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1.
Arch Insect Biochem Physiol ; 108(3): e21845, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34605064

RESUMO

With the wide cultivation of transgenic plants throughout the world and the rising risk of resistance to Bacillus thuringiensis crystal (Cry) toxins, it is essential to design an adaptive resistance management strategy for continued use. Neuropeptide F (NPF) of insects has proven to be valuable for the production of novel-type transgenic plants via its important role in the control of feeding behavior. In this study, the gene encoding NPF was cloned from the diamondback moth, Plutella xylostella, an important agricultural pest. Real-time quantitative reverse transcription-polymerase chain reaction and in situ hybridization showed a relatively high expression of P. xylostella-npf (P. x-npf) in endocrine cells of the midgut of fourth instar larvae, and it was found to participate in P. xylostella feeding behavior and Cry1Ac-induced feeding inhibition. Prokaryotic expression and purification provided structure unfolded P. x-npf from inclusion bodies for diet surface overlay bioassays and the results demonstrated a significant synergistic effect of P. x-npf on Cry1Ac toxicity by increasing intake of noxious food which contains Cry toxins, especially quick death at an early stage of feeding. Our findings provided a potential new way to efficiently control pests by increasing intake of lower dose Cry toxins and a novel hint for the complex Cry toxin mechanism.


Assuntos
Toxinas de Bacillus thuringiensis , Endotoxinas , Proteínas Hemolisinas , Mariposas , Neuropeptídeos , Animais , Toxinas de Bacillus thuringiensis/farmacologia , Endotoxinas/farmacologia , Comportamento Alimentar/fisiologia , Expressão Gênica , Genes de Insetos , Proteínas Hemolisinas/farmacologia , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteínas de Insetos/farmacologia , Mariposas/efeitos dos fármacos , Mariposas/genética , Mariposas/metabolismo , Mariposas/fisiologia , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Neuropeptídeos/farmacologia , Controle de Pragas/métodos
2.
BMC Plant Biol ; 21(1): 402, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34470613

RESUMO

BACKGROUND: Plant-parasitic nematodes and herbivorous insects have a significant negative impact on global crop production. A successful approach to protect crops from these pests is the in planta expression of nematotoxic or entomotoxic proteins such as crystal proteins from Bacillus thuringiensis (Bt) or plant lectins. However, the efficacy of this approach is threatened by emergence of resistance in nematode and insect populations to these proteins. To solve this problem, novel nematotoxic and entomotoxic proteins are needed. During the last two decades, several cytoplasmic lectins from mushrooms with nematicidal and insecticidal activity have been characterized. In this study, we tested the potential of Marasmius oreades agglutinin (MOA) to furnish Arabidopsis plants with resistance towards three economically important crop pests: the two plant-parasitic nematodes Heterodera schachtii and Meloidogyne incognita and the herbivorous diamondback moth Plutella xylostella. RESULTS: The expression of MOA does not affect plant growth under axenic conditions which is an essential parameter in the engineering of genetically modified crops. The transgenic Arabidopsis lines showed nearly complete resistance to H. schachtii, in that the number of female and male nematodes per cm root was reduced by 86-91 % and 43-93 % compared to WT, respectively. M. incognita proved to be less susceptible to the MOA protein in that 18-25 % and 26-35 % less galls and nematode egg masses, respectively, were observed in the transgenic lines. Larvae of the herbivorous P. xylostella foraging on MOA-expression lines showed a lower relative mass gain (22-38 %) and survival rate (15-24 %) than those feeding on WT plants. CONCLUSIONS: The results of our in planta experiments reveal a robust nematicidal and insecticidal activity of the fungal lectin MOA against important agricultural pests which may be exploited for crop protection.


Assuntos
Aglutininas/farmacologia , Arabidopsis/parasitologia , Herbivoria , Marasmius/química , Nematoides/fisiologia , Aglutininas/química , Animais , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Mariposas/fisiologia , Doenças das Plantas/prevenção & controle , Plantas Geneticamente Modificadas
3.
J Insect Sci ; 21(5)2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34536079

RESUMO

Native to the neotropics, the avocado seed moth Stenoma catenifer Walsingham (Lepidoptera: Elachistidae) is a specialist pest of the family Lauraceae and considered one of the most important pests of avocados worldwide. However, little is known regarding its spatial distribution within a single tree. Therefore, we designed a study to evaluate the effects of canopy height and aspect (i.e., side of the tree) on fruit infestation by S. catenifer larvae in avocados. The study was conducted in three commercial organic avocado orchards located in São Paulo, Brazil. At each orchard, 40 fruit from 30 random trees were sampled weekly from October 2017 through February 2018, evaluating the number of fruits infested by S. catenifer larvae at three tree heights (bottom, middle, and top). In addition, fruits on the ground were also sampled. We also evaluated the effect of the side of the tree where the fruits were collected, i.e., whether they were on the side facing the east (sunrise) or the west (sunset). Within the avocado canopy, the level of fruit infestation by S. catenifer larvae was significantly higher at the top of the trees than in the middle and bottom. Fruit on the ground had lower levels of infestation than those on the tree canopy. The level of fruit infestation was also higher on the side of avocado trees facing the east (sunrise). Understanding the within-tree distribution of S. catenifer will help to better target monitoring and control activities against this pest in avocados.


Assuntos
Demografia , Mariposas/fisiologia , Animais , Frutas , Controle de Insetos/métodos , Larva/efeitos dos fármacos , Larva/fisiologia , Persea , Árvores
4.
BMC Plant Biol ; 21(1): 401, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34461825

RESUMO

BACKGROUND: Timing is everything when it comes to the fitness outcome of a plant's ecological interactions, and accurate timing is particularly relevant for interactions with herbivores or mutualists that are based on ephemeral emissions of volatile organic compounds. Previous studies of the wild tobacco N. attenuata have found associations between the diurnal timing of volatile emissions, and daytime predation of herbivores by their natural enemies. RESULTS: Here, we investigated the role of light in regulating two biosynthetic groups of volatiles, terpenoids and green leaf volatiles (GLVs), which dominate the herbivore-induced bouquet of N. attenuata. Light deprivation strongly suppressed terpenoid emissions while enhancing GLV emissions, albeit with a time lag. Silencing the expression of photoreceptor genes did not alter terpenoid emission rhythms, but silencing expression of the phytochrome gene, NaPhyB1, disordered the emission of the GLV (Z)-3-hexenyl acetate. External abscisic acid (ABA) treatments increased stomatal resistance, but did not truncate the emission of terpenoid volatiles (recovered in the headspace). However, ABA treatment enhanced GLV emissions and leaf internal pools (recovered from tissue), and reduced internal linalool pools. In contrast to the pattern of diurnal terpenoid emissions and nocturnal GLV emissions, transcripts of herbivore-induced plant volatile (HIPV) biosynthetic genes peaked during the day. The promotor regions of these genes were populated with various cis-acting regulatory elements involved in light-, stress-, phytohormone- and circadian regulation. CONCLUSIONS: This research provides insights into the complexity of the mechanisms involved in the regulation of HIPV bouquets, a mechanistic complexity which rivals the functional complexity of HIPVs, which includes repelling herbivores, calling for body guards, and attracting pollinators.


Assuntos
Ritmo Circadiano , Herbivoria/fisiologia , Luz , Tabaco/fisiologia , Compostos Orgânicos Voláteis/metabolismo , Ácido Abscísico/farmacologia , Animais , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Regulação da Expressão Gênica de Plantas/fisiologia , Larva/fisiologia , Mariposas/fisiologia , Fitocromo B/genética , Fitocromo B/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Terpenos/metabolismo
5.
BMC Plant Biol ; 21(1): 358, 2021 Aug 04.
Artigo em Inglês | MEDLINE | ID: mdl-34348650

RESUMO

BACKGROUND: The South America pinworm, Tuta absoluta, is a destructive pest of tomato that causes important losses worldwide. Breeding of resistant/tolerant tomato cultivars could be an effective strategy for T. absoluta management but, despite the economic importance of tomato, very limited information is available about its response to this treat. To elucidate the defense mechanisms to herbivore feeding a comparative analysis was performed between a tolerant and susceptible cultivated tomato at both morphological and transcriptome level to highlight constitutive leaf barriers, molecular and biochemical mechanisms to counter the effect of T. absoluta attack. RESULTS: The tolerant genotype showed an enhanced constitutive barrier possibly as result of the higher density of trichomes and increased inducible reactions upon mild infestation thanks to the activation/repression of key transcription factors regulating genes involved in cuticle formation and cell wall strength as well as of antinutritive enzymes, and genes involved in the production of chemical toxins and bioactive secondary metabolites. CONCLUSIONS: Overall, our findings suggest that tomato resilience to the South America pinworm is achieved by a combined strategy between constitutive and induced defense system. A well-orchestrated modulation of plant transcription regulation could ensure a trade-off between defense needs and fitness costs. Our finding can be further exploited for developing T. absoluta tolerant cultivars, acting as important component of integrated pest management strategy for more sustainable production.


Assuntos
Regulação da Expressão Gênica de Plantas , Lycopersicon esculentum/genética , Doenças das Plantas/genética , Folhas de Planta/genética , Transcriptoma , Animais , Perfilação da Expressão Gênica/métodos , Ontologia Genética , Interações Hospedeiro-Parasita , Larva/fisiologia , Lycopersicon esculentum/metabolismo , Lycopersicon esculentum/parasitologia , Mariposas/fisiologia , Doenças das Plantas/parasitologia , Folhas de Planta/metabolismo , Folhas de Planta/parasitologia , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , RNA-Seq/métodos , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Tricomas/genética , Tricomas/metabolismo , Tricomas/parasitologia
6.
J Chem Ecol ; 47(8-9): 732-739, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34347234

RESUMO

The pine brown tail moth, Euproctis terminalis (Walker 1855), is a periodic pest in pine plantations in South Africa. The larvae feed on pine needles and can cause severe defoliation when population densities are high. Population densities fluctuate temporally and spatially, complicating the prediction of potential growth loss and tree mortality. The aim of this study was to identify the sex pheromone of the pine brown tail moth to provide stakeholders with a tool for monitoring it. Gas chromatography-electroantennogram detection and gas chromatography/mass spectrometry analyses of female pheromone gland extracts identified the major component as (Z,Z,Z,Z)-7,13,16,19-docosatetraen-1-ol isobutyrate. Traps baited with (Z,Z,Z,Z)-7,13,16,19-docosatetraen-1-ol isobutyrate caught more males than unbaited traps. A delta trap was shown to be a superior design compared to a bucket funnel trap. This pheromone can now be used for monitoring E. terminalis in pine plantations.


Assuntos
Mariposas/fisiologia , Atrativos Sexuais/análise , Animais , DNA/química , Complexo IV da Cadeia de Transporte de Elétrons/genética , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Isobutiratos/análise , Isobutiratos/farmacologia , Larva/crescimento & desenvolvimento , Masculino , Mariposas/química , Mariposas/crescimento & desenvolvimento , Pinus/parasitologia , Análise de Sequência de DNA , Atrativos Sexuais/farmacologia , Comportamento Sexual Animal/efeitos dos fármacos
7.
J Chem Ecol ; 47(7): 664-679, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34196857

RESUMO

Larval Diaphania indica (Saunders) (Lepidoptera: Crambidae) cause complete defoliation of Trichosanthes anguina L. and reduce crop yield in India. Females lay eggs on the leaf surface, and therefore leaf surface waxes are potentially involved in host selection. Alkanes and free fatty acids are the major constituents of leaf surface waxes, so a study was conducted to determine whether these wax constituents from three T. anguina cultivars (MNSR-1, Baruipur Long, and Polo No.1) could act as short-range attractants and oviposition stimulants in D. indica females. Twenty n-alkanes from n-C14 to n-C36 and 13 free fatty acids from C12:0 to C21:0 were detected in the leaf surface waxes of these cultivars. Heptadecane and stearic acid were predominant among n-alkanes and free fatty acids, respectively, in these cultivars. Females showed attraction towards one leaf equivalent surface wax of each of these cultivars against solvent controls (petroleum ether) in Y-tube olfactometer bioassays. A synthetic blend of heptadecane, eicosane, hexacosane, and stearic acid, a synthetic blend of hexacosane and stearic acid, and a synthetic blend of pentadecane and stearic acid comparable to amounts present in one leaf equivalent surface wax of MNSR-1, Baruipur Long, and Polo No.1, respectively, were short-range attractants and oviposition stimulants in D. indica. Female egg laying responses were similar to each of these blends, providing information that could be used to developing baited traps in integrated pest management (IPM) programs.


Assuntos
Cucurbitaceae/metabolismo , Mariposas/fisiologia , Oviposição/efeitos dos fármacos , Ceras/farmacologia , Alcanos/análise , Alcanos/isolamento & purificação , Alcanos/farmacologia , Animais , Análise Discriminante , Ácidos Graxos não Esterificados/análise , Ácidos Graxos não Esterificados/isolamento & purificação , Ácidos Graxos não Esterificados/farmacologia , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Larva/efeitos dos fármacos , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Olfatometria , Folhas de Planta/metabolismo , Ceras/química , Ceras/isolamento & purificação
8.
Arch Insect Biochem Physiol ; 108(2): e21837, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34293199

RESUMO

The olfactory system must detect and discriminate various semiochemicals in the environment. In response to such diversity, insects have evolved a family of odorant-gated ion channels composed of a common receptor (coreceptor, Orco) and a ligand-binding tuning odorant receptor (OR) that confers odour specificity. This study aims to examine the expression pattern of Orco gene of Grapholita molesta (GmolOrco) and to elucidate the role of GmolOrco in detecting G. molesta sex pheromone and green leaf volatiles by using gene silencing via RNA interference (RNAi) coupled antennal electrophysiological (EAG). Multiple sequence alignment showed that GmolOrco shared high sequence similarities with the Orco ortholog of lepidopterans. The results of real-time quantitative PCR detection demonstrated that GmolOrco was predominantly expressed in adult antennae and had the highest expression quantity in adult period among the different developmental stages. Compared with the noninjected controls, GmolOrco expression in GmolOrcodouble-stranded RNA (dsRNA)-injected males was reduced to 39.92% and that in females was reduced to 40.43%. EAG assays showed that the responses of GmolOrco-dsRNA injected males to sex pheromones (Z)-8-dodecenyl acetate (Z8-12:OAc) and (Z)-8-dodecenyl alcohol (Z8-12:OH) were significantly reduced, and the GmolOrco-dsRNA-injected female to green leaf volatile (Z)-3-hexenyl acetate also significantly declined. We inferred that Orco-mediated olfaction was different in male and female G. molesta adults and was mainly involved in recognizing the sex pheromones released by female moths.


Assuntos
Mariposas , Receptores Odorantes , Animais , Antenas de Artrópodes/metabolismo , Feminino , Expressão Gênica , Genes de Insetos , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Masculino , Mariposas/genética , Mariposas/metabolismo , Mariposas/fisiologia , Odorantes , Plantas/metabolismo , Interferência de RNA , Receptores Odorantes/genética , Receptores Odorantes/metabolismo , Atrativos Sexuais/metabolismo , Caracteres Sexuais , Compostos Orgânicos Voláteis/metabolismo
9.
Neotrop Entomol ; 50(5): 812-827, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34232494

RESUMO

Leaf cuticular wax plays important role in host selection, oviposition, and feeding of phytophagous insects. Thus, the role of cuticular wax of sesame (Sesamum indicum) cultivars (Savitri and Nirmala) in host selection of 3 generalist pests (Spilosoma obliqua Walker, Helicoverpa armigera Hübner, and Spodoptera litura Fabricius) was investigated under laboratory conditions. The GC-MS and GC-FID analyses of leaf surface waxes of both cultivars indicated the presence of 14 n-alkanes from n-C9 to n-C44 and 12 free fatty acids (FFAs) from C9:0 to C20:0. The most predominant n-alkane and FFA of the cultivars were n-C26 (94.3 ± 7.27 µg leaf-1) and C18:1 (110.8 ± 10.07 µg leaf-1), respectively present in Savitri cultivar. The generalists used visual (color and shape), olfactory (odorous n-alkanes and FFAs), tactile (surface ultra-structure), and gustatory (cuticular wax) cues in a synergistic manner for their host selection through attraction (adults and larvae) followed by oviposition (adults) and feeding (larvae) on studied cultivars (Savitri > Nirmala). Their olfactory responses were maximum towards 2 leaf equivalent amount, whereas oviposition and feeding preference were maximum towards 4 leaf equivalent amount of the combined synthetic (4 n-alkanes (n-C16, n-C22, n-C24, n-C26) + 3 FFAs (C12:0, C14:0, C18:1)) mixture-treated intact leaf of cultivar Savitri. This finding can suggest that the synthetic blend (4 n-alkanes + 3 FFAs) in leaf equivalent amount (396.6 ± 4.13 µg leaf-1) or more from cultivar Savitri can be used as lures to develop baited trap. In addition, the cultivar Nirmala can be used as a resistant cultivar in the ecological pest management (EPM) framework of these target pest species.


Assuntos
Mariposas , Sesamum , Ceras , Animais , Feminino , Mariposas/fisiologia , Oviposição , Folhas de Planta
10.
J Chem Ecol ; 47(7): 680-688, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34101117

RESUMO

Past work shows a significant negative correlation between foliar oregonin concentration and western tent caterpillar (Malacosoma californicum Packard) feeding on red alder (Alnus rubra Bong.). Above an oregonin threshold of 20% leaf dry weight, little feeding by caterpillars is observed. Concentrations of defensive chemicals are influenced by plant genotype, environmental conditions, insect feeding, and the interactions of these factors. Our objective was to measure the effects of nitrogen (N) availability and wounding on foliar oregonin and condensed tannin concentrations in red alder genotypes. One-year-old seedlings from 100 half-sib red alder families were treated with two levels of ammonium nitrate (NH4NO3) for two growing seasons in a common garden. In the second year, leaves from 50 families from the fertilization experiment were used in a bioassay feeding experiment to determine the effects of N fertilization and genotype on WTC damage, and to identify a subset of 20 families with a range of damage to analyze for phytochemical composition. In separate experiments, wound-induction treatments were conducted outdoors and, in a greenhouse using the N treated trees in their third and fourth year, respectively. Foliar condensed tannin, oregonin and N concentrations were measured and ranked among the plant genotypes, and between the two N treatments and two wounding treatments. Results showed that oregonin and condensed tannin concentrations varied among the alder genotypes. Leaf N concentration was negatively correlated with concentration of oregonin. Neither of the measured phenolic compounds responded to wounding. The results suggest that red alder foliar oregonin and condensed tannin are likely constitutive defenses that are largely determined by genotype, and that the negative correlation of defense compounds with plant internal N status holds in this N-fixing tree.


Assuntos
Alnus/química , Diarileptanoides/química , Mariposas/efeitos dos fármacos , Compostos Fitoquímicos/farmacologia , Taninos/análise , Alnus/genética , Alnus/crescimento & desenvolvimento , Animais , Cromatografia Líquida de Alta Pressão , Diarileptanoides/farmacologia , Fertilizantes/análise , Genótipo , Herbivoria/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Nitrogênio/química , Nitrogênio/metabolismo , Compostos Fitoquímicos/química , Folhas de Planta/química , Folhas de Planta/metabolismo , Plântula , Espectrofotometria Ultravioleta , Taninos/farmacologia
11.
Toxins (Basel) ; 13(5)2021 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-34065247

RESUMO

Laboratory selection for resistance of field populations is a well-known and useful tool to understand the potential of insect populations to evolve resistance to insecticides. It provides us with estimates of the frequency of resistance alleles and allows us to study the mechanisms by which insects developed resistance to shed light on the mode of action and optimize resistance management strategies. Here, a field population of Mythimna separata was subjected to laboratory selection with either Vip3Aa, Cry1Ab, or Cry1F insecticidal proteins from Bacillus thuringiensis. The population rapidly evolved resistance to Vip3Aa reaching, after eight generations, a level of >3061-fold resistance, compared with the unselected insects. In contrast, the same population did not respond to selection with Cry1Ab or Cry1F. The Vip3Aa resistant population did not show cross resistance to either Cry1Ab or Cry1F. Radiolabeled Vip3Aa was tested for binding to brush border membrane vesicles from larvae from the susceptible and resistant insects. The results did not show any qualitative or quantitative difference between both insect samples. Our data, along with previous results obtained with other Vip3Aa-resistant populations from other insect species, suggest that altered binding to midgut membrane receptors is not the main mechanism of resistance to Vip3Aa.


Assuntos
Bacillus thuringiensis/metabolismo , Proteínas de Bactérias/farmacologia , Inseticidas/farmacologia , Mariposas/fisiologia , Animais , Toxinas de Bacillus thuringiensis/farmacologia , Endotoxinas/farmacologia , Proteínas Hemolisinas/farmacologia , Resistência a Inseticidas , Inseticidas/isolamento & purificação , Larva , Ligação Proteica
12.
Toxins (Basel) ; 13(5)2021 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-34066367

RESUMO

Yellow Peach Moth (YPM), Conogethes punctiferalis (Guenée), is one of the most destructive maize pests in the Huang-Huai-Hai summer maize region of China. Transgenic Bacillus thuringiensis (Bt) maize provides an effective means to control this insect pest in field trials. However, the establishment of Bt resistance to target pests is endangering the continued success of Bt crops. To use Bt maize against YPM, the baseline susceptibility of the local populations in the targeted areas needs to be verified. Diet-overlay bioassay results showed that all the fourteen YPM populations in China are highly susceptible to Cry1Ab. The LC50 values ranged from 0.35 to 2.38 ng/cm2 over the two years of the collection, and the difference between the most susceptible and most tolerant populations was sevenfold. The upper limit of the LC99 estimates of six pooled populations produced >99% larval mortality for representative eight populations collected in 2020 and was designated as diagnostic concentrations for monitoring susceptibility in YPM populations in China. Hence, we evaluated the laboratory selection of resistance in YPM to Cry1Ab using the diet-overlay bioassay method. Although the resistant ratio was generally low, YPM potentially could evolve resistance to Cry1Ab. The potential developmentof resistance by target pests points out the necessity to implement resistance management strategies for delaying the establishment of pest resistance to Bt crops.


Assuntos
Toxinas de Bacillus thuringiensis/genética , Bacillus thuringiensis/genética , Endotoxinas/genética , Proteínas Hemolisinas/genética , Mariposas/fisiologia , Zea mays/genética , Animais , China , Produtos Agrícolas , Resistência a Inseticidas/genética , Larva/genética , Plantas Geneticamente Modificadas/genética
13.
Ecotoxicol Environ Saf ; 220: 112324, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34015630

RESUMO

Insecticides are extensively used worldwide to kill insect pests, yet organisms are most often exposed to insecticides at sublethal concentrations. Our understanding of sublethal effects on life histories is needed to predict the impact of insecticides on population dynamics and improve insecticide use and pest control. Sublethal concentrations can impact life histories directly and indirectly through changes in the intraspecific competition. Yet, few studies have evaluated the sublethal effects on intraspecific competition and these do not disentangle the insecticide effects on interference competition versus exploitative competition. As such, sublethal effects on the relative contribution of each pathways in shaping life histories are largely unknown, despite the fact that this can impact population dynamics. In this study, we focused on the neurotoxic insecticide spinosad and investigated its sublethal effects on interference among the aggressive larvae of the tortrix moth Adoxophyes honmai and the consequences for life histories. We conducted a set of paired experiments to disentangle the insecticide effects on interference from the ones on exploitation. Spinosad was found to amplify interference with most effects on mortality which lets us suggest that the insecticide likely increases the level of aggressive interactions resulting in more conspecific killings (e.g. cannibalism). Spinosad exposure was found to impair movement ability. Less movements may increase susceptibility to conspecific attacks and or increase aggresivity for better defence, two plausible mechanisms that could explain the increase in interference with insecticide. This study shows that insecticide at sublethal concentration can impact life histories by altering the strength of interference competition. Many organisms (pest and non-target species) compete through interference and theory predicts that a change in interference can substantially change dynamics. Our finding therefore reveals the importance of assessing the effect of insecticides on the mechanisms of competition when predicting their impact on populations.


Assuntos
Controle de Insetos , Inseticidas/farmacologia , Macrolídeos/farmacologia , Mariposas/efeitos dos fármacos , Agressão/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Mariposas/fisiologia , Movimento/efeitos dos fármacos , Dinâmica Populacional
14.
Ecotoxicol Environ Saf ; 220: 112334, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34020284

RESUMO

Artificial light at night (ALAN) is a widespread environmental pollutant and stressor. Many nocturnal insects have been shown to experience ALAN stress. However, few studies have been conducted to uncover the mechanism by which nocturnal insects respond to ALAN stress. Previous studies suggest that lysine succinylation (Ksuc) is a potential mechanism that coordinates energy metabolism and antioxidant activity under stressful conditions. Mythimna separata (Walker) (M. separata) is a nocturnal insect that has been stressed by ALAN. In this study, we quantified the relative proteomic Ksuc levels in ALAN-stressed M. separata. Of the 466 identified Ksuc-modified proteins, 103 were hypersuccinylated/desuccinylated in ALAN-stressed moths. The hypersuccinylated/desuccinylated proteins were shown to be involved in various biological processes. In particular, they were enriched in metabolic processes, reactive oxygen species (ROS) homeostasis and the neuromuscular system. Furthermore, we demonstrated that Ksuc might affect moth locomotion by intervening with and coordinating these systems under ALAN stress. These findings suggest that Ksuc plays a vital role in the moth response to ALAN stress and moth locomotion behavior and provide a new perspective on the impact of ALAN on nocturnal insect populations and species communities.


Assuntos
Proteínas de Insetos/química , Luz , Iluminação , Lisina/química , Mariposas/fisiologia , Fototaxia , Proteoma/química , Animais , Antioxidantes/metabolismo , Metabolismo Energético , Estresse Fisiológico
15.
Bull Entomol Res ; 111(5): 595-604, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33998414

RESUMO

With further climate change still expected, it is predicted to increase the frequency with plants will be water stressed, which subsequently influences phytophagous insects, particularly Lepidoptera with limited mobility of larvae. Previous studies have indicated that oviposition preference and offspring performance of Lepidoptera insects are sensitive to drought separately. However, the integration of their two properties is not always seen. Here, we evaluated changes in oviposition selection and offspring fitness of a Lepidoptera insect under three water-stressed treatments using a model agroecosystem consisting of maize Zea mays, and Asian corn borer Ostrinia furnacalis. Results found that female O. furnacalis preferred to laying their eggs on well-watered maize, and then their offspring tended to survive better, attained bigger larvae mass, and developed more pupae and adults on the preferred maize. Oviposition selection of O. furnacalis positively correlated with height and leaf traits of maize, and offspring fitness positively related with water content and phytochemical traits of hosts. Overall, these results suggest that oviposition choice performed by O. furnacalis reflects the maximization of offspring fitness, supporting preference-performance hypothesis. This finding further highlights that the importance of simultaneous evaluation of performance and performance for water driving forces should be involved, in order to accurately predict population size of O. furnacalis under altered precipitation pattern.


Assuntos
Comportamento de Escolha , Mariposas/fisiologia , Oviposição , Zea mays/parasitologia , Animais , Desidratação , Herbivoria , Mariposas/crescimento & desenvolvimento , Zea mays/fisiologia
16.
Bull Entomol Res ; 111(5): 616-627, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33998417

RESUMO

The short-lived polygamous moth Grapholita molesta (Busck) is an important fruit pest worldwide. Trapping males by synthetic female sex pheromones is not an effective reproductive control strategy. It is important to improve this technology by understanding the mating system of G. molesta. This study investigated mating opportunities and fertile egg production by altering the operational sex ratio, mating age, and male mating history in repeated single mating and multiple mating in the two sexes. Our results showed that the mating and reproductive parameters of virgin males were affected by the number and age of virgin females. Males preferred a female number ≤three-fifths of the male number or ≤2-day-old females, while they discriminated against a female number ≥three times of the male number or ≥5-day-old females. On the other hand, the mating and reproductive parameters of virgin females were affected by repeated single mating and especially multiple mating under different male mating histories. Females preferred once-mated males and discriminated against virgin males. These results indicated that mating systems including more and older virgin females for virgin males and different virgin males for virgin females may be suitable for suppressing G. molesta populations. Hence, these results revealed that preventing mating of virgin adults by synthetic female sex pheromones should be most effective in controlling G. molesta.


Assuntos
Mariposas/fisiologia , Razão de Masculinidade , Comportamento Sexual Animal , Fatores Etários , Animais , Feminino , Masculino , Oviposição
17.
Nat Commun ; 12(1): 3029, 2021 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-34031384

RESUMO

Natural sensory environments, despite strong potential for structuring systems, have been neglected in ecological theory. Here, we test the hypothesis that intense natural acoustic environments shape animal distributions and behavior by broadcasting whitewater river noise in montane riparian zones for two summers. Additionally, we use spectrally-altered river noise to explicitly test the effects of masking as a mechanism driving patterns. Using data from abundance and activity surveys across 60 locations, over two full breeding seasons, we find that both birds and bats avoid areas with high sound levels, while birds avoid frequencies that overlap with birdsong, and bats avoid higher frequencies more generally. We place 720 clay caterpillars in willows, and find that intense sound levels decrease foraging behavior in birds. For bats, we deploy foraging tests across 144 nights, consisting of robotic insect-wing mimics, and speakers broadcasting bat prey sounds, and find that bats appear to switch hunting strategies from passive listening to aerial hawking as sound levels increase. Natural acoustic environments are an underappreciated niche axis, a conclusion that serves to escalate the urgency of mitigating human-created noise.


Assuntos
Acústica , Comportamento Animal , Aves/fisiologia , Quirópteros/fisiologia , Rios , Animais , Percepção Auditiva , Ecolocação , Humanos , Insetos , Mariposas/fisiologia , Ruído , Comportamento Predatório , Som
18.
Neotrop Entomol ; 50(4): 622-629, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33942251

RESUMO

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), a severe pest on agricultural crops occurring throughout the tropical Americas, has been reported to occur in China since 2019. To develop novel pest management practices, we studied the effect of delayed mating on the reproductive performance and longevity of S. frugiperda. Delayed mating, progressing from 0 to 7 days, was respectively imposed on both sexes simultaneously, female only, and male only. We demonstrated that delayed mating reduced mating success, number of eggs laid, egg hatch rate, and female oviposition period, while increased copulation duration and longevity. The correlations between the number of delayed days and mating success, number of eggs laid, hatch rate, and oviposition period were all significantly negative irrespective of the sex that was delayed. Meanwhile, there was a positive correlation between delayed days and copulation duration when both sexes were delayed simultaneously or males delayed only. Overall our results indicated that delayed mating in both males and females drastically reduced female reproductive output.


Assuntos
Longevidade , Mariposas , Comportamento Sexual Animal , Animais , Copulação , Feminino , Masculino , Mariposas/fisiologia , Reprodução , Spodoptera
19.
Nat Commun ; 12(1): 2818, 2021 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-33990556

RESUMO

The sex pheromone system of ~160,000 moth species acts as a powerful form of assortative mating whereby females attract conspecific males with a species-specific blend of volatile compounds. Understanding how female pheromone production and male preference coevolve to produce this diversity requires knowledge of the genes underlying change in both traits. In the European corn borer moth, pheromone blend variation is controlled by two alleles of an autosomal fatty-acyl reductase gene expressed in the female pheromone gland (pgFAR). Here we show that asymmetric male preference is controlled by cis-acting variation in a sex-linked transcription factor expressed in the developing male antenna, bric à brac (bab). A genome-wide association study of preference using pheromone-trapped males implicates variation in the 293 kb bab intron 1, rather than the coding sequence. Linkage disequilibrium between bab intron 1 and pgFAR further validates bab as the preference locus, and demonstrates that the two genes interact to contribute to assortative mating. Thus, lack of physical linkage is not a constraint for coevolutionary divergence of female pheromone production and male behavioral response genes, in contrast to what is often predicted by evolutionary theory.


Assuntos
Genes de Insetos , Mariposas/genética , Mariposas/fisiologia , Atrativos Sexuais/genética , Atrativos Sexuais/fisiologia , Aldeído Oxirredutases/genética , Aldeído Oxirredutases/metabolismo , Alelos , Animais , Evolução Molecular , Feminino , Regulação da Expressão Gênica , Estudo de Associação Genômica Ampla , Endogamia , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Desequilíbrio de Ligação , Masculino , Preferência de Acasalamento Animal/fisiologia , Polimorfismo Genético , Locos de Características Quantitativas , Recombinação Genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo
20.
Elife ; 102021 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-33875133

RESUMO

Insect herbivores use different cues to locate host plants. The importance of CO2 in this context is not well understood. We manipulated CO2 perception in western corn rootworm (WCR) larvae through RNAi and studied how CO2 perception impacts their interaction with their host plant. The expression of a carbon dioxide receptor, DvvGr2, is specifically required for dose-dependent larval responses to CO2. Silencing CO2 perception or scrubbing plant-associated CO2 has no effect on the ability of WCR larvae to locate host plants at short distances (<9 cm), but impairs host location at greater distances. WCR larvae preferentially orient and prefer plants that grow in well-fertilized soils compared to plants that grow in nutrient-poor soils, a behaviour that has direct consequences for larval growth and depends on the ability of the larvae to perceive root-emitted CO2. This study unravels how CO2 can mediate plant-herbivore interactions by serving as a distance-dependent host location cue.


Assuntos
Dióxido de Carbono/metabolismo , Herbivoria , Mariposas/fisiologia , Zea mays/metabolismo , Animais , Cadeia Alimentar , Larva/crescimento & desenvolvimento , Larva/fisiologia , Mariposas/crescimento & desenvolvimento , Raízes de Plantas/metabolismo
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