Ecological Studies on Wolf Spiders(Araneae: Lycosidae) in a Northwest Area of Kanto Plain, Central Japan: Diel Activity and Habitat Preference Observed by Pitfall Trapping.

Abstract

Interspecific differences in die! activity and habitat preference of wolf spiders (Araneae: Lycosidae) were observed by pitfall trapping in a northwest area of Kanto Plain, Japan. Pardosa agraria, P.astrigera and P.graminea were all collected only in daytime, and Pirata yaginumai and Pirata piratoides showed slightly diurnal and nocturnal tendency, respectively. Arctosa fujiii, Pirata clercki, Pirata procurvus, Pirata tanakai, and Tricca japonica can be regarded as aperiodic. Lycosid habitats were classified by combining qualities or grades of three environmental elements of substratum (B, bare soil; L, live plants; D, dead plants), light condition (s, sunshine; d, dark or shade) and water condition (0, rain alone; 1, standing water; 2, running water). Though every lycosid species occurred in three or more habitat classes, and seldom on upper parts of live plants, the highest frequency was observed in Bs0 in Pardosa astrigera, Ls0 in Pardosa graminea and Trochosa ruricola, Lsl in Pirata clercki, Ls2 in Pardosa agraria, Pirata piratoides and Pirata yaginumai, Ds0 in Pirata procurvus and Pirata tanakai, Dsl in Arctosa ebicha and Tricca japonica, and in Dd0 in Arctosa fujiii. Other seven lycosid species (Alopecosa virgata, Arctosa depectinata, Arctosa subamylacea, Lycosa coelestis, Pardosa pseudoannulata, Pardosa yaginumai and Pirata subpiraticus) in the study area were not or seldom trapped because of their low mobility or low density at the trapping sites. Differences between stages or sexes were obscure both in die! activity and habitat preference.

Ecological Studies on Wolf Spiders (Araneae: Lycosidae) in a Northwest Area of Kanto Plain, Central Japan: Habitat Preference Observed by Hand-sorting.

“…The trapping was effective in forests and tussocks but not in open habitats, and was inapplicable especially to low-mobile species in wet land (Fujii 1997). In contrast, hand-sorting was applicable to most habitats except dense tussocks and also to low-mobile species or stages.…”

“…Trapping was effective in collecting small lycosids (Pirata procurvus and P. tanakai) at tussocks and forest floors with thick litter, or rare but active males (Arctosa ebicha, Tricca japonica, and Trochosa ruricola), but was not in collecting lycosids of low-mobile species or stages (youngs and females with egg cocoons) (Fujii 1997). I observed in the laboratory that two Arctosa lycosids (A. depectinata and A. subamylacea) and two Pirata lycosids (P, piratoides and P. subpiraticus) made their nests below and above the soil surface, respectively, and seldom walked out of the nests.…”

“…Characteristics of the sampling sites except those already described in Fujii (1997) were as follows.…”