How limited is dispersal in the rare beetle, Cryptocephalus decemmaculatus (Chrysomelidae, Cryptocephalinae)?
2013
Piper, R. W. | Compton, S. G.
As suitable habitat becomes increasingly fragmented the ability of a species to reach new areas may often dictate whether populations persist or perish. An understanding of dispersal ability is a prerequisite for informed management decisions. This is particularly true for species that have become restricted to one or a small number of sites, as is the case for several species of Cryptocephalus beetle in the UK. Using mark–release–recapture, host-plant marking and direct observations we investigated population size, movement through suitable habitat and the flight behaviour of Cryptocephalus decemmaculatus. In the UK this species is known from only two sites and it is listed as a priority species on the UK Biodiversity Action Plan. At the time of the study, the one known English site for this species supported a population of ~500 individuals. The adult beetles move through their habitat using suitable host-plants as ‘stepping stones’. There appears to be no interchange of adults between sub-populations that are separated by small areas of unsuitable habitat (e.g. small tracts of woodland or areas devoid of scrub), a result reinforced by studies of genetic differentiation between sub-populations. The small population size of this beetle and its association with, mid-successional habitats makes it vulnerable to local extinction. Furthermore, its limited dispersal ability means that other habitat patches are unlikely ever to be colonised naturally.
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