RESUMO -Usando um modelo de simulação como ferramenta de análise, quantificou-se o impacto econômico da cigarrinha-das-pastagens em termos de produção animal na Colômbia. Três níveis de infestação (10, 25, 50 adultos/m 2 ) e de área infestada (25, 50, 100%) foram avaliados usando dados obtidos no Brasil com Notozulia entreriana (Berg) em Brachiaria decumbens Stapf. O modelo considerou sistemas de produção de duplo propósito em dois ecossistemas contrastantes: (1) trópico-seco, caracterizado por seis meses bem definidos de estação chuvosa e (2) trópico-umido, caracterizado por distribuição uniforme de chuva durante o ano. Comparada com as pastagens não infestadas, a carga animal e a produtividade de leite e carne tiveram um decréscimo de 1-8, 8-34 e 38-54%, respectivamente, aos níveis de infestação baixo, intermediário e alto, dependendo da área da fazenda infestada. O custo de produção de leite e carne aumentou 0-4, 3-16 and 18-30% nos mesmos níveis de infestação, causando redução no lucro da ordem de 3-16, 17-69 e 67-100%. Em nível regional, o dano econômico nos 1.140.000 ha plantados com pastagens suscetíveis à cigarrinha-das-pastagens nos trópicos úmidos da Colômbia variou de US$7-25, 28-36 e 39-47 milhões/ano. Nos 4.720.000 ha de pastagens suscetíveis no trópico-seco, o prejuízo econômico foi de US$33-118, 132-175 e 228-273 milhões/ano. O investimento requerido para desenvolver variedades resistentes à cigarrinha-das-pastagens e adaptadas a solos de baixa a média fertilidade (US$6 milhões em 12 anos) é baixo quando comparado com o dano econômico causado pelas cigarrinhas-das-pastagens na Colômbia constituindo-se, assim, grande incentivo ao apoio as pesquisas em melhoramento de variedades e manejo da cigarrinha-das-pastagens. PALAVRAS-CHAVE: Gramínea forrageira, impacto econômico, praga das pastagens.ABSTRACT -Using a simulation model as an analysis tool, the economic impact of spittlebugs in pastures of Colombia was quantified in terms of animal production. Three levels of abundance (10, 25, 50 adults/m 2 ) and farm area affected (25, 50, 100%) were evaluated using data obtained in Brazil for Notozulia entreriana (Berg) on Brachiaria decumbens Stapf. The model considered dual-purpose production systems in two contrasting ecosystems: (1) the dry tropics, characterized by a well defined, 6-month rainy season and (2) the humid tropics, characterized by uniform rainfall distribution throughout the year. Compared to healthy pastures, stocking rate, milk and meat productivity decreased 1-8, 8-34 and 38-54%, respectively, at low, intermediate and high abundance levels, depending on farm area infested. The cost of producing milk and meat increased 0-4, 3-16 and 18-30% at the same infestation levels, causing net income to decrease 3-16, 17-69 and 67-100%. At the regional level, economic damage in the 1,140,000 ha sown to grasses susceptible to spittlebugs in the humid tropics of Colombia ranged from US$7-25, 28-36 and 39-47 million/yr. In the 4,720,000 ha of susceptible grasses in the dry tropics, economic damage w...

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1 Outbreaks of root-feeding scarab larvae in turfgrass are widely managed through preventive applications of imidacloprid. Long-residual activity and application before feasible scouting probably lead to its overuse and overexposure. 2 Recent investigations revealed a selective impact of imidacloprid (not trichlorfon or halofenozide) on certain nontarget turf arthropods, motivating the present study on the persistence of abundance effects over 6 years of annual applications. 3 Arthropods were sampled monthly (July to October) in replicated plots using soil core heat extraction and pitfall traps to quantify soil-and surface-active arthropods.Captures were identified to class, order or family. The most represented taxa were analysed to test for cumulative effects and their change over season and year. 4 Imidacloprid had no impact on pitfall captures, although the abundance of Hemiptera, Thysanoptera, Coleoptera and Collembola was suppressed in soil core captures. Among beetles, impact was expressed in adults (not larvae), and in Carabidae and Staphylinidae (not Chrysomelidae or Curculionidae). Among springtails, impact was expressed in Entomobryomorpha (not Poduromorpha or Symphypleona). Impact did not diminish with year but there was variable recovery between applications. 5 There may therefore be a diverging response of soil-and surface-active fauna to the nontarget impacts of imidacloprid. The suppression of predaceous (not phytophagous) beetles indicates an indirect effect mediated through declines in prey populations. 6 The magnitude of abundance effects confirms that the balance between target and nontarget impact should be explicitly examined. Implications are discussed with respect to functional relevance for nutrient cycling and the natural regulation of pests.