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Fall armyworm (FAW, Spodoptera frugiperda) is one of the most destructive and invasive pests worldwide and causes significant economic losses. Intensive and frequent use of insecticides has led to the development of resistance in FAW. Adipokinetic hormone (AKH) have been proven to be involved in insecticide resistance in insects. However, the molecular mechanism underlying chlorantraniliprole resistance mediated by AKH signaling in FAW remains unclear.The expression of SpfAKHR was highest in male adults and lowest in 1st instar larvae. SpfAKH was expressed the highest in eggs and the lowest in 6th instar larvae. AKH signaling was involved in the sensitivity of FAW to chlorantraniliprole through a toxicological bioassay, and the combination of chlorantraniliprole and bithionol (an inhibitor of key enzymes in the AKH pathway) significantly increased the mortality of FAW. Chlorantraniliprole significantly induced the expression of ten P450s, SpfAKH and SpfAKHR in FAW. RNA interference against SpfAKHR significantly decreased the P450 content, downregulated the expression of three P450 genes (SpfCYP6B50, SpfCYP321A9 and SpfCYP9A58) and inhibited the resistance of FAW to chlorantraniliprole. The topical application of AKH peptide significantly increased the P450 content, upregulated the expression of five P450 genes (SpfCYP321A9, SpfCY321A8, SpfCYP321A10, SpfCYP321A7 and SpfCYP6AB12), and enhanced the survival of FAW against chlorantraniliprole.AKH plays an important role in enhancing chlorantraniliprole resistance in FAW by exerting a positive influence on P450 gene expression and P450 content. These results provide valuable insights into insecticide resistance regulation and FAW control strategies. © 2022 Society of Chemical Industry.

High-power microwave radiation of 9.5–13.4 GHz was generated in a plasma-loaded backward-wave oscillator employing a relativistic electron beam of 400–500 keV and 1–3 kA. This experiment was to re-examine and confirm the previous works that had been done in other various institutions. The relativistic electron beam, which was produced from a helium gas-loaded foil-less diode, was injected into the helium gas-loaded rippled-wall waveguide of the backward-wave oscillator, generating a plasma in the waveguide and then the high-power microwave radiation. A sharp increase in the output microwave power has been observed in a narrow range of the helium gas pressure, and two dips in the microwave emission have also been found in a certain range of the axial magnetic field. Additionally, at certain values of the helium gas pressure and guide magnetic field, the total microwave emission of the plasma-loaded backward-wave oscillator was found to be seven times as large as that of the vacuum case. The highest interac...

Relativistic electron beams were generated in a gas-loaded foil-less magnetized diode. The helium gas was employed to fill the diode, and the experimental results have shown that the diode operated normally without the closure problem when the gas pressure was below a certain value (typically, 100 mTorr in the presence of an externally applied guide magnetic field). It has been observed that the current of the electron beam could increase with increasing the gas pressure, and that the presence of helium gas could reduce the operating voltage of the diode producing an electron beam with lower kinetic energy, which implies a decrease in the diode impedance. The externally applied magnetic field along the axial direction also exerted an influence on the electron-beam generation in the gas-loaded diode.

High-power microwaves were measured for a frequency range from 9.5 GHz to 13.4 GHz in a plasma-loaded backward-wave oscillator employing an annular relativistic electron beam with kinetic energy varying from 400 keV to 500 keV and current ranging from 1 kA to 3 kA. The relativistic electron beam, which was produced from a helium gas-loaded foil-less diode, was injected into the helium gas-loaded rippled-wall waveguide of the backward-wave oscillator, generating the plasma in the waveguide and then the high-power microwave. The gas-loaded diode operated stably without encountering the closure problem in the He gas pressure range (less than 100 mTorr) which was of interest to the operation of the backward-wave oscillator. An enhancement in the total microwave power emission over the vacuum case by a factor of up to 7 was found in the experiment, and the highest efficiency of electron beam to microwave radiation was estimated to be about 29%.

A narrow band microwave pulse has been obtained experimentally by using a resonant cavity surrounding virtual cathode oscillation (vircator). There are several separate dominant modes with different frequencies in a resonant cavity. Although, the coupled coefficient of radial extracting slot and Q value for each mode are not the same, but to tune the virtual cathode oscillation by varying the diode voltage, so that its dominant frequency of free- running virtual cathode oscillation is near the passband of every mode in the resonant cavity, respectively, the several narrow band microwave pulses with different frequencies can be obtained. In our experiments, a cylindrical resonant cavity is used with the microwave power being extracted radially through circumferential a slot into rectangular waveguide, and the two narrow band single microwave pulses with different frequencies are observed. The resonant points of the cavity at 4.16 GHz and 5.13 GHz are selected. The measured frequencies of microwave are 4.14 GHz and 5.09 GHz with peak power of 1 approximately 4 MW, 3 dB bandwidth is 0.36% and 0.53% of the central frequency, respectively.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

This paper presents the experimental results of a Cherenkov free-electron laser that employs an annular relativistic electron beam with energy of (gamma) 0