Susceptibilidade de adultos de Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) a fungicidas utilizados no controle de doenças da macieira

Abstract

This study evaluated the susceptibility under laboratory conditions of Trichogrammapretiosum Riley adults to fungicides recommended by the Integrated Production of Apple (IPA). The bioassays were carried out using the International Organization for Biological Control (IOBC), West Palearctic Regional Section (WPRS) standard protocols. Twelve selected fungicides were studied in the doses (g or ml active ingredient/100 L) captan 1 (0.115), captan 2 (0.120), kresoxim-methyl (0.010), sulphur 1 (AG) (0.480), sulphur 2 (0.480), folpet (0.105), mancozeb (0.160), pyraclostrobin (0.010), tebuconazole (0.010), tetraconazole (0.005), thiophanate-methyl (0.050) and triforine (0.024). Distilled water was used as the blank treatment and the insecticide triclorfon (0.150) as a positive control. The parasitoids were exposed to dry residues applied on glass plates. The reduction in the capacity of parasitism was used to measure the effect of the chemical in comparison to the blank treatment. Each treatment was replicated four times. The results allowed us to classify the fungicides tested in four categories: 1, harmless (< 30%); 2, slightly harmful (30-79%); 3, moderately harmful (80-99%); and 4, harmful (> 99%). 75% of the tested substances were classified as selective (classes 1 and 2) to the parasitoid. The fungicides captan 1, captan 2, kresoxim-methyl, folpet, pyraclostrobin, tebuconazole, thiophanate-methyl and triforine were harmless; mancozeb was slightly harmful; sulphur 1 (AG) and tetraconazole were moderately harmful and sulphur 2 was harmful. These findings should be taken into account when selecting fungicides to spray apple orchards against fungi diseases to preserve the egg parasitoid T. pretiosum.