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The tea geometrid Ectropis grisescens is an important pest of tea plant (Camellia sinensis (L.) O. Kuntze). It feeds on the new leaves and tender stems of tea plants, causing serious damage. The green leaf volatile (Z)-3-hexenol (z3HOL) can effectively activate the defense of tea against E. grisescens in the laboratory. In this study, z3HOL was confirmed to activate the tea mitogen-activated protein kinase and jasmonic acid (JA) burst in the laboratory. We investigated effects of z3HOL on the defense responses of tea plants under field conditions. Our results showed that tea plants exposed to z3HOL showed higher levels of JA and polyphenol oxidase (PPO) and emitted increased quantities of volatile organic compounds (VOCs) compared to non-exposed plants. Less E. grisescens larvae were observed in z3HOL-treated plots and less damage was found in z3HOL-treated plants than control. The number of Apanteles sp. and the parasitism of E. grisescens were also enhanced by z3HOL. These findings indicate that synthetic z3HOL can triggers tea defense responses against E. grisescens in the field, and that it could be used as a chemical elicitor to enhance biological control of tea geometrid in the future.

Green leaf volatiles (GLVs) have been reported to play an important role in the host-locating behavior of several folivores that feed on angiosperms. However, next to nothing is known about how the green leafhopper, Empoasca vitis, chooses suitable host plants and whether it detects differing emission levels of GLV components among genetically different tea varieties. Here we found that the constitutive transcript level of the tea hydroperoxide lyase (HPL) gene CsiHPL1, and the amounts of (Z)-3-hexenyl acetate and of total GLV components are significantly higher in tea varieties that are susceptible to E. vitis (Enbiao (EB) and Banzhuyuan (BZY)) than in varieties that are resistant to E. vitis (Changxingzisun (CX) and Juyan (JY)). Moreover, the results of a Y-tube olfactometer bioassay and an oviposition preference assay suggest that (Z)-3-hexenyl acetate and (Z)-3-hexenol offer host and oviposition cues for E. vitis female adults. Taken together, the two GLV components, (Z)-3-hexenol and especially (Z)-3-hexenyl acetate, provide a plausible mechanism by which tea green leafhoppers distinguish among resistant and susceptible varieties. Future research should be carried out to obtain the threshold of the above indices and then assess their reasonableness. The development of practical detection indices would greatly improve our ability to screen and develop tea varieties that are resistant to E. vitis.

Electromagnetic functional ceramics added iron tailings were prepared using the burning method, and the EMWA properties were tested through the arch testing method at 2–18 GHz. It was found that the minimum reflection loss (RL) peak was −16.0 dB at 17.0 GHz, and that the thickness of ceramics was 2.00 cm. With the thickness increasing, the RL value went up, and the RL peak number also increased. The magnetic and dielectric losses of tailing powders acting as an absorbent were the main mechanisms of EMWA properties for ceramics, which could be used for electromagnetic radiation protection of architectural spaces.

The paper discusses a model to estimate the diffraction loss in stacked quantum well slabs for optically pumped lasers. Two quantum well slabs, cleaved from the same strip, are stacked together with the front sides facing each other to form the laser cavity. Misalignment and different slab sizes are possible, which may result in additional diffraction loss. The model is based on the diffraction integral theory to calculate the fundamental mode in a plane mirror resonator. Model results suggest that, for a small misalignment size of a few percent of the wavelength, the diffraction loss is relatively small compared with other sources of loss in the laser system. Hence, the stacked scheme is feasible for the long wavelength far-infrared region but not suitable for shorter wavelengths in the mid- or near-infrared regions. This model is in general applicable to other optically pumped quantum well lasers.