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Maria Gabriela Luna - One of the best experts on this subject based on the ideXlab platform.
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First record of Pseudapanteles dignus (Hymenoptera: Braconidae) as a parasitoid of Tuta absoluta (Lepidoptera: Gelechiidae) in Alto Valle de Río Negro, Argentina
Revista de la Sociedad Entomológica Argentina, 2017Co-Authors: Silvina A. Garrido, Liliana Cichon, Jonatan D. Lago, Daniel Alejandro Aquino, Consuelo Vallina, Maria Gabriela LunaAbstract:The larval endoparasitoid Pseudapanteles dignus (Hymenoptera: Braconidae) is reported for the first time attacking the South American tomato moth Tuta absoluta (Lepidoptera: Gelechiidae) in tomato crops at Alto Valle de Rio Negro, being this the most southern report for Argentina. Besides, P. dignus diagnosis and parasitism percentage are briefly commented.
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Encapsulation and self-superparasitism of Pseudapanteles dignus (Muesebeck) (Hymenoptera: Braconidae), a parasitoid of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)
PLoS ONE, 2016Co-Authors: Maria Gabriela Luna, Nicolas Desneux, Marcela I. SchneiderAbstract:Endoparasitoids can be killed by host encapsulation, a cellular-mediated host immunological response against parasitism that involves hemocytes aggregation. As a counteracting strategy, many parasitoids can evade this host response through self-superparasitism. The objectives of this study were: 1) to describe the parasitoid Pseudapanteles dignus (Hymenoptera: Braconidae) early immature stages (egg and larva) encapsulation by the host Tuta absoluta (Lepidoptera: Gelechiidae), and 2) to determine the occurrence of self-superparasitism and the rate of escaping to encapsulation of this parasitoid. Knowledge of host-parasitoid immunological interaction is crucial when evaluating the potential of an endoparasitoid as a biological control candidate. Parasitoid-exposed T. absoluta larvae were dissected in vivo under light stereoscope microscope at 24-h intervals, for five days after exposition to detect encapsulation. The preimaginal stages of P. dignus and numbers of healthy and encapsulated immature parasitoids per host were recorded. Samples of parasitoid eggs and larvae were processed for SEM visualization of encapsulation. Necropsies evidenced that only the early first larval instar of P. dignus (up to 96 h-old) was partially or completely encapsulated. A non-melanized capsule, formed by layers of granulocyte-type hemocytes enveloping around the parasitoid body, was recorded. Approximately 50% of the parasitized T. absoluta larvae had significantly only one P. dignus egg, meanwhile supernumerary parasitization yielded up to seven immature parasitoids per host. The proportion of single-early first larval instar of P. dignus reached approximate to 0.5 and decreased significantly as the number of parasitoid individuals per host increased. P. dignus encapsulation and its ability to overcome with the host immune defense through self-superparasitism indicate that T. absoluta is a semi-permissive host for this parasitoid.
Toshiharu Tanaka - One of the best experts on this subject based on the ideXlab platform.
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Potential Host Range of the Larval Endoparasitoid () (Hymenoptera: Braconidae)
International Journal of Insect Science, 2017Co-Authors: Satoshi Hiroyoshi, Yutaka Nakamatsu, Jun Mitsuhashi, Hisashi Nemoto, Jeffrey A. Harvey, Takayuki Mitsunaga, Toshiharu TanakaAbstract:Many parasitoid wasps are highly specialized in nature, attacking only one or a few species of hosts. Host range is often determined by a range of biological and ecological characteristics of the host including diet, growth potential, immunity, and phylogeny. The solitary koinobiont endoparasitoid wasp, Cotesia vestalis , mainly parasitizes diamondback moth (DBM) larvae in the field, although it has been reported that to possess a relatively wide lepidopteran host range. To better understand the biology of C vestalis as a potential biological control of hosts other than the DBM, it is necessary to determine suitability for potential hosts. In this study, the potential host range of the wasp and its developmental capacity in each host larva were examined under laboratory conditions using 27 lepidopteran species from 10 families. The wasp was able to parasitize 15 of the 27 species successfully. Some host species were not able to exclude C vestalis via their internal physiological defenses. When parasitization was unsuccessful, most hosts killed the parasitoid at the egg stage or early first-instar stage using encapsulation, but some host species disturbed the development of the parasitoid at various stages. No phylogenetic relationships were found among suitable and unsuitable hosts, revealing that host range in some Endoparasitoids is not constrained by relatedness among hosts based on immunity.
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Different responses of a solitary (Meteorus pulchricornis) and a gregarious (Cotesia kariyai) endoparasitoid to four insecticides in the host Pseudaletia separata.
Journal of Pesticide Science, 2010Co-Authors: Shingo Kanzaki, Toshiharu TanakaAbstract:This study clarified the difference in sensitivity of lepidopteran host larvae parasitized by a gregarious endoparasitoid Cotesia kariyai and a solitary endoparasitoid Meteorus pulchricornis to four insecticides, fenitrothion, cypermethrin, pyriproxyfen and pyridalyl, along with the growth and development of each parasitoid. It is well known that the physiological state of the host is regulated by endoparasitoid after parasitization. It was predicted from our previous report that the detoxification ability of the parasitized hosts was changed by parasitization. The effect of four insecticides on the growth and development of two parasitoids was examined with LD50 or LD95 values of unparasitized hosts. Fenitrothion and cypermethrin had an effect on the growth and development of host larvae parasitized by C. kariyai, but in M. pulchricornis caused low mortality on day 3 and later after parasitization. Pyriproxyfen had no effect on the growth and development of C. kariyai, but inhibited the adult eclosion of M. pulchricornis even when the parasitized hosts were treated with 50 ppm (less than LD10 to unparasitized hosts). Paraffin sections revealed developmental malformations in the abdomen during the pupal stage of M. pulchricornis endoparasitoid. Pyridalyl had a strong effect on larval emergence of C. kariyai from the host during early stages (until day 7 postparasitization), because parasitoid larvae did not grow as lepidopteran larvae became motionless after pyridalyl treatment and could not eat. On the other hand, pyridalyl at LD50 has a little effect on larval emergence and adult eclosion of M. pulchricornis. Gregarious and solitary Endoparasitoids showed different sensitivity to four individual insecticides.
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Differential host growth regulation by the solitary endoparasitoid, Meteorus pulchricornis in two hosts of greatly differing mass.
Journal of Insect Physiology, 2010Co-Authors: Jeffrey A. Harvey, Takeshi Sano, Toshiharu TanakaAbstract:Abstract Solitary koinobiont Endoparasitoids generally reduce the growth of their hosts by a significant amount compared with healthy larvae. Here, we compared the development and host usage strategies of the solitary koinobiont endoparasitoid, Meteorus pulchricornis, when developing in larvae of a large host species (Mythimna separata) and a much smaller host species (Plutella xylostella). Caterpillars of M. separata were parasitized as L2 and P. xylostella as L3, when they weighed approximately 2 mg. The growth of parasitized M. separata larvae was reduced by almost 95% compared with controls, whereas parasitized P. xylostella larvae grew some 30% larger than controls. Still, adult wasps emerging from M. separata larvae were almost twice as large as wasps emerging from P. xylostella larvae, had larger egg loads after 5 days and produced more progeny. Survival to eclosion was also higher on M. separata than on P. xylostella, although parasitoids developed significantly faster when developing on P. xylostella. Our results provide evidence that koinobionts are able to differentially regulate the growth of different host species. However, there are clearly also limitations in the ability of parasitoids to regulate phenotypic host traits when size differences between different host species are as extreme as demonstrated here.
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Comparing the physiological effects and function of larval feeding in closely‐related Endoparasitoids (Braconidae: Microgastrinae)
Physiological Entomology, 2008Co-Authors: Jeffrey A. Harvey, Yutaka Nakamatsu, Rieta Gols, T. M. Bezemer, Toshiharu TanakaAbstract:The larvae of most endoparasitoid wasps consume virtually all host tissues before pupation. However, in some clades, the parasitoid larvae primarily consume haemolymph and fat body and emerge through the side of the host, which remains alive and active for up to several days. The evolutionary significance of this host-usage strategy has attracted attention in recent years. Recent empirical studies suggest that the surviving larva guards the parasitoid broods against natural enemies such as predators and hyperparasitoids. Known as the 'usurpation hypothesis', the surviving larvae bite, regurgitate fluids from the gut, and thrash the head capsule when disturbed. In the present study, the 'usurpation hypothesis' is tested in the association involving Manduca sexta, its parasitoid Cotesia congregata, and a secondary hyperparasitoid Lysibia nana. Percentage parasitoid survival is higher and hyperparasitism lower when cocoons of C. congregata are attached to the dorsum of M. sexta caterpillars. Fat body contents in several associations involving solitary and gregarious parasitoids feeding on haemolymph and fat body are also compared. The amount of fat body retained in parasitized caterpillars varies considerably from one association to another. In M. sexta and Pieris brassicae, considerable amounts of fat body remain after parasitoid emergence whereas, in Cotesia kariyai and Cotesia rufricus, virtually all of the fat body is consumed by the parsasitoid larvae. The length of post-egression survival of parasitized caterpillars differs considerably in several tested associations. In Pseudeletia separata, most larvae die within a few hours of parasitoid emergence whereas, in M. sexta, parasitized larvae live up to 2 weeks after parasitoid emergence. Larvae in other associations parasitized by gregarious and solitary Endoparasitoids live for intermediate periods. The results are discussed in relation to the adaptive significance of different feeding strategies of immature parasitoids and of the costs and benefits of retaining the parasitized caterpillar in close proximity with the parasitoid cocoons.
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The mechanism of the emergence of Cotesia kariyai (Hymenoptera: Braconidae) larvae from the host
European Journal of Endocrinology, 2006Co-Authors: Yutaka Nakamatsu, Toshiharu Tanaka, Jeffrey A. HarveyAbstract:At maturity, the endoparasitoid larvae of several subfamilies of the Braconidae have to emerge from inside of the host to pupate. Although the hosts hormonal milieu and the timing of larval parasitoid emergence have been studied, no report has yet focused on the physiological state of the host in connection with the emergence behavior of Endoparasitoids. We investigated the mechanism of larval emergence behavior in a gregarious endoparasitoid, Cotesia kariyai. The parasitoid larvae inserted their mandi- bles into the host cuticle and perforated the integument by moving their head-capsule backwards and forwards. The emerging parasi- toid larva must have a physical support (an "anchor") with the terminal appendages in order to exert the necessary pressure to cut the host integument. Morphological observations revealed that each parasitoid larva was enveloped in a capsule just before emerging from their host. Eight and nine day-old parasitoid larvae secreted material around their bodies to form these capsules. This material consisted of acid-glycoproteins which coated the exuvium of the 2 nd instar larvae. The haemolymph volume of the parasitised host also decreased in later stages and was dramatically reduced immediatly prior to parasitoid emergence. This final reduction of the host haemolymph volume is the result of absorption by parasitoid larvae. This mechanism allows the parasitoid larvae to create an anchor more easily. The parasitoid larvae could also adhere to each other with the glycoprotein. In addition, these capsules prevent the leaking of host haemolymph through the emergence hole; these holes on the host integument were plugged by the capsules after parasitoid emergence. Although the pressure acquired by the anchor was lost once the head of the parasitoid larvae emerges from the host integument, the parasitoid larvae crawls out of the host cavity using backward pointing spines which enable the parasitoid to grip the capsule and move forward via peristaltic contractions.
Marcela I. Schneider - One of the best experts on this subject based on the ideXlab platform.
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Encapsulation and self-superparasitism of Pseudapanteles dignus (Muesebeck) (Hymenoptera: Braconidae), a parasitoid of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)
PLoS ONE, 2016Co-Authors: Maria Gabriela Luna, Nicolas Desneux, Marcela I. SchneiderAbstract:Endoparasitoids can be killed by host encapsulation, a cellular-mediated host immunological response against parasitism that involves hemocytes aggregation. As a counteracting strategy, many parasitoids can evade this host response through self-superparasitism. The objectives of this study were: 1) to describe the parasitoid Pseudapanteles dignus (Hymenoptera: Braconidae) early immature stages (egg and larva) encapsulation by the host Tuta absoluta (Lepidoptera: Gelechiidae), and 2) to determine the occurrence of self-superparasitism and the rate of escaping to encapsulation of this parasitoid. Knowledge of host-parasitoid immunological interaction is crucial when evaluating the potential of an endoparasitoid as a biological control candidate. Parasitoid-exposed T. absoluta larvae were dissected in vivo under light stereoscope microscope at 24-h intervals, for five days after exposition to detect encapsulation. The preimaginal stages of P. dignus and numbers of healthy and encapsulated immature parasitoids per host were recorded. Samples of parasitoid eggs and larvae were processed for SEM visualization of encapsulation. Necropsies evidenced that only the early first larval instar of P. dignus (up to 96 h-old) was partially or completely encapsulated. A non-melanized capsule, formed by layers of granulocyte-type hemocytes enveloping around the parasitoid body, was recorded. Approximately 50% of the parasitized T. absoluta larvae had significantly only one P. dignus egg, meanwhile supernumerary parasitization yielded up to seven immature parasitoids per host. The proportion of single-early first larval instar of P. dignus reached approximate to 0.5 and decreased significantly as the number of parasitoid individuals per host increased. P. dignus encapsulation and its ability to overcome with the host immune defense through self-superparasitism indicate that T. absoluta is a semi-permissive host for this parasitoid.
Xue-xin Chen - One of the best experts on this subject based on the ideXlab platform.
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the complete mitochondrial genome of asobara japonica hymenoptera braconidae
Mitochondrial DNA Part B, 2020Co-Authors: Xian Zhang, Min Shi, Xue-xin Chen, Zhongqiu Pan, Jiachen Zhu, Zhizhi Wang, Jianhua HuangAbstract:Asobara japonica is an important larval-pupal endoparasitoid of Drosophila melanogaster and some other fruit fly species, such as Drosophila suzukii, and is an invasive and economic pest. In this s...
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Comparative transcriptome analysis of venom glands from Cotesia vestalis and Diadromus collaris , two Endoparasitoids of the host Plutella xylostella
Scientific reports, 2017Co-Authors: Wei Zhao, Min Shi, Ye Xiqian, Xiao-wei Wang, Xue-xin ChenAbstract:Venoms secreted by the venom gland (VG) of parasitoid wasp help ensure successful parasitism by host immune suppression and developmental regulation. Cotesia vestalis, a larval endoparasitoid, and Diadromus collaris, a pupal endoparasitoid, parasitize the diamondback moth (DBM), Plutella xylostella. To explore and compare the venom components of two Endoparasitoids, we sequenced transcriptomes of the VGs and wasp bodies without VGs (BWVGs) of the two Endoparasitoids. Statistically enriched GO terms and KEGG pathways of the two VGs compared to respective whole-body background were similar and reflected active protein biosynthesis activities in the two VGs. 1,595 VG specific genes of the D. collaris VG and 1,461 VG specific genes of the C. vestalis VG were identified by comparative transcript profiling. A total of 444 and 513 genes encoding potential secretory proteins were identified and defined as putative venom genes in D. collaris VG and C. vestalis VG, respectively. The putative venom genes of the two wasps showed no significant similarity or convergence. More venom genes were predicted in D. collaris VG than C. vestalis VG, especially hydrolase-coding genes. Differences in the types and quantities of putative venom genes shed light on different venom functions.
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cotesia vestalis teratocytes express a diversity of genes and exhibit novel immune functions in parasitism
Scientific Reports, 2016Co-Authors: Qijuan Gu, Michael R Strand, Fei Li, Zehua Wang, Qisheng Song, Xue-xin ChenAbstract:Some endoparasitoid wasps lay eggs that produce cells called teratocytes. In this study, we sequenced and analyzed the transcriptome of teratocytes from the solitary endoparasitoid Cotesia vestalis (Braconidae), which parasitizes larval stage Plutella xylostella (Plutellidae). Results identified many teratocyte transcripts with potential functions in affecting host immune defenses, growth or metabolism. Characterization of teratocyte-secreted venom-like protein 8 (TSVP-8) indicated it inhibits melanization of host hemolymph in vitro, while two predicted anti-microbial peptides (CvT-def 1 and 3) inhibited the growth of bacteria. Results also showed the parasitized hosts lacking teratocytes experienced higher mortality after immune challenge by pathogens than hosts with teratocytes. Taken together, these findings indicate that C. vestalis teratocytes secrete products that alter host immune functions while also producing anti-microbial peptides with functions that help protect the host from infection by other organisms.
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the endoparasitoid cotesia vestalis regulates host physiology by reprogramming the neuropeptide transcriptional network
Scientific Reports, 2015Co-Authors: Shuai Dong, Mingtian Li, Yanyan Yang, David Stanley, Xue-xin ChenAbstract:Endoparasitoids develop inside another insect by regulating host immunity and development via maternal factors injected into hosts during oviposition. Prior results have provided insights into parasitism-induced immunosuppression, including the neuropeptide accumulation in parasitized insects. Nonetheless, our understanding of neuropeptide influence on host development and behavior is not yet complete. We posed the hypothesis that parasitization alters expression of genes encoding pro-neuropeptides and used larvae of Plutella xylostella and its endoparasitoid, Cotesia vestalis to test our hypothesis. We prepared transcriptomes from the larval P. xylostella brain-CC-CA complex and identified transcripts encoding 19 neuropeptides. All corresponding cDNAs were confirmed by RACE. Our results demonstrate that parasitism significantly down-regulated, or delayed, expression of genes encoding pro-neuropeptides within 48 h post-parasitization. Changing expression of these genes may account for the previously reported decreased feeding behavior, reduced growth rates and aborted development in the host larvae. In effect, parasitization may operate at the molecular level within the CNS to create global changes in larval host biology. The significance of our finding is that, in addition to the known effects on immunity, parasitoids influence host pro-neuropeptide gene transcription. This finding reveals a new mechanism operating in host-parasitoid relationships to the advantage of the parasitoid.
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The Endoparasitoid, Cotesia vestalis, Regulates Host Physiology by Reprogramming the Neuropeptide
2015Co-Authors: Min Shi, Shuai Dong, Yanyan Yang, David Stanley, Xue-xin ChenAbstract:Endoparasitoids develop inside another insect by regulating host immunity and development via maternal factors injected into hosts during oviposition. Prior results have provided insights into parasitism-induced immunosuppression, including the neuropeptide accumulation in parasitized insects. Nonetheless, our understanding of neuropeptide influence on host development and behavior is not yet complete. We posed the hypothesis that parasitization alters expression of genes encoding pro-neuropeptides and used larvae of Plutella xylostella and its endoparasitoid, Cotesia vestalis to test our hypothesis. We prepared transcriptomes from the larval P. xylostella brain-CC-CA complex and identified transcripts encoding 19 neuropeptides. All corresponding cDNAs were confirmed by RACE. Our results demonstrate that parasitism significantly down-regulated, or delayed, expression of genes encoding pro-neuropeptides within 48 h post-parasitization. Changing expression of these genes may account for the previously reported decreased feeding behavior, reduced growth rates and aborted development in the host larvae. In effect, parasitization may operate at the molecular level within the CNS to create global changes in larval host biology. The significance of our finding is that, in addition to the known effects on immunity, parasitoids influence host pro-neuropeptide gene transcription. This finding reveals a new mechanism operating in host-parasitoid relationships to the advantage of the parasitoid.
Jeffrey A. Harvey - One of the best experts on this subject based on the ideXlab platform.
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detoxification of plant defensive glucosinolates by an herbivorous caterpillar is beneficial to its endoparasitic wasp
Molecular Ecology, 2020Co-Authors: Ruo Sun, Jeffrey A. Harvey, Rieta Gols, Michael Reichelt, Jonathan Gershenzon, Sagar Subhash Pandit, Daniel Giddings VassaoAbstract:Plant chemical defences impact not only herbivores, but also organisms in higher trophic levels that prey on or parasitize herbivores. While herbivorous insects can often detoxify plant chemicals ingested from suitable host plants, how such detoxification affects Endoparasitoids that use these herbivores as hosts is largely unknown. Here, we used transformed plants to experimentally manipulate the major detoxification reaction used by Plutella xylostella (diamondback moth) to deactivate the glucosinolate defences of its Brassicaceae host plants. We then assessed the developmental, metabolic, immune, and reproductive consequences of this genetic manipulation on the herbivore as well as its hymenopteran endoparasitoid Diadegma semiclausum. Inhibition of P. xylostella glucosinolate metabolism by plant-mediated RNA interference increased the accumulation of the principal glucosinolate activation products, the toxic isothiocyanates, in the herbivore, with negative effects on its growth. Although the endoparasitoid manipulated the excretion of toxins by its insect host to its own advantage, the inhibition of herbivore glucosinolate detoxification slowed endoparasitoid development, impaired its reproduction, and suppressed the expression of genes of a parasitoid-symbiotic polydnavirus that aids parasitism. Therefore, the detoxification of plant glucosinolates by an herbivore lowers its toxicity as a host and benefits the parasitoid D. semiclausum at multiple levels.
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Potential Host Range of the Larval Endoparasitoid () (Hymenoptera: Braconidae)
International Journal of Insect Science, 2017Co-Authors: Satoshi Hiroyoshi, Yutaka Nakamatsu, Jun Mitsuhashi, Hisashi Nemoto, Jeffrey A. Harvey, Takayuki Mitsunaga, Toshiharu TanakaAbstract:Many parasitoid wasps are highly specialized in nature, attacking only one or a few species of hosts. Host range is often determined by a range of biological and ecological characteristics of the host including diet, growth potential, immunity, and phylogeny. The solitary koinobiont endoparasitoid wasp, Cotesia vestalis , mainly parasitizes diamondback moth (DBM) larvae in the field, although it has been reported that to possess a relatively wide lepidopteran host range. To better understand the biology of C vestalis as a potential biological control of hosts other than the DBM, it is necessary to determine suitability for potential hosts. In this study, the potential host range of the wasp and its developmental capacity in each host larva were examined under laboratory conditions using 27 lepidopteran species from 10 families. The wasp was able to parasitize 15 of the 27 species successfully. Some host species were not able to exclude C vestalis via their internal physiological defenses. When parasitization was unsuccessful, most hosts killed the parasitoid at the egg stage or early first-instar stage using encapsulation, but some host species disturbed the development of the parasitoid at various stages. No phylogenetic relationships were found among suitable and unsuitable hosts, revealing that host range in some Endoparasitoids is not constrained by relatedness among hosts based on immunity.
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The roles of ecological fitting, phylogeny and physiological equivalence in understanding realized and fundamental host ranges in endoparasitoid wasps.
Journal of evolutionary biology, 2012Co-Authors: Jeffrey A. Harvey, M. G. Ximénez De Embún, Tibor Bukovinszky, Rieta GolsAbstract:Co-evolutionary theory underpins our understanding of interactions in nature involving plant–herbivore and host–parasite interactions. However, many studies that are published in the empirical literature that have explored life history and development strategies between endoparasitoid wasps and their hosts are based on species that have no evolutionary history with one another. Here, we investigated novel associations involving two closely related solitary Endoparasitoids that originate from Europe and North America and several of their natural and factitious hosts from both continents. The natural hosts of both species are also closely related, all being members of the same family. We compared development and survival of both parasitoids on the four host species and predicted that parasitoid performance is better on their own natural hosts. In contrast with this expectation, survival, adult size and development time of both parasitoids were similar on all (with one exception) hosts, irrespective as to their geographic origin. Our results show that phylogenetic affinity among the natural and factitious hosts plays an important role in their nutritional suitability for related parasitoids. Evolved traits in parasitoids, such as immune suppression and development, thus enable them to successfully develop in novel host species with which they have no evolutionary history. Our results show that host suitability for specialized organisms like Endoparasitoids is closely linked with phylogenetic history and macro-evolution as well as local adaptation and micro-evolution. We argue that the importance of novel interactions and ‘ecological fitting’ based on phylogeny is a greatly underappreciated concept in many resource–consumer studies.
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Differential host growth regulation by the solitary endoparasitoid, Meteorus pulchricornis in two hosts of greatly differing mass.
Journal of Insect Physiology, 2010Co-Authors: Jeffrey A. Harvey, Takeshi Sano, Toshiharu TanakaAbstract:Abstract Solitary koinobiont Endoparasitoids generally reduce the growth of their hosts by a significant amount compared with healthy larvae. Here, we compared the development and host usage strategies of the solitary koinobiont endoparasitoid, Meteorus pulchricornis, when developing in larvae of a large host species (Mythimna separata) and a much smaller host species (Plutella xylostella). Caterpillars of M. separata were parasitized as L2 and P. xylostella as L3, when they weighed approximately 2 mg. The growth of parasitized M. separata larvae was reduced by almost 95% compared with controls, whereas parasitized P. xylostella larvae grew some 30% larger than controls. Still, adult wasps emerging from M. separata larvae were almost twice as large as wasps emerging from P. xylostella larvae, had larger egg loads after 5 days and produced more progeny. Survival to eclosion was also higher on M. separata than on P. xylostella, although parasitoids developed significantly faster when developing on P. xylostella. Our results provide evidence that koinobionts are able to differentially regulate the growth of different host species. However, there are clearly also limitations in the ability of parasitoids to regulate phenotypic host traits when size differences between different host species are as extreme as demonstrated here.
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The effect of host developmental stage at parasitism on sex-related size differentiation in a larval endoparasitoid
Ecological Entomology, 2009Co-Authors: Rieta Gols, Jeffrey A. HarveyAbstract:1. For their larval development, parasitoids depend on the quality and quantity of resources provided by a single host. Therefore, a close relationship is predicted between the size of the host at parasitism and the size of the emerging adult wasp. This relationship is less clear for koinobiont than for idiobiont parasitoids. 2. As size differentiation in host species exhibiting sexual size dimorphism (SSD) is likely to occur already during larval development, in koinobiont larval Endoparasitoids the size of the emerging adult may also be constrained based on the sex of the host caterpillar. 3. Sex-specific growth trajectories were compared in unparasitised Plutella xylostella caterpillars and in second and fourth instar hosts that were parasitised by the solitary larval koinobiont endoparasitoid Diadegma semiclausum. Both species exhibit SSD, where females are significantly larger than males. 4. Healthy female P. xylostella caterpillars developed significantly faster than their male conspecifics. Host regulation induced by D. semiclausum parasitism depended on the instar attacked. Parasitism in second-instar caterpillars reduced growth compared to healthy unparasitised caterpillars, whereas parasitism in fourth-instar caterpillars arrested development. The reduction in growth was most pronounced in hosts producing male D. semiclausum. 5. Parasitism itself had the largest impact on host growth. SSD in the parasitoid is mainly the result of differences in growth rate of the parasitoid–host complex producing male and female wasps and differences in exploitation of the host resources. Female wasps converted host biomass more efficiently into adult biomass than males.