©Entomologica Fennica. 9.IV.1991 Bryodema tuberculata and Psophus stridulus in southwestern Finland (Saltatoria, Acrididae) Rauno Vaisanen, Paivo Somerma, Mikko Kuussaari & Marko Nieminen Vaisanen, R. , Somerma, P., Kuussaari M., Nieminen M. 1991: B1yodema tuberculata and Psophus stridulus in southwestern Finland (Saltatoria, Acrididae). - Entomol. Fennica 2:27-32 Bryodema tuberculata (Fabricius) was discovered as a species new to Finland at St: Sakyla, Sakylanha1ju, where it occurred sparsely together with Psophus stridulus (Linnaeus) . The habitat on a SW- facing esker slope is described, and the spati al distribution of the two species is examined. Preliminarily estimates of the population density, aggregation and vagility are calculated for P. stridulus. The biogeography and conservation biology of the species are discussed. Rauno Vaisiinen, Water and Environment Research Institute, P.O. Box 250, SF- 00101 Helsinki, Finland PaivoSomerma, Mikko Kuussaari & Marko Nieminen, Department of Zoology, University of Helsinki, P. Rautatiek. 13, SF-00100 Helsinki, Finland 1. Introduction Grasshoppers and related groups of the Saltatoria When the vegetation of the habitat was examined are quite well-known insects in northern Europe on 25 July 1990, the presence of another threat­ (Holst 1986). This is especially true of the grass­ ened species Psophus stridulus (Linnaeus) hoppers with red hind wings and rattling or (Saltatoria, Acrididae) was observed. Thus, we drumming sounds, since they are among the most commenced a mark-release-recapture study on conspicuous in sects. New pl aces of occurrence this species as well , even though it was not a are seldom found far outside the known ranges of butterfl y. Thi s led to the still more surprising these species. di scovery of another acridid with red hind wings, During a project on the conservati on of Bryodema tuberculata (Fabricius), as a species threatened butterflies in Finl and, special attention new to Finland (Fig. 1). Here we describe the was paid to the population of Pseudophilotes ba­ habitat and publis h some preliminary results on ton (Bergstresser) (Lepidoptera, Lycaenidae) at the population ecology of these species, espe­ St: Sakyla, Sakylanhmju in southwestern Finland. ciall y that of P. stridulus. 28 Vi:iisi:inen et al.: Bryodema and Psophus • ENTOMOL. FENNICA Vol. 2 Fig . 1. 8ryodema tuber­ culata (left) and Psophus stridulus (right) males. In ­ ner area of the hind wing is bright pinkish red in 8. tubercula fa and orange red in P. stridulus. Note that the tip of the fore wing of 8. tuberculata is broken . 2. Biogeography 3. Habitat B. tuberculata has a continental distribution from The Siikyliinhmju esker is situated in southwest­ Central Europe to Siberia, Mongolia and Tibet ern Finland more than 50 km east of the sea. The (Harz 1957, 1975,Bei-B ienko&Mishcenko 1964). surrounding areas lie about 100m above sea level, In Scandinavia, it occurs only in Sweden on the while the hi ghest point of the esker reaches 145m. "alv ar" heaths of Oland (Coulianos & Sylven The esker runs in a SE-NW direction and it is 1983 ). It was once very common on the moorlands loosely connected to some other eskers and the of Jutland, but reclamation of these for agricultural Salpausselkii ridge (Fig. 2). It is mainly covered purposes has reduced the species enormously, and by dry pine forests and dry heath vegetation with it has probably disappeared from Denmark, the Calluna vulgaris, Arctostaphylus uva-ursi and last record being from 1941 (Holst 1986). It has Vaccinium vitis-idaea, but also less common plants also been recorded from the Isthmus of Karelia such as Gypsophilafastigiata and Jasione montana (Nyberg 1905, Fieandt 1916) and Kareli a grow on the more open slopes and fields (Fig. 3). ladogensis of the U.S.S.R. (Albrecht 1979, Holst Examination of the esker showed that P. stridu Ius 1986). In the Zoological Museum of the Univer­ was distributed at least over open and semiopen sity of Helsinki there are old specimens from /k: areas on the SW-facing slope and along the small Metsiipirtti (1936-1937), Sakkola and Valkjiirvi. road at the top. Thus, the new record from St: Siikylii (Finnish The species exhibited an especial preference uniform grid coordinates 6776:258) lies more for a small spot at the western side of the north­ than 400 km outside the previously known range western part of the area, and all the observations of of the species. B. tubercula were made in or near that area (the The total range of P. stridulus reaches from the NW spot). We analysed the vegetation of the NW Pyrenees eastwards through the steppes of Europe spot on the basis of a sample of 12 squares of 100 and Asia, and to Norway and Sweden in the north. m2. The NW spot was almost treeless, the propor­ It was widely distributed in Finland (Nyberg 1905, tional coverage of trees> 1 m being 0-5 %. The Fieandt 1916, Albrecht 1979), but in more recent few "trees" were small saplings of pines, aspens years it has become rarer, and only two other and birches. The proportion of bare ground varied populations are known from Finland: Ab: Pohja, between 1 and 70 % (mean 29, SD 23). Small and N: Miintsalii. A few scattered records are also uncovered stones abounded on the ground. The available from different parts of southern and mean height ofthe predominant vegetation varied central Finland (Hyonteiskartoitus I Insekt­ from 2 to 30 em, the dominant plant species being kartering 81 1985). Cal/una vulgaris (height about 30 em, the other ENTOMOL. FENNICA Vol. 2 • Viiisanen et al.: Bryodema and Psophus 29 ·-, I '· II II 100km Fig. 2. The main esker areas in southern Finland. The arrow ind icates the present study locality at St: Sakyla. The eskers have been major dispersal pathways for many plants (Jalas 1950). plants distinctly lower), Antennaria dioica, fecundity also depend on a plentiful supply of Arctostaphylus uva-ursi, Thymus se1pyllum and green food (Dempster 1963). Convallaria majalis. According to Holst (1986), P. stridulus in particular demands high temperatures, inhabiting sunny spots such as sandy plains, clearings in 4. Population ecology forests, and heathland. This description agrees with the present habitat, too. B. tuberculata in­ The study area was examined for the grasshoppers habited Danish level moorlands with a stunted on 7, 13, 14, and 15 August 1990. Captured insects flora consisting of the shorter Ericaceae, slender were individually marked on the dorsal surfaces Sarrothamnus bushes, Arctostaphylos, Vaccinium, of the hind wings with felt-tipped, permanent ink various Compositae and grasses, and between pens, and they were immediately released after these plants patches of bare soil, clumps of moss marking at the point of capture. The species, sex, and lichen (Norgaard 1942). On the island of number, date, time and quadrate were recorded for Oland, B. tuberculata is a species of lichen "alvar", the initial capture and all subsequent captures. which has very poor vegetation consisting of The microdistribution and individual move­ lichens only (Coulianos & Sylven 1983). The ments of B. tubercula and P. stridulus are de­ present habitat more closely resembles those in scribed in Figs. 4- 5. P. stridulus was distributed Jutland, but the species seemed to prefer the open, along the whole esker, but it was aggregated in hot spots with sparse and lo w vegetation. In gen­ some spots, especially in the NW spot, while B. eral, high survival, particularly of the very young tuberculata was with certainty observed only in acridid nymphs, and high fecundity of the adults this NW spot. In the NW spot ( 12 I 00 m 2), a total both depend on the occurrence of warm, dry, of 94 P. stridulus, including 15 females, were sunny conditions which can be best encountered encountered in the mark-release-recapture study in sparse vegetation. However, high survival and on 155 occasions. Only 1 female and 3 male B. 30 Vi:iisanen et al. : Bryodema and Psophus • ENTOMOL. FENNICA Vol. 2 A B C D E D Pine forest 120 130 I V D Open ground - Road tt--l L.u IB[ .... ~f! N B C D .· 120 130 140 . ( /fI - 30 r- ~ : f- f- I • I • I I 120 f- f- - l"- f- t- r- t- (12o f-- 1 - r-- I • I • I I I I----, I • I • I I 30 -_ ,..--.--t 130 -I- 1/ / " I I II I I I I Fig. 3. The habitat of Bryodema tuberculata and Psophus stridulus at St: Sakyla, Sakylanharju. r- 1\ 1\ I~"' 120 130 - 120 v 140 130 tuberculata individuals were marked, but prior to the study approximately 5 observations of this species were also made on 27 July 1990. Fig. 4. Distribution of Psophus stridulus on the open The distribution pattern of P. stridulus was and semiopen areas of the Sakylanharju esker. The analysed using pooled total samples in the NW location of the esker is shown with isopleths for height above sea level (m). Squares shown in the picture are spot. Morisita's (1959) index 1 was 1.57 (F=l.73, 111 50 x 50 m. Note that the left column base continues at ? <0.001) indicating a slightly aggregated pattern. the top of the right one as indicated by the letter codes. The vagility of P. stridulus males was ana­ A small black square mark indicates general presence lysed in the NW spot as well. The mean length of within a square, a small fi ll ed circle indicates presence 2 movements between subsequent days was 30 m within a 100 m subsquare. (SD 20, maximum 95, N=21). During one day the mean was about 8 m (SD 5, maximum 20, N=ll). The mean minimum speed was 19m/day (SD 19, maximum 95, N=45) .