Parasitoid wasps are very important in reducingpopulations of little spruce sawfly (Pristiphora abietina Christ.), yearly percent of affected cocoons being between 23 and 35,2%. In laboratory conditions, 23% from the monitoredcocoons  was  affected  by  parasitoidwasps, the  largest  sharebeing  owned  byichneumonids   (19%).Was   identified 2   new   species   of   ichneumonids   forRomania fauna  (Mesoleius  ruficollis  Holmgren  and  Ctenochira  flavicauda Roman).It  is  necessary  to  be  made  researches  in  this  domain,  to  know  better the  parasitoid  complex  and  the  significant importancein  pest  controland  the protective measureswhich must be adopted by the forest management

Brudea, Valentin

Pei, Gheorghe

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LUCRĂRI ŞTIINŢIFICE SERIA HORTICULTURĂ, 61 (1) / 2018, USAMV IAŞI 177 PARASITOID WASPS AND THEIR INFLUENCE ON FOREST PEST POPULATIONS  VIESPI PARAZITOIDE ŞI INFLUENŢA LOR ASUPRA POPULAŢIILOR DE DĂUNĂTORI FORESTIERI  PEI Gheorghe1, BRUDEA Valentin2 *Corresponding author e-mail: pey_gheorghe@yahoo.com  Abstract. Parasitoid wasps are very important in reducing populations of little spruce sawfly (Pristiphora abietina Christ.), yearly percent of affected cocoons being between 23 and 35,2%. In laboratory conditions, 23% from the monitored cocoons was affected by parasitoid wasps, the largest share  being owned by ichneumonids (19%). Was identified 2 new species of ichneumonids for Romania fauna (Mesoleius ruficollis Holmgren and Ctenochira flavicauda Roman). It is necessary to be made researches in this domain, to know better the parasitoid complex and the significant importance in pest control and the  protective measures which must be adopted by the forest management. Key words: parasitoid, little spruce sawfly, ichneumonids.  Rezumat. Viespile parazitoide joacă un rol important în reducerea populaţiilor viespii mici cu fierăstrău a acelor de molid (Pristiphora abietina Christ.) procentul anual de parazitare al coconilor variind între 23 şi 35,2%. În condiţii de laborator, 23% dintre coconii monitorizaţi au fost parazitaţi, ponderea cea mai mare fiind deţinută de ichneumonidae (19%). Au fost identificate 2 specii noi de ichneumonidae pentru fauna României (Mesoleius ruficollis Hlgh. şi Ctenochira flavicaudata Rom.). Sunt necesare cercetări cu privire la importanţa şi influenţa parazitoizilor asupra populaţiilor de dăunători forestieri precum şi a măsurilor de protecţie a acestora ce trebuie adoptate de managementul forestier. Cuvinte cheie: parazitoid, viespea mică cu fierăstrău a acelor de molid, ichneumonidae INTRODUCTION Parasitoid wasps play a very important role to keep under control the insects which produce damages in the forest and are one of the most important biotic limitative factor (Ceianu et al, 1965; Pisică, 1980; Brudea, 2007). Knowing of this species is very important for the forest ecosystems management and theirs protection. The necessity of studies regarding the parasitoid contributions to the reduction of forest pest level is represented by the fact that in many cases,  predicted damages was under estimated level, which reinforces the hypothesis that the activity of mortality factors is very high, among them being also and parasitoid insects (Mráček, 1994; Ceianu et al 1965, Brudea & Pei 2006).                                                  1Faculty of Silviculture and Forest Engineering, Transilvania University of Brasov, Romania 2 Forestry Faculty, “Ştefan cel Mare” University of Suceava, Romania LUCRĂRI ŞTIINŢIFICE SERIA HORTICULTURĂ, 61 (1) / 2018, USAMV IAŞI 178 MATERIAL AND METHOD As a case study for the activity of parasitoid wasps and the influence on pest populations, pupa (cocoon) stage of little spruce sawfly Pristiphora abietina Christ. (O. Hymenoptera, F. Tenthredinidae) was chosen.  The research has been carried out in the Eastern Carpathians, in the group of Stâniș oara Mountains, Suceava county, Boroaia administrative unit, forest management unit Fălticeni, on a surface of 856,70 ha, for a period of three years.  To collect cocoons, 32 soil samples/year were taken (25/25/10 centimeters) from the spruce/mixed forest (proportion of spruce over 50%), where the little spruce sawfly Pristiphora abietina Christ. was present. Sorting of the cocoons was made according with specific exit orifices (Stănescu, 1962; Ceianu, 1965) (tab. 1) (fig. 1).   Table 1 Elements used to sort the cocoons affected by parasitoids (Stănescu, 1962) Particularity of the specific exit orifices Probable cause Cocoons with a small, round orifice Ichneumonidae Cocoons with several small, round orifices Chalcidoidae Cocoons with very shiny internal walls Diptere  For the observations regarding the exit of the insects from the cocoons (Pristiphora abietina Christ. and parasitoids), 50 of healthy cocoons was selected and monitored in laboratory conditions. The parasitoid wasps was identified by Prof. Dr. Ionel Andreiescu and Prof. Dr. Constantin Pisică (†) (“AL. I. Cuza” University, Iaşi).                 Fig. 1 Specific exit orifices RESULTS AND DISCUSSIONS After analyzing collected cocoons which were presenting specific leaving orifices by the parasitoid wasps, parasitation ratios of 29.5% (first year), 35.2% (second year) and 23% (third year) (fig. 2) were observed.   LUCRĂRI ŞTIINŢIFICE SERIA HORTICULTURĂ, 61 (1) / 2018, USAMV IAŞI 179            Fig. 2 Proportion of cocoons (Pristiphora abietina Christ.) affected by parasitoids  For the cocoons monitored in laboratory conditions, hatching of the parasitoids occurred for a longer period than the adults of Pristiphora abietina Christ. (fig. 3), maximum having place in the first decade of April. Even that the observations was made in the laboratory conditions, was possible to identify the moment of the hatching for the main parasitoid wasps in comparison with little spruce sawfly adults.              Fig. 3 Dynamic of the hatching from cocoons for adult insects  (laboratory conditions)  Our research showed that the presence of parasitoid wasps in the cocoons was in proportion of 23%. Of this proportion, 2% were chalcidoids, 2% braconids and 19% ichneumonids (fig. 4). LUCRĂRI ŞTIINŢIFICE SERIA HORTICULTURĂ, 61 (1) / 2018, USAMV IAŞI 180   Fig. 4 Main parasitoids wasps obtained  (laboratory conditions)  Chalcidoids wasps: was obtained a species of genus Tritnepsis (fig. 5):, Suprafamily Chalcidoidea, Family Pteromalidae, that was represented by 6 females, 1 male and 1 larva. At the moment of the study this species don’t was identified because are missing recent reviews, the key for identification used in Europe is from 1969, contains only three species of the genus, obtained species does not fit into them.                     Fig. 5 Chalcidoid wasps –Tritnepsis sp.  Braconid wasps: has been identified just de family, at the moment of the study don’t was identified the species. Ichneumonid wasps: a total of 8 species were identified, from 5 subfamilies (Banchinae, Cryptinae, Ctenopelmatinae, Mesochorinae and Tryphoninae) (tab. 2). The species Mesoleius ruficollis Hlgh. and Ctenochira LUCRĂRI ŞTIINŢIFICE SERIA HORTICULTURĂ, 61 (1) / 2018, USAMV IAŞI 181 flavicaudata Rom. are new in Romania. Pristophora abietina Christ. is the new host species in Romania for species: Agrothereutes abbreviatus F., Mesoleius ruficollis Hlgr. Lissonota folii Thoms., Endasys analis Thoms., Endasys brevis Grav., Endasys testaceus Taschb., Mesochorus brevipetiolatus Ratzb. and Ctenochira flavicauda Rom.  Table 2 Ichneumonid wasps obtained from Pristophora abietina Christ. cocoons Family Subfamily Species Ichneumonidae Banchinae Lissonota folii Thomson Cryptinae Agrothereutes abbreviatus Fabricius Endasys analis Thomson Endasys testaceus Taschenberg Endasys brevis Gravenhorst Ctenopelmatinae Mesoleius ruficollis Holmgren Meschorinae Meschorus brevipetiolatus Ratzeburg Tryphoninae Ctenochira flavicauda Roman  CONCLUSIONS 1. The proportion of Pristiphora abietina Christ. cocoons which was affected by parasitoid wasps was between 23% and 35,2% per year, what it proves an intense activity of the parasitoids.  2. Maximum level of the parasitoids adults hatching is registered at 20 days after maximum level of the Pristiphora abietina Christ. (laboratory conditions). 3. The most important parasitoid wasps are represented by ichneumonids (19%). 4. Was identified 8 species of ichneumonids, 2 species are new to Romania fauna (Mesoleius ruficollis Holmgren and Ctenochira flavicauda Roman). 5. It is necessary to be made researches in this domain, to know better the parasitoid complex and the significant role in pest control. 6. Forest management must take in consideration the protection of parasitoid insects populations and the importance of biodiversity (mixed forest, areas with grass vegetation, floral trees, grazing ban). REFERENCES  1. Brudea V., 2007 – Combaterea biologică în Managementul Integrat la Insectelor Dăunătoare, cu referire special la ecosistemele silvice. Editura Universităţii Suceava, p. 240.   2. Brudea V., Pei G., 2006 – Bioecology and control researches concerning the little spruce sawfly Pristiphora abietina Christ (Hymenoptera: Thentredinidae). Analele LUCRĂRI ŞTIINŢIFICE SERIA HORTICULTURĂ, 61 (1) / 2018, USAMV IAŞI 182 Ştiinţifice ale Universităţii “AL. I. Cuza” Iaşi, secţiunea Biologie Animală, Tom LII, p. 131-136. 3. Brudea V., Pei G., 2006 – Viespea acelor de molid. Revista Sănătatea Plantelor, p. 41. 4. Ceianu I., Mihalache Gh., Balinschi I., 1965 - Combaterea biologică a dăunătorilor forestieri. Editura Agrosilvică, Bucureşti, p. 225. 5. Mráček Z., 1994 - Steinernematids and their natural web-spinning sawfly hosts in forest ecosystems – a historical outline. Institute of Entomology, Branišovská, p. 50. 6. Pisică C., Brudea V., 2011 – Speciile de ichneumonide (Hym., Ichneum.) care parazitează viespea acelor de molid Pristiphora abietina (Christ) (Hym. Tenthredinidae) în nord-estul României. Volumul de lucrări al simpozionului “Biodiversitatea şi managementul insectelor din România”, Editura Universităţii “Ştefan cel Mare” Suceava, p. 137-141.  7. Olenici N., 2005 - Pristiphora abietina (Christ) (Hymenoptera, Tenthredinidae) - un dăunător important al molidului din afara arealului natural de vegetaţie. Revista Pădurilor, Anul 120, Nr. 1, p. 3-12. 

Viespi parazitoide şi influenţa lor asupra populaţiilor de dăunători forestieri

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Viespi parazitoide şi influenţa lor asupra populaţiilor de dăunători forestieri

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