Selectivity of organic compounds to the egg parasitoid Telenomus remus Nixon (Hymenoptera: Plastygastridae)

Abstract

The selectivity of insecticides, bio-protective mixtures, and biofertilizers used in organic soybean production was evaluated for adults and pupae of the egg parasitoid Telenomus remus Nixon (Hymenoptera: Platygastridae) under laboratory conditions in accordance with protocols proposed by the International Organization for Biological Control (IOBC). The products sprayed (dosage/180L of water) were: 1) Baculovírus anticarsia 140x109 cpi; 2) Bacillus thuringiensis 16.8g; 3) Azadirachtin-A, azadirachtin-B, nimbina and salamina 9.6 ppm; 4) Rotenoids 4 liters; 5) Nitrogen 1.3%, phosphorus 3.0% and total organic carbon 8.0% 3 liters; 6) Sodium silicate 2% 4 liters; 7) Copper 7% + calcium 3.3% 1.8 liters; 8) Sulfur 20% + quicklime 10% 1.8 liters; 9) Chlorpyrifos 384g (positive control); 10) Distilled H2O (negative control). The results of experiments using pupae indicate that the organic compounds were classified as harmless (Class 1), except for the copper 7% + calcium 3.3% and sulfur 20% + quicklime 10%, which were classified as slightly harmful (Class 2). The contact bioassay with adults showed that all products were classified as harmless (Class 1). Only chlorpyrifos (384g) was classified as harmful (Class 4) for both stages of the parasitoid. However, the use of this product (chlorpyrifos) is not permitted in organic farming, and even in conventional farming is recommended, where feasible, replacement of the product with one compatible with the preservation of T. remus in nature. Thus, the products tested and used in organic soybean production were considered compatible with the parasitoid eggs of T. remus.