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Dopamine (DA) is a key regulator of associative learning and memory in both vertebrates and invertebrates, and it is widely believed that DA plays a key role in aversive conditioning in invertebrates. However, the idea that DA is involved only in aversive conditioning has been challenged in recent studies on the fruit fly (Drosophila melanogaster), ants and crabs, suggesting diverse functions of DA modulation on associative plasticity. Here, we present the results of DA modulation in aversive olfactory conditioning with DEET punishment and appetitive olfactory conditioning with sucrose reward in the oriental fruit fly, Bactrocera dorsalis. Injection of DA receptor antagonist fluphenazine or chlorpromazine into these flies led to impaired aversive learning, but had no effect on the appetitive learning. DA receptor antagonists impaired both aversive and appetitive long-term memory retention. Interestingly, the impairment on appetitive memory was rescued not only by DA but also by octopamine (OA). Blocking the OA receptors also impaired the appetitive memory retention, but this impairment could only be rescued by OA, not by DA. Thus, we conclude that in B. dorsalis, OA and DA pathways mediate independently the appetitive and aversive learning, respectively. These two pathways, however, are organized in series in mediating appetitive memory retrieval with DA pathway being at upstream. Thus, OA and DA play dual roles in associative learning and memory retrieval, but their pathways are organized differently in these two cognitive processes - parallel organization for learning acquisition and serial organization for memory retrieval.
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Dopamina , Drosophila melanogaster , Tephritidae , Animais , Dopamina/metabolismo , Dopamina/farmacologia , Drosophila melanogaster/metabolismo , Memória , Antagonistas de Dopamina/farmacologiaRESUMO
The red imported fire ant (RIFA), Solenopsis invicta, is an invasive pest that causes damage to agricultural and ecological environments worldwide. Fluralaner is a new isoxazoline pesticide with the potential to become a control agent against RIFA. However, it is not clear whether S. invicta responds the same way to fluralaner at different reproductive stages. The present study firstly evaluated the toxicity of fluralaner to S. invicta at different developmental stages, finding that fourth instar larvae (LD50, 1744.23 mg/kg) and worker ants (LD50, 8.62 mg/kg) were differently susceptible to fluralaner, while the mortality rate of fourth instar larvae was significantly lower at the same concentration of 10 mg/L (5.56 ± 3.14%) than that of worker ants (62.22 ± 3.14%), demonstrating a greater tolerance to fluralaner. Subsequently, the metabolic responses of worker and larval ants to fluralaner stress (10 mg/L) were investigated using non-targeted metabolomics, which indicated that the amount of differential metabolites and the KEGG metabolic pathways enriched were different between workers and larvae when exposed to the same dose (10 mg/L) of fluralaner. Differential metabolites of larvae and worker ants under fluralaner stress were mainly concentrated in organic acids and their derivatives, lipids and lipid-like molecules, nucleosides, nucleotides, and analogues, combined with the enriched metabolic pathways, revealed that the differential metabolic responses of larvae and worker ants were mainly in energy metabolism, detoxification metabolism, and neurotransmitter ligands. Workers consumed more substrates in the arginine synthesis pathway (l-glutamic acid, l-aspartic acid, and fumaric acid) to provide energy for the detoxification (glutathione) of pesticides when exposed to fluralaner stress, and the high accumulation of l-aspartic acid induced excitotoxicity in the worker ants. Larval ants consumed more arachidonic acid to synthesize PG D2, and changes in the metabolism of antioxidants such as catechins, hesperidin, and l-ascorbic acid suggested that larvae were more capable of scavenging the ROS response than worker ants. The results of non-targeted metabolomics successfully revealed differences in the sensitivity of larvae and workers to fluralaner agents, providing insights into the fluralaner control of Solenopsis invicta.
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Formigas , Praguicidas , Animais , Ácido Aspártico , Larva , Isoxazóis/toxicidadeRESUMO
The coffee white stem borer, Xylotrechus quadripes Chevrolat, 1863 (Coleoptera: Cerambycidae) - here removed from the synonymy with X. javanicus (Laporte & Gory, 1841) - is the most notorious pest in Arabica coffee plantations in many southeast Asian countries. It can cause damage up to 80% in various gardens. The borer is reported on 16 different host plants other than coffee. The severity of the pest was more commonly recorded on the Arabica coffee than on other species. More pest intensity on the coffee may be due to its innate evolutionary relation compared to other host plants. Studies revealed that the borer is more specific and attracted to the volatile of coffee plants but it is still needs a strong supporting data. Some of the behavioural and ecological-adaptations of borers leads to avoid predation and chemical-pesticides reaching them. Hence, no single method gives perfect control of this pest; therefore, harmonic use of different tools such as cultural, mechanical, physical, bio-control and chemical methods are the best way to combat this pest. Though the pest is economically important, the information on chemical and ecological behaviour, host plant resistance and recent advancements in the pest management are scanty. The present article is an endeavour to shed a light on biology, behaviour, host selection and management of X. quadripes with multiple instances, that will give a new avenue for the researchers to work on the least concerned fields to develop strong management practice and alert against future pest outbreak.
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The composition and structure of fungal communities on healthy and diseased fruits of Cinnamomum burmannii (Nees and Nees) Blume were characterized, with evaluation of the antibacterial activity of secondary metabolites from culturable fungi following the first identification of secondary metabolites in the fungus Medicopsis romeroi (Esf-14; GenBank accession number OK242756). These results are significant for understanding the functional variation in bioactivity in fungal communities and developing a broader range of bioactive resources. High-throughput sequencing results indicated that the fungal community in diseased fruit differed from that in healthy fruit at the phylum, class, order, or genus level, with significant differences in the species and relative abundance of the dominant flora. A total of 49 (healthy fruit) and 122 (diseased fruit) artificially cultivable endophytic fungi were isolated, and 41 different strains (11 from healthy fruit and 30 from diseased fruit) were successfully identified by morphological and molecular biological analyses, which were classified into 8 groups and 23 genera by phylogenetic tree analysis, with Pleosporales, Glomerellales, and Hypocreales being the dominant groups at the order level and Colletotrichum being the dominant group at the genus level. The results of the antibacterial assay demonstrated that the secondary metabolites of all strains had different degrees of antibacterial activity, while the secondary metabolites of endophytic fungi from diseased fruit were generally stronger than those of fungi from healthy fruit, with the active secondary metabolites dominated by small and moderately polar compounds. Combined analysis of fungal communities, phylogenetic tree analysis, and bioactivity analysis of culturable strains revealed strong antibacterial activity of both upregulated and downregulated flora in diseased fruit. Five compounds, including two new (5,6-dimethoxy-[1',1:4,1â³-terphenyl]-2-ol [compound 1] and 5-(methoxycarbonyl)-2-methylbenzo[d][1,3]dioxole-2-carboxylic acid [compound 2]) and three known compounds (3,7-dihydroxy-1,9-dimethyldibenzofuran [compound 3], methyl 3-hydroxybenzoate [compound 4], and uracil [compound 5]), were isolated and identified for the first time from the endophytic fungus Medicopsis romeroi. In general, the diversity of fungal communities on diseased fruit was lower than that on healthy fruits, while the antibacterial activity of artificially cultured endophytic fungi on diseased fruits was generally stronger than that on healthy fruits, suggesting excellent promise for the development of secondary metabolites from active strains on diseased fruit as antibacterial agents. IMPORTANCE Powdery fruit disease is a notorious disease of Cinnamomum burmannii that causes severe loss in fruit production. Studies on the function of endophytic fungal communities in healthy plant tissues are not new, while little is known about the functional changes of fungal communities in disease-causing plant tissues. Our results demonstrate that fungal communities in diseased fruits differ from those in healthy fruits at the level of phylum, class, order, or genus, with significant differences in the species and relative abundance of dominant groups. Endophytic fungi in diseased fruits appeared to produce secondary metabolites with stronger antibacterial properties, although the community diversity was not as varied as that in healthy fruits. In addition, secondary metabolites of the Medicopsis romeroi strain from diseased fruits were identified for the first time. These results have important implications for understanding the functional variation of bioactivity in fungal communities and for developing a broader resource of bioactivity.
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Ascomicetos , Micobioma , Frutas , Filogenia , Endófitos , Fungos/genética , Antibacterianos/farmacologia , Antibacterianos/metabolismoRESUMO
Studies on insects have contributed significantly to a better understanding of learning and memory, which is a necessary cognitive capability for all animals. Although the formation of memory has been studied in some model insects, more evidence is required to clarify the characteristics of memory formation, especially long-term memory (LTM), which is important for reliably storing information. Here, we explored this question by examining Bactrocera dorsalis, an agricultural pest with excellent learning abilities. Using the classical conditioning paradigm of the olfactory proboscis extension reflex (PER), we found that paired conditioning with multiple trials (>3) spaced with an intertrial interval (≥10 min) resulted in stable memory that lasted for at least 3 d. Furthermore, even a single conditioning trial was sufficient for the formation of a 2-d memory. With the injection of protein inhibitors, protein-synthesis-dependent memory was confirmed to start 4 h after training, and its dependence on translation and transcription differed. Moreover, the results revealed that the dependence of memory on protein translation exhibited a time-window effect (4-6 h). Our findings provide an integrated view of LTM in insects, suggesting common mechanisms in LTM formation that play a key role in the biological basis of memory.
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Memória de Longo Prazo , Tephritidae , Animais , Condicionamento Clássico , Olfato , AprendizagemRESUMO
Intercropping with guava (Psidium guajava L.) can assist with the management of Asian citrus psyllid (ACP, Diaphorina citri Kuwayama), the insect vector of the huanglongbing pathogen, in citrus orchards. Sulfur volatiles have a repellent activity and physiological effects, as well as being important components of guava volatiles. In this study, we tested whether the sulfur volatiles emitted by guava plants play a role in plant-plant communications and trigger anti-herbivore activities against ACP in sweet orange plants (Citrus sinensis L. Osbeck). Real-time determination using a proton-transfer-reaction mass spectrometer (PTR-MS) showed that guava plants continuously release methanethiol, dimethyl sulfide (DMS), and dimethyl disulfide (DMDS), and the contents increased rapidly after mechanical damage. The exposure of orange plants to DMDS resulted in the suppression of the developmental performance of ACP. The differential elevation of salicylic acid (SA) levels; the expression of phenylalanine ammonia lyase (PAL), salicylate-O-methyl transferase (SMT), and pathogenesis-related (PR1) genes; the activities of defense-related enzymes PAL, polyphenol oxidase (PPO), and peroxidase (POD); and the total polyphenol content were observed in DMDS-exposed orange plants. The emission of volatiles including myrcene, nonanal, decanal, and methyl salicylate (MeSA) was increased. In addition, phenylpropanoid and flavonoid biosynthesis, and aromatic amino acid (such as phenylalanine, tyrosine, and tryptophan) metabolic pathways were induced. Altogether, our results indicated that DMDS from guava plants can activate defense responses in eavesdropping orange plants and boost their herbivore resistance to ACP, which suggests the possibility of using DMDS as a novel approach for the management of ACP in citrus orchards.
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Citrus sinensis , Citrus , Hemípteros , Psidium , Animais , Catecol Oxidase/metabolismo , Citrus/metabolismo , Citrus sinensis/genética , Dissulfetos , Hemípteros/fisiologia , Peroxidases/metabolismo , Fenilalanina/farmacologia , Fenilalanina Amônia-Liase/metabolismo , Doenças das Plantas/genética , Polifenóis/farmacologia , Prótons , Psidium/química , Ácido Salicílico/metabolismo , Enxofre/metabolismo , Transferases/metabolismo , Triptofano/metabolismo , Tirosina/metabolismoRESUMO
The red imported fire ant (Solenopsis invicta), a worldwide invasive and polyphagous pest, and often nests in residential areas. Finding an alternative pesticide that is both effective on S. invicta and environmentally friendly is urgent and crucial. Fluralaner, a novel isoxazoline insecticide, has been proven to possess selective toxicity for insects versus mammals and has been safe for mammals and non-target organisms, suggesting its potential in pest management. However, little toxicity information is available for the controlment of S. invicta. In this article, we studied the toxicity of fluralaner against S. invicta systematically, and the roles of metabolism-related enzymes in the metabolism process of fluralaner. The toxicity results showed that the topical application and feeding application were all effective for S. invicta. Moreover, fluralaner can be transmitted among workers by contacting and feeding which leads to a toxic reaction among nestmates. By exploring the biochemistry change, we found cytochrome P450 monooxygenase (P450) may be involved in the detoxification of fluralaner as well as carboxylesterase (CarE), but not glutathione S-transferase (GST). Synergism assays gave solid evidence in which piperonyl butoxide, an activity inhibitor of P450, increased the toxicity of fluralaner to S. invicta. Importantly, with the RNAi treatment, four of S.invicta P450 genes were significantly inhibited and showed more sensitivity to fluralaner at LC50 concentration. Our result indicated that fluralaner could be a potential alternative pesticide in S. invicta control. And CYP9AS16, CYP6AS161, CYP6SQ20, and CYP336A45 genes were closely associated with the metabolism process of fluralaner.
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Formigas , Inseticidas , Animais , Hidrolases de Éster Carboxílico , Sistema Enzimático do Citocromo P-450/genética , Glutationa Transferase/genética , Inseticidas/toxicidade , Isoxazóis , Mamíferos , Butóxido de Piperonila/toxicidadeRESUMO
Eucommia ulmoides, a precious Chinese herbal medicine, lack of studies on the detection of its pesticide residues. A simple sample preparation based on the solid-phase extraction (SPE) procedure was established for the analysis of 16 kinds of pesticides in Eucommia ulmoides by gas chromatography mass spectrometry (GC-MS) with selective ion monitoring mode. Here, the type and volume of extraction solvent and eluent, the kinds of sorbents in SPE Cleanert column, were optimized. Under the optimal conditions, a good linear relationship was obtained in the range of 0.005 to 5.0 mg/L with correlation coefficient (r) higher than 0.9990, and the average recoveries (AR) of 16 pesticides ranged from 79.6 to 109.2% at the spiking levels of 0.01, 0.1, and 0.5 mg/kg. The relative standard deviations (RSD) were 0.78 to 9.56% (n = 6). The results show that the established method can not only fully meet the analytical requirements of various pesticides in Eucommia ulmoides, but also have the potential to be applied in the detection of pesticide residues in others Chinese herbal medicine.
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Medicamentos de Ervas Chinesas , Eucommiaceae , Resíduos de Praguicidas , Praguicidas , Medicamentos de Ervas Chinesas/análise , Monitoramento Ambiental , Cromatografia Gasosa-Espectrometria de Massas/métodos , Resíduos de Praguicidas/análise , Praguicidas/análise , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodosRESUMO
Intercropping can reduce agricultural pest incidence and represents an important sustainable alternative to conventional pest control methods. Citrus intercropped with guava (Psidium guajava L.) has a lower incidence of Asian citrus psyllid (ACP, Diaphorina citri Kuwayama) and huanglongbing disease (HLB), but the mechanisms are still unknown. In this study, we tested whether volatile organic compounds (VOCs) emitted by guava plants play a role in plant-plant communications and trigger defense responses in sweet orange (Citrus sinensis L. Osbeck) in the laboratory. The results showed that the behavioral preference and developmental performance of ACP on citrus plants that were exposed to guava VOCs were suppressed. The expression of defense-related pathways involved in early signaling, jasmonate (JA) biosynthesis, protease inhibitor (PI), terpenoid, phenylpropanoid, and flavonoid biosynthesis was induced in guava VOC-exposed citrus plants. Headspace analysis revealed that guava plants constitutively emit high levels of (E)-ß-caryophyllene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), which can induce the accumulation of JA and promote stronger defense responses of citrus to ACP feeding. In addition, exposure to guava VOCs also increased the indirect defense of citrus by attracting the parasitic wasp Tamarixia radiata. Together, our findings indicate that citrus plants can eavesdrop on the VOC cues emitted by neighboring intact guava plants to boost their JA-dependent anti-herbivore activities. The knowledge gained from this study will provide mechanisms underlying citrus-guava intercropping for the ecological management of insect pests.
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The biogenic amine octopamine (OA, invertebrate counterpart of noradrenaline) plays critical roles in the regulation of olfactory behavior. Historically, OA has been thought to mediate appetitive but not aversive learning in honeybees, fruit flies (Drosophila), and crickets. However, this viewpoint has recently been challenged because OA activity through a ß-adrenergic-like receptor drives both appetitive and aversive learning. Here, we explored the roles of OA neurons in olfactory learning and memory retrieval in Bactrocera dorsalis. We trained flies to associate an orange odor with a sucrose reward or to associate methyl eugenol, a male lure, with N,N-diethyl-3-methyl benzoyl amide (DEET) punishment. We then treated flies with OA receptor antagonists before appetitive or aversive conditioning and a memory retention test. Injection of OA receptor antagonist mianserin or epinastine into the abdomen of flies led to impaired of appetitive learning and memory retention with a sucrose reward, while aversive learning and memory retention with DEET punishment remained intact. Our results suggest that the OA signaling participates in appetitive but not aversive learning and memory retrieval in B. dorsalis through OA receptors.
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Aprendizagem da Esquiva , Tephritidae , Masculino , Animais , Abelhas , Aprendizagem da Esquiva/fisiologia , DEET/farmacologia , Neurônios/fisiologia , Sacarose/farmacologia , Comportamento Apetitivo/fisiologiaRESUMO
Since the first identification of the silkworm moth sex pheromone in 1959, significant research has been reported on identifying and unravelling the sex pheromone mechanisms of hundreds of insect species. In the past two decades, the number of research studies on new insect pheromones, pheromone biosynthesis, mode of action, peripheral olfactory and neural mechanisms, and their practical applications in Integrated Pest Management has increased dramatically. An interdisciplinary approach that uses the advances and new techniques in analytical chemistry, chemical ecology, neurophysiology, genetics, and evolutionary and molecular biology has helped us to better understand the pheromone perception mechanisms and its practical application in agricultural pest management. In this review, we present the most recent developments in pheromone research and its application in the past two decades.
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The black soldier fly, Hermetia illucens, is a cosmopolitan insect of the family Stratiomyidae (Diptera). Chemosensory genes encode proteins involved directly in the detection of odorants. In this study, we sequenced the antennal transcriptome of H. illucens adults to identify chemosensory genes. Putative unigenes encoding 27 odorant binding proteins (OBPs), five chemosensory proteins (CSPs), 70 odorant receptors (ORs), 25 ionotropic receptors (IRs), 10 gustatory receptors (GRs) and two sensory neuron membrane proteins (SNMPs) were identified. Tissue-specific expression profiles of the identified OBPs, CSPs and SNMPs were investigated using RT-PCR. Eight OBPs (HillOBP1-2, 9, 11-14, and 17), one CSP (HillCSP5) and one SNMP (HillSNMP1) were predominantly expressed in antennae. Further real-time quantitative PCR analyses revealed that the antennae-enriched unigenes also exhibited significant differences in expression between males and females. Among the sex-biased unigenes, six ORs showed female-biased expression, suggesting that these genes might participate in female-specific behaviors such as oviposition site searching. Sixteen ORs and two OBPs showed male-biased expression, indicating that they may play key roles in the detection of female sex pheromones. Our study is the first attempt to delineate the molecular basis of chemoreception in H. illucens. Our data provide useful information for comparative studies on the differentiation and evolution of Dipteran chemosensory gene families.
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Learning and memory are the most characterized advanced neurological activities of insects, which can associate information with food. Our previous studies on Bactrocera dorsalis have shown that this fly can learn to evaluate the nutritional value of sugar rewards, although whether all metabolizable sugars are equally rewarding to flies is still unclear. To address this question, we used three sweet and metabolizable sugars - sucrose, fructose and glucose - as rewards for conditioning. The flies showed differences in learning and memory in response to the three sugar rewards. The level of learning performance in sucrose-rewarded flies was higher than that in fructose-rewarded and glucose-rewarded flies, and, strikingly, only sucrose and glucose stimulation led to the formation of robust 24-h memory. Furthermore, the unequal rewarding of three sugars was observed in two distinct processes of memory formation: preingestive and postingestive processes. When flies received the positive tastes (preingestive signal) by touching their tarsi and proboscis (mouthparts) to three sugars, they showed differences in learning for the three sugar rewards. The formation of a robust 24-h memory was dependent on the postingestive signal triggered by feeding on a sugar. A deficit of 24-h memory was observed only in fructose-feeding flies no matter what sugar was used to stimulate the tarsi. Taken together, our results suggest that three sweet and metabolizable sugars unequally rewarded B. dorsalis, which might be a strategy for flies to discriminate the nature of sugars.
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Sacarose , Tephritidae , Animais , Frutose , Glucose , Recompensa , AçúcaresRESUMO
The Aedes albopictus mosquito is a vector of several deadly diseases of humans and domesticated animals. Usually, synthetic insecticides are used for mosquito control. The excessive use of synthetic insecticides is hazardous for humans and the environment. Therefore, there is a need to develop environment-friendly and novel mosquito larvicides. In the current study, we evaluated larvicidal and bite protection properties of Seriphidium brevifolium essential oil (SBEO) and its active constituents against this mosquito. SBEO and its active constituents, α, ß-thujone, and limonene, were toxic to A. albopictus, with LC50 values of 21.43, 45.99, 47.38, and 49.46 µg/mL. The cream formulation of EO at 5 % (w/v) provided complete protection against mosquito bites until 70 min after application. Among the EO constituents tested, α and ß-thujone showed considerable protections against mosquito bites but lower as compared with the whole oil. Furthermore, 1:1 combinations of active constituent α-thujone and ß-thujone and 1:1:1 combinations of α-thujone, ß-thujone, and limonene displayed a synergistic effect against the larvae. Particularly, the EO and its active constituents were safer to Poecilia reticulata a mosquito predator, with LC50 ranging from 3934.33 to 14,432.11 µg/mL. Our current study indicated that SBEO and some of its constituents can be used for the control of A. albopictus mosquito, as a novel alternative to hazardous synthetic insecticides and to overcome the problem of increasing insecticides resistance.
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Aedes , Anopheles , Culex , Dengue/transmissão , Inseticidas , Óleos Voláteis , Animais , Humanos , Larva , Controle de Mosquitos , Mosquitos Vetores , Folhas de PlantaRESUMO
BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri, is one of the major pests in citrus production because it transmits huanglongbing, a devastating disease of citrus plants. Odourant-binding proteins (OBPs) play an important role in the olfactory perception of insects. Revealing the function of DcitOBPs is beneficial to the development of new ACP management strategies. RESULTS: An analysis of the components of volatiles from the new shoots of six host plant species showed that ß-caryophyllene was the characteristic volatile compound in flushing shoots and the most abundant volatile compound in three of the six tested ACP host plant species. The tissue expression profiles of nine known DcitOBPs were analyzed based on a transcriptome database, and DcitOBP3 and DcitOBP6 exhibited high expression in the antennae of both sexes and the ovipositor of females. The binding ability of two recombinant proteins with eight ligands was studied through competitive binding analysis; the results showed that DcitOBP6 exhibited stronger binding to ß-caryophyllene. Behavioural trials indicated that sexually mature female adults of D. citri were significantly attracted to ß-caryophyllene at concentrations of 0.1 µL mL-1 and 10 µL mL-1 . RNAi analysis in female D. citri showed that the reduction of DcitOBP6 transcript abundance led to a decrease in antennae EAG activity and behavioural responses to ß-caryophyllene. CONCLUSION: The results demonstrate that DcitOBP6 is involved in the perception of an important host plant volatile, ß-caryophyllene, in the ACP, and provide a theoretical foundation for behavioural interference in ACP management.
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Hemípteros , Animais , Feminino , Masculino , Odorantes , Interferência de RNARESUMO
Insect color morphs are known to vary in detoxification enzyme activity associated with susceptibility to insecticides. Diaphorina citri occurs in three distinct color morphs, and little data are available addressing this question. In this study, susceptibility to nine insecticides was compared among orange/yellow, gray/brown and blue/green morphs of adult D. citri. Imidacloprid and lambda-cyhalothrin resulted in higher mortality in the orange/yellow morph than in the blue/green morph. The orange/yellow morph was significantly more susceptible to acetamiprid, bifenthrin and chlorfenapyr than the blue/green and gray/brown morphs. For clothianidin and chlorpyriphos, the orange/yellow morph was significantly more susceptible than the gray/brown morphs. Susceptibility to dinotefuran and thiamethoxam was not significantly different between the three color morphs of D. citri. Biochemical enzyme assays revealed that the esterase, glutathione S-transferase and cytochrome P450 activities were significantly higher in the gray/brown and blue/green morphs than in the orange/yellow morph; however, the activities of three detoxification enzymes were not significantly different between gray/brown and blue/green morphs. We analyzed the relative expression among the color morphs of six detoxification genes involved in insecticide resistance. GSTS1 and EST-6 were expressed at significantly higher levels in the blue/green morph than in the orange/yellow and gray/brown morphs. The expression levels of CYP4g15, CYP303A1, CYP4C62 and CYP6BD5 were significantly greater in the gray/brown and blue/green morphs than in the orange/yellow morph. These results suggest that insecticide susceptibility in D. citri is associated with color morphs. Detoxification enzyme activity and the relative expression of six detoxification genes may partially explain these differences. These results may facilitate further work to develop a management strategy for control of D. citri.
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Citrus , Hemípteros , Inseticidas , Animais , Inativação Metabólica , Resistência a InseticidasRESUMO
BACKGROUND: The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is a prominent pest of citrus because it transmits Candidatus Liberibacter asiaticus associated with huanglongbing. Phototactic behavior ubiquitously exists in insects and plays essential roles in host-searching and mate-searching in ACP. However, its mechanism has remained unclear to date. In this paper, molecular assays were performed to understand the relation between opsins and the phototactic behavior of ACP. RESULTS: We cloned five opsin genes and analyzed their expression patterns. The main three opsin genes (Dc-UV, Dc-BW and Dc-LW) displayed high expression levels in daytime, and the expression levels of the other two opsin genes (Dc-UV-like and Dc-arthropsin) increased during nighttime. In constant darkness, the expression patterns and levels of opsin genes of ACP were altered. Under starvation, the expression levels of the main three opsins were reduced (53.89-84.10%). In contrast, the expression levels in females increased (27.55-60.58%). Feeding of double-stranded RNA (Dc-UV, Dc-LW or Dc-BW) have reduced the phototactic efficiency of ACP to ultraviolet light (44.79%), green light (54.81%) and blue light (43.00%), respectively. CONCLUSION: The results suggest that the expression levels and patterns of opsins of ACP were influenced by photoperiod and the physiological status of ACP. Our research indicates that opsins play crucial roles in phototactic behavior in ACP. © 2019 Society of Chemical Industry.
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Citrus , Hemípteros , Animais , Feminino , Opsinas , Doenças das Plantas , RNA de Cadeia Dupla , RhizobiaceaeRESUMO
ABSTRACT The excessive use of chemical insecticides has led to negative effects on human health and the environment. Volatile oils are one of the possible potential alternatives to chemical insecticides. Traditionally Seriphidium brevifolium (Wall. ex DC.) Ling & Y.R.Ling, Asteraceae, powder from its leaves is used to treat gastric problems and expel intestinal worms by local peoples, but yet there is no literature available regarding its insecticidal activity. In this study fumigant toxicity and enzyme inhibition activities of the S. brevifolium volatile oil collected from the highlands of Skardu Baltistan, Pakistan, was evaluated against the red imported fire ant Solenopsis invicta. The phytochemical studies indicated that monoterpenes were the most abundant constituents, accounting for 88% of the total oil. The major dominant constituents were 2-bornanone (28.2%), 1,8-cineole (19.9%), α-thujone (7.5%), β-thujone (6.7%) which accounts for 62.3% of total constituents identified, with volatile oil yield of 4.11% (w/w). The fumigation assay indicated that the volatile oil was acutely toxic to fire ants, with an LC50 of 16.47 µl/l. Among the constituents tested, only (α + β) thujone and 1,8-cineole were toxic, with LC50 of 17.68 and 30.66 µl/ after 12 h of exposure. The volatile oil, (α + β) thujone and 1, 8-cineole showed strong fumigant activity against the red imported fire ant workers in a time- and dose-dependent manner. The volatile oil caused 100% mortality of the red imported fire ant workers, even at the lowest concentration of 20 µl/l after 24 h of exposure. In addition, the volatile oil and 1,8-cineole inhibited acetylcholinesterase activity, while (α + β) thujone inhibited carboxylesterase activity in the fire ant workers. It has been concluded that the volatile oil and some of the compounds from S. brevifolium might be developed as eco-friendly approaches for the control of red imported fire ants.
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The ATP-binding cassette (ABC) transporters exist in all living organisms and play major roles in various biological functions by transporting a wide variety of substrates across membranes. The functions of ABC transporters in drug resistance have been extensively studied in vertebrates; however, they are rarely characterized in agricultural pests. The Asian citrus psyllid, Diaphorina citri, is one of the most damaging pests of the Citrus genus because of its transmission of Huanglongbing, also known as Yellow Dragon disease. In this study, the next-generation sequencing technique was applied to research the ABC transporters of D. citri. Fifty-three ABC transporter genes were found in the RNA-Seq data, and among these ABC transporters, 4, 4, 5, 2, 1, 4, 18 and 15 ABC proteins belonged to the ABCA-ABCH subfamilies, respectively. Different expression profiles of 52 genes between imidacloprid-resistant and imidacloprid-susceptible strains were studied by qRT-PCR; 5 ABCGs and 4 ABCHs were significantly upregulated in the imidacloprid-resistant strain. In addition, five of the nine upregulated genes were widely expressed in adult tissues in spatial expression analysis. The results suggest that these genes may play key roles in this phenotype. In general, this study contributed to our current understanding of D. citri resistance to insecticides.
Assuntos
Transportadores de Cassetes de Ligação de ATP , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Hemípteros , Proteínas de Insetos , Família Multigênica , Transportadores de Cassetes de Ligação de ATP/biossíntese , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Citrus/parasitologia , Resistência a Medicamentos/efeitos dos fármacos , Resistência a Medicamentos/genética , Hemípteros/genética , Hemípteros/metabolismo , Proteínas de Insetos/biossíntese , Proteínas de Insetos/genética , Neonicotinoides/farmacologia , Nitrocompostos/farmacologia , Doenças das Plantas/genética , Doenças das Plantas/parasitologiaRESUMO
The oriental fruit fly Bactrocera dorsalis can learn to associate an odor with a sugar reward. However, it is still unclear whether they will learn with different sugar rewards equally. Here, we used a proboscis extension conditioning procedure to investigate the contribution of taste and nutritional value of sugars to learning and memory formation. Three types of sugar were used for conditioning: sweet and nutritional sugar, sucrose; sweet sugar without nutrition, D-arabinose and L-glucose; tasteless sugar with nutritional value, D-sorbitol. The sweet taste is sufficient to produce associative conditioning with an odor and form short-term memory, and the learning and short-term memory performance showed a similar rank order to the proboscis extension reflex evoked by each sugar. However, memory decayed at a greater rate 24â¯h after conditioning for flies conditioned with sweet tasting but non-metabolizable sugars D-arabinose and L-glucose. When D-arabinose or L-glucose was supplemented with D-sorbitol, the deficit of 24â¯h memory was rescued, suggesting that the nutrient value of sugar plays a key role in memory persistence. Our results indicate that B. dorsalis could learn and evaluate sugar quality via both taste and nutritional value, as well as remember nutrient sugars for a long time using a postingestive mechanism.