Physiological effects of thiamethoxam on Zea mays and its electrochemical detection using a silver electrode

Review on Pesticide Abiotic Stress over Crop Health and Intervention by Various Biostimulants

Plants are essential for life on earth, and agricultural crops are a primary food source for humans. For the One Health future, crop health is crucial for safe, high-quality agricultural products and the development of future green commodities. However, the overuse of pesticides in modern agriculture raises concerns about their adverse effects on crop resistance and product quality. Recently, biostimulants, including microecological bacteria agents and nanoparticles, have garnered worldwide interest for their ability to sustain plant health and enhance crop resistance. This review analyzed the effects and mechanisms of pesticide stress on crop health. It also investigated the regulation of biostimulants on crop health and the multiomics mechanism, combining research on nanoselenium activating various crop health aspects conducted by the authors' research group. The paper helps readers understand the impact of pesticides on crop health and the positive influence of various biostimulants, especially nanomaterials and small molecules, on crop health.

Phytotoxic effect of the insecticide imidacloprid in Phaseolus vulgaris L. plant and evaluation of its bioaccumulation and translocation by electrochemical methods

The objective of this work is to study the toxicological effect of the imidacloprid (IMD) on common bean plants (Phaseolus vulgaris L) when used at high doses and its quantification by electrochemical method. Common bean plants were exposed to increasing concentrations of IMD and the different plant tissues were subjected to various analyses. The IMD detection in different tissues of the bean plant was performed after extraction on the metallic silver electrode using square wave voltammetry. The analytical and calibration parameters (Slope, correlation coefficient, linear range, detection limit and relative standard deviation) were calculated for the different plant tissues. The effect of different doses (5.0 × 10^-3 to 5.0 × 10^-2 mol L^-1) of IMD was evaluated on germination, seedling (vigour, growth) and photosynthetic pigments in the bean plant. The results indicate that germination rate and seed vigour index reduced significantly (p ≤ 0.05) only in the applied concentrations above the recommended dose. A similar effect of IMD was observed on seedling development in term of roots length, plant length, number of leaves and number of nods. Concerning pigments content, chlorophyll a, b and total chlorophyll maximally decreased by 95.26%, 80.44% and 82.15% respectively at high applied dose. The bioaccumulation and translocation behaviour of IMD in bean plant was investigated, revealing that the IMD can be bioaccumulated in roots and can easily be translocated into stems and leaves.

Seed treatment for managing fall armyworm as a defoliator and cutworm on maize: plant protection, residuality, and the insect life history

BACKGROUND

The highly polyphagous and invasive fall armyworm (FAW, Spodoptera frugiperda) can feed on different plant parts of host crops, damaging whorls and stalks in early maize growth stages. Systemic insecticide seed treatment (IST) could minimize this damage, although the residual efficacy may vary with the plant tissue damaged. Using damage rating scales and artificial infestation in controlled conditions, we determined the potential of IST against FAW attacking maize whorl leaves or the stalk base.

RESULTS

Chlorantraniliprole, cyantraniliprole, or thiodicarb + imidacloprid IST similarly killed > 80% FAWs for 1 or 2 weeks after plant emergence depending on the plant tissue attacked. The residual efficacy (i.e. time after plant emergence sustaining > 80% larval mortality) lasted from the first to the eleventh day (VE-V3 maize growth stages), while for cutworm on the maize stalk base, it lasted 3-7 days after plant emergence (V1-V2 stages). In terms of damage, the ISTs lasted 15 days after emergence (V4 stage) for FAW on whorl leaves and 10 days (V3 stage) for FAW feeding on the stalk base. The larvae surviving on the seed-treated plants underwent sublethal effects in growth and development, reducing insect fitness.

CONCLUSION

Diamide or carbamate + neonicotinoid seed treatments kill FAW larvae on maize whorls or stalks in favorable edaphoclimatic and insecticide-susceptibility conditions. The cumulative impacts of systemic IST on aboveground insect pests go beyond mortality. The ISTs studied can be valuable against FAW in maize, for instance, to help protect varieties that may not express sufficient insect resistance in maize early growth stages.