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Jacobus C. De Roode - One of the best experts on this subject based on the ideXlab platform.
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The ecology and evolution of animal medication: genetically fixed response versus phenotypic plasticity.
The American naturalist, 2014Co-Authors: Marc Choisy, Jacobus C. De RoodeAbstract:Animal medication against parasites can occur either as a genetically fixed (constitutive) or phenotypically plastic (induced) behavior. Taking the Tritrophic Interaction between the monarch butterfly Danaus plexippus, its protozoan parasite Ophryocystis elektroscirrha, and its food plant Asclepias spp. as a test case, we develop a game-theory model to identify the epidemiological (parasite prevalence and virulence) and environmental (plant toxicity and abundance) conditions that predict the evolution of genetically fixed versus phenotypically plastic forms of medication. Our model shows that the relative benefits (the antiparasitic properties of medicinal food) and costs (side effects of medicine, the costs of searching for medicine, and the costs of plasticity itself) crucially determine whether medication is genetically fixed or phenotypically plastic. Our model suggests that animals evolve phenotypic plasticity when parasite risk (a combination of virulence and prevalence and thus a measure of the strength of parasite-mediated selection) is relatively low to moderately high and genetically fixed medication when parasite risk becomes very high. The latter occurs because at high parasite risk, the costs of plasticity are outweighed by the benefits of medication. Our model provides a simple and general framework to study the conditions that drive the evolution of alternative forms of animal medication.
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The Ecology and Evolution of Animal Medication: Genetically Fixed Response versus Phenotypic Plasticity*
The American Naturalist, 2014Co-Authors: Marc Choisy, Jacobus C. De RoodeAbstract:AbstractAnimal medication against parasites can occur either as a genetically fixed (constitutive) or phenotypically plastic (induced) behavior. Taking the Tritrophic Interaction between the monarch butterfly Danaus plexippus, its protozoan parasite Ophryocystis elektroscirrha, and its food plant Asclepias spp. as a test case, we develop a game-theory model to identify the epidemiological (parasite prevalence and virulence) and environmental (plant toxicity and abundance) conditions that predict the evolution of genetically fixed versus phenotypically plastic forms of medication. Our model shows that the relative benefits (the antiparasitic properties of medicinal food) and costs (side effects of medicine, the costs of searching for medicine, and the costs of plasticity itself) crucially determine whether medication is genetically fixed or phenotypically plastic. Our model suggests that animals evolve phenotypic plasticity when parasite risk (a combination of virulence and prevalence and thus a measure of...
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Host plant species affects virulence in monarch butterfly Blackwell Publishing Ltd
2013Co-Authors: Jacobus C. De Roode, Amy B. Pedersen, Mark D. Hunter, Sonia AltizerAbstract:1. Studies have considered how intrinsic host and parasite properties determine parasite virulence, but have largely ignored the role of extrinsic ecological factors in its expression. 2. We studied how parasite genotype and host plant species interact to determine virulence of the protozoan parasite Ophryocystis elektroscirrha (McLaughlin & Myers 1970) in the monarch butterfly Danaus plexippus L. We infected monarch larvae with one of four parasite genotypes and reared them on two milkweed species that differed in their levels of cardenolides: toxic chemicals involved in predator defence. 3. Parasite infection, replication and virulence were affected strongly by host plant species. While uninfected monarchs lived equally long on both plant species, infected monarchs suffered a greater reduction in their life spans (55 % vs. 30%) on the low-cardenolide vs. the high-cardenolide host plant. These life span differences resulted from different levels of parasite replication in monarchs reared on the two plant species. 4. The virulence rank order of parasite genotypes was unaffected by host plant species, suggesting that host plant species affected parasite genotypes similarly, rather than through complex plant species–parasite genotype Interactions. 5. Our results demonstrate that host ecology importantly affects parasite virulence, with implications for host–parasite dynamics in natural populations. Key-words: Apicomplexa, Asclepias, evolution of virulence, pathogenicity, Tritrophic Interaction
Marc Choisy - One of the best experts on this subject based on the ideXlab platform.
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The ecology and evolution of animal medication: genetically fixed response versus phenotypic plasticity.
The American naturalist, 2014Co-Authors: Marc Choisy, Jacobus C. De RoodeAbstract:Animal medication against parasites can occur either as a genetically fixed (constitutive) or phenotypically plastic (induced) behavior. Taking the Tritrophic Interaction between the monarch butterfly Danaus plexippus, its protozoan parasite Ophryocystis elektroscirrha, and its food plant Asclepias spp. as a test case, we develop a game-theory model to identify the epidemiological (parasite prevalence and virulence) and environmental (plant toxicity and abundance) conditions that predict the evolution of genetically fixed versus phenotypically plastic forms of medication. Our model shows that the relative benefits (the antiparasitic properties of medicinal food) and costs (side effects of medicine, the costs of searching for medicine, and the costs of plasticity itself) crucially determine whether medication is genetically fixed or phenotypically plastic. Our model suggests that animals evolve phenotypic plasticity when parasite risk (a combination of virulence and prevalence and thus a measure of the strength of parasite-mediated selection) is relatively low to moderately high and genetically fixed medication when parasite risk becomes very high. The latter occurs because at high parasite risk, the costs of plasticity are outweighed by the benefits of medication. Our model provides a simple and general framework to study the conditions that drive the evolution of alternative forms of animal medication.
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The Ecology and Evolution of Animal Medication: Genetically Fixed Response versus Phenotypic Plasticity*
The American Naturalist, 2014Co-Authors: Marc Choisy, Jacobus C. De RoodeAbstract:AbstractAnimal medication against parasites can occur either as a genetically fixed (constitutive) or phenotypically plastic (induced) behavior. Taking the Tritrophic Interaction between the monarch butterfly Danaus plexippus, its protozoan parasite Ophryocystis elektroscirrha, and its food plant Asclepias spp. as a test case, we develop a game-theory model to identify the epidemiological (parasite prevalence and virulence) and environmental (plant toxicity and abundance) conditions that predict the evolution of genetically fixed versus phenotypically plastic forms of medication. Our model shows that the relative benefits (the antiparasitic properties of medicinal food) and costs (side effects of medicine, the costs of searching for medicine, and the costs of plasticity itself) crucially determine whether medication is genetically fixed or phenotypically plastic. Our model suggests that animals evolve phenotypic plasticity when parasite risk (a combination of virulence and prevalence and thus a measure of...
Mileny Dos Santos De ,souza - One of the best experts on this subject based on the ideXlab platform.
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Resistência de tomateiros mutantes a Bemisia tabaci(Gennadius, 1889)(Hemiptera: Aleyrodidae) biótipo B e influência sobre Encarsia hispida(Hymenoptera: Aphelinidae)
'Portal de Periodicos UFPB', 2019Co-Authors: Mileny Dos Santos De ,souzaAbstract:The tomato is one of the most cultivated and consumed vegetables in the world, however it is considered a high risk crop when we consider the large number of phytosanitary problems in which it is affected. Being the whitefly Bemisia tabaci biotype B, one of these main problems, given the damages and the cost of control that is inserted in its production. The use of resistant cultivars associated to biological control within an Integrated Pest Management program can act as one of the best solutions to problems with this pest, since the reduction or elimination of control with pesticides. In view of the above, the general objective of this research was to determine if mutant tomatoes confer resistance to Bemisia tabaci biotype B and its influence on the parasitoid Encarsia hispida. The research was carried out in the Laboratory of Entomology of the Federal University of Paraiba, Campus II Areia-PB, addressing in three articles to the topics explained above. The performance of five mutant tomatoes (aurea, cry, phyA, phyB1, phyB2) plus one susceptible standard tomato ('IAC-Santa Clara') were evaluated in a greenhouse and field environment. Article I: The objective of this study was to determine if mutant tomatoes confer resistance to B. tabaci biotype B. In the free choice test (TLE), the number of eggs, nymphs and adults / plants was measured and, furthermore, the index of attractiveness (AI) and the index of preference for IPO oviposition, colonization of nymphs, damage and growth of fumagina. The number of eggs, IPO, insect biology and number of trichomes were measured in the non-choice test (TSE). In the TLE, the standard cultivar presented higher number of eggs, nymphs and adults, higher IPA, IPO, damage and growth of the fumagina, besides high colonization of nymphs and low number of trichomes. In the TLE the aurea provided the largest and the standard cultivar the shortest number of days to complete the insect biology. The aurea presents resistance type antibiosis and antixenosis, less damages to the plants and less growth of the fumagina when infested by B. tabaci biotype B. Article II: The biochemical and physiological behavior of mutant tomatoes against the B. tabaci biotype B attack was verified by measuring the number of eggs, nymphs and adults of the pest after three periods of infestation and the activity of POX, PPO and PAL enzymes as well as the physiological variables A, E, gs, Ci, iWUE, EiC and WUE, fluorescence, chlorophyll and number of trichomes. The mutants presented lower infestation and colonization of the pest; increased activity of oxidative enzymes; and less wear the physiology against the attack of B. tabaci when compared to 'Santa Clara'. The aurea confers greater resistance, activates its biochemical defense mechanisms, and suffers less physiological damage in the face of B. tabaci infestation. Article III: The objective was to investigate the Tritrophic Interaction between mutant tomatoes, B. tabaci biotype B and the parasitoid Encarsia hispida. Tomatoes were used as hosts of the pest, and the 3rd and 4th instar nymphs were submitted to the parasitism of E. hispida. It was evaluated the biological development of the parasitoid and also the natural parasitism index and under releases of this agent. The biological development of the parasitoid was not affected by the mutant tomatoes, as well as the longevity and the sexual ratio. As for the parasitism, the index was higher in protected environment, the mutant aurea and the standard cultivar with the highest values, already in the field no differences were observed among tomato plants. Mutants provide adequate biological development to the parasitoid; the rate of parasitism is higher when the parasitoid is released; aurea and ‘Santa Clara’ have higher rates of parasitism.O tomateiro é uma das hortaliças mais cultivadas e consumidas no mundo. No entanto, é considerada uma cultura de alto risco quando consideramos o grande número de problemas fitossanitário no qual é acometida. A mosca-branca Bemisia tabaci biótipo B, é um desses principais problemas, dado os danos e o custo de controle que insere na produção do tomate. Cultivares resistentes associados ao controle biológico dentro de um programa de Manejo Integrado de Pragas podem atuar como uma das melhores soluções para os problemas com essa praga, visto a redução ou eliminação do controle com pesticidas. Diante do exposto o objetivo geral dessa pesquisa foi determinar se tomateiros mutantes conferem resistência a Bemisia tabaci biótipo B e sua influência sobre o parasitoide Encarsia hispida. A pesquisa foi realizada no Laboratório de Entomologia da Universidade Federal da Paraíba, Campus II Areia-PB, abordando em três artigos as temáticas acima explanadas. Em ambiente telado e campo, avaliou-se o desempenho de cinco tomateiros mutantes (aurea, cry, phyA, phyB1, phyB2) mais um tomateiro padrão suscetível (‘IAC-Santa Clara’). Artigo I: Objetivou-se determinar se tomateiros mutantes conferem resistência a mosca-branca B. tabaci biótipo B. No teste de livre escolha (TLE), mensurou-se o número de ovos, ninfas e adultos/plantas e, calculou-se também o índice de atratividade (IA), índice de preferência para oviposição IPO, colonização das ninfas, danos e crescimento da fumagina. No teste sem chances de escolha (TSE) mensurou-se o nº de ovos, o IPO, a biologia do inseto e o nº de tricomas. No TLE o Santa Clara apresentou maior nº de ovos, ninfas e adultos, maiores IPA e IPO, danos e crescimento da fumagina, além de alta colonização das ninfas e baixo nº de tricomas. No TSE o aurea proporcionou o maior e o cultivar padrão o menor nº de dias para completar a biologia do inseto. O aurea apresenta resistência tipo antibiose e antixenose, menos danos às plantas e menor crescimento da fumagina quando infestados por B. tabaci biótipo B. Artigo II: Verificou-se o comportamento bioquímico e fisiológico de tomateiros mutantes frente ao ataque de B. tabaci biótipo B. Foram mensurados o nº de ovos, ninfas e adultos da praga após três períodos de infestação e a atividade das enzimas POX, PPO e PAL como também as variáveis fisiológicas A, E, gs, Ci, iWUE, EiC e WUE, fluorescência, clorofila e nº de tricomas. Os mutantes apresentaram menor infestação e colonização da praga; maior atividade das enzimas oxidativas; e menor desgaste a fisiologia ao ser exposta ao ataque de B. tabaci quando comparados ao Santa Clara. O aurea confere maior resistência, ativa seus mecanismos bioquímicos de defesa e sofre menos danos fisiológicos diante da infestação de B. tabaci. Artigo III: Teve por objetivo investigar a interação tritrófica entre tomateiros mutantes, B. tabaci biótipo B e o parasitoide Encarsia hispida. Utilizaram-se os tomateiros como hospedeiros da praga, e ninfas de 3º e 4º instares foram submetidas ao parasitismo de E. hispida. Avaliou-se o desenvolvimento biológico do parasitoide e também o índice de parasitismo natural e sob liberações deste agente. O desenvolvimento biológico do parasitoide não foi afetado pelos tomateiros mutantes, assim como a razão sexual. Quanto ao parasitismo, o índice foi maior em ambiente protegido, sendo o mutante aurea e o cultivar padrão com os maiores valores, já em campo não se observou diferenças entre os tomateiros. Os mutantes proporcionam um desenvolvimento biológico adequado ao parasitoide; o índice de parasitismo é maior diante da liberação do parasitoide; o aurea e o Santa Clara apresentam maiores índices de parasitismo
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Resistência de tomateiros mutantes a Bemisia tabaci (Gennadius, 1889)(Hemiptera: Aleyrodidae) biótipo B e influência sobre Encarsia hispida (Hymenoptera: Aphelinidae)
'Portal de Periodicos UFPB', 2019Co-Authors: Mileny Dos Santos De ,souzaAbstract:The tomato is one of the most cultivated and consumed vegetables in the world, however it is considered a high risk crop when we consider the large number of phytosanitary problems in which it is affected. Being the whitefly Bemisia tabaci biotype B, one of these main problems, given the damages and the cost of control that is inserted in its production. The use of resistant cultivars associated to biological control within an Integrated Pest Management program can act as one of the best solutions to problems with this pest, since the reduction or elimination of control with pesticides. In view of the above, the general objective of this research was to determine if mutant tomatoes confer resistance to Bemisia tabaci biotype B and its influence on the parasitoid Encarsia hispida. The research was carried out in the Laboratory of Entomology of the Federal University of Paraiba, Campus II Areia-PB, addressing in three articles to the topics explained above. The performance of five mutant tomatoes (aurea, cry, phyA, phyB1, phyB2) plus one susceptible standard tomato ('IAC-Santa Clara') were evaluated in a greenhouse and field environment. Article I: The objective of this study was to determine if mutant tomatoes confer resistance to B. tabaci biotype B. In the free choice test (TLE), the number of eggs, nymphs and adults / plants was measured and, furthermore, the index of attractiveness (AI) and the index of preference for IPO oviposition, colonization of nymphs, damage and growth of fumagina. The number of eggs, IPO, insect biology and number of trichomes were measured in the non-choice test (TSE). In the TLE, the standard cultivar presented higher number of eggs, nymphs and adults, higher IPA, IPO, damage and growth of the fumagina, besides high colonization of nymphs and low number of trichomes. In the TLE the aurea provided the largest and the standard cultivar the shortest number of days to complete the insect biology. The aurea presents resistance type antibiosis and antixenosis, less damages to the plants and less growth of the fumagina when infested by B. tabaci biotype B. Article II: The biochemical and physiological behavior of mutant tomatoes against the B. tabaci biotype B attack was verified by measuring the number of eggs, nymphs and adults of the pest after three periods of infestation and the activity of POX, PPO and PAL enzymes as well as the physiological variables A, E, gs, Ci, iWUE, EiC and WUE, fluorescence, chlorophyll and number of trichomes. The mutants presented lower infestation and colonization of the pest; increased activity of oxidative enzymes; and less wear the physiology against the attack of B. tabaci when compared to 'Santa Clara'. The aurea confers greater resistance, activates its biochemical defense mechanisms, and suffers less physiological damage in the face of B. tabaci infestation. Article III: The objective was to investigate the Tritrophic Interaction between mutant tomatoes, B. tabaci biotype B and the parasitoid Encarsia hispida. Tomatoes were used as hosts of the pest, and the 3rd and 4th instar nymphs were submitted to the parasitism of E. hispida. It was evaluated the biological development of the parasitoid and also the natural parasitism index and under releases of this agent. The biological development of the parasitoid was not affected by the mutant tomatoes, as well as the longevity and the sexual ratio. As for the parasitism, the index was higher in protected environment, the mutant aurea and the standard cultivar with the highest values, already in the field no differences were observed among tomato plants. Mutants provide adequate biological development to the parasitoid; the rate of parasitism is higher when the parasitoid is released; aurea and ‘Santa Clara’ have higher rates of parasitism.NenhumaO tomateiro é uma das hortaliças mais cultivadas e consumidas no mundo. No entanto, é considerada uma cultura de alto risco quando consideramos o grande número de problemas fitossanitário no qual é acometida. A mosca-branca Bemisia tabaci biótipo B, é um desses principais problemas, dado os danos e o custo de controle que insere na produção do tomate. Cultivares resistentes associados ao controle biológico dentro de um programa de Manejo Integrado de Pragas podem atuar como uma das melhores soluções para os problemas com essa praga, visto a redução ou eliminação do controle com pesticidas. Diante do exposto o objetivo geral dessa pesquisa foi determinar se tomateiros mutantes conferem resistência a Bemisia tabaci biótipo B e sua influência sobre o parasitoide Encarsia hispida. A pesquisa foi realizada no Laboratório de Entomologia da Universidade Federal da Paraíba, Campus II Areia-PB, abordando em três artigos as temáticas acima explanadas. Em ambiente telado e campo, avaliou-se o desempenho de cinco tomateiros mutantes (aurea, cry, phyA, phyB1, phyB2) mais um tomateiro padrão suscetível (‘IAC-Santa Clara’). Artigo I: Objetivou-se determinar se tomateiros mutantes conferem resistência a mosca-branca B. tabaci biótipo B. No teste de livre escolha (TLE), mensurou-se o número de ovos, ninfas e adultos/plantas e, calculou-se também o índice de atratividade (IA), índice de preferência para oviposição IPO, colonização das ninfas, danos e crescimento da fumagina. No teste sem chances de escolha (TSE) mensurou-se o nº de ovos, o IPO, a biologia do inseto e o nº de tricomas. No TLE o Santa Clara apresentou maior nº de ovos, ninfas e adultos, maiores IPA e IPO, danos e crescimento da fumagina, além de alta colonização das ninfas e baixo nº de tricomas. No TSE o aurea proporcionou o maior e o cultivar padrão o menor nº de dias para completar a biologia do inseto. O aurea apresenta resistência tipo antibiose e antixenose, menos danos às plantas e menor crescimento da fumagina quando infestados por B. tabaci biótipo B. Artigo II: Verificou-se o comportamento bioquímico e fisiológico de tomateiros mutantes frente ao ataque de B. tabaci biótipo B. Foram mensurados o nº de ovos, ninfas e adultos da praga após três períodos de infestação e a atividade das enzimas POX, PPO e PAL como também as variáveis fisiológicas A, E, gs, Ci, iWUE, EiC e WUE, fluorescência, clorofila e nº de tricomas. Os mutantes apresentaram menor infestação e colonização da praga; maior atividade das enzimas oxidativas; e menor desgaste a fisiologia ao ser exposta ao ataque de B. tabaci quando comparados ao Santa Clara. O aurea confere maior resistência, ativa seus mecanismos bioquímicos de defesa e sofre menos danos fisiológicos diante da infestação de B. tabaci. Artigo III: Teve por objetivo investigar a interação tritrófica entre tomateiros mutantes, B. tabaci biótipo B e o parasitoide Encarsia hispida. Utilizaram-se os tomateiros como hospedeiros da praga, e ninfas de 3º e 4º instares foram submetidas ao parasitismo de E. hispida. Avaliou-se o desenvolvimento biológico do parasitoide e também o índice de parasitismo natural e sob liberações deste agente. O desenvolvimento biológico do parasitoide não foi afetado pelos tomateiros mutantes, assim como a razão sexual. Quanto ao parasitismo, o índice foi maior em ambiente protegido, sendo o mutante aurea e o cultivar padrão com os maiores valores, já em campo não se observou diferenças entre os tomateiros. Os mutantes proporcionam um desenvolvimento biológico adequado ao parasitoide; o índice de parasitismo é maior diante da liberação do parasitoide; o aurea e o Santa Clara apresentam maiores índices de parasitismo
Zeyaur R Khan - One of the best experts on this subject based on the ideXlab platform.
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signal grass brachiaria brizantha oviposited by stemborer chilo partellus emits herbivore induced plant volatiles that induce neighbouring local maize zea mays varieties to recruit cereal stemborer larval parasitoid cotessia sesamiae
International Journal of Sciences: Basic and Applied Research, 2015Co-Authors: Henlay Juma Otieno Magara, Charles A O Midega, Siprine Akinyi Otieno, Calistus K P O Ogol, Toby J A Bruce, J A Pickett, Zeyaur R KhanAbstract:Plants respond to attack by herbivores with the release of herbivore-induced plant volatiles (HIPVs). In return, natural enemies (predators and parasitoids) respond to these emitted herbivore-induced plant volatiles while foraging for their hosts. Neighboring plants of the same family may be induced by the emitted HIPVs. This is a Tritrophic Interaction that leads to an ‘indirect’ plant defense characteristic within species that recruit the natural enemies to ward off pests. The objective of this study was t o evaluat e the effect of HIPVs of B. brizantha on neighbouring maize plants on the management of Chilo partellus. This was done by entrainment of volatiles from five maize varieties: Nyamula (local maize), jowi (local maize), Cuba 91 (a landrace from Cuba), Western hybrid 505 (WH505) and Pwani hybrid 4 (PH4). In the first set up we exposed the five maize varieties to B. brizantha with C. partellus eggs for 48 hours and removed them from the grass and then entrained them. In the second set up we exposed these five maize varieties to B. brizantha without C. partellus eggs for 48 hours and removed them from the grass and then entrained them. Lastly in the third set up we entrained non-exposed maize plants. Olfactory responses of the cereal stemborer parasitoid Cotesia sesamiae to volatiles emitted by these maize plant varieties were studied in a 4-way olfactometer. Gas chromatography and coupled Gas chromatography-Mass spectrometry was done to identify physiologically active compounds of the collected volatiles. The findings indicated that egg ovi position by the gravid Chilo partellus on signal grass Brachiaria brizantha caused production of HIPVs that further induced smallholder farmers’ own maize varieties (Nyamula and Jowi) and a landrace maize from Latin America (Cuba 91) to attract Cotessia sesamiae , a parasitoid of Chilo partellus . Gravid females of Cotessia sesamiae were significantly more attracted to the volatiles of the smallholder farmers’ own maize varieties and Latin America landrace maize exposed to B. brizantha with Chilo partellus eggs. In contrast, olfactometer bioassays showed that female C. sesamiae were significantly less attracted to HIPVs from plants exposed to B. brizantha without C. partellus eggs and to volatiles from non-exposed maize plants to either grass with eggs or without eggs. Hybrids were not induced hence had no significant result. This holds a promise for development of a sophisticated defense strategy whereby parasitoids are recruited in advance, awaiting the eggs to hatch. When the eggs hatch, the larvae are attacked, stopping them from damaging the maize crop. Our findings indicate that B. brizantha can be used to induce defense in a neighboring maize crop to attract C. sesamiae parasitoids and as a trap crop to ward off stemborers from the maize crop. This trait in B. brizantha should be tested further in other cereal crops to access their potential of being induced. The possible role of signal grass in pest management is discussed.
Ted C. J. Turlings - One of the best experts on this subject based on the ideXlab platform.
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Plant strengtheners enhance parasitoid attraction to herbivore-damaged cotton via qualitative and quantitative changes in induced volatiles.
Pest management science, 2014Co-Authors: Islam S. Sobhy, Matthias Erb, Ted C. J. TurlingsAbstract:BACKGROUND Herbivore-damaged plants release a blend of volatile organic compounds (VOCs) that differs from undamaged plants. These induced changes are known to attract the natural enemies of the herbivores and therefore are expected to be important determinants of the effectiveness of biological control in agriculture. One way of boosting this phenomenon is the application of plant strengtheners, which has been shown to enhance parasitoid attraction in maize. It is unclear whether this is also the case for other important crops. RESULTS The plant strengtheners BTH [benzo (1,2,3) thiadiazole-7-carbothioic acid S-methyl ester] and laminarin were applied to cotton plants, and the effects on volatile releases and the attraction of three hymenopteran parasitoids, Cotesia marginiventris, Campoletis sonorensis and Microplitis rufiventris, were studied. After treated and untreated plants were induced by real or simulated caterpillar feeding, it was found that BTH treatment increased the attraction of the parasitoids, whereas laminarin had no significant effect. BTH treatment selectively increased the release of two homoterpenes and reduced the emission of indole, the latter of which had been shown to interfere with parasitoid attraction in earlier studies. Canonical variate analyses of the data show that the parasitoid responses were dependent on the quality rather than the quantity of volatile emission in this Tritrophic Interaction. CONCLUSION Overall, these results strengthen the emerging paradigm that induction of plant defences with chemical elicitors such as BTH could provide a sustainable and environmentally friendly strategy for biological control of pests by enhancing the attractiveness of cultivated plants to natural enemies of insect herbivores. © 2014 Society of Chemical Industry
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Systemic root signalling in a belowground, volatile-mediated Tritrophic Interaction.
Plant cell & environment, 2011Co-Authors: Ivan Hiltpold, Matthias Erb, Christelle A. M. Robert, Ted C. J. TurlingsAbstract:Plants attacked by leaf herbivores release volatile organic compounds (VOCs) both locally from the wounded site and systemically from non-attacked tissues. These volatiles serve as attractants for predators and parasitoids. This phenomenon is well described for plant leaves, but systemic induction of VOCs in the roots has remained unstudied. We assessed the spatial and temporal activation of the synthesis and release of (E)-β-caryophyllene (EβC) in maize roots upon feeding by larvae of Diabrotica virgifera virgifera, as well as the importance of systemically produced EβC for the attraction of the entomopathogenic nematode Heterorhabditis megidis. The production of EβC was found to be significantly stronger at the site of attack than in non-attacked tissues. A weak, but significant, increase in transcriptional activity of the EβC synthase gene tps23 and a corresponding increase in EβC content were observed in the roots above the feeding site and in adjacent roots, demonstrating for the first time that herbivory triggers systemic production of a volatile within root systems. In belowground olfactometers, the nematodes were significantly more attracted towards local feeding sites than systemically induced roots. The possible advantages and disadvantages of systemic volatile signalling in roots are discussed.
