Casella, Giovanna

Moschini, Valentina

Paola, Migliorini

Sacchetti, Patrizia

Vazzana, Concetta

English

Florence Research

IntroductionThe type and abundanceof biodiversity in agricul-ture change across agroe-cosystems which differ inage, diversity, structureand management. In gen-eral, the degree of biodi-versity in agroecosystemsdepends on four maincharacteristics (South-wood and Way, 1970): 1.The diversity of vegetationwithin and around it; 2.The permanence of thevarious crops within it; 3.The intensity of management; 4. The extent of the isolationof the agroecosystem from natural vegetation. The studiessuggest that the more diverse the agroecosystems and thelonger this diversity remains undisturbed, the more internallinks develop to promote greater insect stability (Altieri,1999). It has been demonstrated that biodiversity is un-doubtedly amplified in organic agroecosystems comparedto conventional ones (Hole et al. 2005) and that biodiversi-ty may be positively improved by managing habitat andfield margins adjacent to cultivated fields (Landis et al.,2000). Although several studies have been dealt with the ef-fects of field margins on beneficial insects in differentcountries, Italy included (Leather et al., 1999; Denys et al.,2002; Burgio et al., 2006), specific researches are needed todefine the most suitable features of field margins accordingto different crops, habitats and agricultural landscape.The aim of this study was to evaluate the effects of dif-ferent type of agriculturalmanagement (two organicagro-ecosystems of dif-ferent age and a conven-tional one) and field mar-gins on the presence andevolution of aphid preda-tors populations in com-mon wheat.Material and MethodsThe Montepaldi LongTerm Experiment (MOL-TE) has been active since1991 (Vereijken, 1994;Vazzana et al. 1997;Migliorini and Vazzana,2007; Vazzana et al., 2008) on the farm of the University ofFlorence (location Montepaldi, San Casciano Val di Pesa,Long. 11° 09’ 08’’E, Lat. 43° 40’ 16’’ N) covering a slight-ly sloping surface of about 15 hectares at 90 m a.s.l.. TheMOLTE experiment includes the following three differentmicro agro-ecosystems (AES):– “Old Organic” (OO) of 5.2 ha, divided into 4 fields underorganic management (EC reg. 2092/91 and following reg-ulations) since 1992;– “Integrated/Young Organic” (YO) with an area of 5.2 ha,divided into 4 fields under EC regulations 2078/92 (inte-grated farming) from 1992-2000 and converted into organ-ic management since 2001;– “Conventional” (CO) area of 2.6 ha divided into 2 conven-tional fields, where farming techniques used were thosenormally used in the territory of the study area for conven-tional management.The agroecosystems are surrounded by ecological infra-structures such as natural and artificial hedges. In particu-lar, one natural hedge (260 m x 3 m) physically separatesthe Old Organic system from the Young Organic system(field’s margin C); the second hedge (260 m x 3,5 m), plant-ed at the beginning of ’90 and formed by autochthonsspecies, separates the Old Organic system from the rest ofthe farm (field’s margin D); a herbaceous strips (260 m x 6m) separates the Conventional from the Young Organic sys-tem (field’s margin A). There are also herbaceous strips inPresence of aphid predators in common wheat(Triticum aestivum L.) in organic and conventionalagroecosystems of TuscanyV. MOSCHINI 1, P. MIGLIORINI2, P. SACCHETTI3, G. CASELLA1, C. VAZZANA1AbstractThe aim of this study is to compare the presence and evolution of aphid pred-ator populations in common wheat in three agro-ecosystems of different man-agement, two organic of diverse age and a conventional one, in relation tofield margins. The study was carried out in the Montepaldi Long Term Exper-iment in Tuscany, in 2008. Insect predators belonging to the families of Coc-cinellidae, Syrphidae and Chrysopidae were assessed. The presence of eggs,larvae, pupae and adults in the ecological infrastructures of the field marginsas well as inside wheat crop at three different distance from the field’s margin(0 m, 15 m, 30 m) was estimated. Results show that ladybirds are more affect-ed by agroecosystem management and field margin type than the other insectpredators. In fact they are present in greater numbers in organic farming sys-tems than in conventional one and in the more complex and rich ecological in-frastructure. The number of insect predators within the wheat crop was not af-fected by the distance from the field’s margin.Keywords: Field margins; aphid predators; organic agriculture; wheat; eco-logical infrastructure.571 DIPSA, Department of Plant, Soil and Environmental Science, U-niversity of Florence, Piazzale delle Cascine 18 – 50 144 Firenze, I-taly. E-mail:valentina.moschini@unifi.it; concetta.vazzana@unifi.it,giovanna.casella@unifi.it, Internet: www.dipsa.unifi.it2 University of Gastronomic Sciences, Piazza Vittorio Emanuele, 9– Frazione Pollenzo – 12042 Bra (CN), Italy. E-mail:p.migliorini@unisg.it; Internet: www.unisg.it3 DIBA, Department of Agricultural Biotechnology, University ofFlorence, Via Maragliano 75-77 – 50 144 Firenze, Italy. E-mail: pa-trizia.sacchetti@unifi.it; Internet: www.diba.unifi.itSPECIAL ISSUE NEW MEDIT N. 4/2012drains water between Old and Young Organic systems(field’s margin B). The analysis of ecological infrastructuresbiodiversity (Daget and Poissonet, 1969; Shannon andWeaver, 1963) resulted in a higher biodiversity in term ofnumber of species and Shannon Index in the organic hedgesand strips than conventional (Migliorini and Vazzana, 2007;Moschini, 2011) (data not shown). Climatic conditions ofthe experimental area are typical of the Mediterranean sub-Apennines zone. The annual rainfall is about 770 mm withits maximum in autumn and spring and minimum in the pe-riod June-August. The annual mean temperature is 14.1 °Cwith a maximum which can exceed 30°C in summer andminimum temperatures in January.A survey of the most important groups of predators feed-ing on cereal aphids in Central Italy was carried out in2008. Seven samplings were carried out from May to July,from the beginning of aphid infestation up to the wheat har-vest. In each agroecosystem the presence of aphid predatorswas evaluated in the wheat field at three different distancesfrom the field margin (0, 15 and 30 m) as well as in the ad-jacent ecological infrastructure(hedge or herbaceous strip). More-over, in both wheat fields and fieldmargins, samplings were replicatedthree times in the top, middle andbottom area. The relative density ofCoccinellid predators, Syrphids(Diptera) and Chrysopids (Neu-roptera) was estimated by samplingadults with the aid of a sweepingnet. This sampling technique waspreferred for its easy usage and reli-ability in evaluating predators of ce-real aphid (Schotzko and O’Keeffe,1989). Each sample consisted in 4sweeps whilst walking slowly downthe row. The number of insects col-lected was divided by the sampledsurface. Besides adults, the pres-ence of preimaginal instars was e-valuated by counting the number ofeggs or egg batches, larvae and pupae of thethree studied families in a one-square-meterarea by accurate visual examination. Insectssampled were identified up to family level ex-cept for Propylea quatuordecimpunctata (L.),Coccinella septempunctata L. and Adonia var-iegata (Goetze), since in previous investiga-tions in the same habitat they resulted as themost abundant predators on cereal aphids (un-published data). The experimental data weresubjected to ANOVA fixed model and the sig-nificance of variances was tested by Fisher’s Ftest. Mean comparison was carried out accord-ing to MSD and Bonferroni tests (Systat 9.0).ResultsWheat fields in organic and conventional agro-ecosystemsThe analysis of variance (ANOVA) for the variables num-ber of eggs, larvae, pupae and adults of insects sampled forthe factors “agro-ecosystem’s management” and “distancefrom the field margin” are reported in tables 1 and 2. Dataon number of ladybird egg batches, syrphid eggs andchrysopid adults, are not shown since these insect stageswere occasionally detected.The type of agro-ecosystem management significantly af-fected the number of P. 14-punctata adults, that is higher inthe Old Organic (0.329 n/m2) compared to the Convention-al system (0.154 n/m2). Also total ladybird adults are moreabundant in the Old (0.364 n/m2) and Young (0.308 n/m2)Organic systems than in the Conventional one (0.162 n/m2).Moreover the overall number of ladybirds is significantlyhigher in the Old Organic (0.563 n/m2) and Young Organic(0.476 n/m2) systems than in the Conventional one (0.289n/m2) (Table 1).58SPECIAL ISSUE NEW MEDIT N. 4/2012yCoccinellidae in the wheat fields  P. 14-punctata adults A.variegata adults C. 7-punctata adults other ladybird adults total ladybird adults ladybird larvae ladybird pupae total ladybirds n/m2Agroecosystem’s management (S) * n.s. n.s. n.s. ** n.s. n.s. ** OO 0.329a 0.012 0.019 0.004 0.364A 0.198 0.000 0.563A YO 0.277ab 0.015 0.004 0.012 0.308A 0.158 0.008 0.476A CO 0.154b 0.004 0.004 0.000 0.162B 0.123 0.004 0.289B Distance from field margin (D) n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. Top  - 0 m  0.238 0.023 0.012 0.000 0,273 0.083 0.000 0.357 Top  - 15 m  0.238 0.000 0.000 0.000 0,238 0.214 0.000 0.452 Top  - 30 m  0.226 0.000 0.012 0.000 0,476 0.178 0.000 0.416 Bottom  – 0 m  0.190 0.000 0.000 0.023 0,213 0.154 0.000 0.369 Bottom  – 15 m  0.381 0.035 0.012 0.012 0,440 0.154 0.000 0.595 Bottom - 30 m  0.238 0.035 0.000 0.000 0,273 0.202 0.023 0.500 Middle -  0 m  0.226 0.000 0.012 0.000 0,238 0.119 0.000 0.357 Middle - 15 m  0.309 0.000 0.023 0.000 0,332 0.142 0.000 0.476 Middle - 30 m  0.238 0.000 0.012 0.012 0,262 0.190 0.012 0.464  S * D n.s. n.s. n.s. n.s. n.s. n.s. n.s. n.s. Table 1 - Effect of agro-ecosystem management and the distance from field’s margin on the num-ber of Coccinellidae (n/m2). OO: Old Organic system; YO: Young Organic system; CO: Conven-tional system.** significant for P ≤ 0.01; * significant for P ≤ 0.05; n.s. not significant.Syrphidae in the wheat fields  Chrysopidae in the wheat fields hoverfly adults hoverfly larvae total hoverflies green lacewing eggs green lacewing larvae total green lacewings n/m2Agroecosystem’s management  (S) n.s. n.s. n.s. n.s. n.s. n.s. OO 0.095 0.008 0.103 0.000 0.004 0.012 YO 0.095 0.000 0.095 0.035 0.012 0.047 CO 0.087 0.008 0.095 0.083 0.004 0.087 Distance from field margin (D) n.s. n.s. n.s. n.s. n.s. n.s. S * D n.s. * n.s. n.s. n.s. n.s. Table 2 - Effect of agroecosystem management and the distance from field’s marginon the number of Syrphidae and Chrysopidae (n/m2). OO: Old Organic system; YO:Young Organic system; CO: Conventional system.** significant for P ≤ 0.01; * significant for P ≤ 0.05; n.s. not significant.SPECIAL ISSUE NEW MEDIT N. 4/2012Ecological infrastructure at field’s margin of organic andconventional agro-ecosystemsThe results of insects sampling in the ecological infra-structures at field’s margin of organic and conventional a-gro-ecosystems are shown in tables 3 and 4. The analysis ofvariance (ANOVA) highlights as the number of ladybird’sPropylea adults is higher in D ecological infrastructure(0,333 n/m2) in Old Organic system, than in C (0,095 n/m2)and B (0,071 n/m2) field’s margin, respectively placed be-tween Old and Young Organic systems the first and in Y-oung Organic system the second one. Also the total numberof ladybirds is higher in D ecological infrastructure (0,559n/m2) compared to all the other infrastructures (A: 0,240n/m2; B: 0,154 n/m2; C: 0,131 n/m2) (Table 3). The factor“Ecological infrastructure zone” did not produce statistical-ly significant difference in variables analysed.Discussion and conclusionAphid predators investigated in this research were differ-ently affected by the type of agro-ecosystem managementas well as by ecological infrastructures adjacent to fields.As expected, Coccinellids showed the highest relative den-sity among predators feeding on cereal aphids, similarly tooutcomes obtained in comparable field investigations (Bur-gio et al., 2006). Syrphids, although are known to be reli-able landscape bioindicators (Burgio and Sommaggio,2007), did not show consistent activities: nei-ther in wheat fields nor in the ecological infra-structures their presence (as adult or egg) maybe related to any of the factors here considered.Alike considerations may be drawn examiningresults obtained for green lacewings. In additionthe number of Chrysopids collected was alwayssparse, with the highest value recorded in theoldest hedgerow, more complex and highly bio-diverse. Syrphids and Chrysopids may appearnot suitable to highlight the effects of agro-e-cosystem management, anyway data may be af-fected also by the short sampling period and/orby sampling technique not effective for theseinsects. On the contrary Coccinellids allowed toevidence differences among different types of a-gro-ecosystem management: as a matter of factthe relative density of P. 14-punctata, as well as of the den-sity of ladybirds was higher in the organic wheat than in theconventional one. Although in the present study all the fac-tors which potentially may affect ladybird activity and distri-bution were not examined, the higher presence of Coccinel-lids in the long term organically managed wheat (Old organ-ic) undoubtedly show the positive effect of agro-ecosystemmanagement on this beneficial insect predators. The Coc-cinellid activity appear to be comparable in the three zones a-long fields or ecological infrastructures. Likewise, no differ-ences have been displayed between wheat field edges and in-ner zones. Coccinellid populations show a homogeneous dis-persion and distribution in the fields as well in the adjacentfield margins, as a consequence the field size seems to be ap-propriate for the local environment. The uniform dispersal ofcoccinellids may be explained by the abundant presence of P.14.punctata which is known for taking advantageof non-crop habitats more than other species(Zhou et al., 1994).In conclusion, organic agro-ecosystem man-agement contributed to increase the relativedensity of Coccinellid predators in wheat andthe presence of ecological infrastructures bor-dering fields positively affected their consistentdistribution.AcknowledgmentThis study was carried out in the frameworkof the SIMBIOVEG (www.simbioveg.org) re-search project, funded by the Italian Ministry of Universityand Scientific Research.ReferencesAltieri, M.A. (1999): The ecological role of biodiversityin agroecosystems. Agri., Ecos. and Enviro. 74: 19–31.Buiatti, M., Esquinas-Alcázar, J., Lazzerini, G., Merante,P., Migliorini, P. (2010): Biodiversità ed ecosistemi. p.7-12.In: AAVV. Politiche alimentari e sostenibilità. SlowFooded. ISBN: 978-88-8499-278-959Number of Coccinellidae in the field’s margin P. 14-punctata adults A.variegata adults C. 7-punctata adults other ladybird adults total ladybird adults ladybird larvae total  ladybirds n/m2Field's margin (FM) ** n.s. n.s. n.s. ** n.s. ** A - CO 0.139AB 0.002 0.004 0.055 0,196B 0.043 0.240B B – YO 0.071B 0.000 0.000 0.012 0,083B 0.071 0.154B C – YO/OO 0.095B 0.000 0.012 0.000 0,107B 0.023 0.131B D - OO 0.333A 0.035 0.000 0.154 0,523A 0.035 0.559A Ecological infrastructure zone (Z) n.s. n.s. n.s. n.s. n.s. n.s. n.s. Top  0.185 0.000 0.001 0.058 0,244 0.050 0.294 Bottom 0.127 0.008 0.010 0.067 0,213 0.039 0.252 Middle  0.167 0.017 0.001 0.040 0,226 0.041 0.267 FM*Z n.s. n.s. n.s. n.s. n.s. n.s. n.s. Table 3 - Effect of field’s margin on number of Coccinellidae (n/m2).** significant for P ≤ 0.01; * significant for P ≤ 0.05; n.s. not significantSyrphidae in the field’s margin Chrysopidae in the field’s margin hoverfly adults hoverfly eggs total hoverflies green lacewing eggs total green lacewings n/m2Field's margin (FM) n.s. n.s. n.s. n.s. n.s. A - CO 0.109 0.015 0.094 0.053 0.000 B – YO 0.035 0.059 0.095 0.023 0.095 C – YO/OO 0.047 0.000 0.047 0.000 0.000 D - OO 0.119 0.000 0.119 0.190 0.762 Ecological infrastructure zone (Z) n.s. n.s. n.s. n.s. n.s. FM*Z n.s. n.s. n.s. n.s. n.s. Table 4 - Effect of field’s margin on number of Syrphidae and Chrysopidae (n/m2).** significant for P ≤ 0.01; * significant for P ≤ 0.05; n.s. not significantSPECIAL ISSUE NEW MEDIT N. 4/2012Burgio, G., Ferrari, R., Boriani, L., Pozzati, M., VanLenteren, J. 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Presence of aphid predators in common wheat (Triticum aestivum L.) in organic and conventional agroecosystems of Tuscany

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Presence of aphid predators in common wheat (Triticum aestivum L.) in organic and conventional agroecosystems of Tuscany

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