A Nano-Delivery System Enhances the Stomach Toxicity of Methoxyfenozide against Spodoptera litura by Suppressing the Synthesis of Insect Cuticle Protein

Abstract

There is a growing demand for applying green pesticides instead of traditional synthetic pesticides to minimize potential threats to food and environmental safety. Insect growth regulators (IGRs) are regarded as a secure alternative, but their control efficacy needs to be improved to meet actual demands. Herein, a star polymer (SPc) was constructed and applied as an efficient pesticide nanocarrier, which could be spontaneously conjugated with IGR methoxyfenozide via hydrogen bonding with a high pesticide loading content of 32.66%. The combination of the methoxyfenozide/SPc complex at a mass ratio of 1:1 could break the self-aggregated methoxyfenozide, reducing its particle size from 1084 to 27 nm, and the methoxyfenozide/SPc complex consisted of smooth spherical nanoparticles with uniform distribution. Importantly, with the aid of SPc, the mortality of methoxyfenozide-treated Spodoptera litura larvae was significantly increased by 1.2 times at 1 day and 2.2 times at 7 days after the oral feeding. Meanwhile, the weight and length of the survival larvae fed with the methoxyfenozide/SPc complex were less than those with methoxyfenozide alone. Transcriptome results revealed that the oral feeding of the methoxyfenozide/SPc complex could further disturb the expression of various key genes related to insect hormone synthesis and metabolism, hormone receptor, and cuticle biosynthesis. In larvae exposed to the methoxyfenozide/SPc complex, we observed the downregulation of key genes involved in hormone synthesis and metabolism, including cytochrome P450 18a, farnesol dehydrogenase, and juvenile hormone acid O-methyltransferase. This disruption in hormone regulation resulted in impaired insect molting. Simultaneously, the expression of genes associated with cuticle formation, such as chitin synthase 2, obstructor-E, and larval cuticle protein, was also suppressed. The current study provides an efficient nano-delivery system for IGRs to improve stomach toxicity against insect pests, which shows great potential in green pest management.

Construction of a nontoxic nano-pesticide and its co-application with natural predators for perfect cooperative pest management: an innovative strategy for pesticide reduction

“…SPc can self-assemble with various insecticides, such as imidaclothiz, methoxyfenozide, and thiamethoxam, to enhance their bioactivity. 23,24,37 In the current study, it was found that SPc could assemble with TTP into TTP/SPc complex via hydrogen bonding and van der Waals force, and the PLC was calculated to be 32.2%, which was relatively higher than those toward thiamethoxam (20.63%), cyantraniliprole (24.79%), and monosultap (19.3%). 23,58–60 The SPc can combine with an insecticide via various interactions, such as electrostatic interaction, hydrophobic interaction, and hydrogen bonding.…”

“…All other reagents were bought from Beijing Chemical Works (China). The SPc was synthesized in a two-step process following the methods described by Li et al 22 and Jiang et al 37 In the initial step, a solution containing pentaerythritol in dry THF and triethylamine at 0 °C was subjected to the gradual addition of 2-bromo-2-methylpropionyl bromide. After stirring for 24 h, the reaction was terminated with methanol.…”

“…The loading capacity of SPc toward TTP was measured using the freeze-drying method. 37 First, TTP was dissolved in dimethyl sulfoxide (DMSO) and ddH 2 O (6 : 14 v : v). The SPc solution (100 mg) was mixed with the TTP solution (100 mg).…”

Star Polymer-Based Nanodelivery System for Pesticides: Enhanced Broad-Spectrum Toxicity and Selective Toxicity

“…As shown in Table , the PLC of SPc toward spirotetramat was examined using the freeze-drying method, and it was calculated to be 36.16%, which was comparable to methoxyfenozide (32.66%) and higher than dinotefuran (17.41%) and thiamethoxam (20.63%). ,, …”

“…Our group has designed and synthesized a star polymer (SPc) as an efficient nanocarrier for various substances . The SPc-based nanodelivery system is fit for the efficient delivery of nucleic acids and synthetic/botanical pesticides. − The SPc can assemble with several synthetic/botanical pesticides spontaneously, including osthole, matrine, dinotefuran, thiocyclam, methoxyfenozide, etc. ,− The self-assembly with SPc can reduce the particle sizes of pesticides and improve their delivery efficiency for enhanced bioactivity. We have confirmed that the bioactivities of SPc-loaded pesticides can be improved by 20–40% compared with conventional pesticides.…”