Effect of two herbicides on Xenylla welchi (Hexapoda:Collembola) under laboratory conditions

Ultimate fate, transformation, and toxicological consequences of herbicide pretilachlor to biotic components and associated environment: An overview

Herbicides are applied for effective weed management in order to increase the crop yield. In recent decades, the overuse of these chemicals has posed adverse effects on different biotic components of the environment. Pretilachlor has been widely used during last few decades for weed management in paddy crop. Its excessive use may prove fatal for environment, various organisms, and nontarget plants. Thus, it is pertinent to know the extent to which herbicide residues remain in environment. The potential mobility and the release rate of herbicide in the soil are important factors governing ecotoxicological impact and degradation rate. Therefore, several techniques are being investigated for its effective removal from the contaminated sites. Furthermore, efforts have also been made to study the degradation of pretilachlor by various physicochemical processes, resulting into the formation of different types of metabolites. This review summarizes the available information on environmental fate, various degradation processes, microbial biotransformation, metabolites formed, ecotoxicological effects, techniques for detection in environmental samples, effect of safener, and various control release formulations for sustained release of pretilachlor in applied fields. The information so obtained will be very advantageous in deciding the future policies for safe and judicious use of the herbicide by maintaining health and environmental sustainability.

Dinitroaniline herbicides: a comprehensive review of toxicity and side effects on animal non-target organisms

The widespread use of herbicides has increased concern about the hazards and risks to animals living in terrestrial and aquatic ecosystems. A comprehensive understanding of their effective action at different levels of biological organization is critical for establishing guidelines to protect ecosystems and human health. Dinitroanilines are broad-spectrum pre-emergence herbicides currently used for weed control in the conventional agriculture. They are considered extremely safe agrochemicals because they act specifically on tubulin proteins and inhibit shoot and root growth of plants. However, there is a lack of toxicity information regarding the potential risk of exposure to non-target organisms. The aim of the present review is to focus on side effects of the most commonly used active ingredients, e.g. pendimethalin, oryzalin, trifluralin and benfluralin, on animal non-target cells of invertebrates and vertebrates. Acute toxicity varies from slightly to high in terrestrial and aquatic species (i.e. nematodes, earthworms, snails, insects, crustaceans, fish and mammals) depending on the species-specific ability of tested organisms to adsorb and discharge toxicants. Cytotoxicity, genotoxicity and activation of oxidative stress pathways as well as alterations of physiological, metabolic, morphological, developmental and behavioural traits, reviewed here, indicate that exposure to sublethal concentrations of active ingredients poses a clear hazard to animals and humans. Further research is required to evaluate the molecular mechanisms of action of these herbicides in the animal cell and on biological functions at multiple levels, from organisms to communities, including the effects of commercial formulations.

Effects on Life-History Traits of Hypogastrura viatica (Collembola) Exposed to Imidacloprid Through Soil or Diet

Collembola (springtails) are important members of soil communities worldwide by contributing to degradation of organic matter. In nature, Collembola might be exposed to the neonicotinoid insecticide imidacloprid, which is fairly persistent in soil. We exposed the widespread Hypogastrura viatica to imidacloprid through soil or food and monitored the animals during exposure and a post exposure period. We recorded effects on life-history traits affecting individual fitness, that is, mortality, behavioral activity, several reproduction traits, and molting frequency. Exposure through soil led to a concentration-dependent mortality, while the mortality from dietary exposure possibly reflected reduced feeding activity. The body burden of imidacloprid in the Collembola did not differ between treatments. We found no sign of recovery in behavioral activity following exposure in either experiment. The egg production of H. viatica was not significantly affected by imidacloprid at 0.01 mg/kg dry soil but showed a tendency to reduce number of eggs per batch and reduced hatching success. At higher concentrations, reproduction was close to, or completely, stopped. The molting frequency decreased during exposure, while in the post exposure period, we saw milder effects at the highest concentrations, suggesting elimination through molting or reduced toxic response as a result of reduced feeding activity. Overall, H. viatica was more sensitive to imidacloprid than previously studied Collembola, which highlights the importance of considering species sensitivities when risk-assessing soil environments. Environ Toxicol Chem 2021;40:3111-3122. © 2021 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Short-term biochemical ill effects of insect growth regulator (IGR) pesticides in Cyphoderus javanus Borner (Collembola: Insecta) as potential biomarkers of soil pollution

The insect growth regulator (IGR) chemicals are considered as safe alternatives to synthetic organic pesticides, but only scant information are available on their possible impact on non-target and ecologically important soil insect fauna of croplands. Previous studies by the authors showed that recommended agricultural doses of IGRs buprofezin (Applaud 25SC at 250 g a.i. ha(-1)), flubendiamide (Takumi 20WG at 50 g a.i. ha(-1)) and novaluron (Rimon 10EC at 100 g a.i. ha(-1)) produced less mortality of adults of a non-target soil insect Cyphoderus javanus Borner (Collembola) but decreased major life history parameters namely moulting, fecundity and egg hatching success. This detritivorous microarthropod is very sensitive to soil characteristics and is ecologically relevant to the tropical soils. Present microcosm study showed strong biochemical impact of the above doses of IGRs on tissue nutrient levels and digestive enzyme activities in C. javanus within 7 days of exposure to treated sandy loam soil. The levels of tissue proteins, carbohydrates, lipids and free amino acids declined significantly and persistently in the specimens reared in IGR-treated soils than in the specimens of untreated soil. Similarly, α-amylase, cellulase and protease activities declined significantly in the specimens of IGR-treated soil. These nutritional scarcities would reduce metabolism, growth and reproduction in the affected insects. Therefore, the observed biochemical responses, especially the levels of tissue proteins, carbohydrates and α-amylase activity in C. javanus are early warning indices and potential biomarkers of soil pollution in croplands.