. An odour-mediated preference for Gonopus or conspeci fics could not be shown for Herpiscius, nor was Parastizopus odour avo ided. Here, a higher relative humidity in inhabited burrows was sugges ted as the proximate factor promoting association. A possible advantag e of aggregation for desert tenebrionids is discussed.