Correspondence Between Larval Development and Adult Residence

Latvijas entomologs 2007, 44: 109-118. 109

Correspondence Between Larval Development and Adult Residence Habitats of Dolichopodid Flies (Diptera, Empidoidea: Dolichopodidae) in a Heterogeneous Mosaic of Seacoast Grassland Habitats

1, 2 KRISTAPS VILKS

1 Department of Zoology and Animal Ecology, Faculty of Biology, University of Latvia, 4 Kronvalda Blvd., LV-1586 Rga, Latvia; e-mail: [email protected] 2 Institute of Biology, University of Latvia, 3 Miera Str., LV-2169 Salaspils, Latvia

VILKS K. 2007. CORRESPONDENCE BETWEEN LARVAL DEVELOPMENT AND ADULT RESIDENCE HABITATS OF DOLICHOPODID FLIES (DIPTERA, EMPIDOIDEA: DOLICHOPODIDAE) IN A HETEROGENEOUS MOSAIC OF SEACOAST GRASSLAND HABITATS. – Latvijas entomologs, 44: 109-118.

Abstract: Spatial distribution of dolichopodid adults and larvae was investigated in a heterogeneous mosaic of seacoast habitats in the Lake Engure Nature Park (Latvia) in July 2006. The patchy coastal landscape was dominated by dry dune grasslands, wet seacoast grasslands and reed beds. Larval development habitats were determined by using soil emergence traps, while the flight activity of adult flies was examined by yellow water traps. In total, 30 dolichopodid species were recorded. The most abundant species were Dolichopus nubilus, D. notatus, Teuchophorus spinigerellus, Sympucnus pulicarius, Dolichopus acuticornis, D. pennatus, D. plumipes and Sciapus maritimus. There were much higher species richness and abundance for adult flies flying above the ground in comparison with those species emerging from soils. In general, dolichopodids were more abundant in humid habitats. Flying adult dolichopodids concentrated in reed beds, while their emergence activity, representing larval development habitats, was significantly higher in wet seacoast grasslands. Thus, habitats of larval development did not correspond to adult residence habitats. The article discusses several alternative explanations for such spatial distribution of different development stages. Behavioural aspects seem to be the most important for the habitat selection of adult flies. In conclusion, this study shows that dolichopodid flies may require a highly heterogeneous environment during their life cycle.

Key words: Adult flight activity, Diptera, Dolichopodidae, Empidoidea, larval development, Latvia, migration, seacoast.

Introduction species (Frouz 1999). There is an urgent need to improve our knowledge on the spatial There is no doubt, that insects are the distribution of different development stages of most species-rich animal group in any terrestrial dipterans in the context of biodiversity research environment (Steffan-Dewenter, Tscharntke and bioindication. If dipteran species depend on 2002), and that they make up most of the different habitats during their life cycle, this biodiversity in the world (Speight et al. 1999). should take into account planning the Dipterans have been recorded as one of the conservation of endangered and rare dipteran largest insect order (Speight et al. 1999, Frouz species or communities. Further, species 1999), and they clearly dominate in a wide showing multi-habitat use should indicate fine- range of terrestrial habitats (Melecis et al. scale habitat or landscape heterogeneity and 1999), representing an important component of could be used as bioindicators of habitat quality soil and grass-dwelling faunas (Frouz 1999). and diversity. Despite of this, dipterans still belong to The subject of the present study is the least investigated animals, mainly due to dolichopodid flies occurring in a highly taxonomical and methodological difficulties complex seacoast landscape. Dolichopodids (Frouz 1999, Hövemeyer 2000). Furthermore, represent a diverse and species-rich dipteran the majority of ecological studies related to group worldwide (Grichanov 2006), and dipterans considers the adult stage only, and heterogeneous mosaic of clearly different thus obtains only simplified knowledge on the coastal habitats was used as a model ecosystem, actual diversity and distribution of different allowing studying small-scale distribution of 110 Correspondence Between Larval Development and Adult Residence Habitats… species. Reed beds and less frequently adjacent There are two main aims for the present lower situated grasslands were regularly study: to determine dolichopodid larval overflooded during high level of seawater. Dry development sites (1), and to try to answer the dune grasslands were formed by scarce question, weather dolichopodid larval vegetation dominated by Festuca rubra, Leymus development habitats correspond with habitats arenarius and Achilea millefolium and by dense preferred by the adult flies (2). layer of mosses, however some patches of bare sandy ground were also present. A dense Methods vegetation of Juncus gerardii, Lathyrus Study area palustris, Galium palustre dominated wet seacoast grasslands and Elytrigia repens, and This study was performed in the territory patches of dense grass litter were frequently of the Lake Engure Nature Park (Western present in this habitat. Both dry and wet Latvia) near the village Mrsrags. Two grasslands were slowly overgrown with sampling plots (plot A: 57°19.481Ń, common reed Phragmites australis, as habitat 23°08.249É and plot B: 57°19.461Ń, management in the investigated site has not 23°08.265É) (~30x30 m) were selected within been carried out for at least ten years. Reed beds a heterogeneous mosaic of coastal habitats were strongly dominated by a tall vegetation of composed of patches of dry dune grasslands and common reeds, although Galium palustre was wet seacoast grasslands as well reed beds in the also relatively abundant. depressions of microrelief (Fig.1).

Figure 1. Scheme of the investigated sampling plots situated in a heterogeneous mosaic of three coastal habitats in the Lake Engure Nature Park (Western Latvia) and location of emergence and water traps.

Sampling and identification order to decrease surface tension. Water traps were placed on the ground or 5-10 cm above Aerial activity of flying adult ground attached to piles of wood within dolichopodids was registrated by using yellow inundated reed beds as such locations allow to water traps (diameter 12 cm, depth 6 cm), which collect the highest numbers of dolichopodid have been previously recorded as an excellent species as shown by Pollet and Grootaert method for the investigation of dipteran (1994). In dense vegetation, the surrounding communities (Pollet, Grootaert 1999, De Bruyn plants were cut off at distance of 10 cm around et al. 2001). All water traps were filled at two- the water traps. thirds with a 4% formaldehyde solution to Larval distribution pattern was assessed which a few drops of detergent was added in using soil emergence traps (basal area 0.25 m2, Latvijas entomologs 2007, 44: 109-118. 111 height 50 cm), which registrate freshly emerged adults of dolichopodids from soils in such a way Data analysis allowing to detect their breeding sites. Prior to placing of the emergence traps, all vegetation in Non-parametric Kruskal-Wallis H test was the basal area of traps was cut off. In order to performed for testing differences in species obtain an effective isolation, lower margins of richness and abundance among investigated emergence traps were digged in the soil at the habitats. If significant differences were found, deep of 10 cm. Sampling bottles at the tips of non-parametric Mann-Whitney U test was used emergence traps were filled with a 4% then for the pairwise comparisons of variables. formaledhyde solution to which a few drops of Differences in the proportions were examined detergent was added. In each habitat type, six using the 2-test (Sokal, Rohlf 1995). Detailed water traps and six emergence traps were analyses for individual species were performed installed. Traps were placed with a minimum for those species only, representing 30 or more distance of 5 m from each other. individuals in the total catch. All statistical Dolichopodids were collected in July of analyses were performed using SPSS 15.0 for 2006. This period of season was selected, while, Microsoft Windows® software. according to my previous investigations (unpublished data), the majority of species Results shows the highest adult activity in July. The Dolichopodid emergence from soils materials from traps were emptied two times per investigation period. In total, 13 species with 87 individuals In the laboratory, dolichopodids were were caught with soil emergence traps (Table sorted and stored in 70% alcohol. Identification 1). Despite of low numbers of emerging was performed by means of the keys compiled individuals, the calculated mean abundance per by Grichanov (2006), Meuffels and Grootaert area was quite high, at least in the patches of (1990), Negrobov and Stackelberg (1969) and wet meadows (37 ind./m2). Dolichopus nubilus Pollet (1990, 1996). Nomenclature follows (39%), Teuchophorus spinigerellus (14%), Grichanov (2006). The materials of the sampled Achalcus vaillanti (8%), Dolichopus plumipes dolichopodids are deposited within the (8%) and D. popularis (7%) were the most collection of the Faculty of Biology of the abundant species. Latvian University (Rga).

Table 1. Summary of dolichopodid species collected with water traps and emergence traps in a heterogeneous mosaic of three coastal habitats in July of 2006. Abbreviations: I – reed beds, II - wet seacoast grasslands, III – dry dune grasslands.

Water traps Emergence traps Species I II III Total I II III Total Achalcus vaillanti BRUNHES, 1987 3 3 0 6 2 5 0 7 Campsicnemus scambus (FALLÉN, 1823) 0 0 0 0 3 0 0 3 Chrysotus cilipes MEIGEN, 1824 3 9 4 16 0 1 0 1 Chrysotus femoratus ZETTERSTEDT, 1843 0 1 0 1 0 0 0 0 Chrysotus gramineus (FALLÉN, 1823) 1 0 0 1 0 0 0 0 Chrysotus pulchellus KOWARZ, 1874 0 0 1 1 0 0 0 0 Dolichopus acuticornis WIEDEMANN, 1817 90 1 6 97 0 0 4 4 Dolichopus claviger STANNIUS, 1831 0 1 0 1 0 0 0 0 Dolichopus diadema HALIDAY, 1832 2 1 4 7 0 0 0 0 Dolichopus latipennis FALLÉN, 1823 2 2 0 4 0 0 0 0 Dolichopus nitidus FALLÉN, 1823 3 0 2 5 0 2 0 2 Dolichopus notatus STAEGER, 1842 232 12 4 248 0 0 0 0 Dolichopus nubilus MEIGEN, 1824 138 62 75 275 7 27 0 34 To be continued 112 Correspondence Between Larval Development and Adult Residence Habitats…

Continuation of Table 1 Dolichopus pennatus MEIGEN, 1824 47 30 5 82 0 4 0 4 Dolichopus plumipes (SCOPOLI, 1763) 25 25 10 60 2 4 1 7 Dolichopus popularis WIEDEMANN, 1817 4 3 0 7 6 0 0 6 Dolichopus sabinus HALIDAY, 1838 0 1 1 2 0 0 0 0 Dolichopus simplex MEIGEN, 1824 6 4 2 12 0 0 0 0 Dolichopus ungulatus (LINNAEUS, 1758) 3 0 2 5 0 0 0 0 Hercostomus aerosus (FALLÉN, 1823) 3 3 1 7 0 0 0 0 Hercostomus assimilis (STAEGER, 1842) 1 0 0 1 0 0 0 0 Hercostomus chalybeus (WIEDEMANN, 1817) 2 1 0 3 0 0 0 0 Hercostomus chrysozygos (WIEDEMANN, 1 5 1 7 0 0 0 0 1817) Medetera plumbella MEIGEN, 1824 0 0 7 7 0 0 1 1 Rhaphium riparium (MEIGEN, 1824) 4 0 7 11 0 0 0 0 Sciapus lobipes (MEIGEN, 1824) 2 0 0 2 0 0 2 2 Sciapus maritimus BECKER, 1918 20 1 16 37 0 0 4 4 Sympucnus pulicarius (FALLÉN, 1823) 83 10 22 115 0 0 0 0 Syntormon pallipes (FABRICIUS, 1794) 2 0 3 5 0 0 0 0 Teuchophorus spinigerellus (ZETTERSTEDT, 153 25 12 190 0 12 0 12 1843) Total number of individuals 830 200 185 1215 20 55 12 87 Number of species 24 20 20 29 5 7 5 13

The highest numbers of emerging flies similar in all investigated habitats (Table 1), was observed in wet meadows and decreased although there were significant higher species both in reed beds and dry meadows (Kruskal- richness per trap in wet meadows in comparison Wallis test: H=9.31, df=2, p<0.05) (Fig. 2A). with the other habitats (Kruskal-Wallis test: Total species richness was found approximately H=7.25, df=2, p<0.05) (Fig. 3A).

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Figure 2. Boxplots (median, quartiles and min/max values) for the abundance of dolichopodid flies emerged from soils (A) and flying above the ground (B) in a mosaic of three coastal habitats in July 2006. Kruskal-Wallis H test shows significant (p<0.05) differences in abundance among habitats. Pairwise comparisons were carried out using Mann-Whitney U test; different letters above the bars indicate significant (p<0.05) differences. Abbreviations: I – reed bed, II – wet coastal grassland, III – dry dune grassland. Latvijas entomologs 2007, 44: 109-118. 113

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Figure 3. Boxplots (median, quartiles and min/max values) for the species richness of dolichopodid flies emerged from soils (A) and flying above the ground (B) in a mosaic of three coastal habitats in July 2006. Kruskal-Wallis H test shows significant (p<0.05) differences in species richness among habitats for emerging dolichopodids only. Pairwise comparisons were carried out using Mann-Whitney U test; different letters above the bars indicate significant (p<0.05) differences. Abbreviations: I – reed bed, II – wet coastal grassland, III – dry dune grassland.

Dolichopus plumipes emerged from soils spinigerellus (16%), Sympucnus pulicarius (9%) in all habitats, but other species showed a more and Dolichopus acuticornis (8%) were the most specific emergence pattern, and the majority of abundant species. species (77%) were registrated by soil eclectors Adult dolichopodids preferred clearly reed in a single habitat only. D. acuticornis, beds and the abundance of individuals flying Medetera plumbella, Sciapus lobipes and S. above the ground decreased gradually from wet maritimus were recorded only in dry meadows, to dry habitats (Kruskal-Wallis test: H=11.57, Dolichopus popularis and Campsicnemus df=2, p<0.05) (Fig. 2B). In contrast to the scambus were registrated in reed beds only, and emerging dolichopodids, species richness of Chrysotus cilipes, Dolichopus nitidus, D. adult dolichopodids flying above ground was pennatus and Teuchophorus spinigerellus were not significantly different among investigated specific for wet meadows. Detailed analysis of habitats (Kruskal-Wallis test: H=4.53, df=2, emergence pattern for individual species was p>0.05), although slightly larger values were possible to conduct only for the most abundant recorded for samples from reedmarsh habitat species Dolichopus nubilus, which showed (Fig. 3B). similar emergence patterns as in the case of total Table 2 gives a summary on differences in dolichopodid numbers (Kruskal-Wallis test: abundance pattern of adult flies flying above the H=13.13, df=2, p<0.01). The abundance of ground for abundant dolichopodid species, other species was too low to compare the which were represented at least with 30 distribution of adults emerging from soils individuals in the total catch. All species except among different habitats. Dolichopus plumipes showed significant differences in abundance among investigated Flight activity of adult dolichopodids habitats. Adult flies of Dolichopus nubilus, D. notatus, Teuchophorus spinigerellus, In total, 29 dolichopodid species with Dolichopus acuticornis, Sympucnus pulicarius 1215 individuals were sampled with yellow were most abundant in reedmarshes, Dolichopus water traps (Table 1). Dolichopus nubilus pennatus was less abundant in dry meadows (23%), D. notatus (20%), Teuchophorus respectively Sciapus maritimus less abundant in 114 Correspondence Between Larval Development and Adult Residence Habitats… wet meadows in comparison with the other two literature data can be considered as typical for habitats. coastal habitats. Among most abundant species, Dolichopus nubilus has been called halophilous Emergence activity versus flight activity (Dyte 1959, Emeis 1964, Meyer and Heydemann 1990), D. notatus has been The proportion of collected dolichopodids recorded from coastal marshlands (Falc, among habitat types was significantly different Crossley 2005), D. acuticornis and Sciapus for adult flies flying in the vegetation layer and maritimus have been found in coastal dunes flies emerging from soils and thus representing (Ardö 1957, Emeis 1964, Pollet, Grootaert larval development sites (2 = 116.3, df=2, 1996). Further, among less abundant species p<0.01). there are also other species such as Dolichopus diadema, D. latipennis, D. sabinus, Rhaphium Discussion riparium and Syntormon pallipes, which frequently inhabit coastal habitats (Ardö 1957, Dolichopodid communities studied were Emeis 1964, Meyer, Heydemann 1990, Pollet dominated by species, which according to the 1992, Crossley 1996, Falc, Crossley 2005).

Table 2. Differences in abundance (mean value per trap ± SE) of adult dolichopodids of dominant species (n>30 individuals in total collection) catched by yellow water traps in a heterogeneous mosaic of three coastal habitats in July 2006. Differences among habitats were tested using Kruskal-Wallis test. Residence habitat of adult dolichopodids flying above the ground was evaluated with pairwise comparisons performed using Mann-Whitney U test (values with different letters are significantly (p<0.05) different in this test). Abbreviations: I – reed bed, II – wet coastal grassland, III – dry dune grassland.

Species Kruskal-Wallis test I II III Adult (H statistic, p value) residence habitat Dolichopus acuticornis H=8.55, p<0.05 15.0±3.5 (a) 0.2±0.2 (b) 1.0±0.6 (b) I Dolichopus notatus H=12.64, p<0.01 38.7±10.8 (a) 2.0±0.7 (b) 0.7±0.4 (b) I Dolichopus nubilus H=6.71, p<0.05 23.0±2.8 (a) 10.3±2.5 (b) 12.5±3.8 (b) I Dolichopus pennatus H=8.58, p<0.05 7.8±1.7 (a) 5.0±1.4 (a) 0.8±0.5 (b) I,II Dolichopus plumipes H=4.71, n.s. 4.2±1.4 4.2±0.7 1.7±0.7 I,II,III Sciapus maritimus H=11.16, p<0.01 3.3±0.8 (a) 0.2±0.2 (b) 2.7±0.8 (a) I,III Sympucnus pulicarius H=9.02, p<0.05 13.8±3.7 (a) 1.7±0.9 (b) 3.7±2.0 (b) I Teuchophorus spinigerellus H=9.83, p<0.01 25.5±6.8 (a) 4.2±1.4 (b) 2.0±0.8 (b) I

The present study shows that there are some xerophilous species such as dolichopodids both adults and larvae were Medetera plumbella and Sciapus wiedemanni, observed mainly in reed beds and wet which prefer dry dune habitats (Pollet, Grootaert grasslands in comparison with dry dune 1996). I have also found that dolichopodids of grasslands. This statement agrees with literature species Medetera plumbella and both Sciapus data that the majority of dolichopodid species species emerged from soils in dry dune can be characterized as more or less grasslands, although a remarkable part of adult hygrophilous (Dyte 1959, Emeis 1964, Meyer, S. maritimus was observed in an adjacent reed Heydemann 1990, Pollet, Grootaert 1991, Pollet bed. These findings support conclusion, et al. 1992, Bährmann 1993, Pollet, Grootaert previously obtained by Pollet and Grootaert 1999, Pollet et al. 2003). Pollet and Grootaert (1999), that dolichopodids are ecologically (1996) investigated dolichopodids in a dune diverse group of dipterans, occurring in every landscape along the Belgian coast and have also terrestrial or semi-terrestrial habitat. found that species diversity and abundance The current knowledge on dolichopodid increased from dry to humid sites. However, ecology has been based to a great extent on the Latvijas entomologs 2007, 44: 109-118. 115 studies on adult flies, and there is only a limited concluded that part of species originated from number of literature data on larval development habitats not sampled in their study. habitats. Dyte (1959) has reported that larvae of The present study shows that spatial many species occur in mud, humid soil, leaf distribution of dolichopodid larvae and adults litter and in other various substrata near ponds does not correspond well with each other. Both and streams. Dolichopodids may emerge also the highest abundance as well as the highest from stagnant or running water (Caspers, species richness of emerging dolichopodids Wagner 1982, Negrobov, Silina 1987, from soils were found in wet grasslands. Thus, Grichanov 1999, Reeves et al. 2003). However, larval development was observed mainly in this this is contradicted by Meyer and Speth (1995), habitat. On the other hand, adult flies preferred Hedström (1997) and Meyer and Filipinski clearly reed beds. The most abundant species (1998) who argumented that the majority of Dolichopus nubilus showed just the same dolichopodids, catched by swimming pattern of spatial distribution. Although there emergence traps, are actually terrestrial species were not enough data for a detailed quantitative attracted to water for mating or feeding, and analysis for other seven most abundant species, thus trapped by the emergence traps. Meyer it is clearly visible, that observed occurrences of (2006) has demonstrated that dolichopodid emerging flies were located in habitats others larvae develop in great numbers in soils of wet than those preferred by flying adults. D. meadows. Similarly, I have also found that the plumipes was an exception, because both larvae majority of dolichopodids emerged from wet and adult flies were recorded from all grasslands, which can be characterized by investigated habitats. Further, occurrences of intermediate moisture comparing to other emergence of some other numerous species, investigated habitats. It is somewhat such as Teuchophorus spinigerellus and surprisingly that emergence from reed beds was Dolichopus acuticornis, were located in habitats lower than in grasslands. Dyte (1959) and with significantly lower abundance of adult flies Sommer (1978) showed that preimaginal stages in comparison with the other habitats of some dolichopodid species have adaptations investigated. This implies that dolichopodids to periodically inundated environment such as migrated at small-scale distances through a elongated respiratory horns of pupae of mosaic of different seacoast habitats from Machaerium maritimae. This implies that reed patches of wet meadows to reed beds, where beds could be also a suitable habitat for the concentration of adult flies occurred. It remains development of larvae. Probably, some unclear, however, whether these migrations are dolichopodid species may be true ecotone a specific feature of species life cycle or simply species with their larvae developing at direct a response to changes in their environment, for margins of ponds or reed beds, and thus not example, in variable inundation or soil moisture catched in this study. regime at certain places in different years. It There were much higher numbers of should take also a note, that this study dolichopodid individuals and species flying considered only dolichopodid emergence in above the ground in comparison with those July, although catches of adults flying above emerging from soils. Further, two dominant ground may include individuals which emerged species observed as adult flies, namely earlier in the season. Thus, this study was Dolichopus notatus and Sympucnus pulicarius, unable to detect spatial pattern of species if a were not found emerging from soils in any of remarkable part of dolichopodids emerged investigated habitat. The most probably, both before the period of investigations. My previous are immigrated species from adjacent habitats. research (unpublished data) in this area, Alternative explanations could be: 1) that some however, showed that abundance of adult dolichopodid species originated from ecotone dolichopodids increased only in July, which habitats, not studied in this investigation or 2) means that emergence is also restricted to this that individuals of some species emerged before period. the study. Delettre et al. (1998) obtained similar In literature, there are only few other results in the investigations on empidid flies and studies comparing the spatial distribution of 116 Correspondence Between Larval Development and Adult Residence Habitats… larval and adult dolichopodids. Frequently, it is between flies (Zimmer et al. 2003). Thus, adult assumed that adult flies are found in close dolichopodids require free space for feeding and proximity to the larval development sites sexual behaviour, and reed beds with bare soil (Corpus 1980 after Reeves et al. 2003). The and sparse vegetation may be more suitable as reason for this is that adults oviposit in the adult residence sites in comparison with wet direct vicinity of their emerging sites (Frouz, grasslands, characterized by dense vegetation Paoletti 2000). There should not be a necessity and well developed litter layer. for dispersion or migration to other sites, if In conclusion, the results of the present larval development in certain habitat was study show that distribution of dolichopodid successful. Frouz and Paoletti (2000) larvae and adults was different among various investigated various dipterans in an agricultural habitats in a patchy seacoast landscape. This landscape in the northern Italy and have found indicates, that dolichopodids may use different that the distribution of dolichopodid larvae and habitats for different behaviour expressions adults correspond well with each other. At the during their life-cycle, although further more same time, they mentioned that dolichopodids detailed investigations are still necessary. As developed in various habitats but concentrated dolichopodids require seemingly highly in a single one as adult flies. Results of present heterogeneous environment during their life- study are similar to those obtained by Delettre et cycle, they can be used probably as an tool for al. (1992, 1999), who studied empidid flies in a the fine-scale assessment of habitat mosaic landscape near an oligotrophic pond in heterogeneity and diversity. Further, this study France and have found that empidids use illustrates that abundance data in invertebrate different habitats during their life-cycle. They studies should be carefully evaluated, as habitats concluded that reproduction sites and space with the highest numbers of species or used by adults differed for the dominant individuals may not always represent the best empidid species, because empidids emerged ones, which conforms with all specific mainly from heathland in comparison to adult requirements of species. residence near pond banks. Similarly, the present study also shows that adult Acknowledgements dolichopodids are distributed in more humid places than their larvae. This study was supported by the European Delettre et al. (1992) reported that Social Fund (ESF). I thank Dr. Viesturs Melecis behaviour of empidid flies is the reason for (University of Latvia), Dr. Hans Meyer migration of adult flies. Empidids show specific (University of Kiel, Germany) and Dr. behaviour expressions, and each of them Voldemrs Spuis (Faculty of Biology, requires different environmental resources University of Latvia, Rga) for valuable (Delettre et al. 1992). There are also published comments on the manuscript. Many thanks to data on the complex behaviour of dolichopodid Drta Kavia for given help in the fieldwork. flies, including mating, feeding, migration and oviposition (Frouz, Olejníćek 1999). References Dolichopodids search for soft-bodied arthropods and annellids (Ulrich 2004) on soil surface, on Ardö P. 1957. Studies in the marine shore dune the surface of lower vegetation (Frouz, ecosystem with special reference to the Olejníćek 1999) or use surface of pools and dipterous fauna. – Oppuscula ponds as their hunting ground (Hedström 1997). Entomologica, Suplementum 14: 1-225. As many chironomid and culicid larvae and Bährmann R. 1993. Zur ökologischen adults are common in humid places, this may Einnischung einheimischer increase attractiveness of such habitats for adult Dolichopodiden-Arten (Diptera, dolichopodids (Frouz, Olejníćek 1999). Further, Dolichopodidae). – Deutsche courtship and mating behaviour of Entomologische Zeitschrift 40, No 2: 221- dolichopodids occur also, at least partly, on the 243. ground and involves visual communication Caspers N., Wagner R. 1982. Emergenz- Latvijas entomologs 2007, 44: 109-118. 117

Untersuchungen an einem field margin. – Landscape and Urban Mittelgebirgsbach bei Bonn. VII. Planning 48: 19-29. Empididen- und Dolichopodiden- Grichanov I.Ya. 1999. Dolichopodidae. – In: Emergenz 1976 (Insecta, Diptera, Tsalolikhin S.J. (ed.). Key to freshwater Brachycera). – Archiv für Hydrobiologie invertebrates of Russia and adjacent 93, No 2: 209-237. lands. St.Petersburg: 323-326 (in Crossley R. 1996. Notes on the Empidoidea Russian). (Diptera) of a Yorkshire salt-marsh. – Grichanov I.Ya. 2006. A checklist and keys to Naturalist 121: 67-68. North European genera and species of De Bruyn L., Thys S., Scheirs J., Verhagen R. Dolichopodidae (Diptera). – In: Plant 2001. Effects of vegetation and soil on protection news. Supplement. species diversity of soil-dewlling Diptera St.Petersburg, VIZR RAAS: 120. in a heathland ecosystem. – Journal of Hedström L. 1997. Diptera Dolichopodidae, Insect Conservation 5: 87-97. Long-legged flies. – In: Nilsson A. (ed.). Delettre Y.R., Tréhen P., Grootaert P. 1992. Aquatic insects of North Europe. A Space heterogeneity, space use and short- taxonomic handbook, Vol. 2. Odonata – range dispersal in Diptera: a case study. – Diptera. Apollo Books, Stenstrup: 440 pp. Landscape Ecology 6, No 3: 175-181. Hövemeyer K. 2000. Ecology of Diptera. – In: Delettre Y.R., Morvan N., Tréhen P., Grootaert Papp L., Darvas B. (ed.). Contributions to P. 1998. Local biodiversity and multi- a manual of Palaearctic Diptera, 1. habitat use in empidoid flies (Diptera, Budapest, Science Herald: 437-490. Empidoidea). – Biodiversity and Melecis V., Karpa A., Kabucis I., Savićs F., Conservation 7: 9-25. Liepia L. 1999. Influence of vegetation Dyte C.E. 1959. Some interesting habitats of structure on the distribution of grass- larval Dolichopodidae (Diptera). – The dwelling insects of salty coastal meadows. Entomologist’s Monthly Magazine 95: – In: Elberg K., Martin M., Pekkarinen A. 139-143. (ed.). Proceedings of the XXIV Nordic Emeis W. 1964. Untersuchungen über die Congress of Entomology, Tartu: 101-110. ökologische Verbreitung der Meuffels H.J.G., Grootaert P. 1990. The identity Dolichopodiden (Ins. Dipt.) in Schleswig- of Sciapus contristans (WIEDEMANN, Holstein. – Schriften der 1817) (Diptera: Dolichopodidae), and a Naturwissenschaftlichen Vereins für revision of the species group of its Schleswig-Holstein 35: 61-75. relatives. – Bulletin de l’institut royal des Falk S.J., Crossley R. 2005. A review of the sciences naturelles de Belgique, scarce and threatened flies of Great Entomologie 60: 161-178. Britain. Part 3: Empidoidea. – In: Species Meyer H., Heydemann B. 1990. Faunistisch- Status 3: 1-134. Joint Nature Conservation ökologische Untersuchungen an Committee, Peterborough. Dolichopodiden und Empididen (Diptera Frouz J. 1999. Use of soil dwelling Diptera – Dolichopodidae u. Empididae, (Insecta, Diptera) as bioindicators: a Hybotidae) in Küsten- und review of ecological requirements and Binnenlandbiotopen Schleswig-Holsteins. response to disturbance. – Agriculture, – Faunistisch-Ökologische Mitteilungen ecosystems and environment 74: 167-186. 6: 147-172. Frouz J., Olejníćek J. 1999. Flight patterns of Meyer H., Speth S. 1995. Empidoidea (Diptera: Chironomidae and Dolichopodidae Dolichopodidae, Empididae, Hybotidae) (Diptera) in a suburban fallow area: the aus Emergenzfängen eines Norddeutschen effect of vegetation mosaic. – Biologia Tieflandbachsystems im Bereich von (Bratislava) 54, No 2: 169-178. Osterau und Rodenbek (Holsteinische Frouz J., Paoletti M.G. 2000. Spatial Vorgeest). – Mitteilungen Deutschen distribution of different life stages of one Gesellschaft für Allgemeine und Dipteran community along hedgerow and Angewandte Entomologie 9: 649-655. 118 Correspondence Between Larval Development and Adult Residence Habitats…

Meyer H., Filipinski B. 1998. Empidoidea genus Achalcus LOEW (Diptera: (Diptera: Dolichopodidae, Empididae, Dolichopodidae) with the description of four Hybotidae, Microphoridae) aus Emergenz new species. – Systematic Entomology 21: fängen von zwei Seeausflüssen (Oberer und 353-386. Unterer Schierenseebach) in Norddeutschland Pollet M., Grootaert P. 1996. An estimation of the (Holsteinische Jungmoräne). – Studia natural value of dune habitats using dipterologica 5, No 1: 123-144. Empidoidea (Diptera). – Biodiversity and Meyer H. 2006. Die Langbein- und Conservation 5: 859-880. Tanzfliegenfauna (Diptera: Empidoidea: Pollet M., Grootaert P. 1999. Dolichopodidae Dolichopodidae, Empididae, Hybotidae) (Diptera): poorly known but excellent agents extensiv genutzer Feuchtwiesen im for site quality assessment and nature Schwentinetal bei Raisdorf (Schleswig- conservation. – Proceedings of Experimentall Holstein). – Mitteilungen Deutschen and Applied Entomology, N.E.V. Amsterdam Gesellschaft für Allgemeine und Angewandte 10: 63-68. Entomologie 15: 393-397. Pollet M., Meuffels H., Grootaert P. 2003. Status Negrobov O.P., Stackelberg A.A. 1969. of Dolichopodidae of the Flemish Red Data Dolichopodidae. – In: Keys to the insects of Book in the Netherlands (Insecta: Diptera). – European Part of SSSR. 5, No 2: Diptera and In: Proc. 13th Int.Coll.EIS, September 2001: Siphonaptera: 670-752 (in Russian). 61-68. Negrobov O.P., Silina A.E. 1987. Some date on Reeves W.K., Hurley R.L., Runyon J.B. 2004. habits of dolichopodid larvae (Diptera). – Larval development sites for aquatic Two-wingled insects: systematics, Dolichopodidae (Diptera). – Journal of morphology and ecology. USSR Academy of Entomological Science 39, No 2: 284-286. Sciences, Zoological Institute, Leningrad: 91- Sokal R.R. and Rohlf F.J. 1995. Biometry — The 93 (in Russian). Principles and Practice of Statistics in Pollet M. 1990. Phenetic and ecological Biological Research, 3rd edn. W.H. Freeman, relationships between species of the subgenus New York: 887 pp. Hercostomus (Gymnopternus) in western Sommer R.G. 1978. Experimentell-ökologische Europe with the description of two new Untersuchungen an Dolichopodiden species (Diptera: Dolichopodidae). – (Diptera, Brachycera) im Grenzenbereich Systematic Entomology 15: 359-382. Land-Meer. – Dissertation, Mathematisch- Pollet M., Grootaert P. 1991. Horizontal and Naturwissenschaftliche Fakultät der vertical distribution of Dolichopodidae Christian-Albrechts Universität Kiel: 123 pp. (Diptera) in a woodland ecosystem. – Journal Speight M.R., Hunter M.D., Watt A.D. 1999. of Natural History 25: 1297-1312. Ecology of Insects. Concepts and Pollet M. 1992. Impact of environmental variables Applications. Blackwell Science ltd.: 350 pp. on the occurrence of dolichopodid flies in Steffan-Dewenter I., Tscharntke T. 2002. Insect marshland habitats in Belgium (Diptera: communities and biotic interactions on Dolichopodidae). – Journal of Natural fragmented calcareous grasslands – a mini History 26: 621-636. review. – Biological Conservation 104: 275- Pollet M., Meuffels H., Grootaert P. 1992. 284. Dolichopodid flies at De Mandelhoek nature Ulrich H. 2004. Predation by adult reserve (Belgium): an example of the Dolichopodidae (Diptera): a review of importance of small nature reserves to literature with an annotated prey-predator list. invertebrates. – Bulletin et Annales de la – Studia dipterologica 11, No 2: 369-403. Sociéte royale belge d’Entomologie 128: 213- Zimmer M., Diestelhorst O., Lunau K. 2003. 227. Courtship in long-legged flies (Diptera: Pollet M., Grootaert P. 1994. Optimizing the Dolichopodidae): function and evolution of water trap technique to collect Empidoidea signals. – Behaviour Ecology 14, No 5: 526- (Diptera). – Studia dipterologica 1, No 1: 33- 530. 48. Pollet M. 1996. Systematic revision and Received: June29, 2007. phylogeny of the Palaearctic species of the