Aphids In China Research Articles

Biological Control of Aphids in China: Successes and Prospects.

Aphids are small, soft-bodied insects, and many are notorious pests of field crops, vegetables, fruit trees, ornamental plants, and trees. In China, there is an increasing emphasis on utilizing biological control agents, including aphidopathogenics, and selective pesticides for the management of aphids. In particular, preventive integrated pest management strategies with early interventions reduce the financial and environmental costs associated with treatments of outbreaks. Decades of progress have proved that biological control is a cost-effective and environmentally safe control option. Here, we review the history and progress of aphid control, with an emphasis on major natural enemies, mass-rearing, and conservation, and provide two successful cases, constraints, and future perspectives on aphid biological control in China.

Recruitment of Hippodamia variegata by active volatiles from Glycyrrhiza uralensis and Alhagi sparsifolia plants infested with Aphis atrata.

Hippodamia variegata (Goeze) (Coleoptera: Coccinellidae), a dominant predatory natural enemy species in cotton-planting, is a key biological control agent for aphids in China. Our previous study showed that herbivore-induced plant volatiles (HIPVs) from Glycyrrhiza uralensis (Fisch.) (Fabales: Fabaceae) and Alhagi sparsifolia (Desv.) (Fabales: Fabaceae) plants infested with Aphis atrata (Zhang) (Homoptera: Aphididae), were important semiochemicals for Hippodamia variegata to locate aphids. However, little was known about the varieties and function of active volatiles from HIPVs of the two plant species. In this study, results from gas chromatography-electroantennography detection (GC-EAD) demonstrated that seven HIPVs (butyl acrylate, α-pinene, butyl isobutyrate, β-pinene, butyl butyrate, 1,3-diethylbenzene and 1,4-diethylbenzene) identified from the two damaged plant species elicited antennal responses from Hippodamia variegata. Also, results from gas chromatograph-mass spectrometry (GC-MS) analysis showed that the concentrations of the seven active volatiles were significantly higher than those from corresponding healthy plants. Hippodamia variegata exhibited varying degrees of response to each active volatile in electroantennography (EAG) trials, however, only α-pinene, butyl isobutyrate, β-pinene and butyl butyrate significantly attracted Hippodamia variegata in behavioral trials conducted in the laboratory. They also had a better trapping effect on Hippodamia variegata in cotton fields. Four active compounds (α-pinene, butyl isobutyrate, β-pinene and butyl butyrate) identified from two damaged plant species were considered the most effective HIPVs that attract Hippodamia variegata. These findings provide possibilities for the development of Hippodamia variegata attractants. They also provide a theoretical basis for the biological prevention and control of aphids using Hippodamia variegata. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Population dynamics of migrant wheat aphids in China's main wheat production region and their interactions with bacterial symbionts.

Sitobion miscanthi, Rhopalosiphum padi, and Schizaphis graminum are the three main pests in Chinese wheat-producing regions. In 2020, they are classified into the Chinese Class I list of agricultural diseases and pests, due to their severe harm to wheat plantings. S. miscanthi, R. padi, and S. graminum are migrant pests, and understanding their migration patterns and simulating their migration trajectories would improve forecasting and controlling them. Furthermore, the bacterial community of the migrant wheat aphid is also less known. In this study, we employed a suction trap to uncover the migration patterns of the three wheat aphid species in Yuanyang county, Henan province, during 2018 to 2020. And then the migration trajectories of S. miscanthi and R. padi were simulated using the NOAA HYSPLIT model. The interactions between wheat aphids and bacteria were further revealed by specific PCR and 16S rRNA amplicon sequencing. The results showed that the population dynamics of migrant wheat aphids was varied. Most of the trapped samples were identified to be R. padi, and S. graminum was the least collected sample. Typically, R. padi had two migration peaks in the 3 years, whereas S. miscanthi and S. graminum only exhibited one migration peak in 2018 and 2019. Moreover, the aphid migration trajectories varied over the years. Generally, the aphids originated from the south and migrated to the north. Herein, the infections of three main aphid facultative bacterial symbionts, Serratia symbiotica, Hamiltonella defensa, and Regiella insercticola, were detected in S. miscanthi and R. padi with specific PCR. Rickettsiella, Arsenophonus, Rickettsia, and Wolbachia were further identified with 16S rRNA amplicon sequencing. Biomarker searching indicated that Arsenophonus was significantly enriched in R. padi. Furthermore, diversity analyses showed that the bacterial community of R. padi had a higher richness and evenness than that of S. miscanthi. In conclusion, this study expands our knowledge about the migration patterns of aphids in the main wheat plant region of China and reveals the interactions between bacterial symbionts and migrant aphids.

Identification of differentially expressed microRNAs under imidacloprid exposure in Sitobion miscanthi

Imidacloprid is a neonicotinoid that targets sucking pests, such as aphids and the green leaf bug and has been widely applied in wheat fields to control wheat aphids in China. To investigate the involvement of miRNAs in imidacloprid resistance, we sequenced small RNA libraries of Sitobion miscanthi Fabricius, across two different treatments using Illumina short-read sequencing technology. As a result, 265 microRNAs (miRNAs), of which 242 were known and 23 were novel, were identified. Quantitative analysis of miRNA levels showed that 23 miRNAs were significantly up-regulated, and 54 miRNAs were significantly down-regulated in the nymphs of S. miscanthi treated with imidacloprid in comparison with those of the control. Modulation of the abundances of differentially expressed miRNAs, smi-miR-316, smi-miR-1000, and smi-miR-iab-4 by the addition of the corresponding antagomir/inhibitor to the artificial diet significantly changed the susceptibility of S. miscanthi to imidacloprid. Subsequently, the post-transcriptional regulatory mechanism was conducted, smi-miR-278 and smi-miR-316 were confirmed to be participated in the post-transcriptional regulation of nAChRα1A and CYP4CJ6, respectively. The results suggested that miRNAs differentially expressed in response to imidacloprid could play a critical regulatory role in the metabolism of S. miscanthi to imidacloprid.

Favorable compatibility of nitenpyram with the aphid predator, Coccinella septempunctata L. (Coleoptera: Coccinellidae).

The increasing demand for lessening the chemical input in agricultural ecosystems requires an efficient combination of pesticides and biological controls. Thus, fully understanding the compatibility of pesticides and beneficial arthropod predators is helpful and essential. In this study, we evaluated the influence of nitenpyram on both larvae and adults of Coccinella septempunctata using exposure doses of 10, 25, 50, 100, and 150% of the maximum recommended field rate (MRFR) (3, 7.5, 15, 30, and 45ga.i.ha-1, respectively) and a blank control based on a preliminary acute 72-h toxicity experiment. In the long-term test, the LR50 (application rate causing the mortality of 50% of the individuals) of nitenpyram for C. septempunctata decreased from 73.43 to 63.0ga.i.ha-1, while the HQ (hazard quotient) values remained below the threshold value of 2. Nitenpyram did not significantly influence the survival rate, fecundity, pupation, or adult emergence at 150% of the label rate (lowest LR50= 63.0ga.i.ha-1), and its demonstrated NOER (No Observed Effect application Rates) values are all above 45ga.i.ha-1. Likewise, the total developmental time and egg hatchability were not significantly affected at 100% of the label rate (NOER = 30ga.i.ha-1). The assessment of the total effect (E) suggested that nitenpyram could be classified as harmless to C. septempunctata below/at a dose of 30ga.i.ha-1. The lowest LR50 and NOER values were both above the maximum recommended field application rate for nitenpyram (30ga.i.ha-1) for controlling aphids in China. All results indicated that the on-label use of nitenpyram is compatible with the natural enemy C. septempunctata in agricultural ecosystems.

Expression profile changes of cytochrome P450 genes between thiamethoxam susceptible and resistant strains of Aphis gossypii Glover

Cytochrome P450 monooxygenases represent a key detoxification mechanism in neonicotinoids resistance in Aphis gossypii Glover. Synergism analysis has indicates that P450s are involved in thiamethoxam resistance. In this study, expression changes in the transcripts of P450 genes were determined in thiamethoxam-susceptible and thiamethoxam-resistant strains. Nine P450 genes in CYP3 clade were significantly overexpressed in the resistant strain (especially CYP6CY14, which was increased 17.67-fold) compared with the susceptible strain. Transcripts of ecdysone synthesis-related P450 genes, including CYP302A1, CYP306A1, CYP307A1 and CYP315A1, were up-regulated in the resistant strain, which may accelerate molting hormone production. The ecdysone response genes (ecdysone receptor (EcR), ultra-spiracle (USP) and Broad-complex protein (Br-C)) were overexpressed in the resistant strain. RNA interference (RNAi) targeting CYP6CY14 significantly increased the sensitivity of the resistant aphid to thiamethoxam. The results of the present study indicate the possible involvement of these P450 genes in thiamethoxam resistance. Our findings may facilitate further work to validate the roles of these P450s in thiamethoxam resistance based on heterologous expression, and show that screening the expression changes in P450 genes can reveal the impact of thiamethoxam on ecdysone synthesis-related P450 genes. These results are useful for understanding the mechanism of thiamethoxam resistance and will contribute to the management of insecticide-resistant cotton aphids in China.

Full-length cloning, sequence analysis and expression detection of the \u03b2-tubulin gene from the Chinese gall aphid (Schlechtendalia chinensis)

Some insect galls are formed on sumac plants by certain aphid species and have been used for medicinal and chemical purposes as they are rich in tannins. The most prominent species among gall aphids in China is Schlechtendalia chinensis, which formed horn-shaped galls on the winged rachis of Rhus chinensis. S. chinensis has a complex life cycle, with a switch of hosts between R. chinensis and certain mosses, and a switch of sexual and asexual reproduction (cyclical parthenogenesis). We have cloned a full-length cDNA of the β-tubulin gene from S. chinensis, using qPCR and RACE. This cDNA has 1606 base pairs with a 251 bp 5′-untranslated region (5′-UTR) and a 15 bp 3′-untranslated region (3′-UTR). The gene encodes a protein with 376 amino acids residues. The expression levels of the β-tubulin gene in S. chinensis were investigated among fundatrigeniae and overwintering larvae rearing under either natural conditions, or at 7.5 °C and 18 °C. No significant differences (P > 0.01) in gene expression levels were found in insects under these conditions. It is indicates that the β-tubulin gene is highly conserved and then it may be used as a reference for further research in gene expression and reproduction determination in this important aphid.

Cross-resistance pattern and basis of resistance in a thiamethoxam-resistant strain of Aphis gossypii Glover

A thiamethoxam-resistant strain of cotton aphid (ThR) displayed a 13.79-fold greater resistance to thiamethoxam than a susceptible cotton aphid (SS) strain. Piperonyl butoxide (PBO) and triphenyl phosphate (TPP) synergistically increased the toxicity of thiamethoxam in the resistant strain, whereas diethyl maleate (DEM) did not exhibit significant synergistic effects. Bioassay results indicated that the ThR strain developed increased levels of cross-resistance to bifenthrin (11.71 fold), cyfluthrin (17.90 fold), esfenvalerate (6.85 fold), clothianidin (6.56 fold), methidathion (5.34 fold) and alpha-cypermethrin (4.53 fold) but did not show cross-resistance to malathion, omethoate, acephate, chlorpyrifos, methomyl, sulfoxaflor or imidacloprid. PBO and TPP increased bifenthrin toxicity in the resistant strain by 2.38 and 4.55 fold, respectively. Quantitative real-time PCR results indicated that the mRNA expression levels of the α1, α4-1, α4-2, α5 and α7 subunits decreased significantly by 3.32, 1.60, 2.05, 5.41 and 1.48 fold, respectively, in the resistant strain compared with those in the susceptible strain. However, significant differences were not observed in the expression of the α2, α3 and β1 subunits. No target-site mutations within the α1, α2 and β1 subunits of nicotinic acetylcholine receptors (nAChRs) were detectable in the ThR strain. In conclusion, the levels of thiamethoxam resistance and cross-resistance to other insecticides observed in the ThR strain are likely regulated by two mechanisms, which include the overexpression of detoxification-related P450s and esterase. These results should be useful for the understanding thiamethoxam resistance mechanism and the management of insecticide-resistant cotton aphids in China.

De novo sequencing-based transcriptome and digital gene expression analysis reveals insecticide resistance-relevant genes in Propylaea japonica (Thunberg) (Coleoptea: Coccinellidae).

The ladybird Propylaea japonica (Thunberg) is one of most important natural enemies of aphids in China. This species is threatened by the extensive use of insecticides but genomics-based information on the molecular mechanisms underlying insecticide resistance is limited. Hence, we analyzed the transcriptome and expression profile data of P. japonica in order to gain a deeper understanding of insecticide resistance in ladybirds. We performed de novo assembly of a transcriptome using Illumina's Solexa sequencing technology and short reads. A total of 27,243,552 reads were generated. These were assembled into 81,458 contigs and 33,647 unigenes (6,862 clusters and 26,785 singletons). Of the unigenes, 23,965 (71.22%) have putative homologues in the non-redundant (nr) protein database from NCBI, using BLASTX, with a cut-off E-value of 10−5. We examined COG, GO and KEGG annotations to better understand the functions of these unigenes. Digital gene expression (DGE) libraries showed differences in gene expression profiles between two insecticide resistant strains. When compared with an insecticide susceptible profile, a total of 4,692 genes were significantly up- or down- regulated in a moderately resistant strain. Among these genes, 125 putative insecticide resistance genes were identified. To confirm the DGE results, 16 selected genes were validated using quantitative real time PCR (qRT-PCR). This study is the first to report genetic information on P. japonica and has greatly enriched the sequence data for ladybirds. The large number of gene sequences produced from the transcriptome and DGE sequencing will greatly improve our understanding of this important insect, at the molecular level, and could contribute to the in-depth research into insecticide resistance mechanisms.

Widespread infection and diverse infection patterns of Wolbachia in Chinese aphids

Wolbachia are intracellular symbionts that infect a wide range of arthropods and filarial nematodes. Aphids are engaged in diverse and complex relationships with their endosymbionts. Four supergroups (A, B, M and N) of Wolbachia were previously detected in aphids and supergroups M and N were only found in aphids. In this study, we detected and described Wolbachia infections in natural populations of aphids in China. Three supergroups (A, B and M) were found in the examined aphid species. Supergroup M was preponderant, whereas supergroups A and B were only detected in certain species. Supergroup N was not found in this study. There were four infection patterns of Wolbachia in aphids, namely, infection with supergroup M alone, co-infection with supergroups A and M, co-infection with supergroups B and M, and co-infection with supergroups A, B and M. The pattern of infection only with supergroup M was universal and was found in all evaluated subfamilies. Only two subfamilies, Aphidinae and Lachninae, manifested to present all four infection patterns. Three patterns were observed in Calaphidinae (M, A&M, B&M) and Eriosomatinae (M, B&M, A&B&M). Two patterns were observed in the Anoeciinae (M, A&M) and Greenideinae (M, B&M), and only one pattern (M) was observed in the remaining families and/or subfamilies of Aphidoidea. These results indicated that Wolbachia infections in Chinese aphids are widespread. Phylogenetic analyses suggest that Wolbachia supergroup M spread rapidly and recently among all host species of aphids in China. Reasons for this spread and its mechanisms are discussed along with the possible effects of Wolbachia on their aphid hosts.

E-β-farnesene synergizes the influence of an insecticide to improve control of cabbage aphids in China

Extensive use of pesticides to control insect pests can have negative effects on the environment, natural enemies and food safety. The aphid alarm pheromone, E-β-farnesene (Eβf), appears to hold strong potential for controlling a wide variety of aphid pests. To understand the control potential of Eβf, we used field experiments in a factorial design to test its influence and that of the insecticide imidacloprid on populations of aphids Lipaphis erysimi (Kaltenbach) and Myzus persicae (Sulzer) on Chinese cabbage, Brassica rapa pekinensis (Brassicales: Brassicaceae). Our results showed imidacloprid treatment alone can significantly decrease aphid populations, and that combining insecticide with Eβf further reduced numbers of apterous aphids at distances of 5 m from pheromone emitters in two years of our experiments. Our results demonstrate that imidacloprid can be effective in reducing the abundance of aphids in Chinese cabbage fields, but the degree of control can be even stronger in the presence of Eβf.

Galling Aphids (Hemiptera: Aphidoidea) in China: Diversity and Host Specificity

Gall formation is an interesting plant response to aphid feeding. This paper presents a review of galling aphids in China. Altogether, 157 species and subspecies in ten families and subfamilies are found to induce galls on their host plants. As many as 39% species are endemic to China. The Eriosomatinae include the highest percentage of gall-inducing species. The great diversity of gall morphology may be described in terms of five characteristics: type, site, size, shape, and structure. The host association and host specificity of galling aphids are also discussed.

Review of larvalAllothrombium(Acari: Trombidioidea), with description of a new species ectoparasitic on aphids in China

Larvae of Allothrombium (Acari: Trombidioidea) are ectoparasites of aphids and other arthropods. This paper reviews the systematics of larval Allothrombium. The larvae of 11 species of Allothrombium Berlese, 1903 (= Aphithrombium Childers and Vercammen-Grandjean, 1980; = Nippotrombium Southcott, 1986) are recognized, and a key to known species provided. Larvae of Allothrombium ovatum sp. nov., ectoparasitic on aphids in China, are described. Host records of larval Allothrombium mites, whenever known, are also given.