Isolating the components of activity-density for the carabid beetle Pterostichus melanarius in farmland

Abstract

The activity and density of the carabid beetle, Pterostichus melanarius, were studied over 10 weeks in a continuous mark-recapture experiment using a grid of pitfall traps spanning a hedgerow and extending approximately 30 m into two cereal fields; 1777 beetles were individually marked. The recapture rate was approximately 60% and 40% for males and females, respectively. Activity-density rose and fell four times between early June and mid August. Jolly-Seber estimates of density showed population density increasing to a single peak in late July. The mean population density in late July and August was relatively stable at approximately 0.26 m. Activity varied over the 10 weeks and was significantly higher during August than in June or July. The daily displacement distance frequencies, calculated from 750 male and 485 female recaptures of individually marked beetles, were distributed exponentially. Mean displacement distances were approximately 2.6 m day during June and July, and 5.3 m day during August. A diffusion model provided diffusion coefficients of 23.7 and 27.9 m day for female and male beetles, respectively. The spatial distribution of P. melanarius was aggregated in patches. Spatial analysis by distance indices showed the spatial distribution of counts between successive periods of activity-density to be significantly associated. Approximately 5.75% of recaptures were from releases on the opposite side of the hedgerow. Approximately 20% of recaptures were from releases in opposite halves of the grid within the same field. The hedgerow acted as a significant barrier to dispersal between fields, with implications for the metapopulation structure of the species.

Constancy and asynchrony of Osmoderma eremita populations in tree hollows

“…The same pattern has also been recorded from pitfall trapping of some other taxa Thomas et al 1998). …”

“…Therefore, a temporal environmental correlation between local populations could severely increase the risk of extinction risks for the metapopulation (e.g. Harrison and Quinn 1989;Thomas and Hanski 1997). Studies on populations of aphids, moths and butterflies suggest that fluctuations often occur more or less in synchrony over areas of 200,000 km 2 or more (Hanski and Woiwod 1993;Pollard and Yates 1993;Sutcliffe et al 1996).…”

Some analytical and numerical approaches to understanding trap counts resulting from pest insect immigration

“…Traps are routinely used in insect monitoring as well as in general insect studies and the need for a relevant theory has long been recognized (e.g. Byers 1993; Perry 1996; Thomas et al 1998). Yet a consistent mathematical theory allowing for trap count modelling and simulation is missing, although some attempts to develop such theory have recently been made (Petrovskii et al , 2014Petrovskaya et al 2012; Petrovskaya and Embleton 2013).…”

“…However, relating the trap count to the population density is a much more difficult problem. Previous approaches tended to provide a relative rather than absolute estimate (Thomas et al,1998). Recently, Petrovskii et al ( , 2014 showed that, if information is available about the insect movement pattern, the population density can be obtained by placing the sequence of daily counts against the predictions of a relevant mean-field mathematical model of the population dispersal.…”

Morphological polymorphism in an urban population of <em>Pterostichus melanarius</em> (Illiger, 1798) (Coleoptera, Carabidae)

“…Under certain conditions this species undergoes two-year summer-autumn recycles, in other microclimatic conditions a one year variant of the cycle with overwintering of older larvae, and in others a two year cycle variant with overwintering imagines (Jørum, 1980;Basedov, 1994;Matalin, 2006Matalin, , 2007. The high abundance of this species and its significance in destroying agricultural pests is acknowledged in many studies in field and laboratory conditions Wallin, 1988;Wallin & Ekbom, 1994;Frampton et al, 1995;Fadl et al, 1996;Symondson, 1997;Thomas et al, 1998;Chapman et al, 1999;Raworth & Choi, 2001;Collins et al, 2002;Fournier & Loreau, 2002;Raworth et al, 2004;Kitaev et al, 2011). The morphological variability of populations of this ground beetle species has until now remained poorly studied.…”