Corn rootworms (CRW) are among the most destructive pests in corn production across the Corn Belt, causing considerable damage through larval feeding on roots. While crop rotation and Bt technologies are widely adopted management strategies, their effectiveness is increasingly compromised by the pest's evolution of resistance and behavioral adaptability. Chemical insecticides applied at planting to target larvae directly serve as an additional tool for corn rootworm control. In this study, we evaluated the performance of various insecticides, applied in-furrow, for managing corn rootworms by assessing Node Injury Scale (NIS), lodging rates, and grain yields from 2020 to 2024. We found that Mode of Action (MOA) 3A insecticides (sodium channel modulators), such as Force Evo (tefluthrin) and Capture LFR (bifenthrin), did not provide substantial efficacy in reducing NIS and lodging rates. In contrast, MOA 1B+3A insecticides (acetylcholinesterase (AChE) inhibitors + sodium channel modulators), such as INDEX (chlorethoxyfos + bifenthrin) and AZTEC HC (tebupirimphos + cyfluthrin), significantly reduced CRW larval damage, particularly under high pest pressure in 2020, 2021 and 2023. Differences in insecticide concentrations did not significantly impact larval control efficacy. Additionally, seasonal rainfall during larval hatching and variation in cumulative corn growing degree days (GDD) strongly influenced the root injury and lodging outcomes. Lower GDD likely limits root regeneration, increasing lodging risk under CRW pressure. These findings demonstrate the values of in-furrow insecticides in managing corn rootworms, particularly under high pest pressure and provide valuable insights for developing integrated pest management strategies to sustain effective CRW larval control and improve crop productivity.
The global spread of Fall Armyworm (FAW, Spodoptera frugiperda) has posed significant challenges to crop productivity and food security, with current pest management relying heavily on synthetic pesticides. This study explores the green synthesis of neem extract and neem oil-based Azadirachtin nanopesticides using cellulose acetate (CA) as a carrier polymer, focusing on their efficacy against FAW. The objective was to assess whether CA-NEP (neem extract nanopesticides) and CA-NOL (neem oil nanopesticide) formulations were effective at FAW control with minimal ecological impact. The nanopesticides were synthesized by electrospinning at concentrations of 5 %, 10 %, 20 %, 33 %, and 50 % (w/w) and characterized using Scanning Electron Microscopy and Fourier Transform Infrared spectroscopy. Azadirachtin content was quantified using Liquid Chromatography-Mass Spectroscopy. CA-NEP and CA-NOL followed first-order, and Korsmeyer-Peppas release kinetics, respectively. Feeding bioassays showed high FAW mortality rates, with 20 %-50 % CA-NEP achieving greater than 40 % mortality in less than 3 days and 50 % CA-NEP reaching 100 % mortality by day five. The mortality rates of FAW due to feeding on CA-NOL-treated corn leaves reached 40 % after 4 and 6 days, respectively, for 50 % and 33 % CA-NOL. Placing nanopesticide fibers next to corn seeds during planting significantly reduced FAW leaf damage. The lethal dose 50 (LD50) analyses showed that 13 % CA-NEP is the optimal concentration for FAW control. Environmental safety assessments on earthworms showed no acute or chronic toxicity, indicating that the nanopesticides suit ecologically sensitive areas. Therefore, these nanopesticide formulations provide a promising, eco-friendly alternative for sustainable FAW control and management with enhanced efficacy and safety.
Weed control in medicinal and aromatic plants (MAP) is particularly challenging as many species have a low competitiveness at early growth stages. Intra-row (within the row) mechanical weed control is most challenging since crops may be damaged as well. Here we compared five different devices for mechanical intra-row weeding (finger, torsion and rotative weeders, tine harrow, ridger share) in lemon balm and parsley, focusing on the critical stage of crop establishment. In total, eight field trials were carried out in 2020 and 2021 at two experimental farms of the University Bonn in the west of Germany. The devices were tested in replicated trials after optimising the settings on test plots. Data on weed control efficacy (WCE) and crop damage were analysed with ANOVA. The average WCE was 66 % and had a high variability ranging from 0 % to 100 %. Tine harrows could be applied most often and at earlier growth stages, followed by finger weeder. Highest crop damage was noted after use of rotative weeder. Yield decreasing effects were only significant in two cases and tended to be lower in transplanted than in sown lemon balm and parsley. However, due to variable operating conditions a consistent ranking of weeding devices was not possible. We conclude that despite significant technical progress during the last two decades, a complete replacement of herbicides is difficult at present, unless weed control is carried out manually. Further research is needed to ascertain under which environmental and management conditions mechanical intra-row weeding is most effective in the field, and how these techniques can be best integrated with other weed control methods.
Root-knot nematodes (RKNs) are a vital pest that causes significant yield losses and economic damage to potato plants. The use of chemical pesticides to control these nematodes has led to environmental concerns and the development of resistance in the nematode populations. Endophytic fungi offer an eco-friendly alternative to control these pests and produce secondary metabolites that have nematicidal activity against RKNs. The objective of this study is to assess the efficacy of Aspergillus flavus (ON146363), an entophyte fungus isolated from Trigonella foenum-graecum seeds, against Meloidogyne incognita in filtered culture broth using GC-MS analysis. Among them, various nematicidal secondary metabolites were produced: Gadoleic acid, Oleic acid di-ethanolamide, Oleic acid, and Palmitic acid. In addition, biochemical compounds such as Gallic acid, Catechin, Protocatechuic acid, Esculatin, Vanillic acid, Pyrocatechol, Coumarine, Cinnamic acid, 4, 3-indol butyl acetic acid and Naphthyl acetic acid by HPLC. The fungus was identified through morphological and molecular analysis, including ITS 1-4 regions of ribosomal DNA. In vitro experiments showed that culture filtrate of A. flavus had a variable effect on reducing the number of egg hatchings and larval mortality, with higher concentrations showing greater efficacy than Abamectin. The fungus inhibited the development and multiplication of M. incognita in potato plants, reducing the number of galls and eggs by 90% and 89%, respectively. A. flavus increased the activity of defense-related enzymes Chitinas, Catalyse, and Peroxidase after 15, 45, and 60 days. Leaching of the concentrated culture significantly reduced the second juveniles' stage to 97% /250 g soil and decreased the penetration of nematodes into the roots. A. flavus cultural filtrates via soil spraying improved seedling growth and reduced nematode propagation, resulting in systemic resistance to nematode infection. Therefore, A. flavus can be an effective biological control agent for root-knot nematodes in potato plants. This approach provides a sustainable solution for farmers and minimizes the environmental impact.
Quantifying the efficacy of different climate forcings is important for understanding the real-world climate sensitivity. This study presents a systematic multimodel analysis of different climate driver efficacies using simulations from the Precipitation Driver and Response Model Intercomparison Project (PDRMIP). Efficacies calculated from instantaneous radiative forcing deviate considerably from unity across forcing agents and models. Effective radiative forcing (ERF) is a better predictor of global mean near-surface air temperature (GSAT) change. Efficacies are closest to one when ERF is computed using fixed sea surface temperature experiments and adjusted for land surface temperature changes using radiative kernels. Multimodel mean efficacies based on ERF are close to one for global perturbations of methane, sulfate, black carbon, and insolation, but there is notable intermodel spread. We do not find robust evidence that the geographic location of sulfate aerosol affects its efficacy. GSAT is found to respond more slowly to aerosol forcing than CO2 in the early stages of simulations. Despite these differences, we find that there is no evidence for an efficacy effect on historical GSAT trend estimates based on simulations with an impulse response model, nor on the resulting estimates of climate sensitivity derived from the historical period. However, the considerable intermodel spread in the computed efficacies means that we cannot rule out an efficacy-induced bias of +/- 0.4 K in equilibrium climate sensitivity to CO2 doubling when estimated using the historical GSAT trend.
Using idealized climate model simulations, we investigate the effectiveness of black carbon (BC) aerosols in warming the planet relative to CO2 forcing. We find that a 60-fold increase in the BC aerosol mixing ratio from the present-day levels leads to the same equilibrium global mean surface warming (similar to 4.1 K) as for a doubling of atmospheric CO2 concentration. However, the radiative forcing is larger (similar to 5.5 Wm(-2)) in the BC case relative to the doubled CO2 case (similar to 3.8 Wm(-2)) for the same surface warming indicating the efficacy (a metric for measuring the effectiveness) of BC aerosols to be less than CO2. The lower efficacy of BC aerosols is related to the differences in the shortwave (SW) cloud feedback: negative in the BC case but positive in the CO2 case. In the BC case, the negative SW cloud feedback is related to an increase in the tropical low clouds which is associated with a northward shift (similar to 7 degrees) of the Intertropical Convergence Zone (ITCZ). Further, we show that in the BC case fast precipitation suppression offsets the surface temperature mediated precipitation response and causes similar to 8% net decline in the global mean precipitation. Our study suggests that a feedback between the location of ITCZ and the interhemispheric temperature could exist, and the consequent SW cloud feedback could be contributing to the lower efficacy of BC aerosols. Therefore, an improved representation of low clouds in climate models is likely the key to understand the global climate sensitivity to BC aerosols.