Intraguild predation, activity patterns, growth and longitudinal distribution in running water odonate larvae
published: Mar 23, 2001
ArtNo. ESP141015101001, Price: 29.00 €
I studied predation by larval Cordulegaster boltonii on larvae of two other dragonfly species in a laboratory artificial stream. Onychogomphus forcipatus unguiculatus suffered significantly higher predation than Onychogomphus uncatus. Activity was much lower in O. uncatus, which is interpreted as an antipredation trait against C. boltonii. The higher activity of O. f. unguiculatus makes it vulnerable to the sit-and-wait predator C. boltonii due to increased encounters. Rearing of both Onychogomphus in field cages under the same conditions of temperature, food availability and density revealed lower growth rates of O. uncatus, which may be interpreted as a cost of the antipredation behaviour. To test whether experimental results have relevance for largescale distribution patterns of the two Onychogomphus, samples were taken at 23 sites in river-systems of southern France where both species co-occur. In the field I found that O. f. unguiculatus does not coexist with C. boltonii at sites where the latter occurs in high numbers. In contrast, O. uncatus is established even at high density of C. boltonii.