Jianguo Feng,Nuo Wei,Zhiyang Chen,Chaoqun Hou,Qianwei Liang,Yifei Tan
Mesoporous silica nanoparticles (MSN) are ideal carriers for agrochemical control release systems due to their smart environmental stimulus response by easy modification. Herein, MSN loaded with indoxacarb (IN) were successfully prepared using the hard template method. Dopamine (DA) and α-cyclohexapentylose (α-CD) were encapsulated around the MSN surface to obtain pH and enzyme dual-response nanoparticles (IN@MSN@PDA@α-CD). The prepared nanoparticles showed a spherical core-shell structure with a loading content of 22.5 %, and the polymer coating covering the surface of the nanoparticles effectively protected IN from photolysis. Moreover, different biostimuli associated with Spodoptera frugiperda can trigger the release of IN from nanoparticles. Compared with the commercial emulsifiable concentrate (14.93 mg L −1 ), IN@MSN@PDA@α-CD (8.89 mg L −1 ) extended the effective duration of IN against Spodoptera frugiperda , and considerably decreased the toxicity of IN to Eisenia fetida , zebrafish and human BEAS-2B cells. Thus, pH/enzyme dual-responsive nanoparticles have substantial potential for sustainable on-demand targeted delivery of agrochemicals and for improving their environmental safety.
Hafeez Muhammad,Li Xiaowei,Ullah Farman,Zhang Zhijun,Zhang Jinming,Huang Jun,Fernández-Grandon G. Mandela,Khan Muhammad Musa,Siddiqui Junaid Ali,Chen Limin,Ren Xiao Yun,Zhou Shuxing,Lou Yonggen,Lu Yaobin
The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), is a pest of many important crops globally. Effective control is challenging, with the pest exhibiting resistance to different synthetic pesticides across various groups. However, the mechanisms employed by resistant insects for overexpression of relevant detoxification genes remain unclear. The activity of detoxification enzymes was investigated in this study. Additionally, using RNA interference (RNAi), a functional analysis was completed of two P450s genes in an indoxacarb resistant population of fall armyworms. Elevated resistance levels (resistance ratio = 31.37-fold) in indoxacarb-selected populations of FAW were observed after 14 generations. The qRT-PCR showed higher expression of two cytochrome P450 genes, CYP321A7 and CYP6AE43, in this selected population compared to the control population. RNAi was applied to knock down the P450 dsCYP321A7 and dsCYP6AE43 genes in the FAW larvae. Droplet feeding of the dsRNAs (CYP321A7 and CYP6AE43) via an artificial diet significantly increased mortality rates in the indoxacarb treated population. A shorter larval developmental time of FAW was detected in all dsRNAs-fed larvae. Correspondingly, larval mass was reduced by dsRNAs in indoxacarb resistant populations of fall armyworm. Larval feeding assays demonstrate that dsRNAs targeting, specifically of CYP321A7 and CYP6AE43 enzymes, could be a beneficial technique in the management of indoxacarb resistant populations. Further study on the potential use of dsRNA and its application should be conducted in efforts to counter the development of resistance in FAW against various insecticides in the field.
The invasion area of red imported fire ants (RIFAs) in China continues to expand due to factors such as ecological changes and human activities, and the resulting damage is becoming increasingly severe. The development of smart nanopesticides that respond to environmental stimuli response with precisely controlled release has great potential in improving insecticidal effects. In this work, a smart pH and α-amylase dual stimuli-responsive pesticide delivery system was constructed by combining mono-(6-amino-6-deoxy)-β-cyclodextrin (β-CD-NH 2 ) with zeolitic imidazole skeleton-90 (ZIF-90) nanoparticles ( [email protected] ) loaded with indoxacarb. The average particle size of the prepared [email protected] was 249 nm, and the loading efficiency was 18.43%. The β-CD-NH 2 coating on the surface of nanoparticles reduced the photodegradation of indoxacarb and prevented the premature release of the active ingredient. In vitro release kinetics showed that [email protected] rapidly released IDC under acidic and amylase conditions, consistent with the oral and intestinal environment of RIFAs. The results of bioactivity tests showed that [email protected] enhanced the toxicity of IDC toward RIFAs by increasing feeding and damaging intestinal cells. The mortality rate of the [email protected] group was significantly higher than that of the IDC EC-treated group at 72 h. The nontargeted metabolomic results showed that [email protected] affected the metabolism of RIFAs by interfering with the metabolic pathways of six amino acids and one amino acid transport carrier, whereas IDC EC interfered with only two of these amino acid metabolic pathways. Overall, this work provides insight into the effective control of RIFA damage for sustainable pest management.
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