Evaluating the selectivity of registered fungicides for soybean against Trichogramma pretiosum Riley, 1879(Hymenoptera: Trichogrammatidae)

Abstract

The aim of this study was to evaluate the effects of fungicides registered for soybean on the parasitoid Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae). Bioassays wereconducted in laboratory exposing adult insects to dried residues of fungicides, using the methodology proposed by the International Organization for Biological and Integrated Control of Noxious Animals and Plants (IOBC). The experimental design was completely randomized with four replications per treatment. The parameter used for classification of fungicides was based on the reduced parasitism (RP) evidenced by the number of parasitized eggs per female in the control treatment. Based on these results, we found that fungicides are classified in different classes of selectivity to adults of T. pretiosum regarding the tested fungicides. The fungicides cyproconazole, epoxyconazole + kresoxim-methyl, metconazole, thiophanatemethyl (CS), pyraclostrobin, difenoconazole, were classified as harmless (Class 1); carbendazim, carbendazim + thiram, tetraconazole, tetraconazole+ azoxystrobin, epoxyconazol + pyraclostrobin, tebuconazole, prothioconazole + trifloxystrobin, tebuconazole + trifloxystrobin, azoxystrobin, azoxystrobin + cyproconazole, and thiophanate methyl (WG) were slightly harmful (Class 2); flutriafol, thiophanate methyl (WP), epoxyconazole + pyraclostrobin, and cyproconazole+ trifloxystrobin were moderately harmful (Class 3); and Kumulus DF was harmful (Class 4) to the adult parasitoids.

Compatibility of powdered sulphur and natural enemies for the control of Drosophila suzukii (Diptera: Drosophilidae): Effects on Anthocoris nemoralis (Hemiptera: Anthocoridae) and Trichopria drosophilae (Hymenoptera: Diapriidae) activity

“…Sulphur and its different formulations have been widely used as fungicides and insecticides over the last century due to their low ecological impact and compatibility with organic management (Pérez‐Guerrero & Molina, 2016; Williams & Cooper, 2004; Zappalà et al., 2011). Sulphur‐based compounds interfere in biochemical processes resulting in chelates with heavy metals and causing damage to the respiratory system of insects (Magano et al., 2015). For instance, in southwestern Spain, powdered sulphur is currently authorised as a fungicide for organic production of strawberries, and farmers use it at least once or twice a year at a rate of 20–30 kg per hectare.…”

Selectivity of insecticides with two active ingredients on the parasitoid >i<Trichogramma pretiosum>/i< (Hymenoptera: Trichogrammatidae)

“…Hassan (1998) tested this fungicide, cyproconazole, on T. cacoeciae and classified it as innocuous. Magano et al (2015) tested cyproconazole on T. pretiosum and found a similar outcome. The classification of "moderately harmful" obtained here could be explained by the mixture with thiamethoxam, a neonicotinoid insecticide, which acts as an agonist of acetylcholine receptors in the insect central nervous system, causing first paralysis and eventually death (IRAC, 2020;Tomizawa and Casida, 2005).…”