Assessing the effects of cultivating genetically modified glyphosate-tolerant varieties of soybeans (Glycine max (L.) Merr.) on populations of field arthropods

Effects of glyphosate on earthworms: From fears to facts

Glyphosate is the most widely applied herbicide worldwide, contaminating water, soils, and living organisms. Earthworms are emblematic soil organisms used as indicators of soil quality, but knowledge about the impacts of glyphosate and glyphosate-based herbicides (GBH) on these key soil organisms is scattered. Here, we examine this knowledge in detail to answer four questions: (1) Which endpoint is the most sensitive when assessing the effects of glyphosate or GBH in earthworms? (2) Which is most toxic to earthworms: glyphosate or GBH? (3) Are glyphosate and GBH harmful to earthworms when used at the recommended application dose? (4) What are the interactions between glyphosate or GBH and other chemicals in earthworms? The results indicate that a weak legislation led to improper assessment of the ecotoxicity of glyphosate during the last renewal in 2017. Our findings also highlighted that negative effects can occur in earthworms at the recommended application rate, although not after only a single application or when considering only the mortality of adult individuals. However, under more realistic conditions, that is, when assessing sensitive endpoints (e.g., reproduction, growth) and using species present in the field, after several applications per year, the negative effects of glyphosate or GBH on earthworms were observed at the subindividual, individual, population, and community levels, as well as on earthworm-mediated functions. Our recommendations are as follows: (i) competent agencies should collect more information on the toxicity of these compounds to earthworms before the next renewal deadline, with emphasis on the use of the updated legislation on the topic, and (ii) scientists should increase research on the effects of these herbicides on soil invertebrate species, with emphasis on earthworms, using guideline tests and obtain data from long-term field testing. Integr Environ Assess Manag 2023;00:1-7. © 2023 SETAC.

Non-target Effects of Hyperthermostable α-Amylase Transgenic Nicotiana tabacum in the Laboratory and the Field

Thermostable α-amylases are important enzymes used in many industrial processes. The expression of recombinant Pyrococcus furiosus α-amylase (PFA) in Nicotiana tabacum has led to the accumulation of high levels of recombinant protein in transgenic plants. The initial steps to registering the transgenic tobacco at a commercial production scale and growing it in the field requires a risk assessment of potential non-target effects. The objective of this study was to assess the effect of feeding on transgenic tobacco with 2 indigenous insect species commonly associated with wild and commercial tobacco involving plants grown and evaluated under laboratory and field conditions. The highest levels of PFA ranged from 1.3 to 2.7 g/kg leaf fresh weight produced in the field-grown cultivars Con Havana and Little Crittenden, respectively. These two cultivars also had the highest nicotine (ranging from 4.6 to 10.9 mg/g), but there was little to no negative effect for either tobacco hornworm Manduca sexta L. or aphid Myzus nicotianae (Blackman). Both laboratory and field trials determined no short term (5 days) decrease in the survival or fecundity of the tobacco aphid after feeding on PFA transgenic tobacco compared to non-transgenic plants. In the field, tobacco hornworm larvae showed no differences in survival, final larval weights or development time to adult stage between transgenic lines of four cultivars and their corresponding wild type controls. Laboratory studies confirmed the field trial results indicating the low risk association of PFA expressed in tobacco leaves with tobacco hornworms and aphids that would feed on the transgenic plants.

Effects of glyphosate on the non-target leaf beetle Cerotoma arcuata (Coleoptera: Chrysomelidae) in field and laboratory conditions

This study aimed to assess the glyphosate application effects on the Cerotoma arcuata Oliver (Coleoptera: Chrysomelidae) population in glyphosate-resistant soybean crops. Field studies were conducted with glyphosate and the insecticide endosulfan to observe the effects of these pesticides on C. arcuata, on its damages in the crop and on the populations of natural enemies in glyphosate-resistant soybean crops. Moreover, the lethal and behavioral sublethal response of C. arcuata to glyphosate and endosulfan was conducted in the laboratory. The results of the field and laboratory experiments showed that glyphosate caused moderate toxicity and high irritability in C. arcuata and that endosulfan caused high toxicity and irritability. Therefore, the direct effect of glyphosate on C. arcuata was negative and does not explain the population increases of this pest in glyphosate-resistant soybean. However, the glyphosate also decreased the density of predators. Thus, the negative effect of glyphosate on the predators may be related to population increases of C. arcuata in glyphosate-resistant soybean crops, however, more studies are needed to better evidence this relationship. This study suggests that glyphosate can impact other non-target organisms, such as herbivorous insects and natural enemies and that the use of this herbicide will need to be carefully stewarded to prevent potential disturbances in beneficial insect communities in agricultural systems.