Invasive alien ants (IAAs) are among the most aggressive, competitive, and widespread invasive alien species (IAS) worldwide.  Wasmannia auropunctata, the greatest IAAs threat in the Pacific region and listed in “100 of the world’s worst IAS”, has established itself in many countries and on islands worldwide.  Wild populations of W. auropunctata were recently reported in southeastern China, representing a tremendous potential threat to China’s agricultural, economic, environmental, public health, and social well-being.  Estimating the potential geographical distribution (PGD) of W. auropunctata in China can illustrate areas that may potentially face invasion risk.  Therefore, based on the global distribution records of W. auropunctata and bioclimatic variables, we predicted the geographical distribution pattern of W. auropunctata in China under the effects of climate change using an ensemble model (EM).  Our findings showed that artificial neural network (ANN), flexible discriminant analysis (FDA), gradient boosting model (GBM), Random Forest (RF) were more accurate than categorical regression tree analysis (CTA), generalized linear model (GLM), maximum entropy model (MaxEnt) and surface distance envelope (SRE).  The mean TSS values of ANN, FDA, GBM, and RF were 0.820, 0.810, 0.843, and 0.857, respectively, and the mean AUC values were 0.946, 0.954, 0.968, and 0.979, respectively.  The mean TSS and AUC values of EM were 0.882 and 0.972, respectively, indicating that the prediction results with EM were more reliable than those with the single model.  The PGD of W. auropunctata in China is mainly located in southern China under current and future climate change.  Under climate change, the PGD of W. auropunctata in China will expand to higher-latitude areas.  The annual temperature range (bio7) and mean temperature of the warmest quarter (bio10) were the most significant variables affecting the PGD of W. auropunctata in China.  The PGD of W. auropunctata in China was mainly attributed to temperature variables, such as the annual temperature range (bio7) and the mean temperature of the warmest quarter (bio10).  The populations of W. auropunctata in southern China have broad potential invasion areas.  Developing strategies for the early warning, monitoring, prevention, and control of W. auropunctata in southern China requires more attention.

Fruit development and ripening is a complex procedure (Malus×domestica Borkh.) and can be caused by various factors such as cell structure, cell wall components, and cell wall hydrolytic enzymes.  In our study, we focused on the variations in fruit firmness, cell wall morphology and components, the activity of cell wall hydrolytic enzymes and the expression patterns of associated genes during fruit development in two different types of apple cultivars, the hard-crisp cultivar and the loose-crisp cultivar.  In this paper, the aim was to find out the causes of the texture variations between the different type cultivars.  Cell wall materials (CWMs), hemicellulose and cellulose content were strongly associated with variations in fruit firmness during the fruit development.  The content of water soluble pectin (WSP) and chelator soluble pectin (CSP) gradually increased, while the content of ionic soluble pectin (ISP) showed inconsistent trends in the four cultivars.  The activities of polygalacturonase (PG), β-galactosidase (β-gal), cellulase (CEL), and pectate lyase (PL) gradually increased in four cultivars.  And the activities of PG, β-gal, and CEL were higher in ‘Fuji’ and ‘Honeycrisp’ fruit with the fruit development, while the activity of PL of ‘Fuji’ and ‘Honeycrisp’ was lower than that of ‘ENVY’ and ‘Modi’.  Both four cultivars of fruit cells progressively became bigger as the fruit expanded, with looser cell arrangements and larger cell gaps.  According to the qRT-PCR, the relative expression levels of MdACO and Mdβ-gal were notably enhanced.  Our study showed that there were large differences in the content of ISP and hemicellulose, the activity of PL and the relative expression of Mdβ-gal between two different types of apple cultivars, and these differences might be responsible for the variations in the texture of the four cultivars.

Global food security is threatened by the impacts of the spread of crop pests and changes in the complex interactions between crops and pests under climate change.  Schrankia costaestrigalis is a newly-reported potato pest in southern China.  Early-warning monitoring of this insect pest could protect domestic agriculture as it has already caused regional yield reduction and/or quality decline in potato production.  Our research aimed to confirm the potential geographical distributions (PGDs) of S. costaestrigalis in China under different climate scenarios using an optimal MaxEnt model, and to provide baseline data for preventing agricultural damage by S. costaestrigalis.  Our findings indicated that the accuracy of the optimal MaxEnt model was better than the default-setting model, and the minimum temperature of the coldest month, precipitation of the driest month, precipitation of the coldest quarter, and the human influence index were the variables significantly affecting the PGDs of S. costaestrigalis.  The highly- and moderately-suitable habitats of S. costaestrigalis were mainly located in eastern and southern China.  The PGDs of S. costaestrigalis in China will decrease under climate change.  The conversion of the highly- to moderately-suitable habitat will also be significant under climate change.  The centroid of the suitable habitat area of S. costaestrigalis under the current climate showed a general tendency to move northeast and to the middle-high latitudes in the 2030s.  The agricultural practice of plastic film mulching in potato fields will provide a favorable microclimate for S. costaestrigalis in the suitable areas.  More attention should be paid to the early warning and monitoring of S. costaestrigalis in order to prevent its further spread in the main areas in China’s winter potato planting regions.

In insects, ecdysteroids are synthesized by genes of the Halloween family and play important roles in several key developmental events, including molting and metamorphosis.  However, the roles of these genes in Agasicles hygrophila are still largely unknown.  In this study, the expression patterns of the two Halloween genes AhCYP307A2 and AhCYP314A1 were determined by quantitative PCR (qPCR) at different developmental stages.  Moreover, the functions of these two genes were explored using RNA interference (RNAi), and ovarian development was observed by dissecting the ovaries of A. hygrophila females.  The qPCR results showed that AhCYP307A2 and AhCYP314A1 were highly expressed in last instar larvae and in adult females.  In addition, AhCYP307A2 was also highly expressed in eggs and pupae but was markedly lower than in third-instar larvae and females.  The RNAi results showed that the injection of dsAhCYP307A2 or dsAhCYP314A1 markedly inhibited their expression and the transcription levels of three related AhVgs.  Knockdown of AhCYP307A2 or AhCYP314A1 significantly inhibited larval molting, impaired last instar larva–pupa–adult transition, delayed ovarian development, and stopped egg production (i.e., no eggs were laid).  These results indicate that AhCYP307A2 and AhCYP314A1 play important regulatory roles in last instar larva–pupa–adult transition and reproduction in A. hygrophila.

Diglyphus wani (Hymenoptera: Eulophidae) is a dominant parasitoid that attacks agromyzid leafminers.  Two reproductive types occur in D. wani: arrhenotoky (in which virgin females produce only male offspring; and virgin females mate with males to produce bisexual offspring) and thelytoky (in which virgin females produce female offspring).  As a potential biological control agent, exploring the differences in the relevant biological parameters of both strains is necessary.  In this study, comparisons between the two strains of D. wani were performed by evaluating the life table and host-killing rate.  The thelytokous strain exhibited significantly better life table parameters than its arrhenotokous counterpart.  Higher values for the intrinsic rate of increase, finite rate of increase, net reproductive rate, and fecundity were found in the thelytokous strain.  The thelytokous strain also performed better than the arrhenotokous strain in terms of net parasitism, host-feeding, host-stinging, and total host-killing rates.  Thus, populations of the thelytokous strain could grow fast and kill more hosts.  In conclusion, the thelytokous strain of D. wani may be the more promising biological agent against agromyzid leafminers compared to its arrhenotokous counterpart.  Also, since the thelytokous strain of D. wani is only known to produce females, it should be given priority in future biocontrol applications owing to the cost savings of breeding only females.

The crown root system is the most important root component in maize at both the vegetative and reproductive stages.  However, the genetic basis of maize crown root traits (CRT) is still unclear, and the relationship between CRT and aboveground agronomic traits in maize is poorly understood.  In this study, an association panel including 531 elite maize inbred lines was planted to phenotype the CRT and aboveground agronomic traits in different field environments.  We found that root traits were significantly and positively correlated with most aboveground agronomic traits, including flowering time, plant architecture and grain yield.  Using a genome-wide association study (GWAS) coupled with resequencing, a total of 115 associated loci and 22 high-confidence candidate genes were identified for CRT.  Approximately one-third of the genetic variation in crown root was co-located with 46 QTLs derived from flowering and plant architecture.  Furthermore, 103 (89.6%) of 115 crown root loci were located within known domestication- and/or improvement-selective sweeps, suggesting that crown roots might experience indirect selection in maize during domestication and improvement.  Furthermore, the expression of Zm00001d036901, a high-confidence candidate gene, may contribute to the phenotypic variation in maize crown roots, and Zm00001d036901 was selected during the domestication and improvement of maize.  This study promotes our understanding of the genetic basis of root architecture and provides resources for genomics-enabled improvements in maize root architecture.

Leaf-mining flies (Diptera: Agromyzidae) are a diverse family of small-bodied insects that feed on living plant tissues as larvae.  Various species in this family are considered globally invasive and have caused great agricultural economic losses.  In China, economically important vegetable crops have been seriously damaged by these pest insects, especially by species of the genus Liriomyza.  However, these species are difficult to differentiate because of their morphological similarities, and the Chinese fauna remains poorly known.  To explore the relevant pest species in China and their phylogeny, agromyzid leafminers were collected from 2016 to 2019, and identified based on morphological characteristics and DNA barcodes.  In total, 27 species from five genera of Agromyzidae were sampled and identified, including 16 species of Liriomyza.  Both mitochondrial and nuclear genes were used to reconstruct their phylogenetic relationships and estimate the divergence time.  Highly congruent and well-supported phylogenetic trees were obtained using the Bayesian inference and maximum-likelihood methods.  This analysis revealed two main clades in Liriomyza, and clade 2 was inferred to have diverged from clade 1 approximately 27.40 million years ago (95% highest posterior density: 23.03–31.52 million years ago) in the Oligocene.  Differences were observed in the distribution patterns and host associations between the Liriomyza clades.  Clade 2 species are distributed in cool, high-latitude environments, suggesting that they may have evolved into a cool-adapted lineage.

Temperature, as a critical abiotic factor, might influence the effectiveness of biological control by parasitoids in host-parasitoid systems. In this study, Neochrysocharis formosa (Westwood), a larval endoparasitoid, is used to investigate the efficacy of biological control on a vegetable agriculture pest, Liriomyza sativae Blanchard, reared on kidney bean (Phaseolus vulgaris L.), at four constant temperatures (26, 29, 32, and 35°C) under laboratory conditions. Our results show that high temperatures (29, 32, and 35°C) do not significantly affect lifetime host-killing events of female adults by increased daily host-killing events compared to temperature 26°C, although their lifespans decrease with an increase in temperatures. Each life-history trait of female adults (lifespan, parasitism, stinging, or nonreproductive host-killing events) present a linear relation with temperatures and host-feeding events, respectively. Our findings contribute to a better understanding of biocontrol efficacy of parasitoid N. formosa against agromyzid leafminers at high-temperature seasons or environments.

The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith), is an important agricultural pest with a strong migratory ability.  While the species is native to the Americas, it has recently invaded China, ravaging crops in many provinces (autonomous regions, municipalities).  Its long-distance migration, which is critical to understand for pest management programs, has been well studied in its native region.  In other regions however, the moth’s migration patterns have not yet been characterized.  Here, the migratory behavior of FAW populations in China was studied on an isolated island located in the center of the Bohai Strait from spring to autumn 2019, the year in which FAW first reached this region, by using searchlight trapping, stable carbon isotopes and trajectory simulation.  The main results were summarized as follows: (i) The number of FAW moths caught by searchlight trapping provided direct evidence that the species migrated across the Bohai Sea.  (ii) Species identification was confirmed by both morphology and molecular methods, and only the “corn-strain” that preferentially infests maize and sorghum was found in the collections.  (iii) Stable carbon isotope measurements showed that up to 95.07% of captured moths displayed the C4 isotope signature, thus providing additional evidence that this species is a migrant as there are no major C4 plants at the trapping site.  (iv) Backward trajectory analysis indicated that the pest now threatens to expand its range into the agriculturally important region of Northeast China, and thus authorities in this region should be vigilant to the threat posed by this species.  Together, these findings add to our knowledge concerning the occurrence of FAW in northern China, and will help us to develop sustainable and effective monitoring, forecasting, and pest management strategies.

   The whitefly Bemisia tabaci is a species complex, of which two invasive species, called MEAM1 and MED whiteflies, have invaded many parts of the world in the past 30 years and replaced native whitefly populations in many regions of invasions including many areas in China. One of the possible reasons for the invasion is that MEAM1 and MED whiteflies are more fecund than the native species. However, factors that affect reproduction and the molecular mechanism of vitellogenesis among various B. tabaci cryptic species are not clearly known. In this study, cDNAs of vitellogenin (Vg) genes were sequenced from native B. tabaci Asia II 1 and invasive B. tabaci MED in China. The deduced amino acid sequences were 2 182 residues in Asia II 1 and 2 217 residues in MED. Compared to the Vg gene cDNA sequence of Asia II 1 species, the Vg gene in MED could be cleaved at least into four subunits, with deduced molecular weight of 50, 90, 150 and 190 kDa, respectively. However, only two different subunits were cleaved between residues 459 and 460 in the Asia II 1. In addition, more than two serine-rich stretches located in both the N-terminal and the C-terminal region in invasive species. More GHN domains were revealed only in the N-terminal region of B. tabaci MED. Vg gene expression pattern was characterized using quantitative real-time (qRT)-PCR to compare the dynamic of vitellogenin gene mRNA level. Vg gene transcription reached the peak level at 13 d after eclosion in B. tabaci Asia II 1, 3 d later than that in MED and another invasive species of the B. tabaci complex MEAM1. We assumed that the present difference of Vg gene expression pattern is due to the different regulation pattern of vitellogenesis among species of the B. tabaci complex. These results provide useful information to reveal the mechanisms of reproduction in whitefly species complex.

This study aimed to investigate the effects of dietary supplementation of yeast β-glucan on the nutrient digestibility and serum profiles in pre-ruminant Holstein calves. Forty-two neonatal Holstein calves ((39.6±4.2) kg) were randomly allotted to six groups, and each was offered one of the following diets: a basal diet (control) or the basal diet supplemented with 25, 50, 75, 100 or 200 mg of yeast β-glucan kg–1 feed (dry matter basis). The basal diet consisted of a milk replacer and a starter feed. The trial lasted for 56 d. Two digestibility trials were conducted from d 14 to 20 and from d 42 to 48. Blood samples were collected on d 0, 14, 28 and 42 for serum profile analyses. On d 56, three calves from each group were slaughtered, and intestinal samples were collected to assess the villous height, crypt depth and mucosal thickness. Although feed intake was not affected by dietary treatment (P>0.05), the average daily gain (ADG) and gain-to-feed ratios were higher (P<0.05) for the calves fed 75 mg of yeast β-glucan kg–1 feed than those in the other groups. The supplementation of yeast β-glucan at 75 mg kg–1 feed increased the apparent digestibility of dry matter (DM), crude protein (CP), ether extract (EE), and phosphorus (P) (P<0.05) and the ratio of intestinal villous height to crypt depth (V/C) (P<0.05) when compared with the control group. No effects of yeast β-glucan on the serum concentrations of total protein (TP), albumin (ALB), serum urea nitrogen (SUN) and glucose (GLU) were observed (P>0.05). Compared with the control group, supplementation of yeast β-glucan decreased (P<0.05) the serum concentrations of triglycerides (TG) and total cholesterol (TC). The serum concentration of immunoglobulin G (IgG) and immunoglobulin M (IgM) increased quadratically (P<0.05), whereas the serum concentration of immunoglobulin A (IgA) was unaffected by dietary treatments (P>0.05). The supplementation of yeast β-glucan stimulated the enzymatic activity of alkaline phosphatase (ALP) (P<0.05) compared with the control group. The lysozyme (LYZ) concentration increased quadratically (P<0.05) with increasing yeast β-glucan levels. The results suggested that dietary supplementation of yeast β-glucan at 75 mg kg–1 feed improved nutrient digestibility, enhanced immunity by increasing the immunoglobulin concentration and stimulating ALP, and exerted no adverse effects on metabolism in pre-ruminant calves.

The detection of chemical contaminants is critical to ensure dairy safety. These contaminants include veterinary medicines, antibiotics, pesticides, heavy metals, mycotoxins, and persistent organic pollutants (POPs). Immunoassays have recently been used to detect contaminants in milk because of their simple operation, high speed, and low cost. This article describes the latest developments in the most important component of immunoassays — antibodies, and then reviews the four major substrates used for immunoassays (i.e., microplates, membranes, gels, and chips) as well as their use in the detection of milk contaminants. The paper concludes with prospects for further applications of these immunoassays.

Combined with remote sensing data and meteorological data, cold damage risk was assessed for planting area of double cropping rice (DCR) in Hunan Province, China. A new methodology of cold damage risk assessment was built that apply to grid and have clear hazard-affected body. Each station cold damage annual frequency and average annual intensity of cold damage was calculated by using 1951-2010 station daily mean temperature and simple cold damage identification index. On this basis, average annual cold damage risk index was obtained by their product. The spatial analysis models of cold damage risk index about double-season early rice (DSER) and double-season later rice (DSLR) were established respectively by the relation of average annual cold damage risk index and its geographic factors. Critical threshold of level of average annual cold damage risk index for DSER and DSLR were respectively divided by the correlative equation of cold damage annual frequency and average annual intensity of cold damage. 2001-2010 planting area of DCR, acquired by time series analysis of MOD09A1 8-d composite land surface reflectance product, was as target of assessment. The results show average annual intensity of cold damage is exponential function of cold damage annual frequency, average annual cold damage risk index is directly proportional to cold damage cumulant and cold damage annual frequency, and is inversely proportional to happen times of cold damage and the square of statistical time sequence length. Cold damage risk of DSER is higher than DSLR in Hunan Province. In the 10-yr stacking map, DCR planting in low risk area accounted for 11.92% of total extraction area, in moderate risk area accounted for 69.62%, in high risk area accounted for 18.46%. According to the cold damage risk assessment result, DCR production can be guided to reduce cold damage losses.

The spatiotemporal characteristics of hydrothermal resources in southern rice production area of China have changed under the background of climate change, and this change would affect the effectiveness of hydrothermal resources during local rice growing period. According to the cropping system subdivision in southern rice production area of China during 1980s, this study used climate data from 254 meteorological stations and phonological data from 168 agricultural observation stations in the south of China, and adopted 6 international evaluation indices about the effectiveness of hydrothermal resources to analyze the temporal and spatial characteristics of hydrothermal resources during the growing period of single cropping rice system and double cropping rice system for 16 planting zones in the whole study area. The results showed that: in southern rice production area of China, the effectiveness of thermal resources of single cropping rice area (SCRA) was less than that of double cropping rice area (DCRA), whereas the effectiveness of thermal resources of both SARA and DCRA showed a decreasing trend. The index value of effective precipitation satisfaction of SCRA was higher than that of DCRA, nevertheless the index value of effective precipitation satisfaction of both SCRA and DCRA showed a decreasing trend. There was a significant linear relationship between effective thermal resource and water demand, likely water demand increased by 18 mm with every 100°C d increase of effective heat. Effective precipitation satisfaction index (EPSI) showed a negative correlation with effective heat, yet showed a positive correlation with effective precipitation. EPSI reduced by 1% when effective heat resource increased by 125°C d. This study could provide insights for policy makers, land managers or farmers to improve water and heat resource uses and rationally arrange rice production activities under global climate change condition.

Thermal adaptation plays a fundamental role in shaping the distribution and abundance of insects, and heat shock proteins (Hsps) play important roles in the temperature adaptation of various organisms. To better understand the temperature tolerance of the indigenous ZHJ2-biotype of whitefly Bemisia tabaci species complex, we obtained complete cDNA sequences for hsp90, hsp70, and hsp20 and analyzed their expression profiles under different high temperature treatments by real-time quantitative polymerase chain reaction. The high temperature tolerance of B. tabaci ZHJ2-biotype was determined by survival rate after exposure to different high temperatures for 1 h. The results showed that after 41°C heat-shock treatment for 1 h, the survival rates of ZHJ2 adults declined significantly and the estimated temperature required to cause 50% mortality (LT50) is 42.85°C for 1 h. Temperatures for onset (Ton) or maximal (Tmax) induction of hsps expression in B. tabaci ZHJ2-biotype were 35 and 39°C (or 41°C). Compared with previous studies, indigenous ZHJ2- biotype exhibits lower heat temperature stress tolerance and Ton (or Tmax) than the invasive B-biotype.