Glyphosate-based herbicides toxicity on life history parameters of zoophytophagous Podisus nigrispinus (Heteroptera: Pentatomidae).

The increase of agricultural areas with glyphosate-resistant (GR) crops, and use of this herbicide in Brazil, makes necessary to assess its impacts on non-target organisms. The objective was to evaluate the development, reproduction and life table parameters of Podisus nigrispinus (Heteroptera: Pentatomidae) reared on GR-soybean plants treated with glyphosate formulations (Zapp-Qi, Roundup-Transorb-R and Roundup-Original) at the recommended field dose (720g acid equivalent ha-1). Glyphosate formulations had no affect on nymph and adult weight of this predator. Fourth instar stage was shortest with Zapp Qi. Egg-adult period was similar between treatments (26 days) with a survival over 90%. Zapp-Qi and Roundup-Transorb-R (potassium-salt: K-salt) reduced the egg, posture and nymph number per female, and the longevity and oviposition periods of this predator. Podisus nigrispinus net reproductive rate was highest in GR-soybean plants treated with Roundup-Original (isopropylamine-salt: IPA-salt). However, the duration of one generation, intrinsic and finite increase rates, and time to duplicate the population, were similar between treatments. Glyphosate toxicity on P. nigrispinus depends of the glyphosate salt type. IPA-salt was least harmless to this predator. Formulations based on K-salt altered its reproductive parameters, however, the development and population dynamic were not affect. Therefore, these glyphosate formulations are compatible with the predator P. nigrispinus with GR-soybean crop.

Toxicity and repellent activity of monoterpene enantiomers to rice weevils (Sitophilus oryzae).

BACKGROUND: The rice weevil, Sitophilus oryzae (L., 1763) (Coleoptera: Curculionidae), is a stored grain/seed pest of several crops. Botanicals represent an option to manage this pest, especially those with high toxicity determined by its structure and physicochemical properties and low residue left behind on treated grains/seeds. Enantiomers are bioactive molecules in organic processes. The aim of this study was to evaluate the insecticidal activity of two enantiomeric forms of the monoterpenes citronellal, limonene, linalool, menthone and α-pinene against S. oryzae adults through contact, fumigant and repellent assays. RESULTS: All results were compared with absolute acetone as the negative control and those from contact assays also with malathion as the positive control. (S)-(-)-linalool was the most toxic by contact to S. oryzae and (S)-(-)-menthone through fumigation, while the two enantiomeric forms of menthone and α-pinene were the best repellents. CONCLUSIONS: The high toxicity of only one of the two monoterpene enantiomers showed the importance of form and percentage of enantiomer in the commercial product, which affect the success of the product to controlling S. oryzae. © 2021 Society of Chemical Industry.