Behavioral and Reproductive Strategies of Porcellio Species (Oniscidea) in Tunisian Pre-Desert Ecosystems

Abstract

Oniscids inhabiting xeric habitats are of particular interest because these habitats may be one of the important agents for desert soil fertility. Although numerous studies have examined the relationship between the environment and population ecology in woodlice that live in mesic habitats, very little is known about these desert species. Tunisia is known for its arid regions south of the Tunisian Dorsal, habitats in which several species of terrestrial isopods are well adapted. Porcellio is the most widely represented within these habitats: their species richness reaches eight in arid bioclimatic stage. The most widespread of the Porcellio is P. buddelundi, and the least widespread is P. albicornis. Behavioral and reproductive studies carried out in Zarat and Matmata on the two species P. albinus and P. buddelundi showed that the xeric Porcellio species are mainly active at night and they shelter from the extreme heat and dryness of their habitats either in burrows they dig or by vertical migration. The reproductive pattern is seasonal with two breeding seasons. Life history traits allow P. buddelundi to be an r-strategist and P. albinus a k-strategist. The latter displays a fairly developed social behavior, which allowed him to be the most evolved of Porcellio.

Daily and seasonal time partitioning in surface activity of Porcellio albinus (Isopoda, Oniscidea) in the arid region of Zarat (Gabes, Tunisia)

“…The desert species P. albinus survives extreme heat and drought in desert regions thanks to the microclimate within the burrows they dig, analoguous to the behaviour of H. reaumurii ( Medini-Bouaziz 2018 ; Linsenmair 1975 ; Hoffmann 1983 ). The burrows are dug according to standards that consider the prevailing wind direction, the geo-environmental conditions, and the type of vegetation covering the nebkas ( Medini-Bouaziz et al 2017a ).…”

“…Specimens of P. albinus were active every night except during rainy nights. Despite its scarcity in desert environments, rainfall can play an important role in regulating the activity of P. albinus , which remains inside the burrow for days after rain falls and shows no activity outside its shelter until the sand is completely dry ( Medini-Bouaziz 2018 ). This could be explained by the fact that P. albinus , when leaving its burrow for foraging, piles up sand from the burrow in front of the opening ( Linsenmair 2007 ).…”

“…Only Linsenmair (1989 , 2007 ) provided some information on its reproduction and behaviour, while the density and the distribution of P. albinus burrows were studied by Fraj et al (2008) in the Kebili region (Tunisia). Recently, Medini-Bouaziz (2018) and Medini-Bouaziz et al (2017a , b ) carried out field studies on the abiotic factors determining the spatial distribution of burrows, the population dynamics, and the reproductive aspects of P. albinus in the Zarat area in Tunisia. Previous studies on behavioural and reproductive strategies of Porcellio species ( Medini-Bouaziz et al 2017b ; Medini-Bouaziz 2018 ) in the Zarat region showed that specimens of P. albinus were observed outside their burrows at night and never during the day in contrast to H. reaumurii .…”

“…Recently, Medini-Bouaziz (2018) and Medini-Bouaziz et al (2017a , b ) carried out field studies on the abiotic factors determining the spatial distribution of burrows, the population dynamics, and the reproductive aspects of P. albinus in the Zarat area in Tunisia. Previous studies on behavioural and reproductive strategies of Porcellio species ( Medini-Bouaziz et al 2017b ; Medini-Bouaziz 2018 ) in the Zarat region showed that specimens of P. albinus were observed outside their burrows at night and never during the day in contrast to H. reaumurii . However, these patterns have never been studied in detail.…”

“…Living often alongside H. reaumurii (Medini-Bouaziz et al 2017a), the burrowing desert isopod Porcellio albinus Budde-Lund, 1885 is one of the few terrestrial isopod species well adapted to the sandy desert habitats of North-Africa (Monod 1932;Medini-Bouaziz 2002). Despite its wide distribution, there have been few studies on this species' ecology.…”