Spiders of soybean crops in Santa Fe province, Argentina: influence of surrounding spontaneous vegetation on lot colonization

Abstract

Trials during two consecutive soybean cycles were performed in central Santa Fe in order to determine the main spider families present in the crop and to determine the influence of spontaneous margin flora on colonization towards the lot. Samplings were done by sweeping net and pitfall traps. It was concluded that:1. Oxyopidae was the most frequent family in the herbaceous layer of both the margins and the soybean crop, and Lycosidae in the lower layer; 2. Margin strips in a soybean lot contribute to the colonization of the crop by spiders of aerial habits and also promote re-colonization following pesticide applications, since they act as shelters. The influence on spiders of terrestrial habits was somewhat lower; 3. The distribution of the populations of spiders of terrestrial habits was homogeneous in a soybean crop seeded directly and these predators had a greater capacity to control pests at all points of the lot.Keywords: spiders, soybean, colonization. RESUMOAranhas no cultivo da soja no estado de Santa Fé, Argentina e a influência da vegetação espontânea ao redor sobre a colonização da parcelaCom o objetivo de determinar as principais famílias de aranhas presentes em cultivos de soja na zona central de Santa Fé e de determinar a influência da flora espontânea das bordas, na colonização, para o lote, realizaram-se, durante dois ciclos de cultivo de soja, amostragens mediante rede de arraste e armadilhas de queda. Concluiu-se que: 1) a família de aranhas mais freqüente no estrato herbáceo das bordas e do cultivo de soja foi Oxyopidae, enquanto no estrato inferior foi Lycosidae; 2) as faixas marginais do cultivo em um lote de soja contribuem na colonização das aranhas de hábitos aéreos, sendo também promotoras da recolonização posterior às aplicações de pesticidas, ao atuar como zona de refúgio. Uma menor incidência, foi encontrada na colonização das aranhas de hábitos terrestres e sua distribuição populacional foi homogênea em um cultivo de soja de semeadura direta, proporcionando maior capacidade para controlar as pragas em todos os pontos do lote.Palavras-chave: aranhas, soja, colonização.

Evaluation of the design effects of different agropastoral systems on the diversity and density of spiders

“…These families coincided partially with those recorded in crops of soybeans, alfalfa, wheat and cotton (Liljesthröm et al, 2002;Beltramo et al, 2006;Armendano & González, 2009Almada et al, 2012, respectively), where Anyphaenidae, Salticidae and Linyphiidae were the main families in terms of their abundance. These families are also represented with greater abundance in livestock systems (Toti et al, 2000;Warui et al, 2005), as well as in reserves and national parks (Corronca & Abdala, 1994;Rubio et al, 2004;Grismado, 2007;Avalos et al, 2009;Rubio, 2015).…”

“…The results showed that the communities of spiders in the North of Santa Fe are affected by the design of fields within agropastoral systems. The araneofauna registered in the studied area represents 43% of the total number of families cited in Argentina (World Spider Catalog, 2016), and the richness of collected species exceeds the values known to the province of Santa Fe in soybean crops (Beltramo et al, 2006) and cotton (Almada et al, 2012) and to that of other regions or other crops studied in the country (Liljesthröm et al, 2002;Armendano & González, 2009;Benamú Pino, 2010).…”

Diversidad de arañas (Araneae, Araneomorphae) en la selva de montaña: un caso de estudio en las Yungas Argentinas

“…Asimismo, la riqueza específica obtenida en esta investigación no difiere a las observadas en otros estudios realizados en selvas tropicales amazónicas (Höfer, 1990;Raizer et al, 2005;Machado Pinto-Leite et al, 2008;Ricetti & Bonaldo, 2008;Bonaldo & Dias, 2010;Carvalho & Avelino, 2010). Aunque en un marco menos comparable, en Argentina existen estudios sobre ecología de comunidades de arañas en agroecosistemas que revelaron niveles de riqueza más bajos, debido sin duda a la pérdida de la heterogeneidad del paisaje: cultivos de soja (Liljesthrom et al, 2002;Beltramo et al, 2006), y alfalfa (Armendano & González, 2010).…”

“…Los estudios sobre arañas exclusivamente en Argentina se enfocaron, en su mayoría, en aspectos taxonómicos y sistemáticos de algunas familias; siendo los trabajos de diversidad principalmente orientados en agroecosistemas con distintos manejos (Liljesthröm et al, 2002;Beltramo et al, 2006;Armendano & González, 2010;Avalos et al, 2013), muy pocos en áreas naturales protegidas (Rubio et al, 2008;Rubio & Moreno, 2010) o en ambientes degradados (Avalos et al, 2007). Aún hay mucho por conocer sobre la fauna nativa de arañas en Argentina, y en especial en áreas con un valor agregado (como las yungas) debido a la diversidad ambiental y biológica y al incremento de la pérdida de muchos de sus hábitats.…”

Activity of Juvenile Tarantulas in and Around the Maternal Burrow

“…As a typical megadiverse group, spiders have gained wide acceptance in ecological studies as indicators of environmental quality (Clausen 1986;Maelfait et al 1990;Churchill 1997). In Argentina, research on ecological aspects of communities of spiders associated with natural (Corronca and Abdala 1994;Ávalos et al 2005;Grismado 2007;Rubio et al 2008;Ferretti et al 2010a) and altered areas (Beltramo et al 2006;Ávalos et al 2007;Armendano and González 2010) has been conducted, but knowledge gaps still exist for most of the natural areas. Moreover, there is no data on ecological aspects of the spider community in the Ventania system.…”