Moscas-das-frutas (Diptera: Lonchaeidae e Tephritidae) em faixa de fronteira no Rio Grande do Sul

Abstract

The region of West Frontier of Rio Grande do Sul is located in an area of the international border, next to Argentina and Uruguay. Fruit growing region presents itself as an activity still in development. Among the major obstacles to the expansion of the fruit, the fruit-flies (Diptera: Lonchaeidae and Tephritidae) stand out as key pests of many fruit crops. These insects represent the biggest obstacle to the free movement of fruit in international trade, due to quarantine restrictions imposed by importing countries. Accordingly, the aim of this study was to detect, from the gathering of fruits, the occurrence of fruit flies in native and exotic hosts; assess the level of infestation and the influence of human activities on the occurrence of this group of insects. The study was conducted in the cities of Itaqui, Quaraí, Santana do Livramento and Uruguaiana, in the years 2011 and 2012. There were collections of fruits, 19 fruit species in the region, covering urban and rural areas. The fruits were quantified, weighed and packaged in plastic trays containing a layer of sand to obtain the puparia. These were placed in gerbox with filter paper and kept in a germination chamber at 25 °C (± 1) and humidity of 75% (± 10) until adult emergence. The association between species of fruit flies and their hosts was established only found when a single species of fly in the analyzed sample. Infestation levels were expressed by the number of pupae/kg of fruit and puparia/fruit number. The anthropic action on the occurrence of fruit flies was assessed by frequency of pupae in relation to the total obtained in urban and rural areas in all four counties. Data were analyzed for abundance, constancy and dominance. Analysis was performed using simple linear correlation between the number and total fruit of fruit flies obtained in order to detect the sample sufficiency. The significance and the interactions between factors: city, fly species, type of host (native / exotic) and location (rural / urban) were tested using the GLM procedure of the system SAS. It was found that Ceratitis capitata is the most abundant species in the border region of Rio Grande do Sul with Argentina and Uruguay. This study shows the presence of lonchaeids infesting exotic fruits. Among tefritids, it was found that C. capitata infested preferably nectarine, while Anastrepha fraterculus, cherry, both with high infestation levels. It was observed that C. capitata and A. fraterculus occur proportionally in both rural and urban areas in the region of the West Frontier of Rio Grande do Sul.