Rashmi
Pandey‡
ac,
Ranjana
Chauhan‡
ab,
Sharad
Saurabh
a,
Anoop Kumar
Shukla
a,
Farrukh
Jamal
c,
Sheelendra Pratap
Singh
d,
Pradhyumna Kumar
Singh
ab and
Manisha
Mishra
*a
aMolecular Biology and Biotechnology Division, Council of Scientific and Industrial Research-National Botanical Research Institute (CSIR-NBRI), 435, Rana Pratap Marg, Lucknow, Uttar Pradesh 226001, India. E-mail: manisha.nbri@gmail.com
bAcademy of Scientific and Innovative Research (AcSIR), CSIR – Human Resource Development Centre (CSIR-HRDC), Campus Postal Staff College Area, Sector 19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh 201002, India
cDepartment of Biochemistry, Dr. Ram Manohar Lohia Avadh University, Ayodhya, Uttar Pradesh 224001, India
dRegulatory Toxicology Division, Council of Scientific and Industrial Research-Indian Institute of Toxicology Research (CSIR-IITR), Vishvigyan Bhawan, 31 Mahatma Gandhi Marg, Lucknow, 226001, Uttar Pradesh, India
First published on 10th April 2024
Spodoptera litura (Lepidoptera: Noctuidae) is globally considered one of the most important agricultural pests. It is a highly prevalent insect pest that severely damages several vegetables and crops, including cotton, castor, tobacco, beet, soybean, and cabbage. The implementation of integrated pest management (IPM) practices has led to a slight controlling of its population in the field; however, these practices are always linked with the high economic and environmental costs for eradication. In the last decade, many researchers have reported the control of this devastating insect via the utilization of nanoparticles (NPs); however, the mechanism behind its toxicity is still a gap area. In our study, we investigated the toxic impact of carbon nanoparticles (CNPs) on S. litura when administered orally. A range of immunomodulatory responses were observed, including a distorted morphology (such as abnormal pupa, distorted wings in insects, etc.) and reproductive physiology, weight reduction, and even insect death. Mass spectrometric analysis of differentially expressed proteins suggests significant downregulation of storage proteins in the larval hemolymph, which in turn resulted in an altered expression/synthesis of developmental and reproductive proteins, including vitellogenin (the major egg-filling protein required for developing embryo nourishment), in the treated insects. The poor accumulation of vitellogenin in developing eggs led to a disrupted life cycle and restricted population growth. This is the first study that provides insights into the molecular mechanism behind the toxicity offered by these tiny carbon particles.
Environmental significanceThis study envisaged the use of carbon nanoparticles (CNPs) derived from waste candle soot as a substitute to chemical insecticides for controlling the globally significant agricultural pest Spodoptera litura. The research demonstrates that the oral administration of CNPs disrupts the growth, physiology, and reproductive behavior of S. litura, leading to a distorted morphology, reduced larval weight, and disrupted reproductive physiology. The study elucidates the molecular mechanisms behind this toxicity, emphasizing the downregulation of storage proteins and the subsequent disruption of vital reproductive proteins. Notably, this study advocates the environment friendly nature of candle soot-derived CNPs and suggests their potential role as a sustainable candidate for pest control. The findings encourage further exploration of nanotechnology-based approaches in integrated pest management, promoting a more ecologically responsible agricultural future. |
Nanotechnology is an emerging branch of science that deals with the manipulation of matter in a size ranging from 1 nm to 100 nm.6 The alteration of any matter within this size offers unique physical and chemical properties that become the reason for the wide application of nanotechnology in various fields of science and technology, including agriculture.7 Nanoparticles (NPs) are used for innumerable purposes in agriculture, including pest control, plant growth and enhanced productivity, and numerous studies have focused on the use of NPs for insect pest management.8 Several metals and carbon NPs have been reported to have insecticidal properties against various groups of insect pests such as Lepidopterans, Hemipterans, and Dipterans.9 The most damaging genera that come under the order Lepidoptera are Helicoverpa spp., Spodoptera spp., and Plutella spp. They cumulatively cause up to 305–40% yield loss in cotton, 205–40% in tomato, and 22.135–46.83% in other vegetables.10 Though a variety of metal and carbon NPs have been tested for their effectiveness against these insect pests, few of them, typically silica, silver, carbon NPs, and their oxides, are repeatedly tested by many scientists around the globe. CNPs, carbon nanofibers (CNFs), carbon nanotubes (CNTs), and graphene/graphene oxide (GO) have previously demonstrated their utility for pest management.11 AgNPs synthesized either from a plant source or via a chemical process exhibit a range of toxicity. For example, AgNPs from the leaf extract of Leonotis nepetifolia and Ocimum basilicum, and seed and peel extract of Glycine max and Punica granatum caused increased antioxidant activity and larval mortality (56–100%) in S. litura.12–15 AgNPs and AuNPs prepared from various plant sources reduced the larval weight and caused mortality in the larva and pupa of Helicoverpa armigera (Hübner) and Plutella xylostella (Linnaeus).16–22 SiNPs generated from various plant sources caused 85–100% mortality of H. armigera, S. litura, and P. xylostella larvae by disruption of the cuticle, resulting in dehydration along with spiracle and tracheal blockage.23–26 Carbon nanoparticles in the form of fly ash have been used to control the lepidopteran pest.27 The ingestion of GO and multiwalled CNTs (MWCNTs) was shown to significantly reduce the fecundity and fertility of Spodoptera frugiperda (J.E. Smith).28 Waste candle soot-derived CNPs showed somewhat similar effects on the reproductive behavior of H. armigera.29 A few other carbon nanomaterials, such as CNFs and CNPs, were reported to lower larval survival rates, causing developmental abnormality and a poor reproductive rate in Drosophila melanogaster.29,30
In addition to the toxicity assessment, researchers have also tried to investigate the underlying mechanism behind the toxicity offered by these tiny particles.31 In general, NPs induce immune responses that lead to the altered expression of genes/proteins, resulting in the disruption of metabolic processes with increased cellular toxicity. Other common responses include the disruption of nutrition intake, formation of reactive oxygen species, and altered metabolic activities.32 All these cumulatively affect the growth, development, and reproductive ability of the pest insects. Further, the extent of toxicity is highly dependent on the type and physical properties of the selected NPs, while the mode of toxicity is reliant on the route of administration (ingestion/inhalation/physical contact).33 However, knowledge of the molecular mechanism of NP-mediated toxicity, including the implication of an altered protein profile in insect pests, is still not clear.
In this study, we investigated the toxic impact of carbon nanoparticles (CNPs) against S. litura upon oral administration and found them to be very effective for controlling the target insect pests. We investigated the underlying NPs-mediated toxicity in insects using differential proteomics of the hemolymph (larvae, pupae) and eggs, in order to identify the potential proteins and their role in CNP-induced toxicity in insect pests. Our study demonstrates the remarkable efficacy of carbon nanoparticles in controlling S. litura through oral administration, elucidating the underlying toxicological mechanisms via hemolymph proteomics.
We also measured the larval, pupal, and adult longevity, larval movement, male–female ratio, and consistency of excreta, and found no significant differences compared with the control group.
Disruption of any one of these factors can cause highly compromised egg filling and development. The decreased fecundity of the CNPs-fed insects might be influenced by one or more of the aforementioned factors. Additionally, the pesticides commonly employed in the IPM programs target decreasing the fecundity in insects. In this respect, hindrance in reproductive progression of an insect by CS-CNPs may come up as a better alternative to harmful insecticides.
Comparative profiling of the proteins showed significant differences in the amount of the proteins present in the treatment moths with respect to the controls (Fig. 4b and c). The majority of the proteins were found absent and/or significantly reduced in the treatment groups (the reduction was directly proportional to the administered concentration of NPs). Mass spectrometric analysis of the bands representing differential proteins (Fig. 4b and c) suggested that the majority of downregulated proteins were involved in the process of growth and development, energy metabolism, reproduction, cell signaling, and transportation, while the proteins related to stress and immune response were found to be upregulated (Table 1). The said pathways also get altered in other insect pests (H. armigera, and Spodoptera) after exposure to harmful insecticides (azadirachtin-A, pyriproxyfen, and camptothecin), indicating the susceptibility of proteins related to the pathways described earlier toward toxicants.
In the case of larval proteomics, one of the major bands at 60–70 kDa was identified as a group of storage proteins (basic juvenile hormone suppressible proteins, methionine-rich storage proteins, arylphorin, and riboflavin binding hexamerin). These, all high-molecular-weight proteins that are cumulatively called storage proteins, play a very important role in many vital biological processes, including metamorphosis (basic juvenile hormone suppressible proteins and methionine-rich proteins) and reproduction (arylphorins and hexamerins).43 The compromised expression of these proteins can lead to developmental abnormalities and reproductive failures. In another study, it was reported that bacterial challenge on eri-silk worm led to the downregulation of storage proteins, which in turn resulted in compromised metamorphosis.44 We could also observe similar results in our study (Fig. 1 and 2). Here, ∼80% of the larvae could not reach phenotypically healthy adulthood due to incomplete metamorphosis, which might be because of the significant down-expressions of the proteins like basic juvenile hormone suppressible proteins, methionine-rich proteins and others. The role of storage proteins in the generation advancement of insects has been well established by other researchers.45 Furthermore, we also found a nearly complete absence of other high kDa proteins, such as vitellogenin and vitellogenin-like proteins in the eggs. This yolk protein is produced by the process of vitellogenesis in the fat body cells from storage proteins and transported into developing oocytes via hemolymph through receptor-mediated transportation. Following oviposition, Vg is necessary for egg maturation and embryonic growth.46 The lower availability/synthesis of vitellin/vitellogenin in developing eggs leads to lowered fecundity and egg hatchability in insects, like the cotton leaf worms in our study (Fig. 4d) and also in other insects, like house cricket, red palm weevil, and warehouse moth.47,48 It is noteworthy that in insects, storage proteins are the major reservoir to produce proteins involved in reproductive processes, including ‘vitellogenin’.49 The hindered synthesis of storage proteins is directly linked to the decreased production of vitellogenin and the compromised process of egg development. This study further demonstrates that CNPs contribute to the failure in synthesizing storage proteins, resulting in an inadequate accumulation and synthesis of vitellogenin. Vitellogenin, an essential female-specific egg-yolk protein, is indispensable for oogenesis.
Footnotes |
† Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3en00939d |
‡ Authors contributed equally to this work. |
This journal is © The Royal Society of Chemistry 2024 |