Licorice strips enhance predator-mediated biological control in China's cotton crop.

BACKGROUND: Habitat management such as field- or farm-level diversification can conserve arthropod natural enemies, enhance biological pest control and lower (or suspend) insecticide use in agricultural crops. These approaches however have been underexploited to manage the aphid Aphis gossypii in cotton cropping systems of Xinjiang, China. In this study, we investigated whether the presence of licorice (Glycyrrhiza uralensis) at the field edge benefits generalist predator abundance and aphid biological control in local cotton crops. RESULTS: Field trials during 2020 and 2021 showed that licorice strips enhanced the in-field abundance of generalist predators (primarily ladybeetles) 2.2-4.3 fold during early season, i.e. initial growth before A. gossypii peak infestation pressure. During peak outbreak conditions in July, treatment fields with licorice strips experienced a respective 17.5-61.2% lowered aphid density and 12.3-14.6-fold higher predator-to-aphid abundance ratio (PAR) than control fields. In late season (aphid decline phase) of either year, cotton fields with licorice strips also attained a respective 4.7-9.9 fold higher PAR. Exclusion cage assays quantitatively assessed predator-mediated A. gossypii biological control and the relative contribution of licorice strips. The biocontrol services index (BSI) was 2.8 times (2020) and 1.4 times (2021) higher at 5 m distances from the licorice strip as compared to control fields. CONCLUSION: Licorice strips in the immediate vicinity of cotton fields benefit generalist arthropod predators and improve aphid biological control throughout the cotton cropping season. These findings help to integrate habitat management within integrated pest management (IPM) frameworks in the biggest cotton production region of China. © 2022 Society of Chemical Industry.

Effect of Tm³âº Concentration and Temperature on Blue and NIR Upconversion Luminescence in Tm³âº/Yb³âº Co-Doped NaY(WO4)2 Microstructures.

Tm³âº/Yb³âº codoped NaY(WO4)2 microstructures with various Tm³âº concentrations and 10 mol% Yb³âº concentration were prepared by a microwave-assisted hydrothermal method, and their upconversion luminescence (UCL) was investigated. Under excitation at 980 nm, Tm³âº/Yb³âº codoped NaY(WO4)2 exhibited strong blue and near infrared (NIR) emissions, respectively, corresponding to ¹G4 --> ³H6 and ³H4 --> ³H6 transitions, with weak red emission due to the ¹G4 --> ³H4 transition. The optimum doping concentrations of Tm³âº for the highest blue and NIR UCL were investigated, and it was found that the optimal concentrations for blue and NIR emissions were 0.5 mol% and 1.5 mol%, respectively. In addition, an analysis of temperature dependent blue and NIR UCL in both the samples with low and high Tm³âº concentrations, respectively, was undertaken. The results implied that the sample with low Tm³âº concentration displayed more obvious effect on the thermal quenching of ¹G4 level.