Publications by authors named "Awawing A Andongma"

9 Publications

  • Page 1 of 1

Optimization of dietary RNA interference delivery to western flower thrips Frankliniella occidentalis and onion thrips Thrips tabaci.

Arch Insect Biochem Physiol 2020 Mar 19;103(3):e21645. Epub 2019 Nov 19.

Applied Molecular Microbiology Group, Swansea University School of Medicine, Institute of Life Sciences, Swansea, UK.

In insect reverse genetics, dietary delivery of interfering RNAs is a practical approach in nonmodel species, such as thrips, whose small size, and feeding behavior restricts the use of other delivery methods. In a laboratory context, an unsuitable diet could confound the interpretation of an RNA interference (RNAi) phenotype, however well-formulated artificial diets can minimize experimental variability, reduce the need for insect handling, and can further be used for roles, such as delivering double-strand RNA (dsRNA)-expressing recombinant bacteria. In this study, artificial diets for oral delivery of dsRNA were developed for two important pest thrips species, western flower thrips (Frankliniella occidentalis) and onion thrips (Thrips tabaci), with the goal of (a) stimulating feeding behavior, (b) supporting optimal growth rates of dsRNA-expressing symbiotic bacteria, and (c) nutritionally supporting the thrips for sufficient periods to observe RNAi phenotypes. The efficacy of artificial diets for ingesting "naked" dsRNA or dsRNA-expressing symbionts and dsRNA delivery via host plant uptake was evaluated. Compared with previously published diet formulations, new combinations based on tryptone, yeast, and soy were superior for enhancing feeding and longevity. However, simply adding "naked" dsRNA to an artificial diet was an unreliable form of RNAi delivery in our hands due to dsRNA degradation. Delivery via host plants was more successful, and the new diet formulation was suitable for symbiont-mediated dsRNA delivery, which we believe is the most convenient approach for large-scale knockdown experiments. This study, therefore, provides alternative methodologies for thrips rearing, dietary RNAi delivery, and insights into the challenges of performing dietary RNAi in nonmodel insects.
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http://dx.doi.org/10.1002/arch.21645DOI Listing
March 2020

Mutation of doublesex induces sex-specific sterility of the diamondback moth Plutella xylostella.

Insect Biochem Mol Biol 2019 09 3;112:103180. Epub 2019 Jul 3.

CAS Key Laboratory of Insect Developmental and Evolutionary Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai, 200032, China. Electronic address:

DOUBLESEX (DSX): the downstream gene in the insect sex determination pathway, plays a critical role in sexual differentiation and development. The functions of dsx have been characterized in several model insect species. However, the molecular mechanism and functions of sex determination of dsx in Plutella xylostella, an agricultural pest, are still unknown. In present study, we identified a male-specific and three female-specific Pxdsx transcripts in P. xylostella. Phylogenetic analyses and multiple sequence alignment revealed that Pxdsx is highly conserved in lepidopterans. The CRISPR/Cas9 technology was used to induce mutations in the male-specific isoform, the female-specific isoform, and common regions of Pxdsx. Disruptions of Pxdsx sex-specific isoforms caused sex-specific defects in external genitals and partial sexual reversal. In addition, we found that female specific transcripts were detected in Pxdsx male mutants and male-specific transcripts were detected in Pxdsx female mutants. Mutations also caused changes in expression of several sex-biased genes and induced sex-specific sterility. This study demonstrates that Pxdsx plays a key role in sex determination of P. xylostella and suggests novel genetic control approaches for the management of P. xylostella.
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http://dx.doi.org/10.1016/j.ibmb.2019.103180DOI Listing
September 2019

Gut bacteria of the cowpea beetle mediate its resistance to dichlorvos and susceptibility to Lippia adoensis essential oil.

Sci Rep 2019 04 23;9(1):6435. Epub 2019 Apr 23.

Department of Biological Sciences, Faculty of Science, University of Ngaoundere, P.O Box 454, Ngaoundere, Cameroon.

Bacteria inhabiting the gut of insects provide many benefits to their hosts, such as aiding in food digestion, reproduction, and immunity, tissue homeostasis, adaptation to environment and resistance to pathogen and pesticides. The cowpea beetle, Callosobruchus maculatus, is a serious cosmopolitan pest of pulses. This beetle has lent itself as a guinea pig for several ecological studies. It harbors a consortium of bacterial communities in its gut, but the evidence for their role in its physiology is fragmentary. In this work, we hypothesized that gut microbiota mediates C. maculatus resistance to dichlorvos (DDVP or O,O-dimethyl O-2,2-dichlorovinylphosphate) and represent the target of Lippia adoensis (Gambian Tea Bush) essential oil (EO). Symbiotic and aposymbiotic beetles were exposed to artificial cowpea seeds earlier treated with DDVP or EO. Adult mortality and changes in gut bacterial community composition and abundance were examined at F and F generations. The susceptibility of experimental beetles to DDVP was significantly affected by their symbiotic status. The adult mortality decreased across generations in DDVP treatments, and remained significantly higher in aposymbiotic groups. In EO treatments, the mortality was consistent irrespective of symbiotic status and experimental generations. When compared to DDVP and the Control, EO treatments had significantly lower bacterial richness and diversity, as well as lower abundance of Proteobacteria, Firmicutes, and Bacteroidetes. These results support our hypothesis and describe the responses of gut microbial communities to pesticide treatments. This could be of interest for developing new management strategies of this pest.
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http://dx.doi.org/10.1038/s41598-019-42843-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6478711PMC
April 2019

Intestinal bacteria modulate the foraging behavior of the oriental fruit fly Bactrocera dorsalis (Diptera: Tephritidae).

PLoS One 2019 16;14(1):e0210109. Epub 2019 Jan 16.

Department of Entomology, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.

The gut microbiome of insects directly or indirectly affects the metabolism, immune status, sensory perception and feeding behavior of its host. Here, we examine the hypothesis that in the oriental fruit fly (Bactrocera dorsalis, Diptera: Tephritidae), the presence or absence of gut symbionts affects foraging behavior and nutrient ingestion. We offered protein-starved flies, symbiotic or aposymbiotic, a choice between diets containing all amino acids or only the non-essential ones. The different diets were presented in a foraging arena as drops that varied in their size and density, creating an imbalanced foraging environment. Suppressing the microbiome resulted in significant changes of the foraging behavior of both male and female flies. Aposymbiotic flies responded faster to the diets offered in experimental arenas, spent more time feeding, ingested more drops of food, and were constrained to feed on time-consuming patches (containing small drops of food), when these offered the full complement of amino acids. We discuss these results in the context of previous studies on the effect of the gut microbiome on host behavior, and suggest that these be extended to the life history dimension.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0210109PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6334898PMC
September 2019

Rh6 gene modulates the visual mechanism of host utilization in fruit fly Bactrocera minax.

Pest Manag Sci 2019 Jun 28;75(6):1621-1629. Epub 2018 Dec 28.

Hubei Key Laboratory of Insect Resource Application and Sustainable Pest Control, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, China.

Background: Vision plays a critical role in host location and oviposition behavior for herbivorous insects. However, the molecular mechanisms underlying visual regulation in host recognition and oviposition site selection in insects remains unknown. The aim of this study was to explore the key visual genes that are linked to the host plant location of the fruit fly, Bactrocera minax.

Results: Using a host specialist fruit fly, B. minax, which lays eggs only into immature green citrus fruit, we undertook behavioral, transcriptomic, and RNAi research to identify the molecular basis for host fruit color recognition. In laboratory and field assays we found that adults prefer green over other colors, and this preference is significantly increased in sexually mature over immature flies. Furthermore, we identified that the Rh6 gene, responsible for green spectral sensitivity, has elevated expression in mature flies over immature flies. RNAi suppression of Rh6 eliminated the preference for green, resulting in a significant decrease in the number of eggs laid by B. minax in green unripe citrus.

Conclusion: These results show that the Rh6 gene modulates the visual mechanism of host utilization in B. minax, providing a genetic basis for visual host location in a non-model insect herbivore. © 2018 Society of Chemical Industry.
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http://dx.doi.org/10.1002/ps.5278DOI Listing
June 2019

The impact of nutritional quality and gut bacteria on the fitness of (Diptera: Tephritidae).

R Soc Open Sci 2018 Jul 11;5(7):180237. Epub 2018 Jul 11.

College of Plant Science & Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China.

To examine how nutritional quality and resident gut bacteria interplay in improving the fitness of an oligophagous fruit fly, , artificial sucrose diets and full diets (sucrose, tryptone and yeast extract) were fed to flies with and without antibiotic supplementation. Furthermore, and were supplemented to sucrose-only diets. Flies were maintained in the laboratory and the fitness parameters, male and female longevity, number of copulations and female fecundity, were recorded. Full diet without bacterial depletion significantly increased fecundity and copulation. In the absence of gut bacteria, flies fed with full diets had significantly decreased mean fecundity and copulation rate. Flies that were fed with sucrose diet had a very low copulation rate and produced no eggs. Diet type and the presence of bacteria did not have any effect on the average longevity of male and female flies. Bacterial supplementation in sucrose diets did not improve any of the measured parameters. The results demonstrate that gut bacteria interact with diet to influence mating and reproduction in . Symbiotic bacteria significantly and positively impact reproduction in ; however, their impact can only be fully realized when the flies are fed with a nutritionally complete diet.
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http://dx.doi.org/10.1098/rsos.180237DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6083673PMC
July 2018

Essential oil optimizes the susceptibility of and enhances the nutritional qualities of stored cowpea .

R Soc Open Sci 2017 Aug 23;4(8):170692. Epub 2017 Aug 23.

College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.

The intensive use of synthetic pesticides in cowpea storage has led to the development of resistance by and subsequent degradation of grain quality. In an attempt to circumvent these constraints, the susceptibility of to 2,2-dichlorovinyldimethyl phosphate (DDVP) and essential oil (EO) was investigated and variations in the proportions of nutritional values of treated grains 150 days after storage were assessed. The survival rate was recorded after five generations. The resistance index and biochemical parameters of grains were determined. The results from this study revealed that the survival rate and resistance index significantly increased proportionally with damage in DDVP treatments ( = 0.889;  = 0.018) while in EO treatments, those values remained low without significant variations ( = 0.0764) throughout the generations. DDVP stored grains yielded higher crude protein values, but lower carbohydrates, tannins, phenolics and minerals compared to EO. Eighteen amino acids were detected in EO treated grains and 14 in DDVP which was devoid of albumin and prolamin. EO could therefore represent a safe alternative bio-pesticide to cope with insect resistance and enhance the nutritional qualities of stored cowpea seeds.
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http://dx.doi.org/10.1098/rsos.170692DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5579128PMC
August 2017

Pupal diapause termination in Bactrocera minax: an insight on 20-hydroxyecdysone induced phenotypic and genotypic expressions.

Sci Rep 2016 06 8;6:27440. Epub 2016 Jun 8.

College of Plant Science &Technology, Huazhong Agricultural University, Wuhan 430070, China.

The Chinese citrus fruit fly, Bactrocera minax, is an economically important pest of citrus. It exhibits pupal diapause from November to May to combat harsh environmental conditions. Such a long pupal diapause is a barrier for laboratory rearing and development of control strategies against this pest. In the present study, 20-hydroxyecdysone (20E) was used to break pupal diapause of B. minax by topical application. After diapause termination by 20E treated, the pupal ontogenetic processes were observed along the temporal trajectory. The pupal response time to 20E was estimated by detecting the relative expression of 20E responsive genes at different times after 20E-treatment. Results revealed that 20E could effectively terminate the pupal diapause in a dose-dependent manner and significantly shorten the time for 50% adult emergence (Et50). 20E response genes, including ecr, broad and foxo, were up-regulated within 72h, indicating these genes are involved in pupal metamorphosis and diapause termination processes. Morphological changes showed the pupal metamorphosis began ~7 days after 20E-treatment at 22 °C. This study does not only pave the way for artificial rearing in the laboratory through manipulating of pupal diapause termination, but also deepens our understanding of the underlying pupal diapause termination mechanism of B. minax.
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http://dx.doi.org/10.1038/srep27440DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4897610PMC
June 2016

Pyrosequencing reveals a shift in symbiotic bacteria populations across life stages of Bactrocera dorsalis.

Sci Rep 2015 Mar 30;5:9470. Epub 2015 Mar 30.

College of Plant Science &Technology, Huazhong Agricultural University, Wuhan 430070, China.

Bactrocera dorsalis is one of the most economically important fruit flies around the world. In this study, 454 pyrosequencing was used to identify the bacteria associated with different developmental stages of B. dorsalis. At ≥ 97% nucleotide similarity, total reads could be assigned to 172 Operational Taxonomic Units belonging to six phyla. Proteobacteria dominated in immature stages while Firmicutes dominated in adult stages. The most abundant families were Enterococcaceae and Comamondaceae. The genus Comamonas was most abundant in pupae whereas completely absent in adults. Some identified species had low sequence similarity to reported species indicating the possibility of novel taxa. However, a majority sequence reads were similar to sequences previously identified to be associated with Bactrocera correcta, suggesting a characteristic microbial fauna for this insect genus. The type and abundance of different bacterial groups varied across the life stages of B. dorsalis. Selection pressure exerted by the host insect as a result of its habitat and diet choices could be the reason for the observed shift in the bacteria groups. These findings increase our understanding of the intricate symbiotic relationships between bacteria and B. dorsalis and provide clues to develop potential biocontrol techniques against this fruit fly.
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http://dx.doi.org/10.1038/srep09470DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5380164PMC
March 2015