Insecticidal Effect of the Entomopathogenic Fungus Lecanicillium araneicola HK-1 in Aphis craccivora (Hemiptera: Aphididae).

Aphis craccivora (Hemiptera: Aphididae) is an important pest affecting various crops worldwide. However, only few studies have been conducted on the infection of A. craccivora by Lecanicillium and related insecticidal mechanisms. We investigated the infection process of A. craccivora by Lecanicillium araneicola HK-1 using fluorescence microscopy and scanning electron microscopy (SEM), and our results indicated that the conidia of strain HK-1 easily attached to the feet and dorsum of A. craccivora. The activities of chitinase and extracellular protease were induced in the aphid after treatment with HK-1. A bioassay on A. craccivora showed that the median lethal concentration (LC50) of the fungus crude extract was 24.00 mg mL-1 for 24 h of treatment. Additionally, the results showed that the crude extract disrupted the enzyme system of A. craccivora, inducing the inhibition of carboxylesterase (CarE) and the induction of glutathione S-transferase (GST) and acetylcholinesterase (AChE). Combining these results with those of a gas chromatography-mass spectrometry (GC-MS) analysis, it is suggested that p-cymene, hymecromone, 9,12-octadecadienoic acid (Z, Z) methyl ester, and 9,12-octadecadienoic acid (Z, Z) may be connected to the insecticidal effects we observed. This study provides a theoretical basis for the use of L. araneicola HK-1 as a potential biological control agent.

Mitochondria-Targeting Polymer Micelles in Stepwise Response Releasing Gemcitabine and Destroying the Mitochondria and Nucleus for Combined Antitumor Chemotherapy.

Mitochondrial DNA and nuclear DNA are essential genetic material which play an important role in maintaining normal metabolism, survival, and proliferation of cells. Constructing a mitochondria-targeting stimuli-responsive nano-drug delivery system releasing chemotherapeutic agents in a stepwise response manner and destroying mitochondrial DNA and nuclear DNA simultaneously is an effective way to improve the anti-tumor effect of chemotherapeutic agents. In this study, a new mitochondria-targeting pH/ROS dual-responsive block copolymer TPP-PEG2k-b-(BS-AA)n (P1), untargeted pH/ROS dual-responsive copolymer mPEG2k-b-(BS-AA)n (P2), pH single-responsive copolymer (mPEG2k-b-(AH-AA)n (P3), ROS single-responsive copolymer mPEG2k-b-(SA-TG)n (P4), and non-responsive copolymer mPEG-b-PCL (P5) were constructed. pH/ROS-responsive properties were characterized by proton nuclear magnetic resonance (1H NMR) and dynamic light scattering (DLS). Anticancer chemotherapeutic agent gemcitabine (GEM) or fluorescent substance Nile Red (NR) were loaded in the polymer micelles. Results of the mitochondrial colocalization experiment indicate that (5-carboxypentyl)(triphenyl)phosphonium bromide (TPP)-functionalized P1 micelles could be efficiently targeted and located in mitochondria. Results of the cellular uptake experiment showed that pH/ROS dual-responsive GEM-loaded P1 and P2 micelles have faster internalized and entry nucleus rates than single-responsive or non-responsive GEM-loaded micelles. The in vitro release experiment suggests pH/ROS dual-responsive GEM/P1 and GEM/P2 micelles have higher cumulative release than single-responsive GEM/P3 and GEM/P4 micelles. The in vitro cytotoxic experiment shows that the mitochondria-targeted dual-responsive GEM/P1 micelles had the lowest IC50 values, and the cytotoxic effect of dual-responsive GEM/P2 micelles was superior to the single-responsive and non-responsive drug-loaded micelles.

Perceived Value Influencing the Household Waste Sorting Behaviors in Rural China.

Waste sorting is the cardinal measurement to solve the problem of low efficiency of rural environmental governance and to alleviate environmental pollution by reduction, recycling, and harmlessness in rural areas. However, non-excludable and non-rival features of public goods easily cause a wide free-rider problem, which results in a low frequency of participation in the waste sorting of rural people. Based on the theory of the utility maximization of the rational economic man, this paper investigates survey data of 688 farm households in three cities and three counties of Shaanxi Province to explore the effect of the perceived value on the household waste classification behavior based on cost-benefit analysis. The results show that perceived benefit and perceived cost are important perceived value factors affecting farmers' participation in waste sorting. Specifically, the spiritual benefit of the perceived benefit has a significantly positive impact on classification behavior, while the time cost, physical cost, and material cost of the perceived cost have a negative impact on waste classification behavior. Further study of the heterogeneity of income impact shows that time cost only has a significant impact on the high-income group of farmers' classification behavior, while spiritual benefit and learning cost only affect the low-income group of farmers' waste classification behavior. Material cost has different influence directions on high- and low-income groups. In view of the aforementioned findings, this study highlights corresponding policy implications from the perspective of perceived benefit and perceived cost.