Abstract
Information on the dispersal ability of flightless insect species associated with woodlands is severely lacking. Therefore, a study was conducted examining the dispersal ability of wood cricket (Nemobius sylvestris) juveniles (nymphs) and adults in a wooded landscape on the Isle of Wight, UK, to further our understanding of the ecology and management of this and other flightless insects. A series of experiments were conducted where nymphs and adults were released and observed at a range of spatial-temporal scales within different habitat environments. The results of this investigation indicated no difference in the dispersal ability of wood cricket nymphs and adults. However, adult females moved less than adult males. Adult males were found to spread twice as fast as females, and males were found capable of traversing up to 55 m away from woodland habitat through semi-natural and grazed grassland. Additionally, rates of population spread of both wood cricket nymphs and adults (males and females) were found to be accurately described by the inverse-power function, predicting only few individuals dispersing over time. Together this indicates that overall colonization success and rate of population spread, being female dependent, is likely to be low for this species. Wood crickets were found to live in and able to move along mature woodland edges directly bordering agricultural land. This indicates that conservation initiatives focusing on creating woodland corridors and developing woodland habitat networks have the potential to facilitate the spread and population viability of wood crickets, if the woodland edges are given enough time to develop. However, long-term monitoring is needed to evaluate the overall effectiveness of such approaches.
Highlights
Dispersal is widely considered to be a key process influencing the survival of populations of species within fragmented landscapes (Hanski & Gilpin, 1997; Kindvall, 1999; Turner et al, 2001; Fahrig, 2003; Diekötter et al, 2005; Ranius, 2006)
After the first 24 h following release, males were heard stridulating within the enclosures and over time (0–96 h) males and females were increasingly observed in pairs
Except for one female, only males were observed at the periphery of the 7 m enclosure, together indicating a lower dispersal ability/tendency for females than males
Summary
Dispersal is widely considered to be a key process influencing the survival of populations of species within fragmented landscapes (Hanski & Gilpin, 1997; Kindvall, 1999; Turner et al, 2001; Fahrig, 2003; Diekötter et al, 2005; Ranius, 2006). Few studies have examined the dispersal ability of relatively immobile invertebrate species that are grounddwelling and move by walking (Diekötter et al, 2005; Diekötter et al, 2010). Compared to flying invertebrates, such species move over finer scales, and may be considered more vulnerable to habitat fragmentation (Tscharntke et al, 2002; Diekötter et al, 2005). Most dispersal studies of ground-dwelling invertebrates have focused on species associated with open seminatural grassland habitats Most dispersal studies of ground-dwelling invertebrates have focused on species associated with open seminatural grassland habitats (e.g. Vermeulen, 1994; Baur et al, 2005; Öckinger & Smith, 2008), where similar studies for woodland-associated species are rare in the literature (Brouwers & Newton, 2009c)
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