Syrphid flies in natural grass ecosystems of some areas of the Kraishte region (Bulgaria) (Insecta, Diptera, Syrphidae)

7 Pages·1997·2.3 MB·

by  E Markova

SPIXIANA
Fig.1. Schemeoftheinvestigatedregionandtheecosystemsfromwhichthematerialwasgathered.
thatischaracterizedbylessrainfallduringthespringandsummermonthsincomparisonwiththatof
autumnand winter.
AcertaindifferencebetweentheKyustendilareandtheotherstudiedareasisnotedinaccordance
withthespeciescompositionofthenaturalgrassecosystems.Thegrasscommunitiesintheecosystems
studiedintheareasofTrun, Breznik, Divlya,Pernikand Dupnitsaarecomposedofxeromesophytic
andxerothermicgrassformationsofAgrostiscapiUaris,Festucavalesiaca,Feshicastojanovü,Chrysopogon
grylliandothers.ThegrassecosystemstudiedintheareaofKyustendilisamesophyticgrassformation
ofPoasilvicola (Bondev 1991).
Resultsand discussion
Asaresultoftheinvestigation,22speciesofsyrphidflieswerenotedin 1990and 18speciesin1991.
Thetotalnumberofrecorded speciesis26. 15ofthembelongtosubfamilySyrphinaeand 11 species
tosubfamilyMilesiinae.Togetherwiththe6speciesfoundbyNedjalkov(1912),the6speciesrecorded
byDrenski(1934),andthe24speciesrecordedbyMarkovathenumberofsyrphidflyspeciesreported
forthispartofBulgariais36.Fourspeciesarenewforthesyrphidfaunainthisregion.Theyaremarked
withanasterixinthelistbelow.Foreachspeciesthenumbersoftheindividualsper1 haaregivenin
brackets behind the coUection date. The recorded species are arranged after the Classification of
Vockeroth(forsubfamilySyrphinae)andofThompson&Hippa(forsubfamilyMilesiinae)afterPeck
(1988):
74
1. Dasysyrphuslunulatus (Meigen, 1822)*
Breznik(8/28/1990:67).
2. Episyrphus balteatus (DeGeer, 1776)
Trun(5/25,8/28/1990:67,133and6/1,8/3/1991:100,100);Breznik(5/25/1990:67and6/1/1991:
133);Kyustendil (5/26/1990: 67and 6/2,8/4/1991: 133,33).
3. Metasyrphuscorolne(Fabricius,1794)
Breznik(5/25,8/28,10/1/1990:67,133,67and6/1,8/3/1991:33,200);Divlya(8/27,10/2/1990:
133, 200 and 8/3, 10/5/1991: 200, 100); Pernik (8/26/1990: 67 and 8/4/1991: 67); Kyustendil
(8/30/1990:267and6/2,8/4/1991: 100,100);Dupnitsa(8/25/1990:133and6/2,8/4,10/6/1991:
33,33,33).
4. Metasyrphuslatifasciattis(Macquart, 1829)
Breznik(8/28/1990:67).
5. Metasyrphusluniger(Meigen, 1822)
Kyustendil (9/27/1990: 67and8/4/1991: 33).
6. Sphaerophoriaphilauthus(Meigen, 1822)
Dupnitsa (8/4/1991:33).
7. Sphaerophoriarueppelli(Wiedemann,1830)
Breznik(5/25/1990: 67);Divlya (8/27/1990: 67);Kyustendil(8/30/1990: 67and8/4/1991: 33).
8. Sphaerophoriascripta(Linnaeus, 1758)
Trun(5/25,8/25,10/1/1990:200,267,400and6/1,8/3,10/5/1991:233,100,200);Breznik(5/25,
8/28, 10/1/1990: 667, 200, 133 and 6/1, 8/3, 10/5/1991: 433, 233, 167); Divlya (5/28, 8127,
10/2/1990:200,33,133and6/1,8/3,10/5/1991:167,133,67);Pernik(5/25/1990:133and6/2,8/4,
10/6/1991:67,167,33);Kyustendil(8/30,9/27/1990:67,67and6/2,8/4,10/6/1991:100,100,33);
Dupnitsa (5/27, 8/25/1990: 200,267and 6/2,8/4/1991: 167, 67).
9. SyrphusvitripennisMeigen, 1822
Kyustendil(8/4/1991: 33).
10. Melanostomamellinum (Linnaeus, 1758)
Trun (5/25, 8/28/1990: 133, 67 and 6/1, 8/3, 10/5/1991: 100, 100, 33); Breznik (5/25, 8/28,
10/1/1990:200,200,67and6/1,8/3,10/5/1991:100,133,133);Divlya(5/28/1990:67and6/1,8/3,
10/5/1991: 67, 33, 67); Pernik (8/26, 9/30/1990: 67, 67 and 6/2, 8/4, 10/6/1991: 33, 67, 33);
Kyustendil(9/27/1990: 67and6/2,8/4, 10/6/1991: 67, 100, 167);Dupnitsa (5/27/1990: 133and
6/2,8/4, 10/6/1991: 100,33,67).
11. Platycheirusangustatus(Zetterstedt, 1843)*
Breznik(8/28/1990:67).
12. Platycheirusimmarginatus(Zetterstedt, 1849)
Trun (8/28, 10/1/1990: 67, 67 and 10/5/1991: 67); Breznik (5/28/1990: 133 and 6/1, 8/3/1991:
100,67).
13. Platycheiruspodagratus (Zetterstedt, 1838)
Kyustendil(8/30/1990: 67).
14. Paragustibialis (Fallen, 1817)
Trun(10/1/1990:67and8/3/1991:33);Breznik(10/1/1990:267and6/1,8/3, 10/5/1991:33,67,
167); Divlya (8/27/1990: 67 and 6/4, 8/3/1991: 133, 67); Pernik (8/4/1991: 33); Kyustendil
(5/26/1990:67).
15. Paragusbicolor(Fabricius, 1794)
Breznik(5/25,8/28/1990:67,67and6/1,8/3/1991:100,33);Divlya(8/27/1990:67and8/3/1991:
33).
16. Pipizellavirens(Fabricius, 1805)*
Breznik(5/25/1990:67).
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10-13
11
9
3 4 3 4
1990 1991
Fig. 3. Syrphid flies density in theinvestigated ecosystems. Verticalbars indicate95%,confidenceintervals for
arithmeticmeans. 1.Trun; 2.Breznik; 3.Divlya; 4.Pernik; 5.Kyustendil; 6.Dupnitsa.
Inthedifferentecosystemsthespeciesnumbervariesfrom6to17in1990andfrom6to11 in1991.For
thewholeinvestigationperiodthemaximumspeciesnumberisfoundintheecosystemofBreznik,i.e.
17. The smallest number is that of the species estabUshed in the ecosystem ofTrun and Pernik, i.e.
7speciesineachofthem.hitheecosystemofKyustendilthespeciesnumberis13,inthatofDupnitsa9,
and intheecosystem ofDivlya 8.
It becomes clear that the most frequent species in the region studied in 1990 are S. scripta and
M.mellinum. Theyarefound inallecosystemsand ineachsamplingperiod. Thesamespeciesinthe
regionplus S.pipienswereestablishedasconstantlypermanentonlyin 1991. Permanentspecies,i.e.
specieswithfrequencyover50 % oftheecosystemsinbothyearsoftheinvestigationare M. corollae
andP. tibialis.Therestofthespecieshasalowerdegreeoffrequency. In 19908speciesareaccessory
and 9speciesaccidental; in 1991 6speciesareaccessoryand 7speciesaccidental.
Thedifferencesamongthespeciesspectraofthesyrphidfliesintheexaminedecosystemsshould
beconsideredasaresultofvariousfrequencyofthespecies.ThetaxonomicCommunityofthesyrphid
complexesis,withinsimilarlimits,varyingfrom23to63%in1990andfrom29to70%in1991 (Fig.2).
Thesimilarityismiddleinbothyearsinmostcomplexes.ThecomplexintheecosystemofKyustendil,
howeverisoutstanding,becauseitstaxonomicsimilaritywiththeothercomplexesisverylow.In1990
thetaxonomicsimilarityofthiscomplexvaried from23 to42% and in 1991 from29to38 %.
Theaveragedensityofthesyrphid fliesintheexaminedecosystemspresentedduringthetimeof
studyisgiveninFig.3.In1990thedensityofthesyrphidfliesiswithinthelimitsof244±75ind./ha
to 1.133±128ind./ha, and in 1991 from 253±60md./ha to 811 ±101 ind./ha. During the whole
investigationperiodthedensityintheecosystemofBreznikisthehighestandreliablylarger(2-3xin
1990and1.6-3.2xin1991)thanthatoftherestoftheecosystems.ThedensityintheecosystemofTrun
isthesecondin1990,butin1991 thesecondisthatintheecosystemofDvipnitsa.Thedensityinthese
ecosystemsisreliablylargerwiththeexceptionofPernik.Thedifferencesinthedensityoftherestof
theecosystemsarestatisticallynegligible.InbothyearsthedensityoftheecosystemofPernikisproved
to be the lowest. The same is also established for most of the agroecosystems studied by Pernik
(Markova 1995).
A differenceamong thesyrphid complexes in the variousecosystems is observed in accordance
with thedensityofthepopulationsofthespecies (Fig. 4). In 1990thesimilarityamongthedifferent
complexesaccordingtopopulationdensityiswithinthelimitsof16 to41 % asin9ofthevariantsit
ismiddleand in6ofthem low. In 1991 itvaries from26 to46% and ismiddleinall variants.
Thenumberofthedominantspecies,i.e.thespecieswithrelativenumber>10% isfrom2to5in
thedifferentecosystems.Generally9speciesappeartobedominant,namely: E. balteatus,M. corollae,
S.scripta,M. mellinum,P. tibialis,E.strigatiis, E.arbustoriim,C. viduataand S.pipiens. However,onlya
partofthemainspecieshasaconsiderablerelativepartfromthetotalnumberofallindividuals.In1990
theseare3species,i.e.54.1 %fromallindividuals.S.scriptahasthebiggestrelativesignificance:32.7%,
77

AnideaabouttheStatusofthesyrphidcenosesinthedifferentecosystemsisalsopresentedbythe
IntegrationindexofVainshtein. Summarizingtheindexes forquantitativeandqualitativesimilarity
amongthesyrphidcomplexesitcanbesaidthattheindexofVainshteinvariesfrom4to24%in1990
in1991 itisslightlyhigherandvariesfrom10to32%.TheextraordinaryStatusofthecomplexinthe
ecosystematKyustendilisclearlyseenespeciallyconsideringthegraphicexpressionofthebiocenotic
similarityshown inFig. 5 withthehelpofClusteranalysis. Thisdeterminationisdueto theclimatic
characteristicsandthedifferencesofthespeciescompositionofthenaturalgrassecosysteminthearea
ofKyustendilwhichaffectsdirectlyand indirectlythequalitativeindexesofthesyrphid cenoses.
Consideringthetypeofnutrition,themostrecordedspeciesbelongtothegroupofthezoophages:
16species.Thesaprophagesarerepresentedbyeandthephytophagesbyonly2species.Thezoophag-
es are 73% ofall individuals, the saprophages 26%, and the phytophages only 1 %. S. scripta and
M.mellimimpredominateinthecomplexofzoophagesand S. pipiens in thecomplexofsaprophages
mostlydistributed intheregionofinvestigation.
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