A survey of Tuta absoluta (Meyrick) ( Lepidoptera : Gelechiidae ) outbreaks in tomato greenhouses in Southern Sardinia (Italy).

摘要

The first reports of the tomato borer Tuta absoluta (Meyrick) in Sardinia date back to 2008, firstly in open field tomatoes and successively in protected crops. In order to monitor the population trends of T. absoluta in greenhouse tomatoes and to evaluate the effectiveness of the control measures applied by growers, from February 2009 to July 2010 we surveyed several commercial crops grown in a major fresh market tomato production area. During the study period we recorded the number of adults caught by pheromone traps every week and assessed monthly the percentage of infested plants, the mean number of live larvae per plant, and the mortality of 2nd-4th-instar larvae. Finally, for each crop we noted the treatment schedules. The highest numbers of moths caught in traps were observed between April and June and in September-October. Similarly, the highest levels of tomato borer infestation were observed in spring and, to a lesser extent, in autumn. In fact, while in spring T. absoluta frequently reached maximum densities of 30-100 larvae/plant, during autumn infestation did not exceed 25 larvae/plant. This may probably explain the intensive application of insecticides recorded in spring. The products most commonly used by growers for pest management were spinosad, abamectin and azadirachtin, but Bacillus thuringiensis-based insecticides and indoxacarb were also applied. Evidence of enhanced biological control of the tomato borer by native natural enemies was observed in several crops at the end of the growing period.