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Otto Schmidt - One of the best experts on this subject based on the ideXlab platform.
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An empirical model of the sympatric coexistence of two strains of the endoparasitoid wasp Venturia canescens.
Archives of insect biochemistry and physiology, 2006Co-Authors: Harry L.s. Roberts, Michael A. Keller, Otto SchmidtAbstract:Recent research has demonstrated that a laboratory culture of the asexual solitary endoparasitoid wasp Venturia canescens Grav. (Hymenoptera: Ichneumonidae) contains two genetically and phenotypically distinct lines, coexisting on their host the flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). The basis to the coexistence of the two lines appears to be differences in their reproductive success under single parasitism and Superparasitism. Furthermore, examination of field-derived wasps from several locations has shown that the phenotypes displayed by the laboratory colonies also co-occur in field populations. Historically, the impossibility of showing that two species do not occupy separate niches has precluded any demonstration of sympatric coexistence in the field. Here we present the results of an iterative model that uses a range of experimental life history data to predict the stable composition of a mixed population of two lines displaying the laboratory phenotypes under different rates of Superparasitism. The model predicts that sympatric coexistence of the two lines is possible when the overall rate of Superparasitism is between 4 and 12% or greater. These values are within the rates reported for other solitary endoparasitoid wasp species in the field, and so demonstrate that the sympatric coexistence under natural conditions of two species that display the phenotypes observed in the laboratory lines is, in principle, possible.
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The outcome of in-vitro contests between larvae of the endoparasitoid Venturia canescens depends on both their relative and absolute ages
Behavioral Ecology and Sociobiology, 2004Co-Authors: Harry L.s. Roberts, Oliver True, Otto SchmidtAbstract:In a laboratory colony of the asexual solitary endoparasitoid Venturia canescens Grav. (Hymenoptera: Ichneumonidae), two genetically and phenotypically distinct lines (RP and RM) appear to coexist sympatrically, with the reproductive success of the RM-line being greater under con-specific Superparasitism but lower under self Superparasitism. To investigate the basis of the RM-line’s advantage under con-specific Superparasitism, we examined the outcome of inter-larval physical combat under in-vitro conditions. The results showed that the outcome depended on both the relative and absolute ages of the contestants, and that the competitive abilities of the two lines were not symmetric. In contests involving a larva and an egg, the unhatched wasp lost. In contests involving two larvae, at least one of which was newly hatched, the RP-larva tended to lose. Finally, if both larvae were at least 8–10 h post-hatching when the contest occurred, then the larger larva tended to lose, with the probability increasing with the difference in length between the two larvae. Thus, the higher reproductive success of the RM-line under competing Superparasitism with the RP-line is due to a physiological difference between the newly hatched larvae of the two lines, which results in an advantage to the RM-larva independent of the order or time interval between ovipositions.
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The development of the endoparasitoid wasp Venturia canescens in superparasitised Ephestia kuehniella.
Journal of insect physiology, 2004Co-Authors: Harry L.s. Roberts, Oliver True, Otto SchmidtAbstract:Using a molecular marker that allows the differentiation of two strains of the solitary endoparasitoid wasp Venturia canescens, the study investigated the influence of host mass and the time interval between ovipositions on the survival and development of larvae from both the first and second laid eggs in superparasitised Ephestia kuehniella. As the time interval between ovipositions increased both overall and Superparasitism success decreased, however, time between, and order of, ovipositions had little effect on other developmental parameters. Adult size increased with host mass under both parasitism and Superparasitism, while host mortality decreased with host mass under Superparasitism. In addition, wasps emerging from superparasitised hosts were larger than wasps from parasitised hosts. The results confirm that for V. canescens on the host E. kuehniella both self- and conspecific-Superparasitism will be an adaptive strategy when hosts are the limiting factor.
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Two coexisting lines of the endoparasitoid Venturia canescens show differences in reproductive success under conspecific Superparasitism
Journal of Insect Physiology, 2003Co-Authors: Annette Reineke, Harry L.s. Roberts, Otto SchmidtAbstract:In a laboratory colony of the endoparasitic wasp Venturia canescens Grav. (Hymenoptera: Ichneumonidae), two genetically distinct lines (RP, RM) appear to coexist sympatrically. The two lines display pronounced differences in ovarian morphology, parasitism behaviour and number of offspring produced under competing Superparasitism. Since V. canescens is a solitary endoparasitoid, larvae inside superparasitised hosts must compete for host possession. We examined the outcome of conspecific Superparasitism between the wasp lines with different time intervals between ovipositions. The results showed that the competitive abilities of the two lines were not symmetrical. Further, the RM-line won a significantly higher fraction (around 60%) of the overall contests. Dissection of parasitoid larvae from their hosts indicated that most contests between competing larvae had occurred within the first 24 h of the eggs hatching, suggesting the advantage of the RM-line relates to physical combat. It was previously thought that the coexistence of the two lines was exclusively due to maternal effects. The results of this study indicate for the first time that these differences are based on phenotypic variations in both the larval offspring and the mother.
Harry L.s. Roberts - One of the best experts on this subject based on the ideXlab platform.
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An empirical model of the sympatric coexistence of two strains of the endoparasitoid wasp Venturia canescens.
Archives of insect biochemistry and physiology, 2006Co-Authors: Harry L.s. Roberts, Michael A. Keller, Otto SchmidtAbstract:Recent research has demonstrated that a laboratory culture of the asexual solitary endoparasitoid wasp Venturia canescens Grav. (Hymenoptera: Ichneumonidae) contains two genetically and phenotypically distinct lines, coexisting on their host the flour moth Ephestia kuehniella Zeller (Lepidoptera: Pyralidae). The basis to the coexistence of the two lines appears to be differences in their reproductive success under single parasitism and Superparasitism. Furthermore, examination of field-derived wasps from several locations has shown that the phenotypes displayed by the laboratory colonies also co-occur in field populations. Historically, the impossibility of showing that two species do not occupy separate niches has precluded any demonstration of sympatric coexistence in the field. Here we present the results of an iterative model that uses a range of experimental life history data to predict the stable composition of a mixed population of two lines displaying the laboratory phenotypes under different rates of Superparasitism. The model predicts that sympatric coexistence of the two lines is possible when the overall rate of Superparasitism is between 4 and 12% or greater. These values are within the rates reported for other solitary endoparasitoid wasp species in the field, and so demonstrate that the sympatric coexistence under natural conditions of two species that display the phenotypes observed in the laboratory lines is, in principle, possible.
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The outcome of in-vitro contests between larvae of the endoparasitoid Venturia canescens depends on both their relative and absolute ages
Behavioral Ecology and Sociobiology, 2004Co-Authors: Harry L.s. Roberts, Oliver True, Otto SchmidtAbstract:In a laboratory colony of the asexual solitary endoparasitoid Venturia canescens Grav. (Hymenoptera: Ichneumonidae), two genetically and phenotypically distinct lines (RP and RM) appear to coexist sympatrically, with the reproductive success of the RM-line being greater under con-specific Superparasitism but lower under self Superparasitism. To investigate the basis of the RM-line’s advantage under con-specific Superparasitism, we examined the outcome of inter-larval physical combat under in-vitro conditions. The results showed that the outcome depended on both the relative and absolute ages of the contestants, and that the competitive abilities of the two lines were not symmetric. In contests involving a larva and an egg, the unhatched wasp lost. In contests involving two larvae, at least one of which was newly hatched, the RP-larva tended to lose. Finally, if both larvae were at least 8–10 h post-hatching when the contest occurred, then the larger larva tended to lose, with the probability increasing with the difference in length between the two larvae. Thus, the higher reproductive success of the RM-line under competing Superparasitism with the RP-line is due to a physiological difference between the newly hatched larvae of the two lines, which results in an advantage to the RM-larva independent of the order or time interval between ovipositions.
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The development of the endoparasitoid wasp Venturia canescens in superparasitised Ephestia kuehniella.
Journal of insect physiology, 2004Co-Authors: Harry L.s. Roberts, Oliver True, Otto SchmidtAbstract:Using a molecular marker that allows the differentiation of two strains of the solitary endoparasitoid wasp Venturia canescens, the study investigated the influence of host mass and the time interval between ovipositions on the survival and development of larvae from both the first and second laid eggs in superparasitised Ephestia kuehniella. As the time interval between ovipositions increased both overall and Superparasitism success decreased, however, time between, and order of, ovipositions had little effect on other developmental parameters. Adult size increased with host mass under both parasitism and Superparasitism, while host mortality decreased with host mass under Superparasitism. In addition, wasps emerging from superparasitised hosts were larger than wasps from parasitised hosts. The results confirm that for V. canescens on the host E. kuehniella both self- and conspecific-Superparasitism will be an adaptive strategy when hosts are the limiting factor.
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Two coexisting lines of the endoparasitoid Venturia canescens show differences in reproductive success under conspecific Superparasitism
Journal of Insect Physiology, 2003Co-Authors: Annette Reineke, Harry L.s. Roberts, Otto SchmidtAbstract:In a laboratory colony of the endoparasitic wasp Venturia canescens Grav. (Hymenoptera: Ichneumonidae), two genetically distinct lines (RP, RM) appear to coexist sympatrically. The two lines display pronounced differences in ovarian morphology, parasitism behaviour and number of offspring produced under competing Superparasitism. Since V. canescens is a solitary endoparasitoid, larvae inside superparasitised hosts must compete for host possession. We examined the outcome of conspecific Superparasitism between the wasp lines with different time intervals between ovipositions. The results showed that the competitive abilities of the two lines were not symmetrical. Further, the RM-line won a significantly higher fraction (around 60%) of the overall contests. Dissection of parasitoid larvae from their hosts indicated that most contests between competing larvae had occurred within the first 24 h of the eggs hatching, suggesting the advantage of the RM-line relates to physical combat. It was previously thought that the coexistence of the two lines was exclusively due to maternal effects. The results of this study indicate for the first time that these differences are based on phenotypic variations in both the larval offspring and the mother.
Francisco J Beitia - One of the best experts on this subject based on the ideXlab platform.
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biology of aganaspis daci hymenoptera figitidae parasitoid of ceratitis capitata diptera tephritidae mode of reproduction biological parameters and Superparasitism
Crop Protection, 2018Co-Authors: Jose Tormos, Josep Daniel Asis, Beatriz Sabatermunoz, Luis De Pedro, Francisco J BeitiaAbstract:Abstract Biological parameters of parasitoid wasps have a decisive effect on their effective performance as biological control agents. The mode of reproduction, several mating-dependent biological parameters (such as longevity, fertility, percentage parasitism, induced mortality and population reduction) as well as Superparasitism of the parasitoid Aganaspis daci (Weld) infesting larvae of the medfly Ceratitis capitata (Wiedemann) were assessed under laboratory conditions. The results indicated an arrhenotokous haplodiploid mode of reproduction, with unmated females producing only males and mated females producing a female-biased offspring (♀♀/(♀♀+♂♂) = 0.73) ratio from the first day of life. Additionally, positive mating status showed a significant negative effect on longevity (14–22 days), but no significant differences on fertility, percentage parasitism, induced mortality or population reduction between mated and unmated females. A strong effect of the age of females on fertility and percentage of parasitism was also found, with both decreasing with increasing female age and a similar oviposition pattern for mated and unmated females. Our findings showed the occurrence of Superparasitism in this species, with a significant negative effect of host abundance and a significant positive effect of parasitoid (conspecific females) abundance on Superparasitism rate. The existence of self-Superparasitism was confirmed for females acting alone, whilst female aggregation led to a higher intensity (up to eight eggs/host pupa) and percentage of, presumably, conspecific Superparasitism. The information reported here on several biological aspects of A. daci infesting C. capitata supports the use of this parasitoid in biological control programmes against medfly and highlights the importance of several factors, such as the sex ratio or the parasitoid/host ratio under rearing and field conditions, when planning mass production and field releases of this parasitoid.
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offspring production and self Superparasitism in the solitary ectoparasitoid spalangia cameroni hymenoptera pteromalidae in relation to host abundance
Bulletin of Entomological Research, 2012Co-Authors: E A Bockmann, Jose Tormos, Francisco J Beitia, Klaus FischerAbstract:Parasitoid fitness strongly depends on the availability and quality of hosts, which provide all resources required for larval development. Several factors, such as host size and previous parasitation, may affect host quality. Because self-Superparasitism induces competition among a female's offspring, it should only occur if there is an imperfect recognition of self-parasitized hosts or if there is a fitness advantage to self-Superparasitism. Against this background, we investigated self-Superparasitism and offspring production in Spalangia cameroni (Hymenoptera: Pteromalidae) in relation to the abundance of a novel host, Ceratitis capitata (Diptera: Tephritidae). Individual pairs of parasitoids were provided with either two (low host abundance) or ten (high host abundance) pupae per day. Under high host abundance, lifetime fecundity (number of eggs laid), offspring number, number of pupae parasitized and hosts killed were greater than under low host abundance, whereas the number of eggs per host was lower; and the proportion of hosts that did not produce offspring tended to be lower. The latter suggests the occurrence of ovicide, when hosts are scarce due to an at least imperfect recognition of previously self-parasitized hosts. Offspring production per parasitized pupa was higher when hosts were scarce and levels of self-Superparasitism high, suggesting the existence of beneficial effects of self-Superparasitism.
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Superparasitism in laboratory rearing of spalangia cameroni hymenoptera pteromalidae a parasitoid of medfly diptera tephritidae
Bulletin of Entomological Research, 2012Co-Authors: Jose Tormos, Josep Daniel Asis, Beatriz Sabatermunoz, L Banos, S F Gayubo, Francisco J BeitiaAbstract:The frequency of Superparasitism and its effects on the quality of laboratory-reared Spalangia cameroni (Hymenoptera: Pteromalidae) parasitoids were investigated under laboratory conditions. Numerous variables were measured, such as the number of ‘ovip holes’ per host as a measure of Superparasitism. Adult emergence and sex ratio, as well as female size, emergence ability from soil and longevity were also measured. Finally, an assessment was made of fertility and survival of adult parasitoids emerging from the medfly Ceratitis capitata (Diptera: Tephritidae) pupae with different levels of Superparasitism. A high frequency and prevalence of Superparasitism under laboratory rearing conditions was observed. The number of ‘ovip holes’ per host ranged from one to 17, with an average (±SD) of 2.8±3.4. Sex ratios became increasingly female-biased with increasing levels of Superparasitism, although overall levels of wasp emergence (male, female) declined. Nevertheless, no relationship was discerned between female size and level of Superparasitism. The ‘emergence ability from the soil’ was higher in those parasitoids that emerged from strongly superparasitized hosts, but not related to the type of substrate in which the host pupae were buried. The level of Superparasitism did not have a significant effect on the longevity, fertility and survival of female parasitoids. Our results support the hypothesis that Superparasitism in S. cameroni might be adaptive, since attributes such as ‘emergence ability from the soil’, longevity, fertility and survival were not affected by the level of Superparasitism or the presumably detrimental effects derived from physical combats among conspecific larvae. Our findings are relevant to recommendations for rearing S. cameroni for biological control releases, as well as shedding light on Superparasitism under both laboratory and field conditions.
Gay C. Marris - One of the best experts on this subject based on the ideXlab platform.
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The relationship between conspecific Superparasitism and the outcome of in vitro contests staged between different larval instars of the solitary endoparasitoid Venturia canescens
Behavioral Ecology and Sociobiology, 1996Co-Authors: Gay C. Marris, Julia M. CasperdAbstract:When endoparasitoid wasps oviposit into hosts which have already been parasitized (= Superparasitism), this results in potentially lethal interlarval competition. For solitary species, the decision to lay additional eggs should therefore be based on the probability of superparasite survival in any superparasitized host. In this study, in vitro contests staged between three larval instars of Venturia canescens Grav. (Hymenoptera: Ichneumonidae) reveal that the age difference between competitors affects the outcome of interlarval competition. Three parameters were used to assess parasitoid performance: the number of fights initiated, the number of bites inflicted, and the duration of each bite. When fighting takes place between two first instars, then both competitors were found to be evenly matched. However, at greater age differences, first-instar competitors appeared to win more fights than their larger second instar rivals. The advantage shown by younger competitors is most pronounced in contests staged between first and third instar larvae. These findings are consistent with the increasingly high levels of conspecific Superparasitism shown by V. canescens in the first 5 days after initial host attack, suggesting that this parasitoid can deploy her use of deliberate Superparasitism in an adaptive way.
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The perception of genetic similarity by the solitary parthenogenetic parasitoid Venturia canescens, and its effects on the occurrence of Superparasitism
Entomologia Experimentalis et Applicata, 1996Co-Authors: Gay C. Marris, Stephen F. Hubbard, Charles ScrimgeourAbstract:Observations of oviposition patterns adopted by uniparental lines of the solitary parthenogenetic endoparasitoid Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) reveal that the occurrence of Superparasitism is influenced by the genealogical relationship between adult wasps and conspecific progeny which they encounter within parasitized hosts (larvae of the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae)): the closer the relationship, the lower the occurrence of Superparasitism. This behaviour has an adaptive interpretation because it allows Venturia to avoid selective penalties incurred when larval offspring compete with genetically similar progeny. Venturia 's ability to discriminate between her own eggs, those of her relatives, and those of other conspecifics is mediated by a chemical marker produced by Dufour's gland, an accessory of the adult female's reproductive system. This conclusion is supported by chemical analyses which reveal that, while Dufour's glands from unrelated females show highly significant variation between the spectra of volatile hydrocarbons contained in their respective secretions, closely-related females show negligible differences in their chemical constitutions. These findings lend further weight to current theory that Superparasitism can be deliberately deployed as an adaptive part of a wasp's behavioural repertoire, and also identify the physiological mechanism by which such an oviposition response may be achieved.
Stephen F. Hubbard - One of the best experts on this subject based on the ideXlab platform.
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avoidance of Superparasitism a matter of learning
Animal Behaviour, 1999Co-Authors: Stephen F. Hubbard, Ian F. Harvey, John P FletcherAbstract:Abstract Superparasitism (laying eggs into parasitized hosts) by solitary parasitoids was regarded for a long time as a mistake on the part of the foraging parasitoid, but is now widely accepted as often adaptive. In Venturia canescens the rate of avoidance of Superparasitism has been shown to rise over the first 20 min from the deposition of the first egg, possibly because of a constraint in the detectability of the marker used to label parasitized hosts. Here, we show that the increase in avoidance of Superparasitism with time is the result of a female’s experience of hosts in the interval between laying an egg in a host and re-encountering that same host. Wasps deprived of hosts in this interval showed no avoidance of Superparasitism; those given healthy hosts every 3 min during this interval showed increasing avoidance of Superparasitism with time. Furthermore, the marker was detectable in a host within 3 min of oviposition. The results suggest that wasps quickly acquire information about the abundance of healthy hosts in their environment, and base their decision to superparasitize on this information.
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The perception of genetic similarity by the solitary parthenogenetic parasitoid Venturia canescens, and its effects on the occurrence of Superparasitism
Entomologia Experimentalis et Applicata, 1996Co-Authors: Gay C. Marris, Stephen F. Hubbard, Charles ScrimgeourAbstract:Observations of oviposition patterns adopted by uniparental lines of the solitary parthenogenetic endoparasitoid Venturia canescens Gravenhorst (Hymenoptera: Ichneumonidae) reveal that the occurrence of Superparasitism is influenced by the genealogical relationship between adult wasps and conspecific progeny which they encounter within parasitized hosts (larvae of the Indian meal moth Plodia interpunctella Hübner (Lepidoptera: Pyralidae)): the closer the relationship, the lower the occurrence of Superparasitism. This behaviour has an adaptive interpretation because it allows Venturia to avoid selective penalties incurred when larval offspring compete with genetically similar progeny. Venturia 's ability to discriminate between her own eggs, those of her relatives, and those of other conspecifics is mediated by a chemical marker produced by Dufour's gland, an accessory of the adult female's reproductive system. This conclusion is supported by chemical analyses which reveal that, while Dufour's glands from unrelated females show highly significant variation between the spectra of volatile hydrocarbons contained in their respective secretions, closely-related females show negligible differences in their chemical constitutions. These findings lend further weight to current theory that Superparasitism can be deliberately deployed as an adaptive part of a wasp's behavioural repertoire, and also identify the physiological mechanism by which such an oviposition response may be achieved.
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Host-searching behavior of Venturia canescens (Grav.) (Hymenoptera: Ichneumonidae): Superparasitism
Journal of Insect Behavior, 1994Co-Authors: J. P. Hughes, Ian F. Harvey, Stephen F. HubbardAbstract:The foraging behavior ofVenturia canescens, a solitary endoparasitoid of lepidopteran larvae, was investigated in the laboratory. FemaleVenturia canescens with a larger number of mature eggs to lay were found to have higher levels of Superparasitism (measured as numbers of eggs laid per parasitized host). Increased parasitoid density was found to result in reduced levels of Superparasitism by host-deprived (i.e.,undepleted) wasps. Females which had been allowed access to hosts before the experiment (depleted wasps) laid fewer eggs per parasitized host than undepleted wasps, although there was no significant difference in the levels of Superparasitism among the depletion periods of 1, 2, 5, and 7 h. It was also found that an egg which was encountered less than 15 min after oviposition was much less likely to be avoided than one which was encountered after more than 15 min had elapsed.
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parasitoid diets does Superparasitism pay
Trends in Ecology and Evolution, 1991Co-Authors: Douglas Cullen Speirs, Thomas N Herratt, Stephen F. HubbardAbstract:Abstract The ability of insect parasitoids to discriminate between parasitized and unparasitized hosts is well documented. Despite this, hosts that have been parasitized more than once are frequently found, an occurrence known as Superparasitism. Since Superparasitism results in interlarval competition, it was generally assumed to be caused by discriminatory ‘mistakes’. Recently, theoretical studies have suggested that under certain circumstances Superparasitism can be optimal. Superparasitism can thus be viewed as an active foraging strategy rather than as a passive process. Because parasitoids show a direct link between foraging success and reproductive output, they afford important opportunities to test evolutionary models of behaviour.
