Chromosome-level genome assembly of an oligophagous leaf beetle Ophraella communa (Coleoptera: Chrysomelidae).

The leaf beetle Ophraella communa LeSage (Coleoptera: Chrysomelidae) is an effective biological control agent of the common ragweed. Here, we assembled a chromosome-level genome of the O. communa by combining Illumina, Nanopore, and Hi-C sequencing technologies. The genome size of the final genome assembly is 733.1 Mb, encompassing 17 chromosomes, with an improved contig N50 of 7.05 Mb compared to the original version. Genome annotation reveals 25,873 protein-coding genes, with functional annotations available for 22,084 genes (85.35%). Non-coding sequence annotation identified 204 rRNAs, 626 tRNAs, and 1791 small RNAs. Repetitive elements occupy 414.41 Mb, constituting 57.76% of the genome. This high-quality genome is fundamental for advancing biological control strategies employing O. communa.

Effect of host shift on the gut microbes of Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae).

Background: Gut microbes play an important role in the adaptation of insects. Polyphagous insects usually undergo changes in gut microbiota after host shift. The Bactrocera cucurbitae have a wide range of hosts, but the dynamic of gut microorganisms during host shift have not been thoroughly investigated. To understand the role of gut microbes in insect adaptation, it is necessary to study the dynamics of insect gut microorganisms during host transfer. Methods: Using Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) and its four hosts as study subjects, we investigated the dynamics of gut microbes during host transfer and the effects of different hosts on the gut microbial composition of B. cucurbitae. Results: The results showed that the Chao1 index of B. cucurbitae decreased significantly during host transfer, and the intestinal microorganisms were significantly affected by the original host, host, and generations. Furthermore, predicated changes in the abundance of secondary metabolite pathways after host transfer suggested that microorganisms may play an important role in the degradation of secondary metabolites, among which Providencia and Morganella have important functions in the gut of B. cucurbitae. Conclusion: This implied that microorganisms play a function in the host transfer process of B. cucurbitae and may be an important cofactor in the adaptation of B. cucurbitae to different hosts and environments, providing new research ideas for the future control of B. cucurbitae.

Chromosome-level genome assembly of an agricultural pest Zeugodacus tau (Diptera: Tephritidae).

The fruit fly Zeugodacus tau (Diptera: Tephritidae) is a major pest of melons and other cucurbits in Southeast Asia. In this study, we used Illumina, Nanopore, and Hi-C sequencing technologies to assemble a reference genome of Z. tau at the chromosomal level. The assembled genome was 421.79 Mb and consisted of six chromosomes (one X-chromosome + five autosomes). The contig N50 was 4.23 Mb. We identified 20,922 protein-coding genes, of which 17,251 (82.45%) were functionally annotated. Additionally, we found 247 rRNAs, 435 tRNAs, 67 small nuclear RNAs, and 829 small RNAs in the genome. Repetitive elements accounted for 55.30 Mb (13.15%) of the genome. This high-quality genome assembly is valuable for evolutionary and genetic studies of Z. tau and its relative species.

Rapid response of midgut bacteria in Bactrocera tau (Walker) (Diptera: Tephritidae) to lambda-cyhalothrin- and spinosad-induced stress.

In recent decades, the increasingly widespread application of chemical pesticides has exacerbated the emergence of insecticide resistance among insect pests. In this study, we examined the rapid response of bacteria in the midgut of the fruit fly Bactrocera tau (Walker) (Diptera: Tephritidae) to stress induced by the insecticides lambda-cyhalothrin and spinosad by analyzing the bacterial community structure and diversity in the midguts of 4-day-old B. tau. The results revealed that 4-day-old B. tau females were more resistant to lambda-cyhalothrin and spinosad than their 4-day-old male counterparts. Alpha- and beta-diversity analyses revealed no significant differences between male and female B. tau with respect to the diversity and richness of gut bacteria in response to the same treatments. In response to treatment with lambda-cyhalothrin and spinosad at lethal concentration 50 (LC50), we detected significant changes in the structure and diversity of the bacterial community in the midguts of both male and female B. tau. Particularly among the dominant bacterial genera, there were decreases in the relative abundances of Citrobacter, Enterobacter, Klebsiella, and Pectobacterium. Increases were observed in the relative abundances of Dysgonomonas, Erwinia, and Providencia. Our findings provide a theoretical basis for gaining a better understanding of the relationships between midgut bacteria and the insecticide resistance of B. tau.

Biophysical cues to improve the immunomodulatory capacity of mesenchymal stem cells: The progress and mechanisms.

Mesenchymal stem cells (MSCs) can maintain immune homeostasis and many preclinical trials with MSCs have been carried out around the world. In vitro culture of MSCs has been found to result in the decline of immunomodulatory capacity, migration and proliferation. To address these problems, simulating the extracellular environment for preconditioning of MSCs is a promising and inexpensive method. Biophysical cues in the external environment that MSCs are exposed to have been shown to affect MSC migration, residency, differentiation, secretion, etc. We review the main ways in which MSCs exert their immunomodulatory ability, and summarize recent advances in mechanical preconditioning of MSCs to enhance immunomodulatory capacity and related mechanical signal sensing and transduction mechanisms.

The hsp70 new functions as a regulator of reproduction both female and male in Ophraella communa.

Heat shock proteins (Hsps) function as molecular chaperones that enable organisms to withstand stress and maintain normal life activities. In this study, we identified heat shock protein 70 (encoded by hsp70), which exhibits a higher expression in the mature male testis than in the unmature testis of Ophraella communa. Tissue expression profile revealed that Ochsp70 levels in males were highest in the testis, whereas those in females were highest in the head. Moreover, the expression of Ochsp70 was found to be significantly induced in female bursa copulatrix after mating. Double-stranded RNA dsOchsp70 was injected into males to performance RNA interference, which significantly decreased the male Ochsp70 expression levels within 20 d post-injection, whereas no effect was observed on the Ochsp70 expression level in the females after mating with dsOchsp70-injected males. However, significant downregulation of female fertility was marked simultaneously. Furthermore, knockdown of female Ochsp70 expression also led to a significant reduction in fertility. Finally, comparative transcriptomic analysis identified glucose dehydrogenase and insulin-like growth factor binding protein as putative downstream targets of Ochsp70. Overall, we deduced that Ochsp70 is an indispensable gene and a potential male mating factor in O. communa, which regulates reproduction.

Heat wave event facilitates defensive responses in invasive C3 plant Ambrosia artemisiifolia L. under elevated CO2 concentration to the detriment of Ophraella communa.

To predict and mitigate the effects of climate change on communities and ecosystems, the joint effects of extreme climatic events on species interactions need to be understood. Using the common ragweed (Ambrosia artemisiifolia L.)-leaf beetle (Ophraella communa) system, we investigated the effects of heat wave and elevated CO2 on common ragweed growth, secondary metabolism, and the consequent impacts on the beetle. The results showed that elevated CO2 and heat wave facilitated A. artemisiifolia growth; further, A. artemisiifolia accumulated large amounts of defensive secondary metabolites. Being fed on A. artemisiifolia grown under elevated CO2 and heat wave conditions resulted in the poor performance of O. communa (high mortality, long development period, and low reproduction). Overall, under elevated CO2, heat wave improved the defensive ability of A. artemisiifolia against herbivores. On the other hand, enhanced adaptability to climatic changes may aggravate invasive plant distribution, posing a challenge to the control of invasive plants in the future.

Scanning Electron Microscopic Analysis of Antennal Sensilla and Tissue-Expression Profiles of Chemosensory Protein Genes in Ophraella communa (Coleoptera: Chrysomelidae).

Ophraella communa is an efficient biocontrol agent used against the invasive weed Ambrosia artemisiifolia. It is an herbivorous insect that feeds on specific plants; the olfactory functions of this insects plays an important role in their search for host plants. There are no reports on O. communa sensilla types, morphology, or chemosensory protein (CSP) genes. In this study, we observed the external structure and distribution of antennal sensilla in adult O. communa antennae by scanning electron microscopy; moreover, we cloned 11 CSPs (CSP1-CSP11) and elucidated their tissue-expression profiles using quantitative real-time polymerase chain reaction. Six types of sensilla were identified: sensilla trichodea (including two subtypes), sensilla chaetica, sensilla basiconica (including two subtypes), sensilla styloconica, sensilla coeloconica, and Böhm bristles. Both male and female antennae had all six types of sensilla, and no sexual dimorphism was noted in sensillar types or distribution. We also found that the expression levels of CSP2, CSP3, CSP4, CSP6, and CSP7 in male and female antennae were higher than those in other tissues, which suggests that these five CSPs may be related to olfactory function in O. communa. Ultimately, our results lay the foundation for interpreting the olfactory functions of adult O. communa.

Transcriptome Analysis of Ophraella communa Male Reproductive Tract in Indirect Response to Elevated CO2 and Heat Wave.

Increase in atmospheric CO2 directly affects the insect physiology and behavior, and indirectly affects the herbivorous insects by affecting their hosts. The increase in atmospheric CO2 is accompanied by an increase in temperature and heat waves. Ophraella communa LeSage is a natural enemy of Ambrosia artemisiifolia (common ragweed). The development and reproduction of this beetle is weakened upon eating common ragweed grown under stress conditions. As female behavior and physiology alter after mating, the reproductive tract of males is likely to modulate reproduction and development in this species. Herein, the transcriptional profiles of testes and accessory glands from male O. communa individuals feeding on common ragweed under conditions of high CO2 concentration and heat waves and that grown under ambient CO2 concentration were compared. Differentially expressed genes (DEGs) were identified between the same tissues from beetles fed on common ragweed grown under different stress conditions. There were 3, 2, 3, 1and 5 genes related to decomposition and transport of macromolecular substances, host location, stress response, reproduction, and poisonous food-utilization. No expected response was observed in the male reproductive tract, but some of the identified DEGs might control the development of the population. The results presented here should be helpful in guiding future studies on deciphering the indirect response of other organs to high CO2 concentration and heat waves, as well as the functions of seminal fluid proteins in O. communa.

Identification and Validation of Reference Genes for Quantitative Gene Expression Analysis in Ophraella communa.

Ophraella communa is an effective bio-control agent of the invasive common weed. By now, the reference genes in O. communa have not yet been screened and validated. The aim of this study was to screen for the most stable reference genes in different backgrounds, such as different developmental stages, sexes, tissues, and male reproductive system with different body sizes. We selected 12 common housekeeping genes involved in different biological processes, including GAPDH, ACT1, ACT2, ARF1, ARF4, SDH, ßTUBC, RPL4, RPL19, RPS18, EF1α, and COX as the candidate reference genes. To analyze the stability of the candidate reference genes, we first used three dedicated algorithms, GeNorm, NormFinder, and BestKeeper, and further comprehensive ranking was provided by ReFinder. The results showed that RPL19 and RPL4 exhibited the least variation in different developmental stages/sexes and in male reproductive systems with different body sizes. COX proved to be most suitable for normalizing the gene expression levels in different tissues, and coincidentally, RPL19 was also found to be second in terms of stability in this study. To the best of our knowledge, this is the first study to identify suitable reference genes for analyzing gene expression in O. communa; thus, this study would lay the foundation for future research on the molecular physiology and biochemistry of O. communa and other insects.

Olfactory co-receptor is involved in host recognition and oviposition in Ophraella communa (Coleoptera: Chrysomelidae).

Common ragweed (Ambrosia artemisiifolia) is a notorious invasive weed that has spread across most temperate regions of the world. The beetle (Ophraella communa) is considered to be an effective control agent against A. artemisiifolia. As an oligophagous insect, its olfactory system is extremely important for host seeking in the wild. To the best of our knowledge, there is no report on the molecular mechanisms underlying olfaction recognition in this beetle. Hence, in this study, we characterized the odorant receptor co-receptor of O. communa and named it as 'OcomORco'. Real-time quantitative PCR (qRT-PCR) showed that, compared to the control treatment, RNA interference (RNAi) strongly reduced the expression of OcomORco by 89% in male and 90% in female beetles. Electroantennogram assay showed that the antennal response of both male and female beetles to four volatiles of A. artemisiifolia was significantly reduced. The injected male or female beetles lost their preference for plant leaves as observed in the behavioural tests. In addition, disruption of the expression of OcomORco resulted in a reduction of oviposition, while there was no difference in larval hatching rate between control and knockdown females. We demonstrated that OcomORco plays a vital role in olfactory perception and host search in O. communa, and it is involved in oviposition in an indirect way.

OcomCSP12, a Chemosensory Protein Expressed Specifically by Ovary, Mediates Reproduction in Ophraella communa (Coleoptera: Chrysomelidae).

Chemosensory proteins (CSPs) are considered to be the transporter linking odorant chemicals and receptors on sensory neurons. However, the extensive expression patterns of CSPs in insects suggest that CSPs are also involved in other physiological processes; the range of their functions, however, remains uncertain. In this study, we successfully characterized and cloned the CSP12 of Ophraella communa (OcomCSP12). The open reading frame of OcomCSP12 encodes 131 amino acids, with four conserved cysteine residues. The expression patterns of OcomCSP12 validated by quantitative real-time PCR (qRT-PCR) showed that OcomCSP12 is specifically expressed in female ovary. Furthermore, compared with the control treatment, silencing OcomCSP12 resulted in significantly reduced oviposition in females. Surprisingly, the knock-down rate of OcomCSP12 exceeded 95% and remained depressed for more than 15 days, indicating that RNA interference (RNAi) was a suitable method for exploring the function of CSP12 in O. communa. These findings increase our understanding of the expression profile and function of the CSP gene family in insects.

Transgenic Bt cotton expressing Cry1Ac/Cry2Ab or Cry1Ac/EPSPS does not affect the plant bug Adelphocoris suturalis or the pollinating beetle Haptoncus luteolus.

The widespread cultivation of transgenic Bt cotton makes assessing the potential effects of this recombinant crop on non-target organisms a priority. However, the effect of Bt cotton on many insects is currently virtually unknown. The plant bug Adelphocoris suturalis is now a major pest of cotton in southern China and the beetle Haptoncus luteolus is one of the most ancient cotton pollinators. We conducted laboratory experiments to evaluate the toxicity of the Bt cotton varieties ZMSJ, which expresses the toxins Cry1Ac and Cry2Ab, and ZMKCKC, which expresses Cry1Ac and EPSPS, on adult A. suturalis and H. luteolus. No significant increase in the mortality of either species was detected after feeding on Bt cotton leaves or pollen for 7 days. Trace amounts of Cry1Ac and Cry2Ab proteins could be detected in both species but in vitro binding experiments found no evidence of Cry1Ac and Cry2Ab binding proteins. These results demonstrate that feeding on the leaves or pollen of these two Bt cotton varieties has no toxic effects on adult A. suturalis or H. luteolus.