Pyrrolizidine alkaloids (PAs) are a widespread group of secondary metabolites in plants. PAs are notorious for their acute hepatotoxicity, genotoxicity and neurological damage to humans and animals. In recent decades, the application of PAs for beneficial biological activities to cure disease has drawn greater attention. Here, we review the current knowledge regarding the pharmacological properties of PAs and discuss PAs as promising prototypes for the development of new drugs.

Spodoptera frugiperda has caused serious economic damage to various crops. Entomopathogenic nematodes (EPNs) can be used as biological control agents for many pests, including lepidopteran insects. In this study, 218 soil samples were collected from 46 sites in Guangxi, and EPNs were detected in 15 samples. The ITS region of the rDNA gene was used for the molecular identification of isolated nematodes. In total, four and eleven identified populations belonged to Heterorhabditis and Oscheius, respectively. A series of bioassays were conducted to examine the virulence of EPN isolates from Guangxi to control the larvae and pupae of S. frugiperda. The mortality of the third-instar larvae caused by EPNs was concentration dependent. The same dose of EPNs was used to control the third and sixth-instar larvae of S. frugiperda, and the virulence was lower in the sixth-instar larvae. S. frugiperda pupae were treated with different EPNs strains, and the adult eclosion rate of the treated group was significantly lower than that of the sterile water control group (93.3%). Therefore, EPNs could significantly inhibit the eclosion of S. frugiperda pupae. This study provides important information for the biological control of S. frugiperda with EPNs.

Microplastics have emerged as significant and concerning pollutants within soil ecosystems. Among the soil biota, entomopathogenic nematodes (EPNs) are lethal parasites of arthropods, and are considered among the most effective biological agents against pests. Infective juveniles (IJs) of EPNs, as they navigate the soil matrix scavenging for arthropod hosts to infect, they could potentially encounter microplastics. Howver, the impact of microplastics on EPNs has not been fully elucidated yet. We addressed this gap by subjecting Steinernema feltiae EPNs to polystyrene microplastics (PS-MPs) with various sizes, concentrations, and exposure durations. After confirming PS-MP ingestion by S. feltiae using fluorescent dyes, we found that the PS-MPs reduced the survival, reproduction, and pathogenicity of the tested EPNs, with effects intensifying for smaller PS-MPs (0.1-1 μm) at higher concentrations (10⁵ μg/L). Furthermore, exposure to PS-MPs triggered oxidative stress in S. feltiae, leading to increased reactive oxygen species levels, compromised mitochondrial membrane potential, and increased antioxidative enzyme activity. Furthermore, transcriptome analyses revealed PS-MP-induced suppression of mitochondrial function and oxidative phosphorylation pathways. In conclusion, we show that ingestion of PS-MPs by EPNs can compromise their fitness, due to multple toxicity effects. Our results bear far-reaching consequences, as the presence of microplastics in soil ecosystems could undermine the ecological role of EPNs in regulating pest populations.