Tuta absoluta: dinamica di popolazione, nemici naturali e prove di lotta in Sardegna

Tuta absoluta(Meyrick) (Lep.:Gelechiidae) in Sardinia infests tomato and other cultivated and spontaneous solanaceous plants. In the laboratory, larvae developed on tomato leafs forming only one mine. A relationship among the head capsule width, the larval length and the mine length on leaves was found for each of the four larval instars. The population dynamics was studied from October to June in a non-heated tomato greenhouse, where four generations of the insect pest were recorded. Female oviposited preferentially in the upper part of the plant. Infestation level was low during winter and increased from April on, reaching a density of 4 larvae/compound leaf. The ectophagous parasitoidNecremnusnearartynesparasitized 3,6% of larvae during the whole crop cycle. In field conditions,T. absolutaadults were found during the whole year, achieving a maximum density in summer. On potato plants, during the two winter and summer cycles, low infestation levels were recorded (<0.15 larvae/leaf), while infestation on tomato in summer where higher (<1 larvae/leaf). On tomato, a total parasitism percentage of 21,4% was assessed, especially determined byNeochrysocharis formosa. The use of sexual pheromone was effective in mating disruption trials in greenhouse, but was not efficient for mass trapping. The entomopathogenic microorganismsBacillus thuringiensis,Beauveria bassianaandSteinernema feltiaedid not show a significant efficacy in open field trials on tomato.