Three solid forms of chlorantraniliprole: Structure, characterization, and phase transformation

Size-dependent effect on controllable release and field insecticidal efficacy of diamide insecticide polylactic acid microspheres delivery systems against Ostrinia nubilalis

New nano/microcarriers of pesticides represent a highly promising novel field for sustainable pest management. However, despite extensive laboratory research, few studies on the design and evaluation of nanopesticides for field applications exist. In this study, we present a straightforward and green synthetic method of ultrasonic-assisted and hydrogen-bonded self-assembly at the oil-water interface for the synthesis of polylactic acid (PLA) microspheres encapsulating chlorantraniliprole (CAP), with precise control over the size of the microspheres. The resulting CAP-loaded PLA microspheres (CAP-PLA MS) exhibit both high pesticide encapsulation efficiency and stability in natural environments. It has been determined that non-Fickian diffusion mainly controls pesticide release, thus enabling dynamic control over molecular transport speeds. Importantly, our functional CAP-PLA MS demonstrates superior sustained pesticide release performance under both laboratory and field conditions while maintaining better exceptional insecticidal efficacy than normal CAP in controlling O. nubilalis at a concentration of 30 or 45 g/ha. Consequently, we propose that our functional PLA microspheres could serve as ideal pesticide carriers in the sustained treatment of O. nubilalis.

Potential exposure and risk assessment of agricultural workers to the insecticide chlorantraniliprole in rice paddies

BACKGROUND

Exposure of agricultural workers in rice paddies to the insecticide chlorantraniliprole and its subsequent potential health risks were investigated during two scenarios (mixing/loading and hand-held spraying). The exposure factors, such as the outer dosimeter, inner dosimeter, gauze, and nitrile gloves, were calculated using whole-body dosimetry to measure dermal exposure. The inhalation exposure was determined using a fiberglass filter which is set with an Institute of Occupational Medicine (IOM) sampler. A recovery test was performed to evaluate the accuracy of the analytical method.

RESULTS

The exposure amounts of various matrices were calculated from extraction volume and concentration of the target compound. The dermal exposure to chlorantraniliprole was 0.6 mg [0.001% of the total active ingredient (a.i.)] for mixing and loading, and 28.6 mg (0.066% of the total a.i.) for application. The inhalation exposure to chlorantraniliprole was 7.2 μg (1.3%, 1.2 × 10^-5 % of the total applied a.i.) for mixing and loading, and 1.9 μg (0.006%, 4.4 × 10^-6 % of the total applied a.i.) for application. The most exposed part of the body was the hand (90.4%) during mixing and loading, whereas the primary sites during application were the thighs (32.8%) and shins (22.6%). For mixing and loading, the amount of actual dermal exposure was 5.5 μg day^-1 and that of actual inhalation exposure was 21.9 μg day^-1 . By contrast, in the application, the amounts of actual dermal and actual inhalation exposures were 34 178.7 and 5.9 μg day^-1 , respectively.

CONCLUSIONS

The risk assessment results demonstrated that the risk of chlorantraniliprole exposure in rice paddies was low during application than during mixing and loading. © 2022 Society of Chemical Industry.

Effect of pyriproxyfen exposure on cocooning and gene expression in the silk gland of Bombyx mori （Linnaeus, 1758）

Bombyx mori（Linnaeus, 1758） is an important economical insect, and the sericulture is a flourishing industry in many developing countries. Pyriproxyfen, a juvenile hormone pesticide, is often applied to cultivations widely in the world, and its exposure often resulted in silk yield reduction and non-cocooning. However, the effect of pyriproxyfen exposure on cocooning and gene expression level in the silk gland of B. mori has not been studied yet, and this study focused on the above issues. The result indicated that pyriproxyfen exposure can lead to silk gland injury, reduction of silk yield and cocooning rate. Furthermore, the expression levels of silk protein synthesis related genes were down regulated significantly. The same change trends were shown between PI3K/Akt and CncC/Keap1 pathway, which is the expressions of key genes can be elevated by pyriproxyfen exposure. In addition, the activity of detoxification enzymes (P450, GST and CarE) and the expression levels of detoxification genes were elevated after pyriproxyfen exposure, suggesting that detoxification enzymes may play an important role in detoxification of pyriproxyfen in silk gland. These results provided possible clues to the silk gland injury and gene transcriptional level changes in silkworm after pyriproxyfen exposure.

Effects of pyriproxyfen exposure on immune signaling pathway and transcription of detoxification enzyme genes in fat body of silkworm, Bombyx mori

Sericulture is a very important and flourishing industry in developing countries. Bombyx mori is a kind of important and well-studied economic insects in the whole world. In China, applying of pyriproxyfen pesticide often resulted in non-cocooning and silk yield reduction. However, the effects of pyriproxyfen exposure on immune signaling pathway in fat body of silkworm has not been reported yet now. In the present study, we found that the growth and development of silkworm were significantly affected by pyriproxyfen exposure and the fat body tissues were injured after treatment. It was also showed that the expressions of key genes of PI3K/Akt and CncC/Keap1 pathway can be elevated at 24-96 h after pyriproxyfen exposure. Furtherly, the relative expression levels of detoxification enzyme genes and the activities of detoxification enzymes were both increased by pyriproxyfen exposure. These results provided comprehensive view of fat body injury and gene expression changes in silkworm after pyriproxyfen exposure.

Design, screening, and properties of novel solvates of azoxystrobin based on isomorphism

The molecular size of the solvent is important for the formation of isomorphic azoxystrobin solvates.

Influence of pH and Divalent Metals Relevant to California Rice Fields on the Hydroxide-Mediated Hydrolysis of the Insecticide Chlorantraniliprole

The hydrolysis of chlorantraniliprole (3-bromo-N-[4-chloro-2-methyl-6-(methylcarbamoyl)phenyl]-1-(3-chloro-2-pyridine-2-yl)-1H-pyrazole-5-carboxamide; CAP) was investigated over the pH range of 6-10, reflective of California rice field conditions, with variable additions of Cu²⁺, Zn²⁺, Mn²⁺, or Ni²⁺. Dissipation accelerated as pH increased with half-lives ranging from 26.9 to 2.2 days with slight inhibition in rice field water. The addition of divalent metals was not observed to catalyze the hydrolysis of CAP at pH 6, indicating that the insecticide is likely to remain recalcitrant to hydrolysis in neutral or acidic surface waters. However, Mn²⁺ and Ni²⁺ were observed to inhibit hydrolysis at pH 8 and 9. Attenuated total reflectance Fourier transform infrared analysis supports the conclusion that divalent metals may withdraw electron density from the amide nitrogen via interaction with the amide oxygen, though additional quantum chemical modeling is necessary to provide further mechanistic insights. Overall, the hydrolysis of CAP in California rice fields and their surrounding surface waters will be dominated by pH and inhibited by dissolved metal species.

Effects of chlorantraniliprole exposure on detoxification enzyme activities and detoxification-related gene expression in the fat body of the silkworm, Bombyx mori

Chlorantraniliprole (CAP) can induce excessive calcium release from muscle of insects, causing muscle paralysis until death, and its residues in farmland can cause poisoning in Bombyx mori (B. mori), resulting in the failure of cocooning. No reports have investigated the effects of CAP exposure on detoxification enzyme activities and detoxification-related gene expression in B. mori. In the present study, we treated mulberry leaves with CAP by the leaf-dipping method, and then B. mori larvae were continuously fed with the polluted mulberry leaves. Moreover, the detoxification enzyme activities and the expressions of detoxification-related genes in the fat body of B. mori were examined. The results showed that at 24 h after CAP exposure, the activities of P450 and GST enzymes were all significantly increased, with P450 enzymes responding fastest. CarE enzyme activity was up-regulated in 24 h, and then it was decreased compared with the control group. Furthermore, the expressions of the key genes in the PI3K/Akt/CncC signaling pathway (PI3K, PDK, Akt, CncC and Keap1) at the mRNA were significantly increased. Western blotting analysis revealed that Akt was inhibited at the protein level, resulting in decreased expression of Keap1 and increased expression of CncC. These results indicated that the PI3K/Akt/CncC signaling pathway in the fat body of B. mori responded to CAP exposure and regulated the expressions of downstream detoxification enzymes, thus enhancing the detoxifying capability of B. mori.

Versatile solid forms of boscalid: insight into the crystal structures and phase transformations

The crystal structures of six solid forms of boscalid were reported for the first time and the transformation relationship between different phases was explored in detail.