Field studies were conducted from May to October 2000 to determine the effectiveness of several insecticides in controlling Tuta absoluta and Helicoverpa zea and their impact on emergence of the parasitoid Trichogramma pretiosum. The insecticides tested were: methoxyfenozide (120; 144), clorpirifós (540; 675), tiacloprid (72; 96) and triflumuron (144). Application rates of all insecticides are expressed as g a.i./ha. The experiment was designed as randomized complete block with eight treatments (insecticides and untreated plots) with five replications. Tomato fruits were harvested 58; 80 and 87 days after transplanting and the percentage of damaged fruits by both pests determined. The impact of insecticides on T. pretiosum survival was determined collecting 20 eggs of H. zea/plot 61 days after transplanting and the percentage of emerged parasitoid determined. All insecticides reduced significantly the damage caused by H. zea whereas none of the products were effective in controlling T. absoluta. Methoxyfenozide and clorpirifós (540) did not reduce significantly the number of eggs parasitized by T. pretiosum when comparared with untreated ones.
Tuta absoluta; Helicoverpa zea; Lycopersicon esculentum; chemical control; biological control; selectivity
