As a biocontrol bacteria, Brevibacillus has been the subject of extensive research for agricultural applications. Antibacterial peptides (AMPs) are the main antibacterial products of Brevibacillus. This study isolated a strain of Br. brevis HNCS-1 from tea garden soil, and the strain has an antagonistic effect against five types of pathogens of tea diseases, namely Gloeosporium theae-sinensis, Elsinoe leucospira, Phyllosticta theaefolia, Fusarium sp., and Cercospora theae. To determine the genetic characteristics implicated in the biocontrol mechanism, the genome sequence of the HNCS-1 strain was obtained and analyzed further, and the data are deposited in the GenBank repository (No. CP128411). Comparative genomics analyses revealed that the HNCS-1 strain and 17 public Br. brevis share a core genome composed of 3,742 genes. Interestingly, only one non-ribosomal peptide synthetase (NRPS) gene cluster annotated as edeine is present in the core genome. And UHPLC-MS/MS detection results showd that edeine B and edeine A were the principal antibacterial peptides in the HNCS-1 strain. This study proves that edeine is the main antibacterial peptide of Br. brevis, and provides a new strategy for the identification of antibacterial products from other biocontrol bacteria.

Elevated atmospheric carbon dioxide concentrations (eCO₂) can affect both herbivorous insects and their host plants. The fall armyworm (FAW), Spodoptera frugiperda, is a highly polyphagous agricultural pest that may attack more than 350 host plant species and has developed resistance to both conventional and novel-action insecticides. However, the effects of eCO₂ on host adaptability and insecticide resistance of FAW are unclear. We hypothesized that eCO₂ might affect insecticide resistance of FAW by affecting its host plants. To test this hypothesis, we investigated the effect of eCO₂ on (1) FAW’s susceptibility to chlorantraniliprole after feeding on wheat, (2) FAW’s population performance traits (including the growth and reproduction), and (3) changes in gene expression in the FAW by transcriptome sequencing. The toxicity of chlorantraniliprole against the FAW under eCO₂ (800 µL/L) stress showed that the LC₅₀ values were 2.40, 2.06, and 1.46 times the values at the ambient CO₂ concentration (400 µL/L, aCO₂) for the three generations, respectively. Under eCO₂, the life span of pupae and adults and the total number of generations were significantly shorter than the FAW under aCO₂. Compared to the aCO₂ treatment, the weights of the 3rd and 4th instar larvae and pupae of FAW under eCO₂ were significantly heavier. Transcriptome sequencing results showed that more than 79 detoxification enzyme genes in FAW were upregulated under eCO₂ treatment, including 40 P450, 5 CarE, 17 ABC, and 7 UGT genes. Our results showed that eCO₂ increased the population performance of FAW on wheat and reduced its susceptibility to chlorantraniliprole by inducing the expression of detoxification enzyme genes. This study has important implications for assessing the damage of FAW in the future under the environment of increasing atmospheric CO₂ concentration.

Plant-derived natural products are important resources for pesticide discovery. Acetylcholinesterase (AChE) is a well-validated pesticide target, and inhibiting AChE proves fatal for insects. Recent studies have shown that the potential of various sesquiterpenoids as AChE inhibitors. However, few studies have been conducted with eudesmane-type sesquiterpenes with AChE inhibitory effects. Therefore, in this research, we isolated two new sesquiterpenes, laggeranines A (1) and B (2), along with six known eudesmane-type sesquiterpenes (3–8) from Laggera pterodonta, and characterized their structures and the inhibitory effect they exerted on AChE. The results showed that these compounds had certain inhibitory effects on AChE in a dose-dependent manner, of which compound 5 had the best inhibitory effect with IC50 of 437.33 ± 8.33 mM. As revealed by the Lineweaver-Burk and Dixon plots, compound 5 was observed to suppress AChE activity reversibly and competitively. Furthermore, all compounds exhibited certain toxicity levels on C. elegans. Meanwhile, these compounds had good ADMET properties. These results are significant for the discovery of new AChE targeting compounds, and also enrich the bioactivity activity repertoire of L. pterodonta.

Dodonaea viscosa is a medicinal plant which has been used to treat various diseases in humans. However, the anti-insect activity of extracts from D. viscosa has not been evaluated. Here, we found that the total saponins from D. viscosa (TSDV) had strong antifeedant and growth inhibition activities against 4th-instar larvae of Spodoptera litura. The median antifeeding concentration (AFC₅₀) value of TSDV on larvae was 1621.81 μg/mL. TSDV affected the detoxification enzyme system of the larvae and also exerted antifeedant activity possibly through targeting the γ-aminobutyric acid (GABA) system. The AFC₅₀ concentration, the carboxylesterase activity, glutathione S-transferases activity, and cytochrome P450 content increased to 258%, 205%, and 215%, respectively, and likewise the glutamate decarboxylase activity and GABA content to 195% and 230%, respectively, in larvae which fed on TSDV. However, D. viscosa saponin A (DVSA) showed better antifeedant activity and growth inhibition activity in larvae, compared to TSDV. DVSA also exerted their antifeedant activity possibly through targeting the GABA system and subsequently affected the detoxification enzyme system. Further, DVSA directly affected the medial sensillum and the lateral sensillum of the 4th-instar larvae. Stimulation of Spodoptera litura. with DVSA elicited clear, consistent, and robust excitatory responses in a single taste cell.

Climate is changing globally nowadays because of extensive crucial human activities. This state along with stark in weather measures ultimately affecting the development and growth of crops due to various kinds of stressful field condition at the same time including biotic and abiotic stresses. Thus, various biotic factors including pathogens, weeds and pests and abiotic factors including temperature, humidity and drought etc. are involved in reduction of cotton yield due to which cotton production significantly reduced. Various biotic factors have direct effect on the cotton production and caused significant reduction in cotton crop yield estimated up to 10 to 30%, while as abiotic factors are even worse than biotic stresses and could cause 50% reduction. So, effective agronomic practices, optimal climate and integrated pest management leads to fruitful crop production to cover this yield gap. This chapter will be broadly useful to design projects aimed with inter and intra-disciplinary collaboration for sustainable cotton production.

Spodoptera frugiperda, a globally invasive pest, currently lacks effective control measures beyond certain chemical pesticides. Previous reports have demonstrated the effectiveness of Humulus scandens against various agricultural pests. Here, our aim was to derive toxic compounds and explore the insecticidal potential of the botanical plant H. scandens against S. frugiperda. Through activity-guided isolation, two monoamide compounds, N-p-coumaroyl tyramine (1) and N-trans-feruloyl tyramine (2), were identified from the EtOAc extract of H. scandens. The results showed that both compounds 1 and 2 exhibited good insecticidal effects on S. frugiperda under both contact and dietary toxicity methods, with significant dose-dependent effects; however, compound 2 demonstrated stronger insecticidal activity. On the other hand, both compounds exhibited stronger contact toxicity than ingestion toxicity, with compound 2 having an LC₅₀ (50% lethal concentration) of 47.97 μg/mL. Insecticidal mechanism studies revealed that both compounds act on the acetylcholinesterase (AChE) of S. frugiperda, with compound 2 showing stronger inhibition (50% inhibitory concentration, IC₅₀ = 19.71 ± 1.98 μg/mL). Kinetic studies of the compounds on AChE indicated that both monoamides are reversible competitive inhibitors of AChE, with Ki values of 23.76 μg/mL and 20.79 μg/mL, respectively. This study revealed the active insecticidal compounds from H. scandens and their mechanisms of action. These findings provide new insights into the secondary metabolites of H. scandens which may serve as a basis for the development of novel plant based insecticides. Furthermore, these results suggested the use of these two bioactive compounds in the integrated management of S. frugiperda as alternatives to synthetic insecticides.