Aphid parasitoids are common in Brazilian wheat fields, and parasitize aphids at the wheat tillering stage. However, there is little information available about when this natural enemy occurs in wheat crops. This study investigated the initial occurrence of aphid parasitoids in four commercial wheat crops in northern Paraná during the 2009 crop season. We installed two Malaise traps at each wheat farm, and 400 tillers were assessed weekly in each field for aphid abundance. During this study, we captured 4,355 aphid parasitoids and 197 aphids. Three species of braconid parasitoids were identified, including Aphidius colemani (Viereck 1912), Lysiphlebus testaceipes (Cresson 1880), and Diaeretiella rapae (McIntosh 1855). The aphids species identified were Rhopalosiphum padi (Linnaeus 1758) and Sitobion avenae (Fabricius 1775). This study showed that aphid parasitoids are present in wheat crops even when aphid densities are low, and in one farm, occurred before the aphids colonization. These reports can justified the high efficiency of these natural enemies against aphids in wheat fields.

Non-crop habitats play a key role in maintaining functional diversity and ecosystem services in farmland. However, the interplay between beneficial insects and landscape variables has rarely been investigated in Neotropical agroecosystems. We used flower flies as a model group to investigate the effects of landscape attributes on beneficial insects in agroecosystems across a gradient of landscape complexity. We specifically ask: (i) Do the abundance and species richness of flower flies in cereal crops increase with increasing landscape complexity? (ii) Do the effects of landscape variables on local flower fly communities differ between spatial scales? (iii) How do landscape complexity and local factors (crop size, altitude and insecticide applications) affect beta diversity? We sampled flower flies in 54 edges within 18 wheat crops in Paraná State, southern Brazil. The percentage of non-crop habitats, landscape diversity and edge density were the explanatory variables, Communicated by P. Ponel.

This study aimed to evaluate the influence of the distance from the edge of native forests on the abundance of aphidophagous hoverflies in wheat fields. The study was conducted in four commercial fields in the North of Paraná State, Brazil, during the wheat crop season of 2009. Two transects were surveyed parallel to the edge of the forest at two distances: 25 ("near") and 525 meters ("far") from the edge. The abundance of hoverflies was compared using a χ 2 test (p ≤ 0.05). In total, 1,845 hoverflies adults were collected, which represented 15 species and three genera. The most abundant species was Allograpta exotica (60.43%), followed by Toxomerus dispar (17.78%) and Toxomerus watsoni (7.26%) (Diptera: Syrphidae). An important inference was that all fields showed a higher abundance of aphidophagous hoverflies closer to the edge of the forest (25 m) during the wheat tillering stage. The initial abundance of aphidophagous hoverflies in wheat fields is likely greater near the edge because of the availability of resources in the surrounding forest that enhance hoverfly survival during periods of low aphid infestation.

Aphids (Hemiptera: Aphididae) are the main pest of wheat (Hemiptera: Aphididae) in several countries. In Brazil, the Biological Control of Wheat Aphids released millions of aphid parasitoids (Hymenoptera: Braconidae and Aphelinidae) on wheat fields and in the present moment the chemical control is rarely necessary. However, since the 80's few studies was carried out to evaluate the species established in Brazil. For this reason, the aim of this study was to record the species of aphid parasitoids that occur in wheat in the northern region of Parana state, Brazil. Four commercial wheat fields were investigated in the agricultural years of 2008 and 2009. The aphid parasitoids were captured with traps (Moericke and Malaise) and aphid mummified were collected. In total, six species of parasitoids were found, Aphidius colemani, A. uzbekistanicus, A. ervi, Aphidius rhopalosiphi, Diaeretiella rapae e Lysiphlebus testaceipes. These results contribute with the register of three exotic species in Parana, and confirm the establishment of A. rhopalosiphi in the country. We emphasize the need for further studies in other regions of the country, as other species introduced also need to have their establishment confirmed. Key words: Aphids, natural parasitism, Aphidiinae, biological control agents ResumoOs pulgões (Hemiptera: Aphididae) são pragas de extrema importância em cereais de inverno no mundo todo. No Brasil, o programa Controle Biológico de Pulgões do Trigo liberou milhões de parasitoides (Hymenoptera: Braconidae e Aphelinidae) nas áreas tritícolas, reduzindo expressivamente a população da praga, e atualmente raramente o controle químico se faz necessário. Entretanto, desde a década de 80 poucos trabalhos de campo tem sido realizados para verificar as espécies efetivamente estabelecidas no País. Por esta razão, este estudo objetivou registrar as espécies de parasitoides de pulgões ocorrentes em lavouras de trigo na região Norte no Paraná. O trabalho foi realizado em quatro áreas comerciais de trigo, durante as safras 2008 e 2009. A captura dos parasitoides ocorreu com uso de armadilhas (Moericke e Malaise) e coleta de pulgões mumificados. No total foram encontradas seis espécies de parasitoides, Aphidius colemani, A. uzbekistanicus, A. ervi, Aphidius rhopalosiphi, Diaeretiella rapae e Lysiphlebus testaceipes. Esses resultados contribuem com a comprovação do estabelecimento de três espécies exóticas de parasitoides de pulgões no Paraná, e confirma o estabelecimento de A. rhopalosiphi no País. Ressalta-se a necessidade de estudos complementares em outras regiões do País, pois outras espécies introduzidas necessitam ter o estabelecimento comprovado. Palavras-chave: Afídeos, parasitismo natural, Aphidiinae, agentes de controle biológico

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Resumo -O objetivo deste trabalho foi avaliar a abundância de inimigos naturais de pulgões do trigo (Triticum aestivum) em diferentes distâncias da borda da mata (2,0 a 200 m), nos municípios de Londrina e Ibiporã, PR, na safra 2008. No total, foram quantificados 11.316 pulgões, 682 múmias, 487 parasitoides e 20.366 predadores. Não foi observada influência consistente da distância da borda da mata sobre os pulgões e os parasitoides. Entre os predadores, a família Dolichopodidae foi a mais abundante (87,74 e 98,55% em Ibiporã e Londrina, respectivamente) e apresentou maior população próximo à borda da mata, o que indica que essa área de refúgio favorece esse predador.Termos para indexação: Lysiphlebus testaceipes, Triticum aestivum, controle biológico, pragas do trigo, preservação ambiental. Abundance of natural enemies of wheat aphids at different distances from the edge of the forestAbstract -The objective of this work was to assess the abundance of natural enemies of wheat (Triticum aestivum) aphids at different distances from the edge of the forest (2.0 to 200 m), in the municipalities of Londrina and Ibiporã, in the state of Paraná, Brazil, in the 2008 crop season. A total of 11,316 aphids, 682 mummies, 487 parasitoids, and 20,366 predators were quantified. The effect of the distance from the edge of the forest on aphids and parasitoids was not consistent. Among predators, the Dolichopodidae family was the most abundant (87.74 and 98.55% in Ibiporã and Londrina, respectively) and showed a higher population near the edge of the forest, indicating that this refuge area favors that predator.

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