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Manfred Mackauer - One of the best experts on this subject based on the ideXlab platform.
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The developmental strategy of an idiobiont ectoparasitoid, Dendrocerus carpenteri: Influence of variations in Host Quality on offspring growth and fitness
Oecologia, 1998Co-Authors: Mathias Otto, Manfred MackauerAbstract:Dendrocerus carpenteri (Curtis) (Hymenoptera: Megaspilidae) is a solitary hyperparasitoid, which attacks prepupal and pupal stages of hymenopteran parasitoids inside mummified aphids. The larva feeds externally on the Host, which is envenomed by the female at oviposition. To evaluate the influence of variations in Host Quality on the growth, development and fitness of D. carpenteri, we varied the size and developmental stage of the primary parasitoid Host (Aphidius ervi Haliday), which was reared on different instars of pea aphid [Acyrthosiphon pisum (Harris)] and English grain aphid [Sitobion avenae (F.)]. Within each kind of Host, females eclosed from the relatively larger mummies, while males eclosed from the smaller mummies. Host size and hyperparasitoid size were correlated, and females were larger than males. In hyperparasitoids developing on prepupal and pupal Hosts, development time from oviposition to adult eclosion was proportional to size; females required more time for development than males. The mean relative growth rate was the same in males and females and increased with Host Quality, as predicted by the growth model of Mackauer and Sequeira (1993) for idiobiont parasitoids. Larvae developing on late-pupal stages and pharate adults of A. er vi were unable to consume sclerotized Host tissues; they were smaller and needed more time for development. The average number of mature eggs at eclosion was six, except in females developing on suboptimal Hosts, which contained only one egg or none. Egg volume was correlated with female size, possibly reflecting differences in larval ontogeny. We provide equations describing the relationship between Host Quality as indexed by hind-tibia length of the mummified aphid and adult body size in terms of dry mass, development time and mean relative growth rate of D. carpenteri. We discuss the usefulness of Host size as a proxy of Host Quality for idiobiont parasitoids, and provide examples of exceptions.
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Invitation paper: C.P. Alexander Fund. Host choice by aphidiid parasitoids (Hymenoptera: Aphidiidae): Host recognition, Host Quality, and Host value.
The Canadian Entomologist, 1996Co-Authors: Manfred Mackauer, J.p. Michaud, Wolfgang VölklAbstract:Species in the family Aphidiidae (Hymenoptera) parasitize exclusively ovoviviparous aphids. Females use a variety of information to detect and evaluate suitable Hosts. Olfactory cues associated with aphids, or the aphids’ Host plant, are important for Host location. Visual cues including aphid colour, shape, and movement can be evaluated from a distance without physical contact; aphid movement may act as a releasing stimulus for attack. Contact chemosensory cues (gustatory cues) are evaluated by antennation of the Host cuticle and during ovipositor probing. A potential Host must conform to the wasp’s response profile and satisfy minimum physiological and dietary requirements for immature development and growth. Host Quality is determined in part by attributes specific to each aphid species and in part by each aphid’s individual-specific growth potential. Host Quality for male and female progeny may vary as a result of different patterns of resource allocation and sexual size dimorphism. For an encountered aphid to be accepted as a Host, its perceived value must exceed the wasp’s response threshold for oviposition. Host value, as opposed to Host Quality, varies dynamically with parasitoid state variables such as age, egg load, and prior experience. A conceptual model of Host choice by aphidiid wasps is presented.
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Sexual size dimorphism in solitary parasitoid wasps: influence of Host Quality.
Oikos, 1996Co-Authors: Manfred MackauerAbstract:The relationship between female and male body size is allometric in aphidiid wasps. I present data on sexual size dimorphism in laboratory and field populations of Aphidius ervi, Aphidius smithi, Ephedrus californicus, and Monoctonus paulensis, four species of solitary parasitoids of pea aphid, Acyrthosiphon pisum. In terms of dry mass, females were larger than males developing in the same kinds of Host, but the magnitude of the difference was constant and specific for each species. Size differences were largest among parasitoids developing in small Hosts, with dimorphism declining at a decelerating rate with an increase in parasitoid size and, implicitly, Host Quality. It is proposed that body size is under different selection in males and females. If female size is important for Host capture and oviposition success (e.g., in species with long oviposition times, such as E. californicus), sexual size dimorphism may be accentuated.
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nutritional ecology of an insect Host parasitoid association the pea aphid aphidius ervi system
Ecology, 1992Co-Authors: Richard V Sequeira, Manfred MackauerAbstract:Evolutionary Host-size models assume that Host Quality for parasitoid growth and development is a linear function of Host size. To test this assumption, we compared the growth patterns of the hymenopteran parasitoid Aphidius ervi when it developed in different nymphal instars of apterous pea aphids, Acyrthosiphon pisum. At daily intervals, unparasitized aphids and aphids that were parasitized at age 24, 48, 72, and 120 h (cor- responding to nymphal instars L,-L4) were dissected. We weighed parasitoid larvae and Host remains to determine changes in their relative growth rates, based on wet mass (WM) and dry mass (DM). The growth in DM of unparasitized aphids followed a sigmoid curve. Aphids that were parasitized by A. ervi continued to grow for 5-7 d before their DM started to decline. Trajectories of the parasitoid's growth during its larval and pupal stages could be described by nonlinear equations. The maximum larval DM and the time from ovi- position to adult eclosion of parasitoids varied with Host age at parasitization, and thus suggested differences in Host Quality. We propose that, for parasitoids developing in growing and feeding stages of the Host, Host Quality is not a linear function of Host size at parasit- ization but reflects the degree of integration of the two systems.
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Nutritional Ecology of an Insect Host‐Parasitoid Association: The Pea Aphid‐Aphidius Ervi System
Ecology, 1992Co-Authors: Richard V Sequeira, Manfred MackauerAbstract:Evolutionary Host-size models assume that Host Quality for parasitoid growth and development is a linear function of Host size. To test this assumption, we compared the growth patterns of the hymenopteran parasitoid Aphidius ervi when it developed in different nymphal instars of apterous pea aphids, Acyrthosiphon pisum. At daily intervals, unparasitized aphids and aphids that were parasitized at age 24, 48, 72, and 120 h (cor- responding to nymphal instars L,-L4) were dissected. We weighed parasitoid larvae and Host remains to determine changes in their relative growth rates, based on wet mass (WM) and dry mass (DM). The growth in DM of unparasitized aphids followed a sigmoid curve. Aphids that were parasitized by A. ervi continued to grow for 5-7 d before their DM started to decline. Trajectories of the parasitoid's growth during its larval and pupal stages could be described by nonlinear equations. The maximum larval DM and the time from ovi- position to adult eclosion of parasitoids varied with Host age at parasitization, and thus suggested differences in Host Quality. We propose that, for parasitoids developing in growing and feeding stages of the Host, Host Quality is not a linear function of Host size at parasit- ization but reflects the degree of integration of the two systems.
Jeffrey A. Harvey - One of the best experts on this subject based on the ideXlab platform.
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hyperparasitoids exploit herbivore induced plant volatiles during Host location to assess Host Quality and non Host identity
Oecologia, 2019Co-Authors: Antonino Cusumano, Marcel Dicke, Jeffrey A. Harvey, Erik H. PoelmanAbstract:Although consumers often rely on chemical information to optimize their foraging strategies, it is poorly understood how top carnivores above the third trophic level find resources in heterogeneous environments. Hyperparasitoids are a common group of organisms in the fourth trophic level that lay their eggs in or on the body of other parasitoid Hosts. Such top carnivores use herbivore-induced plant volatiles (HIPVs) to find caterpillars containing parasitoid Host larvae. Hyperparasitoids forage in complex environments where Hosts of different Quality may be present alongside non-Host parasitoid species, each of which can develop in multiple herbivore species. Because both the identity of the herbivore species and its parasitization status can affect the composition of HIPV emission, hyperparasitoids encounter considerable variation in HIPVs during Host location. Here, we combined laboratory and field experiments to investigate the role of HIPVs in Host selection of hyperparasitoids that search for Hosts in a multi-parasitoid multi-herbivore context. In a wild Brassica oleracea-based food web, the hyperparasitoid Lysibia nana preferred HIPVs emitted in response to caterpillars parasitized by the gregarious Host Cotesia glomerata over the non-Host Hyposoter ebeninus. However, no plant-mediated discrimination occurred between the solitary Host C. rubecula and the non-Host H. ebeninus. Under both laboratory and field conditions, hyperparasitoid responses were not affected by the herbivore species (Pieris brassicae or P. rapae) in which the three primary parasitoid species developed. Our study shows that HIPVs are an important source of information within multitrophic interaction networks allowing hyperparasitoids to find their preferred Hosts in heterogeneous environments.
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Effects of plant-mediated differences in Host Quality on the development of two related endoparasitoids with different Host-utilization strategies.
Journal of Insect Physiology, 2018Co-Authors: Jeffrey A. Harvey, Rieta GolsAbstract:Among parasitoids that develop inside the bodies of feeding, growing Hosts (so-called 'koinobiont' endoparasitoids), two strategies have evolved to dispose of Host resources. The larvae of one group consumes most Host tissues before pupation, whereas in the other the parasitoid larvae consume only Host hemolymph and fat body and at maturity emerge through the Host cuticle to pupate externally. Here we compared development and survival (to adult emergence) of two related larval endoparasitoids (Braconidae: Microgastrinae) of the diamondback moth, Plutella xylostella. Larvae of Dolichogenidea sicaria are tissue feeders whereas larvae of Cotesia vestalis are hemolymph feeders. Here, development of P. xylostella and the two parasitoids was compared on three populations (one cultivar [Cyrus], two wild, [Winspit and Kimmeridge]) of cabbage that have been shown to vary in direct defense and hence Quality. Survival of P. xylostella and C. vestalis (to adult eclosion) did not vary with cabbage population, but did so in D. sicaria, where survival was lower when reared on the wild populations than on the cultivar. Furthermore, adult herbivore mass was significantly higher and development was significantly shorter in moths reared on the cultivar. The tissue-feeing D. sicaria was larger but took longer to develop than the hemolymph-feeder C. vestalis. The performance of both parasitoids was better on the cabbage cultivar than on the wild populations, although the effects were less apparent than in the Host. Our results show that (1) differences in plant Quality are diffused up the food chain, and (2) the effects of Host Quality are reflected on the development of both parasitoids.
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Development of the solitary endoparasitoid Microplitis demolitor: Host Quality does not increase with Host age and size
Ecological Entomology, 2004Co-Authors: Jeffrey A. Harvey, T. Martijn Bezemer, Jelmer A. Elzinga, Michael R. StrandAbstract:1. Many studies examining the relationship between Host size, an index of Host Quality, and parasitoid fitness use development time and/or adult parasitoid size as currencies of fitness, while ignoring pre-adult mortality. Because the physiological suitability of the Host may vary in different stages, sizes, or ages of Hosts, a misleading picture of Host Quality may therefore be obtained in cases where fitness is based on only one or two developmental traits. 2. The development of the solitary koinobiont endoparasitoid Microplitis demolitor is examined in different larval age-classes of its Host the soybean looper Pseudoplusia includens. Hosts were parasitised on days 1-8 after hatching from the egg, and development time, adult body size, and mortality of the parasitoid were compared. 3. A comparison of larval growth trajectories (using dry body mass) of M. demolitor revealed that parasitoid larvae attained over twice as much body mass in old Hosts than in younger Hosts. Similarly, adult parasitoid size at eclosion generally increased with Host size, although parasitoids developing in smaller Hosts lost a much lower proportion of mass between pupation and eclosion. 4. Overall egg-to-adult development was most rapid in intermediate-aged Hosts, and longer in Hosts at opposite ends of the age continuum. Moreover, parasitoid mortality varied non-linearly with Host stage, and was generally higher in very young and older Hosts. 5. Based on these results and other empirical data for koinobionts, it is argued that fitness functions in this group of parasitoids are not simply a positive function of Host size or age, but instead may be distinctly dome-shaped, both patterns reflecting the degree of physiological and nutritional compatibility between the two organisms. [KEYWORDS: Development time ; Host Quality ; koinobiont ; Microplitis ; demolitor ; parasitoid ; Pseudoplusia ; includens size]
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Dynamic effects of parasitism by an endoparasitoid wasp on the development of two Host species : implications for Host Quality and parasitoid fitness
Ecological Entomology, 2000Co-Authors: Jeffrey A. HarveyAbstract:1. The study reported here examined growth and developmental interactions between the gregarious larval koinobiont endoparasitoid Cotesia glomerata (Hymenoptera: Braconidae) and two of its Hosts that vary considerably in growth potential: Pieris rapae and the larger P. brassicae (Lepidoptera: Pieridae). At pupation, healthy larvae of P. brassicae are over twice as large, in terms of fresh body mass, as those of P. rapae. 2. Clutch size of C. glomerata was manipulated artificially, and the relationship between parasitoid burden and the maximum weight of the parasitised Host (= Host- parasitoid complex) was measured. In both Hosts, the maximum complex weight was correlated positively with parasitoid burden. Compared with unparasitised Hosts, however, the growth of P. rapae was increased at significantly lower parasitoid burdens than in P. brassicae. Emerging wasp size was correlated negatively with parasitoid burden in both Host species, whereas development time was less affected. 3. After larval parasitoid egress, the weight of the Host carcass increased slightly, but not significantly, with parasitoid burden, although there was a strong correlation between the proportion of Host mass consumed by C. glomerata larvae during development and parasitoid burden. 4. Clutch size was generally correlated positively with instar parasitised in both Hosts, and greater in P. brassicae than in P. rapae. Sex ratios were much more female biased in L1 and L2 P, rapae than in all other Host classes. Adult parasitoid size was correlated inversely with Host instar at parasitism, and wasps emerging from P. brassicae were larger, and completed development faster, than conspecifics emerging from P. rapae. 5. The data reveal that parasitism by C, glomerata has profound species-specific effects on the growth of both Host species. Consequently, optimality models in which Host Quality is often based on Host size at parasitism or unparasitised growth potential may have little utility in describing the development of gregarious koinobiont endoparasitoids. The results of this investigation are discussed in relation to the potential effectiveness of gregarious koinobionts in biological control programmes. [KEYWORDS: Cotesia glomerata; development; Host Quality; Host regulation;parasitism; Pieris rapae; Pieris brassicae Acyrthosiphon-pisum homoptera; aphidius-smithi hymenoptera;pieris-brassicae; clutch size; oviposition decisions;reproductive strategy; nutritional ecology; cotesia-glomerata;food budget; pea aphid]
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The influence of Host Quality on progeny and sex allocation in the pupal ectoparasitoid, Muscidifurax raptorellus (Hymenoptera: Pteromalidae)
Bulletin of Entomological Research, 1998Co-Authors: Jeffrey A. Harvey, G.j.z. GolsAbstract:Muscidifurax raptorellus Kogan & Legner is a gregarious pteromalid ectoparasitoid that attacks pupae and pharate adults from several families of the higher Diptera. Egg-to-adult development time, adult parasitoid size and emerging offspring ( = secondary) sex ratio of M. raptorellus were compared with clutch size in two Hosts that differed greatly in mass, the small Musca domestica Linnaeus and the larger Calliphora vomitoria Linnaeus. The mean number of emerging parasitoids did not vary significantly with Host species, although slightly higher clutch sizes were recorded in C. vomitoria . Irrespective of offspring sex, parasitoids completed development more rapidly in M. domestica than in C. vomitoria . In the small Host, the development time and adult size of M. raptorellus were negatively correlated with clutch size. By contrast, female parasitoid size was unaffected by clutch size in the larger Host, C. vomitoria . In both Hosts, female parasitoids were significantly larger than male parasitoids. The secondary sex ratio (percentage males) of emerging parasitoids was significantly lower in C. vomitoria , and varied with clutch size in both Hosts. In C. vomitoria , the greatest proportion of females emerged from Hosts with the highest clutch sizes, whereas in M. domestica Hosts with the highest clutch sizes produced the lowest proportion of female progeny. The results described here show that the development of M. raptorellus is profoundly affected by interspecific differences in Host Quality. Our results suggest that mating structure and Host Quality have potentially different effects on sex ratio decisions in M. raptorellus , and perhaps other gregarious parasitoids.
Mathias Otto - One of the best experts on this subject based on the ideXlab platform.
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The developmental strategy of an idiobiont ectoparasitoid, Dendrocerus carpenteri: Influence of variations in Host Quality on offspring growth and fitness
Oecologia, 1998Co-Authors: Mathias Otto, Manfred MackauerAbstract:Dendrocerus carpenteri (Curtis) (Hymenoptera: Megaspilidae) is a solitary hyperparasitoid, which attacks prepupal and pupal stages of hymenopteran parasitoids inside mummified aphids. The larva feeds externally on the Host, which is envenomed by the female at oviposition. To evaluate the influence of variations in Host Quality on the growth, development and fitness of D. carpenteri, we varied the size and developmental stage of the primary parasitoid Host (Aphidius ervi Haliday), which was reared on different instars of pea aphid [Acyrthosiphon pisum (Harris)] and English grain aphid [Sitobion avenae (F.)]. Within each kind of Host, females eclosed from the relatively larger mummies, while males eclosed from the smaller mummies. Host size and hyperparasitoid size were correlated, and females were larger than males. In hyperparasitoids developing on prepupal and pupal Hosts, development time from oviposition to adult eclosion was proportional to size; females required more time for development than males. The mean relative growth rate was the same in males and females and increased with Host Quality, as predicted by the growth model of Mackauer and Sequeira (1993) for idiobiont parasitoids. Larvae developing on late-pupal stages and pharate adults of A. er vi were unable to consume sclerotized Host tissues; they were smaller and needed more time for development. The average number of mature eggs at eclosion was six, except in females developing on suboptimal Hosts, which contained only one egg or none. Egg volume was correlated with female size, possibly reflecting differences in larval ontogeny. We provide equations describing the relationship between Host Quality as indexed by hind-tibia length of the mummified aphid and adult body size in terms of dry mass, development time and mean relative growth rate of D. carpenteri. We discuss the usefulness of Host size as a proxy of Host Quality for idiobiont parasitoids, and provide examples of exceptions.
Mark J F Brown - One of the best experts on this subject based on the ideXlab platform.
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dynamic transmission Host Quality and population structure in a multiHost parasite of bumblebees
Evolution, 2012Co-Authors: Mario X Ruizgonzalez, John Bryden, Yannick Moret, Christine Reberfunk, Paul Schmidhempel, Mark J F BrownAbstract:The evolutionary ecology of multiHost parasites is predicted to depend upon patterns of Host Quality and the dynamics of transmission networks. Depending upon the differences in Host Quality and transmission asymmetries, as well as the balance between intra- and interspecific transmission, the evolution of specialist or generalist strategies is predicted. Using a trypanosome parasite of bumblebees, we ask how Host Quality and transmission networks relate to parasite population structure across Host species, and thus the potential for the evolution of specialist strains adapted to different Host species. Host species differed in Quality, with parasite growth varying across Host species. Highly asymmetric transmission networks, together with differences in Host Quality, likely explain local population structure of the parasite across Host species. However, parasite population structure across years was highly dynamic, with parasite populations varying significantly from one year to the next within individual species at a given site. This suggests that, while Host Quality and transmission may provide the opportunity for short-term Host specialization by the parasite, repeated bottlenecking of the parasite, in combination with its own reproductive biology, overrides these smaller scale effects, resulting in the evolution of a generalist parasite.
Bethia H. King - One of the best experts on this subject based on the ideXlab platform.
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Using effects of parasitoid size on fitness to test a Host Quality model assumption with the parasitoid wasp Spalangia endius
Canadian Journal of Zoology, 2006Co-Authors: Bethia H. King, M. E. NapoleonAbstract:How body size affects fitness of males relative to females is relevant to understanding the evolution of sexual size dimorphism and maternal sex-ratio manipulation. In most parasitoid wasps, mothers oviposit a greater proportion of daughters in larger Hosts. The Host-Quality model describes how this may be adaptive. A major assumption of the model is that Host size has a greater effect on the fitness of daughters than of sons. The assumption has often been tested indirectly by examining the effects of parasitoid size on fitness, because a parasitoid’s size generally increases with the size of the Host on which it develops. The validity of this indirect method is examined here for the parasitoid wasp Spalangia endius Walker, 1839 parasitizing Musca domestica L., 1758. If the method is valid, effects of parasitoid size on fitness should match the effects of Host size on fitness that were shown in a previous study. The effects matched in that both parasitoid size and Host size affected the fitness of females...
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Offspring Sex Ratio and Number in Response to Proportion of Host Sizes and Ages in the Parasitoid Wasp Spalangia cameroni (Hymenoptera: Pteromalidae)
Environmental Entomology, 2002Co-Authors: Bethia H. KingAbstract:In rearing parasitoids for biological control releases and in natural populations, female parasitoids may encounter variable distributions of Host Quality. Here I examine how the proportion of Hosts that are small versus large or old versus young affects sex ratio and offspring production of the parasitoid wasp Spalangia cameroni Perkins parasitizing Musca domestica L. pupae. With increasing proportion of small Hosts or old Hosts, overall number of offspring did not significantly decrease and the overall proportion that were male (i.e., from small and large Hosts combined) did not significantly increase. A greater proportion of sons from small versus large and from old versus young Hosts was not restricted to the case of equal numbers of different Host types. The proportion of sons produced from small Hosts as well as the proportion of sons from large Hosts decreased as the proportion of small Hosts increased, and the proportion of sons produced from young Hosts decreased as the proportion of old Hosts increased. These results are relevant to recommendations for rearing S. cameroni for biological control releases and to testing evolutionary sex ratio theory, specifically a combined Host-Quality and local mate competition model.
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Sex ratio response of the parasitoid wasp Muscidifurax raptor to other females
Oecologia, 1993Co-Authors: Bethia H. King, S. E. SeidlAbstract:This study examines the sex ratio response of the parasitoid wasp Muscidifurax raptor to conspecific and confamilial females in relation to two groups of functional sex ratio models, local mate competition and Host Quality models. In some but not all experiments, M. raptor females produced a greater proportion of sons in the presence of a conspecific female than when alone, and this sex ratio effect carried over for a day after the females were isolated from each other M. raptor females also produced a greater proportion of sons in the presence of a female of the confamilial parasitoid Spalangia cameroni than when alone (although only on the second day of exposure to S. cameroni, not on the first). M. raptor's sex ratio increase in the presence of conspecifics is consistent with local mate competition models but not with Host Quality models because the presence of a conspecific female did not cause there to be more, and thus potentially smaller, offspring developing per Host. In contrast, the presence of a S. cameroni female did cause there to be more offspring developing per Host than when a M. raptor female was alone; thus M. raptor's sex ratio increase in the presence of S. cameroni may be explained by Host Quality models. An alternative explanation for the sex ratio increase in response to confamilials is that only a sex ratio response to conspecifics may be adaptive, due to local mate competition; but M. raptor females may be unable to distinguish between conspecific and S. cameroni females.
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Sex-ratios of the wasp Nasonia vitripennis from self-versus conspecifically-parasitized Hosts : local mate competition versus Host Quality models
Journal of Evolutionary Biology, 1992Co-Authors: Bethia H. KingAbstract:Sex ratio patterns in the parasitoid wasp Nasonia vitripennis are frequently cited in support of a major group of evolutionary sex ratio models referred to as local mate competition (LMC) models. It has been shown repeatedly that, as predicted by LMC models, females generally oviposit a greater proportion of sons in previously parasitized Hosts than in unparasitized Hosts. However, this sex ratio pattern is also a prediction of another group of sex ratio models, the Host Quality models. Here I test a prediction of LMC models that is not also a prediction of Host Quality models: a female should produce a greater proportion of sons when she parasitizes a Host previously parasitized by a conspecific female than when she parasitizes a Host previously parasitized by herself. Females made this predicted distinction between self- and conspecifically-parasitized Hosts under some conditions. There was no evidence that a female recognizes a self-parasitized Host when her exposure to the Host is interrupted by exposure to an unparasitized Host, or that a female can distinguish between Hosts parasitized by sisters versus nonsisters.