Involvement of small heat shock proteins (sHsps) in developmental stages of fall armyworm, Spodoptera frugiperda and its expression pattern under abiotic stress condition

Heat shock protein mediates the fumigation activity of terpinen-4-ol and limonene against Tribolium confusum

BACKGROUND

Terpinen-4-ol and limonene are important active components used to control storage pests, comprising an effective strategy to reduce the utilization of chemical pesticides and postpone the development of resistance.

RESULTS

Terpinen-4-ol and limonene had significant fumigation activity against Tribolium confusum, which showed positive association with temperature. Two heat shock protein genes (HSPs) (TcfHSP16.8 and TcfHSP19.0) were selected as candidate targets according to RNA-sequencing data. Following RNA interference-mediated silencing of these two genes, T. confusum showed no notable disparity in eclosion rates between temperatures of 28 °C and 40 °C. Subsequent sensitivity assessments using 30% lethal concentrations demonstrated mortality rates of 58.41% (TcfHSP16.8) and 57.10% (TcfHSP19.0) with terpinen-4-ol, and 58.62% (TcfHSP16.8) and 55.95% (TcfHSP19.0) with limonene at 40 °C, respectively. Thus, silencing TcfHSP16.8 and TcfHSP19.0 increased the susceptibility of T. confusum to both compounds at 40 °C, with limonene showing a more pronounced effect.

CONCLUSION

These results suggested that HSPs mediate and enhance the sensitivity of T. confusum to terpinen-4-ol and limonene, which is important to improve the control to storage pests and reduce the utilization of chemical pesticides. © 2025 Society of Chemical Industry.

Exploring the physiological, biochemical, and enzymatic responses of Vigna mungo varieties to Mungbean Yellow Mosaic India Virus (MYMIV) infection

This study aims to enhance sustainable disease management in black gram by identifying varieties resistant to Mungbean Yellow Mosaic India Virus (MYMIV). We screened sixteen black gram genotypes, assessing physiological, biochemical and enzymatic basis. Results revealed a range of resistance levels, with PANT URD-19 showing the highest resistance (PDI 0.47%) and Pejua the lowest (PDI 37.24%). Seven genotypes demonstrated strong resistance, highlighting the necessity for targeted breeding. Variations in leaf thickness, trichome density, stomatal frequency, and epicuticular wax content were significant, with resistant varieties like LBG-888 and PANT URD-19 exhibiting thicker leaves, higher trichome density, and more wax, correlating with reduced susceptibility. Chlorophyll content was higher in resistant varieties, while susceptible ones had reduced levels and increased sugar content, which may exacerbate MYMIV impact by attracting more whiteflies. Enzymatic analysis showed that resistant genotypes had elevated POD, SOD, and PAL activities, supporting their enhanced defense mechanisms. Multivariate analysis confirmed these findings, with leaf thickness, trichome density, and wax content negatively correlating with disease severity, while stomatal frequency and total sugar content were positively correlated. These results emphasize the potential of these traits in developing MYMIV-resistant black gram varieties and support the advancement of eco-friendly agricultural practices.

Multi-omics analysis reveal the fall armyworm Spodoptera frugiperda tolerate high temperature by mediating chitin-related genes

Climate change facilitates the rapid invasion of agricultural pests, threatening global food security. The fall armyworm Spodoptera frugiperda is a highly polyphagous migratory pest tolerant to high temperatures, allowing its proliferation in harsh thermal environments. We aimed to demonstrate mechanisms of its high-temperature tolerance, particularly transcriptional and metabolic regulation, which are poorly understood. To achieve the aim, we examined the impact and mechanism of heat events on S. frugiperda by using multiple approaches: ecological measurements, transcriptomics, metabolomics, RNAi, and CRISPR/Cas9 technology. We observed that several physiological indices (larval survival rate, larval period, pupation rate, pupal weight, eclosion rate, and average fecundity) decreased as the temperature increased, with the 32 °C treatment displaying a significant difference from the control group at 26 °C. Significantly upregulated expression of genes encoding endochitinase and chitin deacetylase was observed in the chitin-binding, extracellular region, and carbohydrate metabolic process GO terms of hemolymph, fat body, and brain, exhibiting a tissue-specific pattern. Significantly enriched pathways (e.g., cutin, suberin, and wax biosynthesis; oxidative phosphorylation and cofactor biosynthesis; diverse amino acid biosynthesis and degradation; carbon metabolism; and energy metabolism), all of which are essential for S. frugiperda larvae to tolerate temperature, were found in metabolites that were expressed differently. Successful RNA interference targeting of the three chitin-related genes reduced gene expression levels and larval survival rate. Knockout of the endochitinase gene by using the CRISPR/Cas9 system significantly reduced the relative gene expression and increased sensitivity to high-temperature exposure. On the basis of our findings, theoretical foundations for understanding the high-temperature tolerance of S. frugiperda populations and latent genetic control strategies were established.

Fitness effect and transcription profile reveal sublethal effect of nitenpyram on the predator Chrysopa pallens (Neuroptera: Chrysopidae)

Although neonicotinoids are widely used and important insecticide, there are growing concerns about their effect on nontarget insects and other organisms. Moreover, the effects of nitenpyram (NIT), a second generation of neonicotinoid insecticides, on Chrysopa pallens are still unclear. Therefore, this study purposed to investigate the acute toxicity of NIT to C. pallens using the spotting method. To examine the potential effects of a sublethal dose of NIT (LD30 , 1.85 ng of active ingredient per insect) on C. pallens, we constructed the life tables and analyzed the transcriptome data. The life table results showed that the period of second instar larvae, adult pre-oviposition period and total pre-oviposition period were significantly prolonged after exposure to sublethal dose of NIT, but had no significant effects on the other instars, longevity, oviposition days, and fecundity. The population parameters, including the preadult survival rate, gross reproduction rate, net reproductive rate, the intrinsic rate of increase, and finite rate of increase, were not significantly affected, and only the mean generation time was significantly prolonged by NIT. Transcriptome analysis showed that there were 68 differentially expressed genes (DEGs), including 50 upregulated genes and 18 downregulated genes. Moreover, 13 DEGs related to heat shock protein, nose resistant to fluoxetine protein 6, and prophenoloxidas were upregulated. This study showed the potential effects of sublethal doses of NIT on C. pallens and provided a theoretical reference for the comprehensive application of chemical and biological control in integrated pest management.

Evidence of population expansion and insecticide resistance mechanism in invasive fall armyworm (Spodoptera frugiperda)

BACKGROUND

The invasive and calamitous polyphagous pest Spodoptera frugiperda or commonly known as fall armyworm (FAW) poses serious menace to the global agricultural production. Owing to the revamped invasion of FAW in 2018 in India, present study was undertaken for precise assessment of its genetic identity and pesticide resistance to aid in pest-management strategies.

RESULTS

To evaluate the diversity in FAW population across Eastern India, mitochondrial COI sequences were used which revealed a low nucleotide diversity. Analysis of molecular variance indicated significant genetic variation between four global geographical FAW populations with lowest differentiation between India and Africa suggesting a present-day and shared origin of FAW. The study demonstrated existence of two different strains ('R' strain and 'C' strain) based on COI gene marker. However, discrepancies between COI marker and host plant association of FAW was observed. Characterization of Tpi gene revealed abundance of TpiCa1a followed by TpiCa2b and TpiR1a strains respectively. The FAW population showed higher susceptibility towards chlorantraniliprole and spinetoram than cypermethrin. Insecticide resistance genes depicted marked upregulation although with lot of variance. Chlorantraniliprole resistance ratio (RR) exhibited significant correlation with 1950 (Glutathione S-transferase, GST), 9131 (Cytochrome P450, CYP) and 9360 (CYP) genes, while spinetoram and cypermethrin RR was found to correlate with 1950 (GST) and 9360 (CYP) genes.

CONCLUSION

This study manifests Indian subcontinent as the potential new hotspot for the growth and distribution of FAW population that can be effectively controlled using chlorantraniliprole and spinetoram. This study also adds novel significant information on FAW population across Eastern India for developing a comprehensive pest management approach for S. frugiperda.

Transcription dynamics of heat-shock proteins (Hsps) and endosymbiont titres in response to thermal stress in whitefly, Bemisia tabaci (Asia-I)

The sweet potato whitefly, Bemisia tabaci (Gennadius), is one of the several species complexes of whitefly that are currently significant agricultural pests. Bemisia tabaci infests more than 600 plant species and thrives under a wide range of temperature conditions. In addition to the direct damage caused by sucking plant sap, it vectors several plant viruses. Heat-shock proteins play a pivotal role in enabling the insect to extend its geographical location, survival, and reproduction under different stress conditions. B. tabaci harbours several endosymbionts under the genera Portiera, Rickettsia, Hamiltonella, Wolbachia, Arsenophonus, Cardinium, and Fritschea that directly or indirectly affect its fitness. By accelerating cuticle biosynthesis and sclerotisation, symbiotic microbes can reduce or enhance tolerance to extreme temperatures and detoxify heavy metals. Thus, symbionts or microbial communities can expand or constrain the abiotic niche space of their host and affect its ability to adapt to changing conditions. The present study delineates the effect of thermal stress on the expression of heat-shock genes and endosymbionts in B. tabaci. Studies of the expression level of heat-shock proteins with the help of quantitative real-time polymerase chain reaction (qRT-PCR) showed that heat- and cold-shock treatment fuels the increased expression of heat-shock proteins (Hsp40 and Hsp70). However, Hsp90 was not induced by a heat- and cold-shock treatment. A significant decrease in the relative titre of secondary endosymbionts, such as Rickettsia, Arsenophonus, and Wolbachia, were recorded in B. tabaci upon heat treatment. However, the titre of the primary symbiont, C. Portiera, was relatively unaffected by both cold and heat treatments. These results are indicative of the fact that Hsp genes and endosymbionts in B. tabaci are modulated in response to thermal stress, and this might be responsible for the adaptation of whitefly under changing climatic scenario.

Impact of Temperature Change on the Fall Armyworm, Spodoptera frugiperda under Global Climate Change

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith, 1797), known as an important agricultural pest around the world, is indigenous to the tropical-subtropical regions in the Western Hemisphere, although its distribution has expanded over large parts of America, Africa, Asia and Oceania in the last few years. The pest causes considerable costs annually coupled with its strong invasion propensity. Temperature is identified as the dominant abiotic factor affecting herbivorous insects. Several efforts have reported that temperature directly or indirectly influences the geographic distribution, phenology and natural enemies of the poikilothermal FAW, and thus may affect the damage to crops, e.g., the increased developmental rate accelerates the intake of crops at higher temperatures. Under some extreme temperatures, the FAW is likely to regulate various genes expression in response to environmental changes, which causes a wider viability and possibility of invasion threat. Therefore, this paper seeks to review and critically consider the variations of developmental indicators, the relationships between the FAW and its natural enemies and the temperature tolerance throughout its developmental stage at varying levels of heat/cold stress. Based on this, we discuss more environmentally friendly and economical control measures, we put forward future challenges facing climate change, we further offer statistical basics and instrumental guidance significance for informing FAW pest forecasting, risk analyses and a comprehensive management program for effective control globally.