Bacteria inhabiting the gut of insects provide many benefits to their hosts, such as aiding in fo... more 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 F1 and F5 generations. The susceptibility...
In order to understand the role of symbionts for their insect hosts, it is customary to treat the... more In order to understand the role of symbionts for their insect hosts, it is customary to treat them with antibiotics or to sterilize eggs (treatments), resulting in aposymbiotic and axenic insects, respectively. Such axenic insects can then be compared with untreated controls. Fruit flies often bear complex communities which are greatly reduced by such treatments. However, the bacterial community is not completely eliminated. Here, we examine the effect of these procedures on the structure of the remaining bacterial communities in Bactrocera dorsalis (Diptera: Tephritidae) and on the insect longevity. The antibiotics (Norfloxacin and Ceftazedime) were administered to 1-day-old adult flies through sugar meal for 7 days, and eggs were surface sterilized and dechorionated to produce axenic lines. The flies were starved of protein before they were offered full diets or diets containing non-essential amino acids only. Antibiotic and egg disinfection treatments resulted in a significant re...
Background Nitrogen is considered the most limiting nutrient element for herbivorous insects. To ... more Background Nitrogen is considered the most limiting nutrient element for herbivorous insects. To alleviate nitrogen limitation, insects have evolved various symbiotically mediated strategies that enable them to colonize nitrogen-poor habitats or exploit nitrogen-poor diets. In frugivorous tephritid larvae developing in fruit pulp under nitrogen stress, it remains largely unknown how nitrogen is obtained and larval development is completed. Results In this study, we used metagenomics and metatranscriptomics sequencing technologies as well as in vitro verification tests to uncover the mechanism underlying the nitrogen exploitation in the larvae of Bactrocera dorsalis. Our results showed that nitrogenous waste recycling (NWR) could be successfully driven by symbiotic bacteria, including Enterobacterales, Lactobacillales, Orbales, Pseudomonadales, Flavobacteriales, and Bacteroidales. In this process, urea hydrolysis in the larval gut was mainly mediated by Morganella morganii and Klebsi...
Nitrogen is usually a restrictive nutrient that affects the growth and development of insects, es... more Nitrogen is usually a restrictive nutrient that affects the growth and development of insects, especially of those living in low nitrogen nutrient niches. In response to the low nitrogen stress, insects have gradually developed symbiont-based stress response strategies—biological nitrogen fixation and nitrogenous waste recycling—to optimize dietary nitrogen intake. Based on the above two patterns, atmospheric nitrogen or nitrogenous waste (e.g., uric acid, urea) is converted into ammonia, which in turn is incorporated into the organism via the glutamine synthetase and glutamate synthase pathways. This review summarized the reaction mechanisms, conventional research methods and the various applications of biological nitrogen fixation and nitrogenous waste recycling strategies. Further, we compared the bio-reaction characteristics and conditions of two strategies, then proposed a model for nitrogen provisioning based on different strategies.
BackgroundVarious endosymbiotic bacteria, includingWolbachiaof the Alphaproteobacteria, infect a ... more BackgroundVarious endosymbiotic bacteria, includingWolbachiaof the Alphaproteobacteria, infect a wide range of insects and are capable of inducing reproductive abnormalities to their hosts such as cytoplasmic incompatibility (CI), parthenogenesis, feminization and male-killing. These extended phenotypes can be potentially exploited in enhancing environmentally friendly methods, such as the sterile insect technique (SIT), for controlling natural populations of agricultural pests. The goal of the present study is to investigate the presence ofWolbachia,Spiroplasma,ArsenophonusandCardiniumamongBactrocera,DacusandZeugodacusflies of Southeast Asian populations, and to genotype any detectedWolbachiastrains.ResultsA specific 16SrRNAPCR assay was used to investigate the presence of reproductive parasites in natural populations of nine different tephritid species originating from three Asian countries, Bangladesh, China and India.Wolbachiainfections were identified inBactrocera dorsalis,B. c...
BACKGROUND Pair-rule genes were identified and named for their role in segmentation in animal emb... more BACKGROUND Pair-rule genes were identified and named for their role in segmentation in animal embryos. Paired, a homolog of mammalian PAX3, acts as one of several pair-rule genes and is key in defining the boundaries of future parasegments and segments during insect embryogenesis. RESULTS We cloned the paired gene from the oriental fruit fly, Bactrocera dorsalis, and then applied CRISPR/Cas9-mediated genome editing to investigate its physiological function in the embryonic stage of this pest. We identified one transcript for a paired homolog in B. dorsalis, which encodes a protein containing a Paired Box domain and Homeobox domain. Phylogenetic analysis confirmed that the paired gene is highly conserved and the gene was highly expressed at the 12-14 h-old embryonic stage. Knock-out of Bdpaired led to a lack of segment boundaries, cuticular deficiency, and embryonic lethality. Sequence analysis of the CRISPR/Cas9 mutants exhibited different insertion and deletions in the Bdpaired locus. In addition, the relative expression of Wingless (Wg) and Abdominal A (Abd-A) genes were significantly downregulated in the Bdpaired mutant embryos. CONCLUSION These results indicated that Bdpaired gene is critical for embryonic development of B. dorsalis, and could be a novel molecular target for genetic-based pest management practices to combat this serious invasive pest. This article is protected by copyright. All rights reserved.
Diestrammena (Gymnaeta) was erected by Adelung in 1902 (Adelung 1902). The type species is Gymnae... more Diestrammena (Gymnaeta) was erected by Adelung in 1902 (Adelung 1902). The type species is Gymnaeta berezowskii Adelung, 1902. Presently, the subgenus Gymnaeta includes 9 species (Eades et al., 2007). In the present paper, one new species D. (G.) caverna sp. n., the male of D.(G.) brevicauda (Karny, 1933), and the male of D.(G.) tianmushanensis (Liu & Zhang, 2001), D.(G.) borutzkyi Gorochov, 2004 are described. The specific name Gymnaeta brevicauda Karny, 1933 is resurrected. A key to the Chinese species of Diestrammena (Gymnaeta) is given. All the materials are deposited in the Shanghai Entomological Museum, Chinese Academy of Science.
Bactrocera dorsalis (Diptera: Tephritidae) is a serious menace to agricultural production worldwi... more Bactrocera dorsalis (Diptera: Tephritidae) is a serious menace to agricultural production worldwide. In order to prevent further damage, it is of paramount important that cost-effective strategies should be developed for their management. Gut bacteria has established diverse relationships with their insect hosts, which could be exploited in pest management programs to improve on control efficiency. In this study, gut bacteria isolates identified by culture dependent technique were incorporated into larval diets in an attempt to understand the roles they play in the development and survival of oriental fruit fly. From our results, the isolated bacteria belonged to four different phyla including the Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria. The response of the fly to different gut isolates varied greatly. Diets enriched with Enterococcus phoeniculicola had lower larval developmental duration, higher pupal weight, and an increased percentage survival. On the other hand, diets supplemented with Lactobacillus lactis had negative effects on B. dorsalis development. This study provides clues on how symbiotic bacteria could be exploited in mass rearing for an efficient implementation of the Sterile Insect Technique (SIT) in pest management programs.
The Chinese citrus fruit fly, Bactrocera minax, is an economically important pest of citrus. It e... more 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 d...
Over the past decades, the development of an alternative and eco-friendly pest control strategies... more Over the past decades, the development of an alternative and eco-friendly pest control strategies has become a public concern for the sake of mankind. Plant essential oils are complex mixtures of volatile organic compounds, which play indispensable roles in the environment, for the plant itself, as well as for humans. Aims: The objectives of this study were (i) to identify and report the volatile organic compounds of Original Research Article Akami et al.; BBJ, 13(4): 1-16, 2016; Article no.BBJ.26087 2 Lippia adoensis (Hochst. Ex Walp.) (Lamiales: verbenaceae) essential oil (EO, herein after) and to compare the bioactivity of its four major compounds with the crude EO at relatively low dosages on some fitness parameters of Callosobruchus maculatus (F.) (Coleptera: Bruchidae), (ii) to test the persistency of each compounds over time, and (iii) to evaluate the type of interaction of the major constituents of the EO (whether antagonistic, synergistic or additive) in order to project the biological interaction of the whole compounds. Study Design: Young leaves of L. adoensis were randomly collected in Mbe locality (NgaoundereCameroon) for EO extraction which was then analysed by the means of Gas Chromatography (GCFID) coupled with Mass Spectrometry (GC-MS). Bioassays consisted of three shelves treatments for adult mortality, eggs laying, larval development and progeny production. A complete randomized design (CRD) with five replications was set for each treatment. Places and Duration of Study: Laboratory of Biology of the Faculty of Science, University of Ngaoundere (Cameroon) and Pest Control laboratory of Professor Niu Changying HZAU, Wuhan (China) from February 2014 to January 2016. Methodology: Essential oil was extracted with a Clevencher-type apparatus, hydrodistilled and airdried. Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography coupled with Mass Spectrometry (GC-MS) were carried out to analyze the constituents. The toxicity of crude EO and its four major constituents was evaluated at 0.5, 5, 10, 20 and 40 μL/g. Ten glass jars (volume 800mL) containing 50 g of cowpea seeds were prepared. After treatment, ten couples of C. maculatus aged 1-7days were randomly selected and separately introduced in each glass jar and kept at 22.72±1.06°C, 83.73±1.28% RH. Control ja rs were treated only with pure acetone. Each treatment was replicated five times. The exposure lasted for six days post treatment. Data on adult’s mortality, eggs laying, larvae and progeny production were assessed and monitored. Results: The GC–MS analysis allowed the identification of 43 volatile components representing 93.54% of total oil. The major components were Thymol (22.01%), Thymol-acetate (15.21%), paracymene (13.85%) and Triacetin (9.131%). The crude EO suppressed adults, completely inhibited eggs laying and adult emergence at 5 and 10 L/g after 24 h, respectively. Complete adults suppression was observed with thymol and the mixture at 20 L/g. Para-cymene and Triacetin caused complete adult mortality at 40 L/g but did not inhibited eggs laying and progeny production. EO and the mixture have been the most potent and persistent with a higher persistency throughout the experimentation. The synergism ratios (SR) were all higher than 1, thereby suggesting a significant (P = .05) synergistic interaction of major constituents although lower than that of the crude EO. Data on behaviours at death suggests that this EO may be neurotoxic probably through the blocking of the cholinergic receptors through reversible inhibition of acetylcholinesterase. Conclusion: The results obtained from this study revealed a significant (P = .05) insecticidal bioefficacy of EO extracted from young leaves of L. adoensis from Cameroon. This insecticidal properties are due to its richness in chemical constituents (43 in total) that sustained its persistency during the treatment. L. adoensis could therefore be a suitable topical agent to control C. maculatus infestations and could be of value for commercial formulations.
International journal of biological sciences, 2015
RNA interference (RNAi) has been developed as a powerful technique in the research of functional ... more RNA interference (RNAi) has been developed as a powerful technique in the research of functional genomics as well as plant pest control. In this report, double-stranded RNAs (dsRNA) targeting 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene, which catalyze a rate-limiting enzymatic reaction in the mevalonate pathway of juvenile hormone (JH) synthesis in cotton bollworm, was expressed in cotton plants via Agrobacterium tumefaciens-mediated transformation. PCR and Sothern analysis revealed the integration of HMGR gene into cotton genome. RT-PCR and qRT-PCR confirmed the high transcription level of dsHMGR in transgenic cotton lines. The HMGR expression both in transcription and translation level was significantly downregulated in cotton bollworms (helicoverpa armigera) larvae after feeding on the leaves of HMGR transgenic plants. The transcription level of HMGR gene in larvae reared on transgenic cotton leaves was as much as 80.68% lower than that of wild type. In addition, ...
International journal of biological sciences, 2014
Bactrocera minax is a major citrus pest distributed in China, Bhutan and India. The long pupal di... more Bactrocera minax is a major citrus pest distributed in China, Bhutan and India. The long pupal diapause duration of this fly is a major bottleneck for artificial rearing and underlying mechanisms remain unknown. Genetic information on B. minax transcriptome and gene expression profiles are needed to understand its pupal diapause. High-throughput RNA-seq technology was used to characterize the B. minax transcriptome and to identify differentially expressed genes during pupal diapause development. A total number of 52,519,948 reads were generated and assembled into 47,217 unigenes. 26,843 unigenes matched to proteins in the NCBI database using the BLAST search. Four digital gene expression (DGE) libraries were constructed for pupae at early diapause, late diapause, post-diapause and diapause terminated developmental status. 4,355 unigenes showing the differences expressed across four libraries revealed major shifts in cellular functions of cell proliferation, protein processing and ex...
Phenol is a major pollutant in aquatic ecosystems due to its chemical stability, water solubility... more Phenol is a major pollutant in aquatic ecosystems due to its chemical stability, water solubility and environmental mobility. To date, little is known about the molecular modifications of invertebrates under phenol stress. In the present study, we used Solexa sequencing technology to investigate the transcriptome and differentially expressed genes (DEGs) of midges (Chironomus kiinensis) in response to phenol stress. A total of 51,518,972 and 51,150,832 clean reads in the phenol-treated and control libraries, respectively, were obtained and assembled into 51,014 non-redundant (Nr) consensus sequences. A total of 6,032 unigenes were classified by Gene Ontology (GO), and 18,366 unigenes were categorized into 238 Kyoto Encyclopedia of Genes and Genomes (KEGG) categories. These genes included representatives from almost all functional categories. A total of 10,724 differentially expressed genes (P value <0.05) were detected in a comparative analysis of the expression profiles between ...
Bacteria inhabiting the gut of insects provide many benefits to their hosts, such as aiding in fo... more 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 F1 and F5 generations. The susceptibility...
In order to understand the role of symbionts for their insect hosts, it is customary to treat the... more In order to understand the role of symbionts for their insect hosts, it is customary to treat them with antibiotics or to sterilize eggs (treatments), resulting in aposymbiotic and axenic insects, respectively. Such axenic insects can then be compared with untreated controls. Fruit flies often bear complex communities which are greatly reduced by such treatments. However, the bacterial community is not completely eliminated. Here, we examine the effect of these procedures on the structure of the remaining bacterial communities in Bactrocera dorsalis (Diptera: Tephritidae) and on the insect longevity. The antibiotics (Norfloxacin and Ceftazedime) were administered to 1-day-old adult flies through sugar meal for 7 days, and eggs were surface sterilized and dechorionated to produce axenic lines. The flies were starved of protein before they were offered full diets or diets containing non-essential amino acids only. Antibiotic and egg disinfection treatments resulted in a significant re...
Background Nitrogen is considered the most limiting nutrient element for herbivorous insects. To ... more Background Nitrogen is considered the most limiting nutrient element for herbivorous insects. To alleviate nitrogen limitation, insects have evolved various symbiotically mediated strategies that enable them to colonize nitrogen-poor habitats or exploit nitrogen-poor diets. In frugivorous tephritid larvae developing in fruit pulp under nitrogen stress, it remains largely unknown how nitrogen is obtained and larval development is completed. Results In this study, we used metagenomics and metatranscriptomics sequencing technologies as well as in vitro verification tests to uncover the mechanism underlying the nitrogen exploitation in the larvae of Bactrocera dorsalis. Our results showed that nitrogenous waste recycling (NWR) could be successfully driven by symbiotic bacteria, including Enterobacterales, Lactobacillales, Orbales, Pseudomonadales, Flavobacteriales, and Bacteroidales. In this process, urea hydrolysis in the larval gut was mainly mediated by Morganella morganii and Klebsi...
Nitrogen is usually a restrictive nutrient that affects the growth and development of insects, es... more Nitrogen is usually a restrictive nutrient that affects the growth and development of insects, especially of those living in low nitrogen nutrient niches. In response to the low nitrogen stress, insects have gradually developed symbiont-based stress response strategies—biological nitrogen fixation and nitrogenous waste recycling—to optimize dietary nitrogen intake. Based on the above two patterns, atmospheric nitrogen or nitrogenous waste (e.g., uric acid, urea) is converted into ammonia, which in turn is incorporated into the organism via the glutamine synthetase and glutamate synthase pathways. This review summarized the reaction mechanisms, conventional research methods and the various applications of biological nitrogen fixation and nitrogenous waste recycling strategies. Further, we compared the bio-reaction characteristics and conditions of two strategies, then proposed a model for nitrogen provisioning based on different strategies.
BackgroundVarious endosymbiotic bacteria, includingWolbachiaof the Alphaproteobacteria, infect a ... more BackgroundVarious endosymbiotic bacteria, includingWolbachiaof the Alphaproteobacteria, infect a wide range of insects and are capable of inducing reproductive abnormalities to their hosts such as cytoplasmic incompatibility (CI), parthenogenesis, feminization and male-killing. These extended phenotypes can be potentially exploited in enhancing environmentally friendly methods, such as the sterile insect technique (SIT), for controlling natural populations of agricultural pests. The goal of the present study is to investigate the presence ofWolbachia,Spiroplasma,ArsenophonusandCardiniumamongBactrocera,DacusandZeugodacusflies of Southeast Asian populations, and to genotype any detectedWolbachiastrains.ResultsA specific 16SrRNAPCR assay was used to investigate the presence of reproductive parasites in natural populations of nine different tephritid species originating from three Asian countries, Bangladesh, China and India.Wolbachiainfections were identified inBactrocera dorsalis,B. c...
BACKGROUND Pair-rule genes were identified and named for their role in segmentation in animal emb... more BACKGROUND Pair-rule genes were identified and named for their role in segmentation in animal embryos. Paired, a homolog of mammalian PAX3, acts as one of several pair-rule genes and is key in defining the boundaries of future parasegments and segments during insect embryogenesis. RESULTS We cloned the paired gene from the oriental fruit fly, Bactrocera dorsalis, and then applied CRISPR/Cas9-mediated genome editing to investigate its physiological function in the embryonic stage of this pest. We identified one transcript for a paired homolog in B. dorsalis, which encodes a protein containing a Paired Box domain and Homeobox domain. Phylogenetic analysis confirmed that the paired gene is highly conserved and the gene was highly expressed at the 12-14 h-old embryonic stage. Knock-out of Bdpaired led to a lack of segment boundaries, cuticular deficiency, and embryonic lethality. Sequence analysis of the CRISPR/Cas9 mutants exhibited different insertion and deletions in the Bdpaired locus. In addition, the relative expression of Wingless (Wg) and Abdominal A (Abd-A) genes were significantly downregulated in the Bdpaired mutant embryos. CONCLUSION These results indicated that Bdpaired gene is critical for embryonic development of B. dorsalis, and could be a novel molecular target for genetic-based pest management practices to combat this serious invasive pest. This article is protected by copyright. All rights reserved.
Diestrammena (Gymnaeta) was erected by Adelung in 1902 (Adelung 1902). The type species is Gymnae... more Diestrammena (Gymnaeta) was erected by Adelung in 1902 (Adelung 1902). The type species is Gymnaeta berezowskii Adelung, 1902. Presently, the subgenus Gymnaeta includes 9 species (Eades et al., 2007). In the present paper, one new species D. (G.) caverna sp. n., the male of D.(G.) brevicauda (Karny, 1933), and the male of D.(G.) tianmushanensis (Liu & Zhang, 2001), D.(G.) borutzkyi Gorochov, 2004 are described. The specific name Gymnaeta brevicauda Karny, 1933 is resurrected. A key to the Chinese species of Diestrammena (Gymnaeta) is given. All the materials are deposited in the Shanghai Entomological Museum, Chinese Academy of Science.
Bactrocera dorsalis (Diptera: Tephritidae) is a serious menace to agricultural production worldwi... more Bactrocera dorsalis (Diptera: Tephritidae) is a serious menace to agricultural production worldwide. In order to prevent further damage, it is of paramount important that cost-effective strategies should be developed for their management. Gut bacteria has established diverse relationships with their insect hosts, which could be exploited in pest management programs to improve on control efficiency. In this study, gut bacteria isolates identified by culture dependent technique were incorporated into larval diets in an attempt to understand the roles they play in the development and survival of oriental fruit fly. From our results, the isolated bacteria belonged to four different phyla including the Firmicutes, Proteobacteria, Bacteroidetes and Actinobacteria. The response of the fly to different gut isolates varied greatly. Diets enriched with Enterococcus phoeniculicola had lower larval developmental duration, higher pupal weight, and an increased percentage survival. On the other hand, diets supplemented with Lactobacillus lactis had negative effects on B. dorsalis development. This study provides clues on how symbiotic bacteria could be exploited in mass rearing for an efficient implementation of the Sterile Insect Technique (SIT) in pest management programs.
The Chinese citrus fruit fly, Bactrocera minax, is an economically important pest of citrus. It e... more 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 d...
Over the past decades, the development of an alternative and eco-friendly pest control strategies... more Over the past decades, the development of an alternative and eco-friendly pest control strategies has become a public concern for the sake of mankind. Plant essential oils are complex mixtures of volatile organic compounds, which play indispensable roles in the environment, for the plant itself, as well as for humans. Aims: The objectives of this study were (i) to identify and report the volatile organic compounds of Original Research Article Akami et al.; BBJ, 13(4): 1-16, 2016; Article no.BBJ.26087 2 Lippia adoensis (Hochst. Ex Walp.) (Lamiales: verbenaceae) essential oil (EO, herein after) and to compare the bioactivity of its four major compounds with the crude EO at relatively low dosages on some fitness parameters of Callosobruchus maculatus (F.) (Coleptera: Bruchidae), (ii) to test the persistency of each compounds over time, and (iii) to evaluate the type of interaction of the major constituents of the EO (whether antagonistic, synergistic or additive) in order to project the biological interaction of the whole compounds. Study Design: Young leaves of L. adoensis were randomly collected in Mbe locality (NgaoundereCameroon) for EO extraction which was then analysed by the means of Gas Chromatography (GCFID) coupled with Mass Spectrometry (GC-MS). Bioassays consisted of three shelves treatments for adult mortality, eggs laying, larval development and progeny production. A complete randomized design (CRD) with five replications was set for each treatment. Places and Duration of Study: Laboratory of Biology of the Faculty of Science, University of Ngaoundere (Cameroon) and Pest Control laboratory of Professor Niu Changying HZAU, Wuhan (China) from February 2014 to January 2016. Methodology: Essential oil was extracted with a Clevencher-type apparatus, hydrodistilled and airdried. Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography coupled with Mass Spectrometry (GC-MS) were carried out to analyze the constituents. The toxicity of crude EO and its four major constituents was evaluated at 0.5, 5, 10, 20 and 40 μL/g. Ten glass jars (volume 800mL) containing 50 g of cowpea seeds were prepared. After treatment, ten couples of C. maculatus aged 1-7days were randomly selected and separately introduced in each glass jar and kept at 22.72±1.06°C, 83.73±1.28% RH. Control ja rs were treated only with pure acetone. Each treatment was replicated five times. The exposure lasted for six days post treatment. Data on adult’s mortality, eggs laying, larvae and progeny production were assessed and monitored. Results: The GC–MS analysis allowed the identification of 43 volatile components representing 93.54% of total oil. The major components were Thymol (22.01%), Thymol-acetate (15.21%), paracymene (13.85%) and Triacetin (9.131%). The crude EO suppressed adults, completely inhibited eggs laying and adult emergence at 5 and 10 L/g after 24 h, respectively. Complete adults suppression was observed with thymol and the mixture at 20 L/g. Para-cymene and Triacetin caused complete adult mortality at 40 L/g but did not inhibited eggs laying and progeny production. EO and the mixture have been the most potent and persistent with a higher persistency throughout the experimentation. The synergism ratios (SR) were all higher than 1, thereby suggesting a significant (P = .05) synergistic interaction of major constituents although lower than that of the crude EO. Data on behaviours at death suggests that this EO may be neurotoxic probably through the blocking of the cholinergic receptors through reversible inhibition of acetylcholinesterase. Conclusion: The results obtained from this study revealed a significant (P = .05) insecticidal bioefficacy of EO extracted from young leaves of L. adoensis from Cameroon. This insecticidal properties are due to its richness in chemical constituents (43 in total) that sustained its persistency during the treatment. L. adoensis could therefore be a suitable topical agent to control C. maculatus infestations and could be of value for commercial formulations.
International journal of biological sciences, 2015
RNA interference (RNAi) has been developed as a powerful technique in the research of functional ... more RNA interference (RNAi) has been developed as a powerful technique in the research of functional genomics as well as plant pest control. In this report, double-stranded RNAs (dsRNA) targeting 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene, which catalyze a rate-limiting enzymatic reaction in the mevalonate pathway of juvenile hormone (JH) synthesis in cotton bollworm, was expressed in cotton plants via Agrobacterium tumefaciens-mediated transformation. PCR and Sothern analysis revealed the integration of HMGR gene into cotton genome. RT-PCR and qRT-PCR confirmed the high transcription level of dsHMGR in transgenic cotton lines. The HMGR expression both in transcription and translation level was significantly downregulated in cotton bollworms (helicoverpa armigera) larvae after feeding on the leaves of HMGR transgenic plants. The transcription level of HMGR gene in larvae reared on transgenic cotton leaves was as much as 80.68% lower than that of wild type. In addition, ...
International journal of biological sciences, 2014
Bactrocera minax is a major citrus pest distributed in China, Bhutan and India. The long pupal di... more Bactrocera minax is a major citrus pest distributed in China, Bhutan and India. The long pupal diapause duration of this fly is a major bottleneck for artificial rearing and underlying mechanisms remain unknown. Genetic information on B. minax transcriptome and gene expression profiles are needed to understand its pupal diapause. High-throughput RNA-seq technology was used to characterize the B. minax transcriptome and to identify differentially expressed genes during pupal diapause development. A total number of 52,519,948 reads were generated and assembled into 47,217 unigenes. 26,843 unigenes matched to proteins in the NCBI database using the BLAST search. Four digital gene expression (DGE) libraries were constructed for pupae at early diapause, late diapause, post-diapause and diapause terminated developmental status. 4,355 unigenes showing the differences expressed across four libraries revealed major shifts in cellular functions of cell proliferation, protein processing and ex...
Phenol is a major pollutant in aquatic ecosystems due to its chemical stability, water solubility... more Phenol is a major pollutant in aquatic ecosystems due to its chemical stability, water solubility and environmental mobility. To date, little is known about the molecular modifications of invertebrates under phenol stress. In the present study, we used Solexa sequencing technology to investigate the transcriptome and differentially expressed genes (DEGs) of midges (Chironomus kiinensis) in response to phenol stress. A total of 51,518,972 and 51,150,832 clean reads in the phenol-treated and control libraries, respectively, were obtained and assembled into 51,014 non-redundant (Nr) consensus sequences. A total of 6,032 unigenes were classified by Gene Ontology (GO), and 18,366 unigenes were categorized into 238 Kyoto Encyclopedia of Genes and Genomes (KEGG) categories. These genes included representatives from almost all functional categories. A total of 10,724 differentially expressed genes (P value <0.05) were detected in a comparative analysis of the expression profiles between ...
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