Ant communities in organic rain-fed and irrigated olive groves in the Southeast of Alentejo Patanita, M.I.1, Gonçalves, C.1, Santos, S.A.P.2 1Polytechnic Institute of Beja, School of Agriculture, Biosciences Department, R. Pedro Soares, 7800-295 Beja, Portugal 2Mountain Research Center, School of Agriculture, Polytechnic Institute of Bragança, Campus de Sta Apolónia, Apt 1172, 5301-855 Bragança, Portugal. [email protected] INTRODUCTION MATERIAL AND METHODS Table I – Characterization of the study areas. Density The Alentejo region recorded an increase in the area of ​​olive This study was carried out in four olive groves: Olive grove Irrigation Soil management Soil coverage (trees/ha) groves rising from 128 000 ha in 2005 to 159 915 ha in 2009. Of one irrigated organic grove in Póvoa, one Tillage on the row irrigated organic grove located near Serpa Weeds removed Natural these, 45 000 ha correspond to new management systems Organic (Southeast of Alentejo) and two traditional rain- Yes between rows vegetation 238 (28.1%). Among them, the new intensive plantations conducted Serpa Bone meal fertilizer fed organic groves located near Moura. The Sown clover under organic farming regime involving the use of irrigation, the in February predominant olive cultivar is Cordovil. Olive application of mineral and natural pesticides and an increase in Weeds removed on the row and Natural groves have an area of 7, 7, 2 and 19 ha Organic the density of the plantation (200 and 300 trees/ha), resulted in Yes between rows vegetation 278 respectively and the planting density are 7x6 Póvoa Bone meal fertilizer higher yields per ha in just four years after planting. On the other Sown clover meters, 6x6 meters, 10x10 meters and in February hand, traditional rain-fed organic plantations which are more disperse. Others characteristics such as soil Organic Tillage on the row No No 100 common in sloppy or fairly rugged land are characterized by management are shown in Table I. In 2011, Moura 1 and between rows different and more diverse environmental and landscape ants were sampled in four sampling periods Organic Natural No Pasture 70 features. Ants typically dominate the community of arthropods in (May, June, September and November). Moura 2 vegetation the olive grove and are very responsive to human impacts; for In each sampling period, 16 pitfall traps with ethylene glycol were installed 40 m apart and these reasons, they can be used as agents to assess changes in arranged alternately with four traps placed along two rows and the others placed between soil fauna in new organic intensive plantations. Changes in the rows. Traps were left in the field for seven nights and ants were sorted in the laboratory and composition of ant communities are often monitored by centering identified to species. attention on functional group approach. This approach provides a promising way of identifying general rules based on fundamental biological features rather than on particular species identities, offering possibilities for comparing ant responses up to a global scale. The objective of this work was to study the ant community composition in irrigated intensive organic groves when compared with traditional rain-fed organic groves taking into account potential differences of ant biodiversity on the plantation row and between rows. Figure 1 – General view of each type of the study areas: A – irrigated grove, B – rain-fed olive grove RESULTS 120 Aphaenogaster senilis 100 Messor barbarus 90 100 Table II – Ant species collected and their abundance in 80 each habitat. 70 A total of 6359 and 5891 individuals were collected 80 60 IRRIGATED RAIN-FED in rain-fed and irrigated groves, respectively. These 60 50 SPECIES BETWEEN BETWEEN 40 ROW ROW 40 ROW ROW individuals belonged to 25 species, where 19 30 Aphaenogaster senilis 1165 409 815 435 20 species were collected in irrigated groves and 21 in 20 Aphaenogaster gibbosa 1 0 0 0 10 Camponotus pilicornis 0 0 0 2 rain-fed groves. 15 species (60%) were shared 0 0 Camponotus foreli 1 4 0 0 among groves and 3 (12%) were represented by 16 Cataglyphis hispanica 9 Cataglyphis sp. Camponotus micans 0 0 0 0 14 8 7 Camponotus sylvaticus 1 2 0 4 singletons and one (4%) by doubletons. 12 Camponotus lateralis 0 0 8 0 6 Aphaengaster senilis, Messor barbarus and 10 Camponotus cruentatus 0 0 0 0 5 8 Cardiocondyla batesii 0 0 0 0 Pheidole pallidula dominated ant community in 4 6 3 Cataglyphis hispanica 187 133 3 3 irrigated groves while Tapinoma nigerrimum, se) Cataglyphis spp. 92 56 6 5 ± 4 2 Cataglyphis rosenhaurei 0 0 0 0 Messor barbarus, Aphaenogaster senilis dominated 2 1 Crematogaster auberti 108 33 1 0 in rain-fed groves. The main differences were (mean 0 0 Crematogaster scutellaris 0 1 379 3 12 obtained for the genus Cataglyphis (C. hispanica Crematogaster auberti 40 Crematogaster scuterallis Crematogaster sordidula 0 2 10 8 35 Formica cunicularia 0 0 0 0 10 and C. iberica) and Crematogaster (C. auberti and Abundance 30 Formica subrufa 1 0 43 4 8 Goniomma hispanica 0 0 6 16 C. scutellaris). Cataglyphis spp. and C. auberti were 25 Hypoponera eduardi 0 0 0 0 significantly more abundant in irrigated groves and 6 20 15 Messor barbarus 1078 483 1069 256 4 Messor capitatus 1 0 0 0 C. scutellaris in rain-fed groves. Cataglyphis genus 10 Pheidole pallidula 645 64 24 20 2 prefers open areas and can disperse fast and 5 Plagiolepis pygmaea 40 1 66 30 0 0 Plagiolepis schmitzii 12 0 5 1 therefore it is likely they are associated with 80 Tapinoma madeirense 0 0 0 0 Pheidole pallidula 350 Tapinoma nigerrimum disturbed habitats. Crematogaster is a genus mainly 70 Tapinoma nigerrimum 323 252 2706 371 300 60 Tapinoma simrothi 187 56 0 4 arboricoulus that nests on the trunk. However, 250 50 Tetramorium bikrense 0 0 0 0 200 differences observed between C. auberti and C. 40 Tetramorium forte 0 0 25 0 150 30 scutellaris may indicate different the occupation of 100 Tetramorium semilaeve 492 63 18 8 20 Lasius lasioides 0 0 2 2 different niches in the agroecosystem. 10 50 Lasius grandis 0 0 0 0 0 0 IRRIGATED IRRIGATED RAIN-FED RAIN-FED IRRIGATED IRRIGATED RAIN-FED RAIN-FED Lasius sp. 0 0 0 0 ROW BETWEEN ROW BETWEEN ROW BETWEEN ROW BETWEEN Solenopis sp. 0 0 1 0 ROW ROW ROW ROW Figure 2 – Abundance (mean ± SE) of the ant species considered more relevant CONCLUSION Aphaengaster senilis, Messor barbarus and Pheidole pallidula dominated ant community in irrigated groves while Tapinoma nigerrimum, M. barbarus, A. senilis dominated in rain-fed groves. The main differences were obtained for the genus Cataglyphis (C. hispanica and C. iberica) and Crematogaster (C. auberti and C. scutellaris). Cataglyphis spp. and C. auberti were significantly more abundant in irrigated groves and C. scutellaris in rain-fed groves. ACKNOWLEDMENTS This work was funded by Fundação para a Ciência e Tecnologia through project PTDC/AGR - PRO/ 111123 /2009: The use of biological indicators as tools for assessing the impact of agricultural practices in sustainability of olive grove UNIÃO EUROPEIA Fundo Europeu de Desenvolvimento Regional .