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Bemisia tabaci is one of the most destructive agricultural insect pests around the world, and it has developed high levels of resistance to most pesticides. Dimpropyridaz, a novel insecticide developed by BASF, displays excellent activity against piercing-sucking insect pests. In this study, baseline of susceptibility showed all tested field populations of B. tabaci are susceptible to dimpropyridaz. After continuous selection with dimpropyridaz in the lab, a B. tabaci strain (F12) developed 2.2-fold higher level of resistance compared with a susceptible MED-S strain, and the realized heritability (h 2 ) was estimated as 0.0518. The F12 strain displayed little cross-resistance to afidopyropen, cyantraniliprole, sulfoxaflor, or abamectin, and significantly increased activity of cytochrome P450 monooxygenase (P450). The fitness cost of dimpropyridaz resistance was evident in F12 strain, which had a relative fitness of 0.95 and significantly lower fecundity per female compared with MED-S strain. Taken together, B. tabaci displays high susceptibility to dimpropyridaz in the field, and low risk of developing resistance to dimpropyridaz under successive selection pressure. Little cross-resistance to popular insecticides was found, and fitness cost associated dimpropyridaz resistance was observed. Higher activity of cytochrome P450 in the F12 strain, may be involved in the process of detoxifying dimpropyridaz in whitefly., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Combinatorial delivery of different double-stranded RNAs (dsRNAs) can result in competitive inhibition in insect pests and remains one of the obstacles in the way of future applications of the RNA interference (RNAi)-based pest control. In this study, we attempted to discover the basic competition characteristics between dsRNAs and provided insight into the solutions of competitive inhibition. RNAi sensitive insect species Tribolium castaneum were treated, and competitions between dsRNA fragments influencing the effectiveness of RNAi response could be measured. A chimeric dsRNA strategy for conjugating different dsRNA fragments into a single molecule and a nanoparticle carbon quantum dots-mediated dsRNA delivery were confirmed as efficient methods to knock down multiple target genes simultaneously. Furthermore, in vitro assays were conducted for determining the accumulation speed of serially diluted and incubated dsRNA in the midgut tissues. Our data showed that the accumulation of dsRNAs of different treated amounts was 0.25 μg ≈ 0.5 μg > 1 μg ≥ 2 μg > 4 μg, indicating that accumulation speed would be affected by treated dsRNA. Overall, our results strongly suggest that endocytic components influencing cellular uptake might be oversaturated when an excess amount of dsRNAs were treated, thereby causing competitive inhibition of target genes., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Posterior capsule opacification (PCO) after cataract surgery is one of the leading causes of visual impairment and blindness. The cause of PCO is the capsule fibrosis developed on implanted Intraocular Lens (IOLs) by the de-differentiation of Lens Epithelial Cells (LECs) undergoing epithelial mesenchymal transition. How to prevent PCO has been a challenge to scientists and ophthalmologists for decades. Here we demonstrated the use of carboxylated CuInS/ZnS quantum dots (ZCIS QDs), which are free of toxic heavy metals and are more biocompatible, as photothermal nanomedicines. The ZCIS QDs are modified onto the non-optical section of IOLs by a facial activation-immersion method. Under mild NIR laser irradiation, ZCIS QDs modified IOLs (QDs-IOLs) will generate localized heat and prevent the proliferation of LECs onto the surface of QDs-IOLs. Our findings provide experimental evidence for further application of combined nanotechnology and photothermal therapy for the clinical treatment of PCO., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Bemisia tabaci, sweetpotato whitefly, is one notorious insect pest on a series of crops worldwide, and many populations show high resistance to various insecticides. The cyantraniliprole-resistant strain of B. tabaci SX-R (138.4-fold) was obtained by selections with an outdoor-collected cyantraniliprole resistant population. By crossing and repeated backcrossing to a susceptible MED-S strain, the trait of cyantraniliprole resistance from SX-R was moved into MED-S to establish one near-isogenic line (CYAN-R). MED-S and CYAN-R were utilized to build patterns of cross-resistance, CYAN-R strain exhibited 63.317-fold resistance to cyantraniliprole, but no cross-resistance to several other successfully commercialized chemical agents. After that significant inhibition of cyantraniliprole resistance by piperonyl butoxide (PBO) and increased cytochrome P450 (3.4-fold) were observed in CYAN-R strain, indicating putative involvement of P450 in detoxification. Furthermore, five published detoxification-related P450 genes in B. tabaci, CYP4C64, CYP6CM1, CYP6CX1, CYP6CX4, and CYP6DZ7 were selected and expression levels of them were measured for exploring mechanisms of cyantraniliprole resistance. Compare with MED-S, no significant overexpression of the five P450 genes was observed in the CYAN-R strain. Above results could be conductive to study on mechanism of cyantraniliprole resistance and will be very helpful for the management of whitefly., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Bemisia tabaci is one of notorious agricultural insect pests in China, and the strategies of management largely depend on application of insecticides. In order to assess levels of resistance in field populations of B. tabaci to six insecticides including abamectin, cyantraniliprole, pymetrozine, imidacloprid, chlorpyrifos and bifenthrin, we monitored the susceptibility to all tested insecticides in five field populations across China and the results indicated that field populations of B. tabaci have developed various levels of resistance to each chemical agent. Furthermore, para-type voltage gated sodium channel mutations (L925I and T929V) and acetylcholinesterase ace1 mutation (F331W) were confirmed, and expression levels of CYP6CM1, CYP4C64, GSTd7 and ABCG3 were detected for investigating mechanisms of imidacloprid resistance in the five field-collected populations. The results showed that, in all tested populations, frequencies of F331W were 100%, and the frequencies of the L925I and T929V were in the range of 28.5 to 47.0% and 11.0 to 53.5%, respectively. Moreover, CYP6CM1 and CYP4C64 were significantly overexpressed in two tested populations, respectively, and GSTd7 was significantly overexpressed in one population. No overexpression of ABCG3 was observed in all the populations. Above results provided valuable insight into the current status of insecticide resistance and could be contributed to design strategies of management for B. tabaci., (Copyright © 2019 Elsevier Inc. All rights reserved.)

In this study, we explored the efficacy of knockdown four genes required for proper nervous system function by RNAi, in the corn earworm Helicoverpa zea (Boddie). Three of these genes encode components of validated insecticide target sites. We synthesized cDNA sequences orthologous to the Drosophila melanogaster genes Para (paralytic ts ), TipE (temperature-induced paralysis locus E), GluCl (glutamate-gated chloride channel), and Notch, and used these fragments to synthesize double-stranded RNAs (dsRNAs). We then performed experiments in an attempt to induce RNAi-mediated effects on gene expression and viability using three modes of delivery of the dsRNAs: microinjection of eggs, soaking of eggs and feeding of larvae. Microinjection of dsRNAs into eggs induced reduced hatch rates and knockdown of target gene expression for GluCl, para and TipE, but not for Notch. However, neither feeding nor soaking eggs in dsRNA solutions resulted in discernable RNAi effects. These results demonstrated the susceptibility to RNAi effects of the expression of H. zea genes encoding insecticide target sites, which suggests future avenues of research toward practical applications., (Copyright © 2018. Published by Elsevier Inc.)

The Bemisia tabaci (Gennadius) cryptic species complex comprises very destructive insect pests of agricultural crops worldwide and has been found to be resistant to various insecticides in China. Abamectin is one of the most widely used insecticides for insect pest control and the glutamate-gated chloride channel (GluCl) in insects was presumed to be the main target site of abamectin. In this study, a 1353bp full-length cDNA encoding GluCl (named BtGluCl, GenBank ID: MF673854) was cloned and characterized from B. tabaci. BtGluCl encodes 450 amino acids, which shares 71-81% identity with other insect GluCl isoforms. Spatial and temporal expression revealed BtGluCl was highly expressed in the 4th nymphal instar and adult head, and the least expressed in the 1st nymphal instar and adult leg. Dietary ingestion of dsBtGluCl significantly reduced the mRNA level of BtGluCl in the treated adults by 62.9% and greatly decreased abamectin-induced mortality. Thus, our results could be conducive to further understanding the mechanisms of resistance to abamectin in arthropods., (Copyright © 2017 Elsevier Inc. All rights reserved.)