Insects In General Research Articles

Evolution of m6A-related genes in insects and the function of METTL3 in silkworm embryonic development.

N6-methyladenosine (m6A) plays a key role in many biological processes. However, the function and evolutionary relationship of m6A-related genes in insects remain largely unknown. Here we analysed the phylogeny of m6A-related genes among 207 insect species and found that m6A-related genes are evolutionarily conserved in insects. Subcellular localization experiments of m6A-related proteins in BmN cells confirmed that BmYTHDF3 was localized in the cytoplasm, BmMETTL3, BmMETTL14, and BmYTHDC were localized in the nucleus, and FL2D was localized to both the nucleus and cytoplasm. We examined the expression patterns of m6A-related genes during the embryonic development of Bombyx mori. To elucidate the function of BmMETTL3 during the embryonic stage, RNA sequencing was performed to measure changes in gene expression in silkworm eggs after BmMETTL3 knockdown, as well as in BmN cells overexpressing BmMETTL3. The global transcriptional pattern showed that knockdown of BmMETTL3 affected multiple cellular processes, including oxidoreductase activity, transcription regulator activity, and the cation binding. In addition, transcriptomic data revealed that many observed DEGs were associated with fundamental metabolic processes, including carbon metabolism, purine metabolism, amino acid biosynthesis, and the citrate cycle. Interestingly, we found that knockdown of BmMETTL3 significantly affected Wnt and Toll/Imd pathways in embryos. Taken together, these results suggest that BmMETTL3 plays an essential role in the embryonic development of B. mori, and deepen our understanding of the function of m6A-related genes in insects.

Circular RNA ame_circ_000115 regulates expression of genes in larval gusts of Apis mellifera ligustica stressed by Ascosphaera apis

Circular RNAs (circRNAs) are a new class of non-coding RNAs, which have been confirmed to regulate insect gene expression and immune response through multiple manners such as competing endogenous RNA (ceRNA) regulatory network. Currently, function of circRNA in honey bee immune response remains unclear. In this study, PCR and Sanger sequencing were performed to validate the back splicing (BS) site of ame_circ_000115 (in short ac115). RT-qPCR was used to detect the expression profile of ac115 in larval guts of Apis mellifera ligustica stressed by Ascosphaera apis. Dual-luciferase reporter gene assay was conducted to verify the binding relationship between ac115 and ame-miR-13b. Interference of ac115 in larval guts was carried out by feeding specific siRNA, followed by determination of the effect of ac115 interference on expression of six genes relevant to host immune response. The results confirmed the existence of BS site within ac115. Compared with the un-inoculated group, the expression of ac115 in 4-day-old larval gut of the A. apis-inoculated group was up-regulated with extreme significance (P < 0.000 1), while that in 5- and 6-day-old larval guts were significantly up-regulated (P < 0.05). The brightness of specific band for ac115 in 4-, 5- and 6-day-old larval guts of the siRNA-circ_000115-fed group gradually became weak, whereas that of the siRNA-scrambl-fed group was pretty high without obvious variation. Compared with that of the siRNA-scramble-fed group, the expression of ac115 in 4-day-old larval gut of the siRNA-circ_000115-fed group was significantly down-regulated (P < 0.05), whereas that of the 5- and 6-day-old larval guts were down-regulated with extreme significance (P < 0.001). Ame-miR-13b was truly existed and expressed in A. m. ligustica larval guts, and there was true binding relationship between ac115 and ame-miR-13b. Compared with that of the siRNA-scramble-fed group, the expression of antimicrobial peptide genes hymenoptaecin and abaecin in 6-day-old larval gut of the siRNA-circ_000115-fed group was significantly up-regulated (P < 0.05), while that of ecdysone receptor (Ecr) was down-regulated with extreme significance (P < 0.01). These results indicate that ac115 is truly expressed in A. m. ligustica larval guts, BS site truly exists within ac115, and effective interference of ac115 in A. m. ligustica larval guts can be achieved via feeding siRNA. Moreover, ac115 potentially regulates Ecr expression through adsorption of ame-miR-13b and expression of hymenoptaecin and abaecin using a non-ceRNA manner, further participating in host stress-response.

Mitochondrial genomes of soft scales (Hemiptera: Coccidae): features, structures and significance

BackgroundSoft scales (Hemiptera: Coccidae), including important agricultural and forestry pests, are difficult to identify directly by morphological characters. Mitochondrial genomes (mitogenomes) have been widely used in species identification and phylogenetic research. However, only three complete mitogenomes, and very few mitochondrial genes of scale insects (Hemiptera: Coccoidea) can be searched in GenBank. Mitogenome comparisons between scale insects or between scale insects and other hemipteran species have not yet been reported.ResultsIn this study, detailed annotation of three new mitogenomes and comparative analysis of scale insects were completed, as well as comparative analysis of the gene composition, gene arrangement, codon usage and evolutionary forces between scale insects and 488 other hemipteran species for the first time. We found that high A + T content, gene rearrangement and truncated tRNAs are common phenomena in soft scales. The average A + T content and codon usage bias of scale insects are higher and stronger than those of other hemipteran insects, respectively. The atp8 gene of Hemiptera and nine other protein-coding genes of scale insects are under positive selection with higher evolutionary rates.ConclusionsThe study revealed the particularity of the scale insect mitogenomes, which will provide a good reference for future research on insect phylogenetic relationships, insect pest control, biogeography and identification.

Comparative transcriptomics of the irradiated melon fly (Zeugodacus cucurbitae) reveal key developmental genes.

Irradiation can be used as an insect pest management technique to reduce post-harvest yield losses. It causes major physiological changes, impairing insect development and leading to mortality. This technique is used to control the melon fly Zeugodacus cucurbitae, a major pest of Cucurbitaceae in Asia. Here, we applied irradiation to melon fly eggs, and the larvae emerged from irradiated eggs were used to conduct comparative transcriptomics and thereby identify key genes involved in the development and survival. We found 561 upregulated and 532 downregulated genes in irradiated flies compared to non-irradiated flies. We also observed abnormal small-body phenotypes in irradiated flies. By screening the 532 downregulated genes, we selected eight candidate genes putatively involved in development based in described functions in public databases and in the literature. We first established the expression profile of each candidate gene. Using RNA interference (RNAi), we individually knocked down each gene in third instar larvae and measured the effects on development. The knockdown of ImpE2 ecdysone-inducible gene controlling life stage transitions-led to major body size reductions in both pupae and adults. The knockdown of the tyrosine-protein kinase-like tok (Tpk-tok) caused severe body damage to larvae, characterized by swollen and black body parts. Adults subject to knockdown of the eclosion hormone (Eh_1) failed to shed their old cuticle which remained attached to their bodies. However, no obvious developmental defects were observed following the knockdown of the heat shock protein 67B1-like (Hsp67), the insulin receptor (Insr), the serine/threonine-protein kinase Nek4 (Nek4), the tyrosine-protein kinase transmembrane receptor Ror (Ror_1) and the probable insulin-like peptide 1 (Insp_1). We argue that irradiation can be successfully used not only as a pest management technique but also for the screening of essential developmental genes in insects via comparative transcriptomics. Our results demonstrate that ImpE2 and Eh_1 are essential for the development of melon fly and could therefore be promising candidates for the development of RNAi-based pest control strategies.

Black Soldier Fly Larvae as Alternative to Conventional Animal Feed: An Islamic and Science Perspective

The black soldier fly (BSF), Hermetia illucens Linnaeus, is a worthwhile insect genus whose larvae have shown promise for sustainable animal feed because of their economical and premium protein. Concerns arise among Muslims about whether the usage of black soldier fly larvae (BSFL) as animal feed is permissible by Shariah because hasyarat (insect) consumption, excluding grasshoppers, is forbidden based on the majority of Islamic scholars. This study examined the Halal status of animals fed with BSFL, investigated the benefits of BSFL in industrial farming, and analyzed the Maqasid al-Shariah view on the usage of BSFL as animal feed. Library research and document analysis were applied as qualitative methods. The study shows that BSFL has approximately a dry matter of 40% protein and 30% fat, no significant upshot in egg odour produced by hens fed with BSFL, and the whole nutritional exchange of fish meal with BSFL has no negative effects on the physicochemical merit of Atlantic salmon. The study concludes that if animals fed with BSFL are not affected in terms of the odour, colour, and taste of najs (impurity), then the animals are not categorized as Jallalah (contaminated) animals. Hence, the usage of BSFL as animal feed is permissible (Halal) and is classified as Tahsiniyyat (luxuries) based on Maqasid al-Shariah.

RibDif2: expanding amplicon analysis to full genomes.

As previously described, amplicon analysis of the bacterial 16S gene has several limitations owing to fundamental characteristics of both the 16S gene and technological restrictions. Previously, RibDif was introduced to help quantify these limitations by detailed analysis of a given genera and the 16S gene profile of its members, notably multiplicity and divergence of 16S alleles within genomes as well as shared alleles between species. Apart from using amplicon analysis for only the 16S gene, amplicons derived from genus-specific genes or even functional genes are increasingly being utilized. Moreover, long-read technologies are progressively being used to sequence longer amplicons, and since these inherently contain more information, they may likely alleviate the issues proposed in RibDif. Taking these phenomena into account, we here propose RibDif2. RibDif2 retains the 16S-optimized functionality of the original RibDif but can now run any set of primers on any part of the genome in any set of organisms, be it prokaryote, eukaryote, or archaea. We demonstrate this new functionality by showing full species resolution of Pseudoalteromonas using complete rRNA-operon amplicons, as well as selection of optimally discriminatory primers for Staphylococcus and Pseudomonas. Moreover, we show a potential bias toward terrestrial bacteria relative to marine ones for primers amplifying biosynthetic gene clusters and lastly suggest optimal primers to differentiate the members of the insect genus Drosophila. We believe that RibDif2 will facilitate the work of all scientists using amplicon sequencing, especially in the era of long-read sequencing. Ribdif2 is freely available at https://github.com/Rob-murphys/ribdif.

Structure and Evolution of the AqE Gene in Insects

The AqE gene encodes a sulfolactate dehydrogenase-like enzyme of the LDH2/MDG2 oxidoreductase family. The gene is found in bacteria and fungi, as well as in animals and plants whose lifestyles are associated with aquatic environments. The AqE gene is present in arthropods and, in particular, insects that are predominantly terrestrial. The distribution and structure of AqE was studied in insects in order to trace its evolutionary fate. The AqE gene was found to be absent from certain insect orders and suborders, being apparently lost. AqE duplication or multiplication was observed in some orders. AqE was found to vary both in length and intron-exon structure, from intronless to multi-intron. An ancient nature was demonstrated for AqE multiplication in insects, while younger duplications were also detected. It was assumed that a new function might be acquired by the gene with the formation of paralogs.

Gene editing of the ABC Transporter/White locus using CRISPR/Cas9-mediated mutagenesis in the Indian Meal Moth

ATP binding cassette (ABC) proteins are involved in transport of substrates across membranes including eye pigments. Mutations of ABC transporter white, brown and scarlet genes of Drosophila and other insects result in visible eye color phenotypes. White locus was identified in a genome assembly of Plodia interpunctella and was found to extend for 16,670 bp comprising 13 exons. We report here recovery of heritable mutants in white in the Indian meal moth, P. interpunctella, using CRISPR/Cas9-mediated mutagenesis. A white eye strain of P. interpunctella c.737delC (Piw-/-) was previously isolated in 1986. Guide RNA (sgRNA) was designed for exon 1 (sgRNA242). Microinjection of Cas9/sgRNA242 complex into Plodia wild type eggs (≤20 min post oviposition) produced 156 viable larvae of which 81 eclosed as adults. Forty-five (56 %) adults displayed wild type phenotype, while 26 females (32 %) and 10 males (12 %) showed full or partial white eye phenotype. The 26 white eye females were mated with Piw-/- males and 21 matings resulted in F1 white eye progeny. Thirteen of the Piw-242 lines were established and sequencing showed indels at the CRISPR/Cas9 242AM site. Based on RT-PCR analysis, most white mutations resulted in suppressed levels of transcript. These results demonstrate the utility of CRISPR/Cas9 gene editing in Plodia which suggests this technology can be used to characterize the role of various genetic elements including those that encode novel targets or confer insecticide resistance mechanisms.

Insect Feeding on Sorghum bicolor Pollen and Hymenoptera Attraction to Aphid-Produced Honeydew.

Pollinators are declining globally, potentially reducing both human food supply and plant diversity. To support pollinator populations, planting of nectar-rich plants with different flowering seasons is encouraged while promoting wind-pollinated plants, including grasses, is rarely recommended. However, many bees and other pollinators collect pollen from grasses which is used as a protein source. In addition to pollen, Hymenoptera may also collect honeydew from plants infested with aphids. In this study, insects consuming or collecting pollen from sweet sorghum, Sorghum bicolor, were recorded while pan traps and yellow sticky card surveys were placed in grain sorghum fields and in areas with Johnsongrass, Sorghum halepense to assess the Hymenoptera response to honeydew excreted by the sorghum aphid (SA), Melanaphis sorghi. Five genera of insects, including bees, hoverflies, and earwigs, were observed feeding on pollen in sweet sorghum, with differences observed by date, but not plant height or panicle length. Nearly 2000 Hymenoptera belonging to 29 families were collected from grain sorghum with 84% associated with aphid infestations. About 4 times as many Hymenoptera were collected in SA infested sorghum with significantly more ants, halictid bees, scelionid, sphecid, encyrtid, mymarid, diapriid and braconid wasps were found in infested sorghum plots. In Johnsongrass plots, 20 times more Hymenoptera were collected from infested plots. Together, the data suggest that sorghum is serving as a pollen food source for hoverflies, earwigs, and bees and sorghum susceptible to SA could provide energy from honeydew. Future research should examine whether planting strips of susceptible sorghum at crop field edges would benefit Hymenoptera and pollinators.

Multiple drivers and lineage-specific insect extinctions during the Permo–Triassic

The Permo–Triassic interval encompasses three extinction events including the most dramatic biological crisis of the Phanerozoic, the latest Permian mass extinction. However, their drivers and outcomes are poorly quantified and understood for terrestrial invertebrates, which we assess here for insects. We find a pattern with three extinctions: the Roadian/Wordian (≈266.9 Ma; extinction of 64.5% insect genera), the Permian/Triassic (≈252 Ma; extinction of 82.6% insect genera), and the Ladinian/Carnian boundaries (≈237 Ma; extinction of 74.8% insect genera). We also unveil a heterogeneous effect of these extinction events across the major insect clades. Because extinction events have impacted Permo–Triassic ecosystems, we investigate the influence of abiotic and biotic factors on insect diversification dynamics and find that changes in floral assemblages are likely the strongest drivers of insects’ responses throughout the Permo–Triassic. We also assess the effect of diversity dependence between three insect guilds; an effect ubiquitously found in current ecosystems. We find that herbivores held a central position in the Permo–Triassic interaction network. Our study reveals high levels of insect extinction that profoundly shaped the evolutionary history of the most diverse non-microbial lineage.

A sigma class glutathione S-transferase gene regulated by the CncC pathway is required for phytochemical tolerance in the red flour beetle, Tribolium castaneum

Insect glutathione S-transferases (GSTs) play a crucial role in the detoxification of exogenous compounds, especially insecticides and plant allelochemicals. A sigma class GST gene, TcGSTS7, mediates the response to eugenol in Tribolium castaneum. However, the mechanism underlying this effect remains largely unknown. In this study, TcGSTS7, which exhibits a structural motif and domain organization characteristic of GSTs, was cloned from the T. castaneum genome. Spatiotemporal expression analysis revealed that TcGSTS7 was most highly expressed at the late larva stage and was mainly expressed in the fat body and epidermis of larvae and adults, suggesting that TcGSTS7 may play a potential role in the protection against toxic xenobiotics in T. castaneum. Furthermore, the expression of TcGSTS7 was significantly induced after exposure to eugenol, while RNA interference (RNAi) targeting TcGSTS7 enhanced the sensitivity of the beetle to eugenol, indicating that TcGSTS7 is involved in the tolerance of T. castaneum to this insecticide. Interestingly, the depletion of TcCncC, which encodes a transcription factor of the CncC pathway that has been associated with the regulation of detoxification-related genes in insects, led to a reduction in the TcGSTS7 transcript level following exposure to eugenol, which suggests that TcGSTS7 acts downstream of the CncC pathway. Combined, these results indicated that TcGSTS7 participates in the tolerance of T. castaneum to phytochemicals in a CncC pathway-dependent manner. These findings have implications for the development of novel drugs for use in pest control.

Diversity of Land Insect in Polda Plantation South Sulawesi

Land insects function in the soil fertility process, assist the soil decomposition, and to accelerate soil material cycle so as there are equilibrum on food chains and food webs cycle. The study aimed to examine of land insects in the South Sulawesi Regional Polda plantation and their surrounding environment benefits. The sampling technique was purposive sampling with an exploratory method, namely direct observation or observation in the field using the Pitffal Trap method at 5 stations. The study results at the South Sulawesi Regional Polda plantation obtained 172 individuals of soil insects consisting of 14 genera in 13 families. The land insects of Carabidae and Gryllidae families are insect genus with high abundance, while the families of Pentatomidae, Alydidae, Syrphidae, Saturniidae, Stratiomyidae, Blattidae, and Gryllotalpidae families has low abundances. The causing land insects genera high abundance at several research stations are the presence of supportive environmental conditions, where the habitats of some of these land insects are still preserved or natural, abundant food sources, and locations far from residential areas. The land insects found act as pollinators, decomposers, predators, parasitoids and bioindicators.

Review on microbially synthesized nanoparticles: a potent biocontrol agent against Aedes species of mosquito

Aedes aegypti is a principal vector of dengue, chikungunya and Zika illnesses worldwide. Because effective vaccinations or medications for the prevention and/or treatment for these illnesses are not available, vector management has been embraced as the primary method of reducing their transmission. The strategy that is often used for controlling Aedes populations is chemical insecticides; however, despite their efficiency, extensive usage of these pesticides has resulted in high operating costs, the establishment of resistant populations and undesirable non-target impacts. Therefore, the use of nanoparticles derived from multiple synthesis processes as new insecticides has recently attracted the interest of researchers. This study provides an overview of the current understanding concerning the method of action of nanoparticles against mosquitoes. Metal nanoparticles strongly influence antioxidant and detoxifying enzymes in insects, causing oxidative stress and cell death. These nanoparticles similarly inhibited acetylcholinesterase activity. Metal-based nanoparticles can potentially bind to S and P units in proteins and nucleic acids respectively resulting in decreased membrane permeability, organelle and enzyme denaturation which leads to cell death. Furthermore, they upregulate and downregulate critical insect genes, lower protein synthesis and gonadotrophin release, resulting in developmental and reproductive failure. This review critically examines insect nanotoxicology research trends and highlights the ecotoxicological effects of practical usage of nanoparticles as insecticides.

RNAi-mediated knockdown of arginine kinase genes leads to high mortality and negatively affect reproduction and blood-feeding behavior of Culex pipiens pallens.

Arginine kinase (AK) is one of the crucial enzymes involved in energy metabolism in invertebrates, and has been proposed as the target for RNA interference (RNAi)-based control of agricultural insect pests. While there is only one AK gene in most insects, two AK genes were identified in Culex pipiens pallens, the primary vector of lymphatic filariasis and epidemic encephalitis. The full-length cDNA sequences of CpAK1 and CpAK2 genes were obtained by reverse transcription PCR(RT-PCR) and rapid amplification of cDNA ends (RACE). The expression levels of CpAK1 and CpAK2 in different developmental stages and tissues were detected by reverse transcription quantitative PCR (RT-qPCR). The role of CpAK1 and CpAK2 in the reproduction and blood feeding behavior was analyzed using RNA interference (RNAi). Full-length cDNAs of CpAK1 and CpAK2 were isolated from Cx. pipiens pallens. Analysis of the expression pattern revealed that the mRNA level of CpAK1 was significantly higher than CpAK2 in all development stages and tissues examined, and the expressions of both CpAK1 and CpAK2 were upregulated in response to blood feeding. The co-knockdown of CpAK1 and CpAK2 mediated by RNAi led to high mortality (74.3%) of adult female mosquitoes and decreased hatchability (59.9%). Remarkably, the blood feeding rate and the engorgement rate of the female mosquitoes were negatively affected by co-injection of dsRNAs targeting CpAK1 and CpAK2. CpAK1 and CpAK2 were detected in all developmental stages and tissues, but showed divergence in expression level. RNAi-mediated knockdown of AK genes leads to high mortality and negatively affect blood-feeding behavior of Cx. pipiens pallens, suggesting that AK could be used for the target of RNAi-based mosquito control in the future.

A Genetic Compensation Phenomenon and Global Gene Expression Changes in Sex-miR-2766-3p Knockout Strain of Spodoptera exigua Hübner (Lepidoptera: Noctuidae).

MicroRNAs (miRNAs) drive the post-transcriptional repression of target mRNAs and play important roles in a variety of biological processes. miR-2766-3p is conserved and abundant in Lepidopteran species and may be involved in a variety of biological activities. In this study, Sex-miR-2766-3p was predicted to potentially bind to the 3' untranslated region (UTR) of cap 'n' collar isoform C (CncC) in Spodoptera exigua, and Sex-miR-2766-3p was confirmed to regulate the expression of SeCncC through screening with a luciferase reporter system. Although CRISPR/Cas9 has been extensively utilized to examine insect gene function, studies of miRNA function are still relatively uncommon. Thus, we employed CRISPR/Cas9 to knock out Sex-miR-2766-3p from S. exigua. However, the expression of SeCncC was not significantly altered in the knockout strain (2766-KO) compared with that of the WHS strain. This result suggested that a miRNA knockout might lack phenotypes because of genetic robustness. Additionally, we used transcriptome analysis to examine how the global gene expression patterns of the Sex-miR-2766-3p knockout strain varied. RNA-seq data revealed 1746 upregulated and 2183 downregulated differentially expressed genes (DEGs) in the 2766-KO strain, which might be the result of Sex-miR-2766-3p loss or DNA lesions as the trigger for transcriptional adaptation. GO function classification and KEGG pathway analyses showed that these DEGs were enriched for terms related to binding, catalytic activity, metabolic process, and signal transduction. Our findings demonstrated that S. exigua could compensate for the missing Sex-miR-2766-3p by maintaining the expression of SeCncC by other pathways.

Adaptation of Helicoverpa armigera to Soybean Peptidase Inhibitors Is Associated with the Transgenerational Upregulation of Serine Peptidases.

Molecular phenotypes induced by environmental stimuli can be transmitted to offspring through epigenetic inheritance. Using transcriptome profiling, we show that the adaptation of Helicoverpa armigera larvae to soybean peptidase inhibitors (SPIs) is associated with large-scale gene expression changes including the upregulation of genes encoding serine peptidases in the digestive system. Furthermore, approximately 60% of the gene expression changes induced by SPIs persisted in the next generation of larvae fed on SPI-free diets including genes encoding regulatory, oxidoreductase, and protease functions. To investigate the role of epigenetic mechanisms in regulating SPI adaptation, the methylome of the digestive system of first-generation larvae (fed on a diet with and without SPIs) and of the progeny of larvae exposed to SPIs were characterized. A comparative analysis between RNA-seq and Methyl-seq data did not show a direct relationship between differentially methylated and differentially expressed genes, while trypsin and chymotrypsin genes were unmethylated in all treatments. Rather, DNA methylation potential epialleles were associated with transcriptional and translational controls; these may play a regulatory role in the adaptation of H. armigera to SPIs. Altogether, our findings provided insight into the mechanisms of insect adaptation to plant antiherbivore defense proteins and illustrated how large-scale transcriptional reprograming of insect genes can be transmitted across generations.

Further study on the Oriental stick insect genus Paragongylopus Chen &amp; He, 1997, with additional descriptions and one newly recorded species from China (Phasmatodea; Bacillidae; Gratidiini)

The oriental stick insect Paragongylopus Chen &amp; He, 1997 is a small and poorly known genus, including 9 taxa distributed in China, Thailand and Vietnam. The male and egg of most species in this genus are still unknown. In this paper, two subgenera are re-defined with three new combinations: P. (Planoparagongylopus) brevicornis (Ho, 2019) comb. nov., P. (Planoparagongylopus) obtusidentatus (Ho, 2019) comb. nov., P. (Planoparagongylopus) plaumanni (Zompro, 2000) comb. nov. The male of P. (Paragongylopus) sinensis pingbianensis and the male and egg of P. (Planoaragongylopus) obtusidentatus comb. nov. are described for the first time. Photos of P. (Paragongylopus) sinensis sinensis holotype are given with a remark of its identification with another subspecies. P. (Planoparagongylopus) abramovi is firstly recorded from Yunnan Province of China, and it documents that all species of this genus are distributed in China. A key to identifying two subgenera and a distribution map of this genus from Yunnan and the surrounding area are provided as well.

Effects of transgenic cotton lines expressing dsAgCYP6CY3-P1 on the growth and detoxification ability of Aphis gossypii glover.

The pest Aphis gossypii Glover globally causes considerable economic losses on various crops by its feeding damage and disease transmission. Transgenic plants that produce double-stranded RNA (dsRNA) targeted to insect genes are being developed as a pest control strategy. In this study, we evaluated the effects of transgenic cotton-mediated RNA interference (RNAi) on the growth and detoxification ability of A. gossypii after the transgenic cotton lines expressing dsAgCYP6CY3-P1 (the TG cotton lines) were obtained on the basis of exploring the functions of CYP6CY3 in our previous research. The developmental time of third- and fourth-instar nymphs which fed on the TG cotton lines were significantly prolonged. Life table parameters showed that the fitness of cotton aphids from the TG cotton lines decreased. Additionally, the relative expression level of CYP6CY3 in cotton aphids which fed on the TG cotton lines was significantly reduced by 47.3 % at 48 h compared with that from the nontransgenic cotton (the NT cotton). Bioassay showed that silencing of CYP6CY3 increased mortality of the nymphs to imidacloprid by 28.49 % (at 24 h) and to acetamiprid by 73.77 % (at 48 h), respectively. These results indicated that the TG cotton lines delayed the growth and development of A. gossypii, but also decreased population density and increased its sensitivity to imidacloprid and acetamiprid, respectively. The results provide further support for the development and application of plant-mediated RNAi. © 2022 Society of Chemical Industry.

The uncommon function and mechanism of the common enzyme glyceraldehyde-3-phosphate dehydrogenase in the metamorphosis of Helicoverpa armigera.

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH), a key enzyme in glycolysis, is commonly used as an internal reference gene in humans, mice, and insects. However, the function of GAPDH in insect development, especially in metamorphosis, has not been reported. In the present study, Helicoverpa armigera and Spodoptera frugiperda ovarian cell lines (Sf9 cells) were used as materials to study the function and molecular mechanism of GAPDH in larval metamorphosis. The results showed that HaGAPDH was more closely related to GAPDH of S. frugiperda and Spodoptera litura. The transcript peaks of HaGAPDH in sixth instar larvae were 6L-3 (epidermal and midgut) and 6L-1 (fat body) days, and 20E and methoprene significantly upregulated the transcripts of HaGAPDH of larvae in qRT-PCR. HaGAPDH-GFP-His was specifically localized in mitochondria in Sf9 cells. Knockdown of HaGAPDH by RNA interference (RNAi) in sixth instar larvae resulted in weight loss, increased mortality, and decreases in the pupation rate and emergence rates. HaGAPDH is directly bound to soluble trehalase (HaTreh1) physically and under 20E treatment in yeast two-hybrid, coimmunoprecipitation, and colocalization experiments. In addition, knockdown of HaGAPDH increased the Treh1 activity, which in turn decreased the trehalose content but increased the glucose content in larvae. Therefore, these data demonstrated that GAPDH controlled the glucose content within the normal range to ensure glucose metabolism and metamorphosis by directly binding with HaTreh1.

Mitogenomic Comparison of the Mole Crickets Gryllotalpidae with the Phylogenetic Implications (Orthoptera: Ensifera).

Simple SummaryWe sequenced the complete mitochondrial genomes (mitogenomes) of Gryllotalpa henana Cai & Niu, 1998 and the Chinese G. orientalis Burmeister, 1838 for the first time, and reconstructed the mitogenomic phylogeny of the infraorder Gryllidea. The results show that the two new mitogenomes are double-stranded circular molecules with a typical gene complement, gene arrangement and base composition, the same as those of other gryllotalpids and ancestral insects. Tandem repeats of the control region were discovered in Gryllotalpidae for the first time. Considering both the high nucleotide divergence and the elevated ratio of Ka/Ks, the genes nad2 and nad6 may be evaluated as potential markers for future phylogeny and species delimitation in Gryllotalpidae. The results of phylogenetic analyses provide supports for the mitogenomic and transcriptomic trees, but partially contradict those of the multilocus phylogenies.Owing to limited molecular data, the phylogenetic position of the family Gryllotalpidae is still controversial in the infraorder Gryllidea. Mitochondrial genome (mitogenome) plays a crucial role in reconstructing phylogenetic relationships and revealing the molecular evolution of insects. However, only four mitogenomes have been reported in Gryllotalpidae to date. Herein, we obtained the first mitogenomes of Gryllotalpa henana Cai & Niu, 1998 and the Chinese G. orientalis Burmeister, 1838, made a detailed comparison of all mitogenomes available in Gryllotalpidae and reconstructed the phylogeny of Gryllidea based on mitogenomes using Bayesian inference (BI) and maximum likelihood (ML) methods. The results show that the complete mitogenome sequences of G. henana (15,504 bp) and G. orientalis (15,497 bp) are conserved, both exhibiting the double-stranded circular structure, typical gene content and the ancestral insect gene arrangement. The complete mitogenome of G. henana exhibits the lowest average AT content ever detected in Gryllotalpidae, and even Gryllidea. The gene nad2 of both species has atypical initiation codon GTG. All tRNAs exhibit typical clover-leaf structure, except for trnS1 lacking the dihydrouridine (DHU) arm. A potential stem–loop structure, containing a (T)n(TC)2(T)n sequence, is detected in the control region of all gryllotalpids investigated and is likely related to the replication initiation of the minority strand. The phylogenetic analyses recover the six families of Gryllidea as Gryllotalpidae + (Myrmecophilidae + (Mogoplistidae + (Trigonidiidae + (Phalangopsidae + Gryllidae)))), similar to the trees based on transcriptomic and mitogenomic data. However, the trees are slightly different from the multilocus phylogenies, which show the sister-group relationship of Gryllotalpidae and Myrmecophilidae. The contradictions between mitogenomic and multilocus trees are briefly discussed.