Mitochondrial DNA COI characterization of Helicoverpa armigera (Lepidoptera: Noctuidae) from Paraguay and Uruguay

Since its detection in Brazil in 2013, the Old World cotton bollworm Helicoverpa armigera has been reported in Argentina, Paraguay, and Bolivia. Here we present evidence extending the South American range of H. armigera to Uruguay, using polymerase chain reaction and sequencing of the partial mitochondrial DNA (mtDNA) cytochrome oxidase I region. Molecular characterization of this gene region from individuals from Paraguay also supports previous morphological identification of H. armigera in Paraguay. Shared mtDNA haplotypes in H. armigera from Brazil, Uruguay, and Paraguay were identified. Additional surveying of populations in this region will be imperative to better monitor and understand factors that are underpinning its presence and successful adaptation in these South American regions. We discuss our findings with respect to the development of resistance pest management strategies of this invasive insect pest in a predominantly monoculture soybean crop landscape in the Southern Cone region

Tomada de decisão de controle da traça-do-tomateiro através de armadilhas com feromônio sexual Decision making for integrated pest management of the South American tomato pinworm based on sexual pheromone traps

Visou-se estabelecer a relação entre a infestação da traça-do-tomateiro, Tuta absoluta, na planta e adultos capturados em armadilhas com feromônio sexual e a produtividade, para avaliar a influência da infestação na produção da cultura do tomate e aperfeiçoar a tomada de decisão de controle pela densidade de adultos. Armadilhas com feromônio sexual foram instaladas e avaliadas duas vezes por semana, em três áreas de cultivo comercial de tomateiro em São Paulo (Mogi-Guaçu, Tambaú e Sorocaba), em sistema estaqueado, divididas em áreas experimentais com cerca de 18.000 plantas cada (1,5 ha). Nas mesmas datas foi avaliada a infestação de pragas nas plantas, estendendo-se até o término da colheita. A produtividade foi definida pelo total de caixas (24 kg) comercializadas/1.000 plantas. A relação entre a produção da cultura do tomate e a infestação de T. absoluta na planta ou nas armadilhas com feromônio foi expressa por uma equação linear e negativa. A ocorrência de adultos nas armadilhas e a infestação da praga em plantas foram relacionados significativamente com a redução da produtividade. O nível de controle de T. absoluta através do monitoramento com feromônio sexual foi de 45 &plusmn; 19,50 insetos/dia na armadilha.<br>The relationship between the productivity and the infestation of Tuta absoluta on tomato plants and adults caught in sexual pheromone traps was established to evaluate the effect of pest infestation on yield losses as well as on adults' density for decision-making improvement. Sexual pheromone traps were installed in three commercial fields of tomato in São Paulo State, Brazil (Mogi Guaçu, Tambaú and Sorocaba counties) with experimental plots of 18,000 plants each (1.5 ha). The presence of insects in the traps as well as the infestation on plants were evaluated twice a week on the same dates. The evaluations took place until harvesting. The productivity was expressed as marketable boxes of 24 kg/1000 plants. The relationship between tomato production and pest infestation on plants or pheromone traps was linear and negative. The adults' occurrence on traps and plant infestation showed an influence on yield losses. The action level of T. absoluta with sexual pheromone traps was 45 &plusmn; 19.50 insects daily

Molecular Variability and Genetic Structure of Chrysodeixis includens (Lepidoptera: Noctuidae), an Important Soybean Defoliator in Brazil

This study provides the first genetic characterization of the soybean looper, Chrysodeixis includens (Walker, 1857), an important defoliating pest species of soybean crops in Brazil. Population genetic variability and the genetic structure of C. includens populations were evaluated by using ISSR markers with samples from the major soybean producing regions in Brazil in the growing seasons 2011/2012. Seven different primers were applied for population characterization of the molecular variability and genetic structure of 8 soybean looper populations from 8 states of Brazil. The seven ISSR loci generated 247 bands in 246 individuals of C. includens sampled. The expected heterozygosity (H-E) in the populations varied between 0.093 and 0.106, while the overall H-E was 0.099, indicating low genetic diversity. The analysis of molecular variance indicated that 98% of the variability was expressed among individuals within populations (F-ST = 0.021, p = 0.001). The low level of polymorphism over all populations, the high levels of gene flow, and the low genetic structure are indicatives of the exchange of genetic information between the different sampled regions. Population structuring suggests the presence of two major groups which do not correlate with their geographic sampling location in Brazil. These results may indicate recent recolonization of C. includens in Brazil or migration patterns following source-sink dynamics. Furthermore, the presence of two groups within C. includens suggests that a study on development of resistance or any other genetic-based trait needs to be evaluated on both groups, and pest management in soybean fields should be aware that differences may come to the control strategies they use