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Evolution moléculaire et structurale des membres de la famille génique des lipases pancréatique / Structural and functional evolution within the pancreatic lipases gene familyDridi, Kaouther 29 May 2013 (has links)
Helicoverpa armigera et Epiphyas postvittana, deux insectes nuisibles pour l'agriculture, ont développé des résistances contre la plupart des insecticides connus. Les lipides étant les constituants majeurs de leur régime alimentaire, les fonctions digestives des lipases deviennent alors une cible privilégiée pour l'élaboration de nouveaux insecticides. L'identification récente de gènes codant pour l'expression de protéines potentiellement actives et inactives apparentées aux lipases pancréatiques (PLRP) dans le tractus digestif de ces deux insectes et dont le niveau de transcription varie en fonction de leur régime alimentaire a ouvert un nouveau champ de recherche. Dans le but de contribuer à cette thématique, nous avons construit cinq lipases recombinantes d'E. postvittana (EpLIPs) et testé leur expression dans trois systèmes différents (E.coli, P.pastoris et bacculovirus). Le tractus digestif de Helicoverpa armigera a été étudié par chromatographie échangeuse d'ions et les différentes protéines séparées ont été testées en spectrométrie de masse et sur pHstat pour l'activité. Les résultats obtenus ont permis de mettre en évidence, pour la première fois, la présence à la fois d'une lipase active et d'une lipase inactive dans le tractus digestif d'un lépidoptère. Par ailleurs, la caractérisation biochimique d'un mutant GPLRP2-Δ β9 a été faite dans le but de comprendre l'effet de cette boucle, partiellement délétée dans les lipases d'insectes, dans la spécificité du substrat. Nous avons pu montrer que cette boucle β9 est essentielle pour la stabilisation de la chaîne acyle durant la réaction de lipolyse. / Helicoverpa armigera and Epiphyas postvittana, two major pest crops, have developed resistances against most of the known insecticides. Lipids being a major component of insect diet, digestive function of lipase are a target of choice for new insecticide design. The recent identification of active and inactive pancreatic lipase related protein (PLRP) genes in those two insects midgut, with a level of transcription depending on the diet, opened the field of insect digestive lipase study. In order to contribute to this thematic, we built five recombinants lipase from E. postvittana (EpLIPs) and tested their expression in three different systems (E.coli, P.pastoris and bacculovirus). Protein structure prediction of EpLIPs allowed us to develop some functional hypothesis enlightening the role of inactive lipase in lipid transport. H. armigera midgut contents were separated through a one step purification chromatography and the different fractions were tested for activity and mass spectrometry. The results obtained gave the first evidence of the presence of both an active and an inactive lipase in lepidopteran midgut. In addition to this work, a biochemical characterisation of a β9 GPLRP2 mutant was carried out to understand the effect of this loop, partially deleted in insect lipase, in substrate specificity. The result shows that β9 loop is essential for stabilizing the leaving acyl chain during the lipolysis reaction.
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Genes that define the Nucleopolyhedrovirus of Epiphyas postvittanaHyink, Otto, n/a January 2005 (has links)
The nucleopolyhedrovirus of Epiphyas postvittana (EppoMNPV) is being studied as a potential biological control agent for leafroller insects in New Zealand. The aims of this project were for the identification of putative genes that are unique to, variant in or missing from, the EppoMNPV genome and the subsequent analysis of at least one of these genes. The purpose of this was to identify and characterise genes potentially involved in the specific host range and virulence of EppoMNPV. This was achieved in two steps. Three genome regions lacking linearity between EppoMNPV and the closely related OpMNPV were previously identified and the targeted sequencing of these three regions was the first aim of this project. The collation of the entire genome sequence of EppoMNPV and comparison to the genome sequences of 22 other baculoviruses completed the identification of genes that are unique to, variant in or missing from EppoMNPV. The EppoMNPV genome was found to be 118,584 bp in size encoding 136 putative proteins. A total of 29 genes were found to be common to all baculoviruses, while the lepidopteran baculoviruses share a total of 62 genes. The genome of EppoMNPV encodes four putative unique genes, the sequence of which offers no clues as to possible function. EppoMNPV lacks a homologue of the superoxide dismutase gene common to all other lepidopteran baculoviruses The EppoMNPV IE2 homologue was identified as a 311 amino acid protein with a truncation in the N-terminal region. We hypothesised that this truncation would lead to a loss of function, which could contribute to the virulence and/or host range of EppoMNPV For this reason, the characterisation of the EppoMNPV IE2 was taken up as the second part of this project. A comparative study between the AcMNPV and EppoMNPV IE2 proteins identified no differences in function between these two proteins in Sf21 cells. The EppoMNPV IE2 was capable of trans-activating three constitutive promoters and localised to discrete nuclear bodies. Cell cycle arrest was not achieved by either IE2 protein in our cell culture system. The role of four sequence motifs common to all IE2 proteins was studied with the aid of mutational analysis. Mutation of arginine and acidic rich sequences of EppoMNPV IE2 showed only a slight decrease in trans-activation activity while mutation of the RING-finger and coiled-coil motifs reduced trans-activation to less than half that of wild type IE2. Mutation of the coiled-coil motif resulted in reduced amounts of protein localising to discrete nuclear regions. A series of deletion mutants from the N- and C-termini of EppoMNPV IE2 identified that the C-terminal 111 amino acids of EppoMNPV IE2 was sufficient for nuclear targeting. Deletion of the C-terminal 19 amino acids resulted in an IE2 mutant completely defective in both localisation and transactivation. This demonstrates that localisation to discrete nuclear regions is essential for EppoMNPV IE2 to act as a transactivator.
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The ecology of key arthropods for the management of Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) in Coonawarra vineyards, South Australia.Paull, Cate January 2008 (has links)
There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008
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The ecology of key arthropods for the management of Epiphyas postvittana (Walker) (Lepidoptera: Tortricidae) in Coonawarra vineyards, South Australia.Paull, Cate January 2008 (has links)
There is currently little knowledge about the dynamics of invertebrates in Australian viticultural ecosystems. This study was conducted in Coonawarra vineyards over three seasons (years) and has focused on identifying natural enemies, their seasonal phenology, multiple species interactions, and potential for the suppression of the pest lepidopteran Epiphyas postvittana (Tortricidae). The work presented in this thesis shows that endemic natural enemies have far greater potential to control E. postvittana than has been realised. An initial survey identified a diverse and abundant range of potential natural enemies. Of these, the species most likely to attack E. postvittana include a predatory mite Anystis baccarum and a number of hymenopteran parasitoids. The most abundant parasitoid in the vineyards was a braconid, Dolichogenidea tasmanica. Understanding the characteristic behaviour of parasitoids in response to host density can help to gauge their potential for pest suppression. The results of large-scale field experiments showed that the response of D. tasmanica to the density of E. postvittana was inversely density-dependent, and that parasitism was consistently higher in Cabernet Sauvignon compared with Chardonnay varieties. Despite the fact that interactions among multiple species of natural enemies can increase or decrease pest suppression, particularly when they share a common prey/host, few multispecies interactions have been investigated. Laboratory studies identified a novel interaction between the predatory mite A. baccarum an abundant predator in the vine canopy, the parasitoid D. tasmanica and host E. postvittana larvae. Although A. baccarum readily ate E. postvittana eggs and free roaming larvae, they could not access larva in their silk leaf rolls. However, the addition of D. tasmanica significantly increased predation of E. postvittana larvae, by altering the behaviour of host larvae and increasing their vulnerability to the mite. Experiments conducted at a landscape level in the Coonawarra showed that D. tasmanica was also present in habitat other than vineyards including native vegetation. However, it was not present in highly disturbed habitats. Although the exact mechanism for this remains unknown, results indicate that viticultural practices and resources in the surrounding landscape can influence the presence of parasitoids. Together, the findings presented in this thesis make a significant contribution towards developing sustainable pest management in Australian viticulture. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1320930 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2008
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Habitat manipulation to enhance biological control of light brown apple moth (Epiphyas Postvittana)Begum, Mahmuda January 2004 (has links)
Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg �sentinel cards� and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson�s curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered �selective food plants� for T. carverae whereas F. esculentum appears to be a �non-selective food plant�; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.
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Habitat manipulation to enhance biological control of light brown apple moth (Epiphyas Postvittana)Begum, Mahmuda January 2004 (has links)
Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg �sentinel cards� and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson�s curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered �selective food plants� for T. carverae whereas F. esculentum appears to be a �non-selective food plant�; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.
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