RESUMO
The growing demand for spectroscopy applications in the areas of bioimaging, food quality analysis, and temperature sensing has led to extensive research on infrared light sources. It is crucial for the design of cost-effective and high-performance systems that phosphors possess the ability to absorb blue light from commercial LEDs and convert the excitation energy to long-wavelength infrared luminescence. In this work, we obtained Yb3+ luminescence with visible light response by utilizing the energy transfer from Cr3+ to Yb3+ in Mg2GeO4. After the introduction of Yb3+, intense NIR luminescence peaking at 974 nm can be achieved with an increasing intensity. The local structure analysis was performed to investigate the preferential occupation of Yb3+ ions and the energy transfer process in Mg2GeO4. Considering the properties of thermally coupled anti-Stokes and Stokes emissions of Yb3+ and the sensitive variation of the emission intensity, the potential application of Mg2GeO4:Cr3+, Yb3+ as thermometers was demonstrated.
RESUMO
BACKGROUND: Heortia vitessoides Moore is a severe pest of Aquilaria sinensis (Lour.) Gilg, an important source of agarwood. In recent years, large amounts of chemical insecticides have been applied in A. sinensis plantations to deal with the outbreak of H. vitessoides, causing residue problems that reduce the quality and price of agarwood. Herein, we hypothesize that the widely applied biocontrol agent, Metarhizium anisopliae (Metschn.) Sorokin, can effectively kill the gregarious larvae of H. vitessoides through direct contact and horizontal transmission. RESULTS: At the concentration of 1 × 109 conidia/mL, the three M. anisopliae strains caused 100% mortality of H. vitessoides larvae. In addition, mixing donor larvae (previously treated with M. anisopliae conidia) with receptor larvae (which did not directly contact M. anisopliae conidia) caused significantly higher mortality of receptor larvae than the control receptors. This is due to the horizontal transmission of M. anisopliae conidia among live larvae, which was proven by pictures taken by scanning electron microscopy and induced activities of immunity-related enzymes of donor and receptor larvae. Behavioral bioassays showed that M. anisopliae conidia had little effect on the aggregation tendency of H. vitessoides larvae but may trigger feeding-avoidance behavior depending on M. anisopliae strains and concentrations. Interestingly, joint use of sublethal concentrations of M. anisopliae and chemical insecticides significantly increased larval mortality than each agent alone, indicating synergistic effects between M. anisopliae and insecticide against H. vitessoides. CONCLUSION: This study may provide a new strategy to suppress H. vitessoides population and reduce the use of chemical insecticides. © 2023 Society of Chemical Industry.