Effects of Elevated CO2 on the Fitness Parameters of Individually- and Group-Reared Agasicles hygrophila (Coleoptera: Chrysomelidae).

Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae) is a natural enemy of Alternanthera philoxeroides (Mart.) Griseb (Amaranthaceae: Alternanthera), a worldwide invasive weed. Elevated atmospheric CO2 concentrations may have significant impacts plants, herbivorous insects, and natural enemies. To assess the concurrent effect of elevated CO2 on the development time, fecundity, and population parameters of A. hygrophila, the age-stage, two-sex life table was used to understand the fitness and population parameters of individually-reared and group-reared A. hygrophila under elevated CO2 concentration. In individually-reared population, the development time of preadults, adult pre-oviposition period, and total pre-oviposition period of A. hygrophila in the elevated CO2 (eCO2, 750 ppm) treatment were shorter than those in the ambient CO2 (aCO2, 420 ppm) treatment. In group-reared population, the developmental time of preadults, female adult longevity, female proportion, adult pre-oviposition period, and total pre-oviposition period of A. hygrophila in eCO2 were longer than those in aCO2. Additionally, in both individually-reared and group-reared population, fecundity and oviposition days of A. hygrophila in eCO2 were higher than those in aCO2, and a higher intrinsic rate of increase, finite rate of increase, and the net reproductive rate of A. hygrophila were observed at eCO2. Moreover, shorter preadult development time, adult pre-oviposition period, total pre-oviposition period, male adult longevity, and higher fecundity were found in group-reared cohort at both aCO2 and eCO2. The results indicates that elevated CO2 has effects on the growth and reproduction of A. hygrophila, and the population growth rate of group-reared was faster and produced more offspring.

Sublethal and Transgenerational Toxicities of Chlorfenapyr on Biological Traits and Enzyme Activities of Paracoccus marginatus (Hemiptera: Pseudococcidae).

Papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae), is an economically important, invasive insect that is now distributed worldwide. Chlorfenapyr has been demonstrated to have a significant control effect on P. marginatus. In order to evaluate the sublethal and transgenerational effects of chlorfenapyr on P. marginatus, the life table data of three consecutive generations were collected and analyzed by the age stage, two-sex life table method, and the enzyme activities were assayed using a spectrophotometer. The results showed that exposure to the insecticide had significant effects on the biological traits of subsequent generations of P. marginatus, and a higher intrinsic rate of increase (r), finite rate of increase (λ), net reproductive rate (R0), and a shorter mean generation time (T) were observed in the chlorfenapyr-treated F1 mealybugs. Enzyme activity assays showed that chlorfenapyr significantly inhibited the activities of catalase (CAT) and peroxidase (POD) while activating the activities of superoxide dismutase (SOD), which suggested that SOD, CAT, and POD may play an important role in the self-defense of P. marginatus against chlorfenapyr. These results conclusively demonstrated that exposure of P. marginatus to sublethal concentrations of chlorfenapyr induced hormetic effects on the F1 generation while having negative effects on the F0 and F3 generations.

Fitness of the Papaya Mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), after Transferring from Solanum tuberosum to Carica papaya, Ipomoea batatas, and Alternanthera philoxeroides.

The papaya mealybug, Paracoccus marginatus Williams and Granara de Willink (Hemiptera: Pseudococcidae), is a polyphagous invasive pest in China. The effect that the shifting of the host plant has on the fitness of a polyphagous pest is critical to its prevalence and potential pest control. In order to assess the fitness changes of P. marginatus after transferal from potato (Solanum tuberosum (Tubiflorae: Solanaceae)) to papaya (Carica papaya (Parietales: Caricacea)), sweet potato (Ipomoea batatas (Tubiflorae: Convolvulaceae)), and alligator weed (Alternanthera philoxeroides (Centrospermae: Amaranthaceae)), the life table data of three consecutive generations were collected and analyzed using the age-stage, two-sex life table method. The results showed that when P. marginatus was transferred from S. tuberosum to papaya, a higher intrinsic rate of increase (r) and finite rate of increase (λ) were observed. Paracoccus marginatus individuals transferred to I. batatas had the significantly lower population parameters than those on C. papaya; however, the fitness recovered for those on I. batatas after two generations. Paracoccus marginatus individuals were unable to complete development on A. philoxeroides. Our results conclusively demonstrate that P. marginatus individuals can readily adapt to C. papaya and I. batatas even after host plant shifting, and are capable of causing severe damage to these hosts.

Plant Volatile Compounds of the Invasive Alligatorweed, Alternanthera philoxeroides (Mart.) Griseb, Infested by Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae).

Plants release a variety of volatiles and herbivore-induced plant volatiles (HIPVs) after being damaged by herbivorous insects, which play multiple roles in the interactions with other plants and insects. Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae) is a monophagous natural enemy and an effective biocontrol agent for Alternanthera philoxeroides (Mart.) Griseb. Here, we reported differences among the volatiles of A. philoxeroides by solid phase microextraction (SPME) using a gas chromatography-mass spectrometer (GC-MS). We compared the volatile emission of: (1) clean plants (CK); (2) A. philoxeroides plants with mechanical damage treatment (MD); and (3) A. philoxeroides plants infested with A. hygrophila 1st, 2nd, and 3rd larvae and female and male adults. A total of 97 volatiles were recorded, of which 5 occurred consistently in all treatments, while 61 volatiles were only observed in A. philoxeroides infested by A. hygrophila, such as trans-nerolidol, (E)-ß-farnesene, and (3E,7E)-4,8,12-trimethyltrideca-1,3,7,11-tetraene (E, E-TMTT), etc. Among the 97 volatile compounds, 37 compounds belong to alkenes, 29 compounds belong to alkanes, and there were 8 esters, 8 alcohols and 6 ketones. Orthogonal partial least squares-discrimination analysis (OPLS-DA) showed that the different treatments were separated from each other, especially insect feeding from CK and MD treatments, and 19 volatiles contributed most to the separation among the treatments, with variable importance for the projection (VIP) values > 1. Our findings indicated that the alligatorweed plants could be induced to release volatiles by different stages of A. hygrophila, and the volatile compounds released differ quantitatively and qualitatively. The results from this study laid an important foundation for using volatile organic compounds (VOCs) and HIPVs of alligatorweed to improve the control effect of A. hygrophila on A. philoxeroides.

Sildenafil improves hippocampal brain injuries and restores neuronal development after neonatal hypoxia-ischemia in male rat pups.

The hippocampus is a fundamental structure of the brain that plays an important role in neurodevelopment and is very sensitive to hypoxia-ischemia (HI). The purpose of this study was to investigate the effects of sildenafil on neonatal hippocampal brain injuries resulting from HI, and on neuronal development in this context. HI was induced in male Long-Evans rat pups at postnatal day 10 (P10) by a left common carotid ligation followed by a 2-h exposure to 8% oxygen. Rat pups were randomized to vehicle or sildenafil given orally twice daily for 7 days starting 12 h after HI. Hematoxylin and eosin staining was performed at P30 to measure the surface of the hippocampus; immunohistochemistry was performed to stain neurons, oligodendrocytes, and glial cells in the hippocampus. Western blots of the hippocampus were performed at P12, P17, and P30 to study the expression of neuronal markers and mTOR pathway. HI caused significant hippocampal atrophy and a significant reduction of the number of mature neurons, and induced reactive astrocytosis and microgliosis in the hippocampus. HI increased apoptosis and caused significant dysregulation of the normal neuronal development program. Treatment with sildenafil preserved the gross morphology of the hippocampus, reverted the number of mature neurons to levels comparable to sham rats, significantly increased both the immature and mature oligodendrocytes, and significantly reduced the number of microglia and astrocytes. Sildenafil also decreased apoptosis and reestablished the normal progression of post-natal neuronal development. The PI3K/Akt/mTOR pathway, whose activity was decreased after HI in the hippocampus, and restored after sildenafil treatment, may be involved. Sildenafil may have both neuroprotective and neurorestorative properties in the neonatal hippocampus following HI.

Spatio-temporal distribution patterns of Plutella xylostella (Lepidoptera: Plutellidae) in a fine-scale agricultural landscape based on geostatistical analysis.

A detailed knowledge on the spatial distribution of pests is crucial for predicting population outbreaks or developing control strategies and sustainable management plans. The diamondback moth, Plutella xylostella, is one of the most destructive pests of cruciferous crops worldwide. Despite the abundant research on the species's ecology, little is known about the spatio-temporal pattern of P. xylostella in an agricultural landscape. Therefore, in this study, the spatial distribution of P. xylostella was characterized to assess the effect of landscape elements in a fine-scale agricultural landscape by geostatistical analysis. The P. xylostella adults captured by pheromone-baited traps showed a seasonal pattern of population fluctuation from October 2015 to September 2017, with a marked peak in spring, suggesting that mild temperatures, 15-25 °C, are favorable for P. xylostella. Geostatistics (GS) correlograms fitted with spherical and Gaussian models showed an aggregated distribution in 21 of the 47 cases interpolation contour maps. This result highlighted that spatial distribution of P. xylostella was not limited to the Brassica vegetable field, but presence was the highest there. Nevertheless, population aggregations also showed a seasonal variation associated with the growing stage of host plants. GS model analysis showed higher abundances in cruciferous fields than in any other patches of the landscape, indicating a strong host plant dependency. We demonstrate that Brassica vegetables distribution and growth stage, have dominant impacts on the spatial distribution of P. xylostella in a fine-scale landscape. This work clarified the spatio-temporal dynamic and distribution patterns of P. xylostella in an agricultural landscape, and the distribution model developed by geostatistical analysis can provide a scientific basis for precise targeting and localized control of P. xylostella.

Quantum anomalous Hall effect in intrinsic magnetic topological insulator MnBi2Te4.

In a magnetic topological insulator, nontrivial band topology combines with magnetic order to produce exotic states of matter, such as quantum anomalous Hall (QAH) insulators and axion insulators. In this work, we probe quantum transport in MnBi2Te4 thin flakes-a topological insulator with intrinsic magnetic order. In this layered van der Waals crystal, the ferromagnetic layers couple antiparallel to each other; atomically thin MnBi2Te4, however, becomes ferromagnetic when the sample has an odd number of septuple layers. We observe a zero-field QAH effect in a five-septuple-layer specimen at 1.4 kelvin, and an external magnetic field further raises the quantization temperature to 6.5 kelvin by aligning all layers ferromagnetically. The results establish MnBi2Te4 as an ideal arena for further exploring various topological phenomena with a spontaneously broken time-reversal symmetry.

Indirect Effect of Elevated CO2 on Population Parameters and Growth of Agasicles hygrophila (Coleoptera: Chrysomelidae), a Biocontrol Agent of Alligatorweed (Amaranthaceae).

Alligatorweed, Alternanthera philoxeroide (Mart.) Griseb. (Amaranthaceae) is an invasive weed in China that is often kept under control by the alligatorweed flea beetle, Agasicles hygrophila Selman and Vogt (Coleoptera: Chrysomelidae) introduced into China from Argentina in the 1980s. Elevated CO2 levels have been shown to have a direct effect on Ag. hygrophila. In order to fully evaluate the indirect effects of three different atmospheric concentrations of CO2 (420, 550, and 750 ppm) on the population parameters of Ag. hygrophila reared on Al. philoxeroides, we collected life table data for Ag. hygrophila using the age-stage, two-sex life table method. In general, there were no significant differences in the lengths of the preadult parameters among the three treatments. The adult duration and total longevity of males, however, did increase as CO2 increased in concentration. Although the adult preoviposition and total preoviposition periods decreased, the fecundity, oviposition days, eggs per oviposition day, net reproductive rate, intrinsic rate of increase, and finite rate of increase all increased significantly at the high CO2 concentration. Consequently, we determined that the Ag. hygrophila population size will potentially increase rapidly over a short period of time at elevated CO2 concentrations. Our results suggest that 550 and 750 ppm CO2 may also cause physiological changes in Al. philoxeroides that, in turn, provide enhanced nutrition for increasing reproduction in Ag. hygrophila by accelerating maturation of their reproductive system. These results indicate that the efficacy of Ag. hygrophila as a biological control agent against Al. philoxeroides will likely be increased at 550 and 750 ppm CO2.

Demography and Population Projection of Flea Beetle, Agasicles hygrophila (Coleoptera: Chrysomelidae), Fed on Alligator Weed Under Elevated CO 2.

The flea beetle, Agasicles hygrophila Selman and Vogt, was introduced into China in 1987. For a more comprehensive understanding of the effect of elevated CO 2 concentration on the population dynamics, we collected the life table data of the flea beetle, A. hygrophila , at two different CO 2 concentration conditions, i.e., ambient (420 µl/liter) and elevated (750 µl/liter). The raw data were analyzed using the age-stage, two-sex life table theory. At 750 µl/liter CO 2 , shorter developmental durations of the egg, first instar, and pupa were observed, while the duration of the third instar and the total developmental duration of the larva were prolonged. The generation length of A. hygrophila was significantly shortened at the higher concentration. It was observed that the intrinsic rate of increase ( r ), finite rate (λ), and net reproduction rate ( R0 ) were higher and the mean generation time ( T ) was shorter at 750 µl/liter compared with that at 420 µl/liter. The bootstrap techniques were adopted to estimate the variances and standard errors of the developmental time, longevity, fecundity, and the population parameters. The bootstrap technique generated a normal distribution that was consistent with the central limit theorem and critical for following statistical analysis and comparison. Population projections based on age-stage, two-sex life tables could reveal the stage structure of A. hygrophila population and the leaf consumption capacity. Data collected in this study can potentially be used to evaluate the efficacy of A. hygrophila as a biological control agent of the alligator weed.