Occurrence of Ips typographus (Col., Scolytidae) along an urbanization gradient in Brussels, Belgium

Abstract

1 The distribution and dynamics of insect populations in cities is poorly understood. One approach to address this question is to explore the permeability of the urban habitat to species from surrounding rural areas, which can serve as reservoirs in source-sink dynamics. 2 Here, we present data on the distribution of the forest insect pest of spruce, Ips typographus (Coleoptera, Scolytidae), along two axes entering the city of Brussels (Belgium) from the south-east and to the town centre. 3 The insect was caught everywhere along these transects, even in heavily urbanized surroundings, and sometimes in relatively high numbers. The catches were highest near the middle of the transects and lower at both ends of them. 4 This pattern was associated, on the one hand, with an urbanization gradient with the numbers of flying individuals increasing with the distance from the city centre and, on the other hand, with lower catches at the periphery of the city where a high proportion of broadleaved trees may have disrupted the response to aggregation pheromones. 5 In addition to the probable rural origin of the beetles, high catches at the Port of Brussels indicated that some of the insects might be of foreign origin and enter the city with imported timber, highlighting a pathway for unintentional introductions of organisms, including potentially invasive species.

Timber import and the risk of forest pest introductions

“…We fitted the model to the point source mark–recapture experiments of Botterweg (1982). These experiments and the fitted models agree with other empirical studies showing that many individuals attack substrates within short distances (Wichmann & Ravn 2001), whereas some (and sometimes many) individuals may disperse long distances (Nilssen 1978; Stenseth 1984; Piel et al . 2005).…”

Range expansion of the small spruce bark beetle Ips amitinus: a newcomer in northern Europe

“…A limited flight capability does not appear to be the reason for the late northward expansion of I. amitinus in Europe because this species is a stronger flier. In flight mill tests, on average, I. amitinus flew much longer than I. typographus or Ips sexdentatus (Börner, 1776) (Forsse, ), which are two species that are known to fly long distances (Piel et al , ).…”

Trees Wanted—Dead or Alive! Host Selection and Population Dynamics in Tree-Killing Bark Beetles

“…Kin-selected altruism is assumed to play no significant part, since at least some important species are outbreeding and widely dispersing [19], [20], [21],…”