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Lasius niger (L.) Ants Invade the Web of an Agelenid Spider

Elżanowski A., Czechowski W.

Polish Journal of Ecology

2015

Vol. 63, nr 4

623--626

Black garden ants Lasius niger (L.) were observed to invade a web of an agelenid funnel spider (Agelena labyrinthica Clerck or Allagelena gracilens C. L. Koch) and to take the entangled prey away, probably after driving the resident spider out of the web. The observation adds to a few examples of ants invading spider webs and suggests complex interactions between ants and funnel spiders which are known to feed on rather than being ousted by ants.

Relationships between the occurrence of Chaetogammarus ischnus (Stebbing, 1898) and Pontogammarus robustoides (G. O. Sars, 1894) (Crustacea, Amphipoda) in a lowland Polish dam reservoir

Żytkowicz J., Kobak J.

Oceanological and Hydrobiological Studies

2008

Vol. 37, No.2

39-50

Populations of Chaetogammarus ischnus and Pontogammarus robustoides living in the middle part of the Włocławek Dam Reservoir (on the lower Vistula River, central Poland) were studied. The two species coexisted at offshore sites of the reservoir, with P. robustoides being much more abundant than C. ischnus. In samples collected from the bare bottom of the reservoir (sandy or covered by zebra mussel shells) and macrophytes a negative relationship between the two species was observed: C. ischnus occurred in high numbers in those samples in which abundance of P. robustoides was low. This phenomenon is postulated as resulting from the larger size and more predatory nature of P. obustoides, limiting the occurrence of C. ischnus.

Influence of the population density and the amount of food on Chironomus plumosus (L.) and Tubificidae. Laboratory experiments

Kajak Z., Prus P.

Polish Journal of Ecology

2004

Vol. 52, nr 1

47-53

The aim of this paper has been to examine experimentally the importance of the density of larvae and of the addition of the food for Chironomus and Tubificidae using selected parameters and indices of their populations. Increase of the density of Chironomus plumosus larvae (0.5-50.0 thousands ind. m^-2) in laboratory experiments resulted in the decrease of emergence of imagos, number of tube apertures (3.5-0.4 apertures ind.^-1), and in the lower rate of tubes building. The addition of the food (powdered dry daphnids or food tablets for aquarial fish) had only slight effect on tube numbers but it decreased clearly the getting out of larvae from tubes (probably due to improved feeding conditions inside tubes). It had also a slight negative effect on the survival of larvae. Numbers and individual growth of Tubificidae were positively dependent on the addition of the food (also in the form of naturally dead Chironomus larvae) and negatively - on the density of Chironomus