Diploid males support a two-step mechanism of endosymbiont-induced thelytoky in a parasitoid wasp
Ma, W.J. ; Pannebakker, B.A. ; Zande, L. van de; Schwander, T. ; Wertheim, B. ; Beukeboom, L.W. - \ 2015
BMC Evolutionary Biology 15 (2015). - ISSN 1471-2148
leptopilina-clavipes hymenoptera - sex-determination - parthenogenetic populations - quantitative pcr - insect sex - wolbachia - host - reproduction - braconidae - determines
Background Haplodiploidy, where females develop from diploid, fertilized eggs and males from haploid, unfertilized eggs, is abundant in some insect lineages. Some species in these lineages reproduce by thelytoky that is caused by infection with endosymbionts: infected females lay haploid eggs that undergo diploidization and develop into females, while males are very rare or absent. It is generally assumed that in thelytokous wasps, endosymbionts merely diploidize the unfertilized eggs, which would then trigger female development. Results We found that females in the parasitoid wasp Asobara japonica infected with thelytoky-inducing Wolbachia produce 0.7–1.2 % male offspring. Seven to 39 % of these males are diploid, indicating that diploidization and female development can be uncoupled in A. japonica. Wolbachia titer in adults was correlated with their ploidy and sex: diploids carried much higher Wolbachia titers than haploids, and diploid females carried more Wolbachia than diploid males. Data from introgression lines indicated that the development of diploid individuals into males instead of females is not caused by malfunction-mutations in the host genome but that diploid males are most likely produced when the endosymbiont fails to activate the female sex determination pathway. Our data therefore support a two-step mechanism by which endosymbionts induce thelytoky in A. japonica: diploidization of the unfertilized egg is followed by feminization, whereby each step correlates with a threshold of endosymbiont titer during wasp development. Conclusions Our new model of endosymbiont-induced thelytoky overthrows the view that certain sex determination mechanisms constrain the evolution of endosymbiont-induced thelytoky in hymenopteran insects. Endosymbionts can cause parthenogenesis through feminization, even in groups in which endosymbiont-diploidized eggs would develop into males following the hosts’ sex determination mechanism. In addition, our model broadens our understanding of the mechanisms by which endosymbionts induce thelytoky to enhance their transmission to the next generation. Importantly, it also provides a novel window to study the yet-poorly known haplodiploid sex determination mechanisms in haplodiploid insects.
Host preference and offspring performance are linked in three congeneric hyperparasitoid species
Harvey, J.A. ; Gols, R. ; Snaas, H. ; Malcicka, M. ; Visser, B. - \ 2015
Ecological Entomology 40 (2015)2. - ISSN 0307-6946 - p. 114 - 122.
monoctonus-paulensis hymenoptera - optimal bad motherhood - parasitoid wasps - reproductive strategies - sex allocation - age preference - lysibia-nana - braconidae - ichneumonidae - oviposition
1. The optimisation theory predicts that insect mothers should oviposit on resources on which they attain the highest exclusive fitness. The development of parasitoid wasps is dependent on limited host resources that are often not much larger than the adult parasitoid. 2. In the present study preference and development in three congeneric species of secondary hyperparasitoids attacking cocoons of two congeneric primary parasitoids that differ significantly in size were compared. Gelis agilis (Fabricius) and G. acarorum (L.) are wingless hyperparasitoids that forage in grassy habitats, whereas G. areator (Panzer) is fully winged and forages higher in the canopy of forbs. 3. The three species were reared on cocoons containing pupae of a small gregarious endoparasitoid, Cotesia glomerata (L.), and a larger solitary species, C. rubecula (Marshall), both of which develop in the caterpillars of pierid butterflies. 4. Adult mass was correlated with initial cocoon mass in all three species, whereas development time was unaffected. Wasps were larger when developing in C. rubecula. However, for a given host mass, wasps were larger when developing on the smaller host, C. glomerata. This suggests that there is a physiological limit to hyperparasitoid size that was exceeded when C. rubecula served as host. 5. All three hyperparasitoids strongly preferred to attack cocoons of the larger species, C. rubecula, often avoiding cocoons of C. glomerata entirely. 6. Preference and performance are correlated in the three Gelis species. However, owing to variation in the distribution and thus abundance of their hosts, it is argued that cumulative fitness may be still higher in the smaller host species.
Effects of climate change on pest-parasitoid dynamics: Development of a simulation model and first results
Gebauer, K. ; Hemerik, L. ; Meyhöfer, R. - \ 2015
Journal of Plant Diseases and Protection 122 (2015)1. - ISSN 1861-3829 - p. 28 - 35.
diaeretiella-rapae hymenoptera - russian wheat aphid - diuraphis-noxia - brevicoryne-brassicae - cabbage aphid - temperature requirements - thermal requirements - braconidae - population - mintosh
The influence of predicted climatic change on agricultural pest and beneficial insect species is of high importance for growers since increasing temperatures may have a direct impact on the developmental rates of insect populations. These parameters are species-specific and result in variable reactions to climate change, potentially disrupting the synchrony of pest-parasitoid dynamics. This study investigatedthe effect of increasing temperatures caused by climatechange on the population dynamics of the mealy cabbage aphid Brevicoryne brassicae , a worldwide occurring pest species in cruciferous crops, and the endoparasitoid Diaeretiella rapae . For three vegetable growing regions in lower Saxony, the population development of both species was simulatedfor (1) the near future (2041-2050), (2) the far future (2090-2099) and (3) the reference time period (1991-2000), using an age structured simulation model including simulated temperature data. An earlier first occurrence of D. rapae in spring compared to B. brassicae was shown, however with no disruption of the synchrony between the two populations. Despite the earlier occurrence and increased population size of D. rapae in future periods, B. brassicae maximum population size also increased. Furthermore, an earlier occurrence of alate aphids during the season resulted from the model, indicating a potential need to adapt pest management.
Food plant and herbivore host species affect the outcome of intrinsic competition among parasitoid larvae
Poelman, E.H. ; Gols, R. ; Gumovsky, A.V. ; Cortesero, A.M. ; Dicke, M. ; Harvey, J.A. - \ 2014
Ecological Entomology 39 (2014)6. - ISSN 0307-6946 - p. 693 - 702.
cotesia-rubecula hymenoptera - endoparasitoid wasps - insect parasitoids - heliothis-virescens - community structure - braconidae - superparasitism - discrimination - solitary - lepidoptera
1. In nature, several parasitoid species often exploit the same stages of a common herbivore host species and are able to coexist despite competitive interactions amongst them. Less is known about the direct effects of resource quality on intrinsic interactions between immature parasitoid stages. The present study is based on the hypothesis that variation in the quality or type of plant resources on which the parasitoids indirectly develop may be complementary and thus facilitate niche segregation favouring different parasitoids in intrinsic competition under different dietary regimes. 2. The present study investigated whether two herbivore species, the cabbage butterflies Pieris brassicae and Pieris rapae (Pieridae), and the quality of two important food plants, Brassica oleracea and Brassica nigra (Brassicaceae), affect the outcome of intrinsic competition between their primary larval endoparasitoids, the gregarious Cotesia glomerata (Braconidae) and the solitary Hyposoter ebeninus (Ichneumonidae). 3. Hyposoter ebeninus is generally an intrinsically superior competitor over C.¿glomerata. However, C.¿glomerata survived more antagonistic encounters with H.¿ebeninus when both developed in P.¿brassicae rather than in P.¿rapae caterpillars, and while its host was feeding on B.¿nigra rather than B.¿oleracea. Moreover, H.¿ebeninus benefitted from competition by its higher survival in multiparasitised hosts. 4. These results show that both plant and herbivore species mediate the battleground on which competitive interactions between parasitoids are played out and may affect the outcomes of these interactions in ways that enable parasitoids to segregate their niches. This in turn may promote coexistence among parasitoid species that are associated with the same herbivore host.
A bodyguard or a tastier meal? Dying caterpillar indirectly protects parasitoid cocoons by offering alternate prey to a generalist predator
Harvey, J.A. ; Weber, D. ; Clercq, P. De; Gols, R. - \ 2013
Entomologia Experimentalis et Applicata 149 (2013). - ISSN 0013-8703 - p. 219 - 228.
cotesia-glomerata l. - host behavior - insect parasitoids - manipulation - wasp - hyperparasitism - populations - braconidae - strategies - usurpation
In some parasitic Hymenoptera the dying caterpillars remain attached or close to the parasitoid cocoons. It has been suggested that the caterpillars act as ‘bodyguards’ for the vulnerable cocoons and therefore protect them against predators and/or hyperparasitoids (the ‘usurpation hypothesis’). This hypothesis has been demonstrated in associations where the caterpillars remain active and/or aggressive after parasitism. However, in other associations the caterpillars are so physiologically depleted after parasitism that they are unable to physically defend the cocoons and instead sit atop them in a moribund state. In this study a generalist predator, the spined soldier bug, Podisus maculiventris Say (Hemiptera: Pentatomidae), was provided with cocoons of the gregarious endoparasitoid Cotesia glomerata L. and the solitary endoparasitoid Microplitis mediator Haliday (both Hymenoptera: Braconidae), in turn attended by their hosts, Pieris brassicae L. (Lepidoptera: Pieridae) and Mamestra brassicae L. (Lepidoptera: Noctuidae), respectively. Cotesia glomerata produces broods of up to 40 cocoons and the dying caterpillars sit atop the cocoons where they exhibit little response to physical stimuli. Previous studies reported that dying P. brassicae caterpillars were ineffective bodyguards against two species of hyperparasitoids. In both associations, the dying host caterpillars were significantly preferred as food by P. maculiventris over the parasitoid cocoons. However, in absence of caterpillars, the bugs readily attacked the C. glomerata cocoons. Alternatively, the survival of M. mediator was very low, irrespective of whether a caterpillar was present or not. Caterpillars attacked by M. mediator are several times smaller than those attacked by C. glomerata. Consequently, the predators ran out of food much more quickly in the former and switched from one prey to the other. We show that in some host–parasitoid associations the dying caterpillars provide more visually apparent or nutritionally superior prey, rather than acting as bodyguards.
Hyperparasitoids Use Herbivore-Induced Plant Volatiles to Locate Their Parasitoid Host
Poelman, E.H. ; Bruinsma, M. ; Zhu, F. ; Weldegergis, B.T. ; Boursault, A.E. ; Jongema, Y. ; Loon, J.J.A. van; Vet, L.E.M. ; Harvey, J.A. ; Dicke, M. - \ 2012
PloS Biology 10 (2012)11. - ISSN 1545-7885 - 13 p.
higher trophic levels - cotesia-glomerata - natural enemies - hymenoptera - braconidae - rubecula - quality - performance - arthropods - behavior
Plants respond to herbivory with the emission of induced plant volatiles. These volatiles may attract parasitic wasps (parasitoids) that attack the herbivores. Although in this sense the emission of volatiles has been hypothesized to be beneficial to the plant, it is still debated whether this is also the case under natural conditions because other organisms such as herbivores also respond to the emitted volatiles. One important group of organisms, the enemies of parasitoids, hyperparasitoids, has not been included in this debate because little is known about their foraging behaviour. Here, we address whether hyperparasitoids use herbivore-induced plant volatiles to locate their host. We show that hyperparasitoids find their victims through herbivore-induced plant volatiles emitted in response to attack by caterpillars that in turn had been parasitized by primary parasitoids. Moreover, only one of two species of parasitoids affected herbivore-induced plant volatiles resulting in the attraction of more hyperparasitoids than volatiles from plants damaged by healthy caterpillars. This resulted in higher levels of hyperparasitism of the parasitoid that indirectly gave away its presence through its effect on plant odours induced by its caterpillar host. Here, we provide evidence for a role of compounds in the oral secretion of parasitized caterpillars that induce these changes in plant volatile emission. Our results demonstrate that the effects of herbivore-induced plant volatiles should be placed in a community-wide perspective that includes species in the fourth trophic level to improve our understanding of the ecological functions of volatile release by plants. Furthermore, these findings suggest that the impact of species in the fourth trophic level should also be considered when developing Integrated Pest Management strategies aimed at optimizing the control of insect pests using parasitoids.
Assessing non-target effects and host feeding of the exotic parasitoid Apanteles taragamae, a potential biological control agent of the cowpea pod borer Maruca vitrata
Dannon, A.E. ; Tamo, M. ; Huis, A. van; Dicke, M. - \ 2012
BioControl 57 (2012)3. - ISSN 1386-6141 - p. 415 - 425.
busseola-fusca lepidoptera - larval parasitoids - intrinsic competition - lethal interference - population-dynamics - natural enemies - arthropod pests - hymenoptera - braconidae - pyralidae
Apanteles taragamae Viereck is a larval parasitoid introduced in Benin for classical biological control of the cowpea pod borer Maruca vitrata Fabricius. In the laboratory, we evaluated the effects of A. taragamae on non-target herbivore species, and on another parasitoid of M. vitrata, i.e. the egg-larval parasitoid Phanerotoma leucobasis Kriechbaumer. Furthermore, we addressed the host feeding behaviour of A. taragamae. The host specificity of A. taragamae was assessed by offering six other lepidopteran species to the wasp. The competitive ability of A. taragamae was studied by providing the wasp with one- and two-days-old M. vitrata larvae that had hatched from eggs previously parasitized by P. leucobasis. Controls consisted of eggs and larvae offered only to P. leucobasis and A. taragamae, respectively. None of the other six lepidopteran species was successfully parasitized by A. taragamae. The larval parasitoid A. taragamae outcompeted the egg-larval parasitoid P. leucobasis when offered two-days-old host larvae. Competition between the two parasitoid species did not significantly affect one-day-old host larvae that were less suitable to A. taragamae. Host feeding by A. taragamae did not affect survival of one-day-old or two-days-old M. vitrata larvae. However, the percentage parasitism of two-days-old larvae was significantly reduced when exposed to female A. taragamae wasps that had been starved during 48 h. The data are discussed with regard to host specificity, host feeding patterns and to factors underlying the outcome of intrinsic competition between parasitoid species.
The roles of ecological fitting, phylogeny and physiological equivalence in understanding realized and fundamental host ranges in endoparasitoid wasps
Harvey, J.A. ; Ximenez De Embun, M.G. ; Bukovinszky, T. ; Gols, R. - \ 2012
Journal of Evolutionary Biology 25 (2012)10. - ISSN 1010-061X - p. 2139 - 2148.
hyposoter-didymator hym - microplitis-demolitor - developmental strategies - insect parasitoids - cotesia-kazak - arms-race - hymenoptera - evolution - plant - braconidae
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.
Plants under multiple herbivory: consequences for parasitoid search behaviour and foraging efficiency
Bukovinszky, T. ; Poelman, E.H. ; Kamp, A. ; Hemerik, L. ; Prekatsakis, G. ; Dicke, M. - \ 2012
Animal Behaviour 83 (2012)2. - ISSN 0003-3472 - p. 501 - 509.
cotesia-rubecula - induced responses - interaction webs - natural enemies - c-rubecula - communities - heterogeneity - hymenoptera - braconidae - caterpillars
In the field, plants are attacked by several herbivore species both simultaneously and in isolation. Spatial variation in damage to plants by different herbivores may affect the search behaviour of parasitoid wasps, but the consequences of this variation for host–parasitoid interactions are still little understood. We examined the effects of multiple herbivory on the search behaviour of the parasitoid Cotesia glomerata. Reduced parasitism was found in a field tent experiment, when both the host small cabbage white, Pieris rapae, and the nonhost cabbage moth, Mamestra brassicae, were present on Brassica oleracea plants. When hosts and nonhosts occurred on the same or neighbouring plants, this reduction in parasitism was similar, but the underlying behavioural mechanisms were different. In wind tunnel bioassays, parasitoids were equally attracted towards plants infested by the two herbivore species but were more attracted to plants with both herbivore species than to plants with only one. Differences in arrival tendencies therefore could not explain the reduced parasitism in the tent experiment with mixed infestations. Experiments showed that parasitoids readily left nonhost patches, whereas leaving tendencies from mixed patches of hosts and nonhosts were the same as from pure host patches. Therefore, reduced leaving tendencies and reduced host encounters explained the lower parasitism rate in mixed infestations in the tent experiment. Our results show that the spatial context in which hosts and nonhosts attack plants determines the foraging efficiency of parasitoids, with consequences for host–parasitoid interactions
Differing Success of Defense Strategies in Two Parasitoid Wasps in Protecting Their Pupae Against a Secondary Hyperparasitoid
Harvey, J.A. ; Gols, R. ; Tanaka, T. - \ 2011
Annals of the Entomological Society Of America 104 (2011)5. - ISSN 0013-8746 - p. 1005 - 1011.
cotesia-glomerata l. - meteorus-pulchricornis - behavioral manipulation - separata lepidoptera - pseudaletia-separata - insect parasitoids - host caterpillars - life-history - braconidae - hymenoptera
During their larval development, endoparasitoids are known to dispose of host resources in several different ways. Some parasitoid wasps consume most or all tissues of the host, whereas others consume a small fraction of host resources and either ensure that the host moves away from the pupation site or allow the host to remain close to the parasitoid cocoon(s). Using a single host species, Mythimna separata Walker (Lepidoptera: Noctuidae), this study compares the success of the two pupation strategies in the solitary parasitoids Microplitis sp. and Meteorus pulchricornis Wesmael (Hymenoptera: Braconidae) against attack from a secondary hyperparasitoid, Gelis agilis F. (Hymenoptera: Ichneumonidae). The caudal appendages of M. separata caterpillars parasitized by Microplitis sp. remain physically attached to parasitoid cocoons and the caterpillars behave aggressively when disturbed. However, after Me. pulchricornis larvae emerge from caterpillars of their host, M. separata, the parasitoid larvae pupate in cocoons that are suspended by a single thick thread that hangs 1–2 cm from under a leaf. In choice tests conducted in petri dishes, significantly fewer cocoons of Microplitis sp. attended by caterpillars than unattended cocoons were hyperparasitized by G. agilis. By contrast, Me. pulchricornis cocoons that were hanging from corn, Zea mays L., plants were hyperparasitized as frequently as those which were attached to leaves. We discuss the potentially different selection pressures generated among natural enemies such as predators and hyperparasitoids in determining optimal pupal defense strategies in primary parasitoids.
Development and host utilization in Hyposoter ebeninus (Hymenoptera: Ichneumonidae), a solitary endoparasitoid of Pieris rapae and P. brassicae caterpillars (Lepidoptera: Pieridae)
Harvey, J.A. ; Poelman, E.H. ; Gols, R. - \ 2010
Biological Control 53 (2010)3. - ISSN 1049-9644 - p. 312 - 318.
campoletis-sonorensis hymenoptera - parasitoids cotesia-glomerata - rubecula hymenoptera - heliothis-virescens - nutritional ecology - c-rubecula - braconidae - growth - noctuidae - plant
In many parts of the world, the larvae of the cabbage white butterflies, Pieris rapae and P. brassicae, are considered to be major pests in several economically important brassicaceous crops including various cultivars of cabbage and mustard. Thus far, biological control of these pests has focused on parasitoids including species in the genus Cotesia. We examined interactions between the solitary ichneumonid parasitoid, Hyposoter ebeninus, developing in 1st to 3rd (L1–L3) larval instars of both P. rapae and P. brassicae. H. ebeninus is common in central and southern Europe, but has thus far received little attention as a possible biological control agent of cabbage butterflies. Larvae of both pierids continued to grow after they were parasitized, and development was only arrested some 5–7 days later. Caterpillars parasitized in the third instar grew significantly larger than larvae parasitized as L1 or L2. Adult parasitoid body mass was inversely correlated with host instar parasitized, and female wasps were significantly larger than male wasps. Egg-to-adult development time in H. ebeninus did not vary between the two hosts, but the parasitoid exhibited protandry. Parasitoid survival was generally higher in larvae of P. rapae than in larvae of P. brassicae, but varied with instar in the two hosts. Our study shows that H. ebeninus has promise as a biological control agent, particularly against its more suitable host, P. rapae.
Aphidius matricariae: een nieuw wapen tegen rode luis
Schelt, J. van; Messelink, G.J. - \ 2010
Onder Glas 7 (2010)2. - p. 22 - 23.
geïntegreerde plagenbestrijding - vruchtgroenten - capsicum annuum - biologische bestrijding - braconidae - aphidius matricariae - aphidoidea - organismen ingezet bij biologische bestrijding - paprika - sluipwespen - glastuinbouw - groenten - integrated pest management - fruit vegetables - capsicum annuum - biological control - braconidae - aphidius matricariae - aphidoidea - biological control agents - sweet peppers - parasitoid wasps - greenhouse horticulture - vegetables
Uit een zoektocht naar nieuwe sluipwespen tegen bladluis in paprika is Aphidius matricariae als meest effectieve bestrijder naar voren gekomen. Drie kasproeven in verschillende seizoenen laten unaniem zien dat deze soort rode luis beter bestrijdt dan de standaard sluipwesp A. colemani. Door de goede resultaten van de drie kasexperimenten wordt de parasiet Aphidius matricariae snel op de markt geïntroduceerd en is dus snel beschikbaar voor telers
Intrinsic competition and its effects on the survival and development of three species of endoparasitoid wasps
Harvey, J.A. ; Gols, R. ; Strand, M.R. - \ 2009
Entomologia Experimentalis et Applicata 130 (2009)3. - ISSN 0013-8703 - p. 238 - 248.
pseudoplusia-includens lepidoptera - microplitis-demolitor hymenoptera - heliothis-virescens lepidoptera - interspecific competition - host quality - insect parasitoids - life-history - braconidae - noctuidae - growth
In natural systems, pre-adult stages of some insect herbivores are known to be attacked by several species of parasitoids. Under certain conditions, hosts may be simultaneously parasitized by more than one parasitoid species (= multiparasitism), even though only one parasitoid species can successfully develop in an individual host. Here, we compared development, survival, and intrinsic competitive interactions among three species of solitary larval endoparasitoids, Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae), Microplitis demolitor Wilkinson, and Microplitis croceipes (Cresson) (Hymenoptera: Braconidae), in singly parasitized and multiparasitized hosts. The three species differed in certain traits, such as in host usage strategies and adult body size. Campoletis sonorensis and M. demolitor survived equally well to eclosion in two host species that differed profoundly in size, Pseudoplusia includens (Walker) and the larger Heliothis virescens (Fabricius) (both Lepidoptera: Noctuidae). Egg-to-adult development time in C. sonorensis and M. demolitor also differed in the two hosts. Moreover, adult body mass in C. sonorensis (and not M. demolitor) was greater when developing in H. virescens larvae. We then monitored the outcome of competitive interactions in host larvae that were parasitized by one parasitoid species and subsequently multiparasitized by another species at various time intervals (0, 6, 24, and 48 h) after the initial parasitism. These experiments revealed that M. croceipes was generally a superior competitor to the other two species, whereas M. demolitor was the poorest competitor, with C. sonorensis being intermediate in this capacity. However, competition sometimes incurred fitness costs in M. croceipes and C. sonorensis, with longer development time and/or smaller adult mass observed in surviving wasps emerging from multiparasitized hosts. Our results suggest that rapid growth and large size relative to competitors of a similar age may be beneficial in aggressive intrinsic competition
Competition and brood reduction: testing alternative models of clutch size evolution in parasitoids
Pexton, J.J. ; Boer, J.G. de; Heimpel, G.E. ; Vet, L.E.M. ; Whitfield, J.B. ; Ode, P.J. - \ 2009
Behavioral Ecology 20 (2009)2. - ISSN 1045-2249 - p. 403 - 409.
gregarious development - nonsiblicidal behavior - host discrimination - larval aggression - cotesia-flavipes - wasps - hymenoptera - braconidae - transition - solitary
Competition between siblings occurs in many taxa including parasitoid wasps. Larvae of solitary species eliminate competitors by engaging in aggressive behavior, thus restricting brood size to a single individual. In gregarious species, more than one offspring can develop per host. There are 2 models by which gregariousness can arise in a population of solitary individuals: 1) through a reduction in larval mobility (with the retention of aggressive behavior) or 2) through a reduction in fighting behavior or ability. When more larvae are present than can be supported by available host resources, these 2 models make opposing predictions regarding the process of brood size reduction: Mortality occurring early in larval development under the reduced mobility hypothesis versus mortality occurring throughout larval development under the reduced aggression hypothesis. Here, we measure changes in brood size over the course of larval development of the gregarious parasitoid, Cotesia flavipes. Superparasitized hosts contained approximately twice as many C. flavipes eggs as hosts parasitized by a single parasitoid female. Brood sizes in superparasitized hosts declined gradually as C. flavipes individuals developed, whereas brood sizes remained constant during larval development in singly parasitized hosts. An absence of wounded or destroyed larvae suggested no aggressive behavior. Collectively, these results support the reduced aggression hypothesis.
Vlindervaders brengen hun kinderen in gevaar
Mulder, S. - \ 2008
Nature Today 2008 (2008)27-10-2008.
pieris brassicae - braconidae - antigenen - nadelige gevolgen - sluipwespen - insect-plant relaties - pieris brassicae - braconidae - antigens - adverse effects - parasitoid wasps - insect plant relations
Parasitoid load affects plant fitness in a tritrophic system
Smallegange, R.C. ; Loon, J.J.A. van; Blatt, S.E. ; Harvey, J.A. ; Dicke, M. - \ 2008
Entomologia Experimentalis et Applicata 128 (2008)1. - ISSN 0013-8703 - p. 172 - 183.
apanteles-glomeratus hymenoptera - pieris-rapae larvae - cotesia-glomerata - developmental strategies - food-consumption - natural enemies - clutch size - host-plant - braconidae - brassicae
Plants attacked by herbivorous insects emit volatile compounds that attract predators or parasitoids of the herbivores. Plant fitness increases when these herbivorous insects are parasitized by solitary parasitoids, but whether gregarious koinobiont parasitoids also confer a benefit to plant fitness has been disputed. We investigated the relationship between parasitoid load of the gregarious Cotesia glomerata (L.) (Hymenoptera: Braconidae), food consumption by larvae of their host Pieris brassicae L. (Lepidoptera: Pieridae), and seed production in a host plant, Brassica nigra L. (Brassicaceae), in a greenhouse experiment. Plants damaged by caterpillars containing single parasitoid broods produced a similar amount of seeds as undamaged control plants and produced significantly more seeds than plants with unparasitized caterpillars feeding on them. Increasing the parasitoid load to levels likely resulting from superparasitization, feeding by parasitized caterpillars was significantly negatively correlated with plant seed production. Higher parasitoid brood sizes were negatively correlated with pupal weight of Cotesia glomerata, revealing scramble competition leading to a fitness trade-off for the parasitoid. Our results suggest that in this tritrophic system plant fitness is higher when the gregarious parasitoid deposits a single brood into its herbivorous host. A prediction following from these results is that plants benefit from recruiting parasitoids when superparasitization is prevented. This is supported by our previous results on down-regulation of synomone production when Brassica oleracea was fed on by parasitized caterpillars of P. brassicae. We conclude that variable parasitoid loads in gregarious koinobiont parasitoids largely explain existing controversies about the putative benefit of recruiting these parasitoids for plant reproduction.
Do Parasitized caterpillars protect their parasitoids from hyperparasitoids? A test of the 'usurpation hypothesis'
Harvey, J.A. ; Kos, M. ; Nakamatsu, Y. ; Tanaka, T. ; Dicke, M. ; Vet, L.E.M. ; Brodeur, J. ; Bezemer, T.M. - \ 2008
Animal Behaviour 76 (2008)3. - ISSN 0003-3472 - p. 701 - 708.
host behavior - insect parasitoids - wasp - manipulation - braconidae - predation - selection - quality - snail - larva
Caterpillars that are attacked by some species of parasitoid wasps are known to survive for several days after the parasitoid larvae emerge and pupate. It has been argued that the behaviour of the parasitized larva is `usurped¿ by the parasitoid and that it `guards¿ the parasitoid cocoons against their own natural enemies such as hyperparasitoids (the `usurpation hypothesis'). We tested this hypothesis in the association involving a gregarious endoparasitoid, the wasp Cotesia glomerata; caterpillars of its host, the large cabbage white butterfly Pieris brassicae; and a pupal hyperparasitoid, the wasp Lysibia nana. In laboratory experiments, we presented cocoon broods of C. glomerata to single females of L. nana in arenas for 6 h. We tested several treatments for rates of primary parasitoid survival, including variation in the position of the caterpillar and the presence or absence of an additional silk web spun by parasitized caterpillars. Parasitized P. brassicae larvae survived longer than the period necessary for C. glomerata adults to emerge. Rates of parasitoid survival were, however, unaffected by the presence of a P. brassicae larva on the cocoon brood, although significantly more parasitoids emerged when the silk web was present. Analyses of the foraging behaviour of individual L. nana females in arenas, performed using Observer software, revealed that the wasps showed a greater tendency to leave cocoons when caterpillars and silk were present. The laboratory experiments only partially support the usurpation hypothesis. In nature, usurpation of the host of the primary parasitoid may be a more effective strategy against generalist predators than against more specialized and better-adapted hyperparasitoids
Appelbloedluis? laat natuurlijke vijanden hun werk doen
Helsen, Herman - \ 2007
arboriculture - forest nurseries - fruit growing - fruit trees - eriosoma lanigerum - integrated pest management - biological control - natural enemies - forficulidae - braconidae - aphelinus mali - biological control agents - apples - encouragement
Biologische beheersing erwtenluis (Acyrthosiphon pisum)
Broek, R.C.F.M. van den - \ 2007
Wageningen : Praktijkonderzoek Plant & Omgeving B.V. - 15
gewasbescherming - biologische bestrijding - acyrthosiphon pisum - erwten - peulvruchten - biologische landbouw - aphidius ervi - braconidae - landbouwplantenteelt - akkerbouw - plant protection - biological control - acyrthosiphon pisum - peas - grain legumes - organic farming - aphidius ervi - braconidae - crop husbandry - arable farming
De biologische teelt van erwten kan problematisch verlopen. De belangrijkste problemen zijn luizen en voetziekten die de voornaamste oorzaak zijn van een zeer wisselvallige opbrengst. Door deze problemen is de teelt van erwten voor een groot aantal biologische telers een te risicovol gewas geworden met een te laag saldo. In 2007 is nagegaan of de biologische beheersing van de erwtenluis met de sluipwesp Aphidius ervi voldoende perspectieven biedt. Uit onderzoek van het OBS en de Hoeksche Waard is naar voren gekomen dat de aanleg van akkerranden rondom aardappel en graan percelen de ontwikkeling van de luizen dusdanig kan remmen dat de schadedrempel niet wordt overschreden. Nagegaan is of deze randen ook een positief effect hebben op de populatieontwikkeling van luizen in erwten. Daarnaast zijn op 2 momenten in een hoek van een perceel sluipwespen uitgezet om ook dit effect te bestuderen. Het onderzoek is uitgevoerd op 3 percelen op het OBS te Nagele.
Dicke, M. - \ 2007
Natura 104 (2007)2. - ISSN 0028-0631 - p. 36 - 37.
entomologie - diergedrag - cotesia glomerata - cotesia rubecula - braconidae - evolutie - natuurlijke selectie - leervermogen - entomology - animal behaviour - evolution - natural selection - learning ability
Nederland heeft een goede naam als het gaat om gedragsonderzoek. Niko Tinbergen deed onderzoek aan de bijenwolf, een sluipwesp die bijen vangt. Hij maakte de gedragsbiologie tot een wetenschap die verder ging dan het beschrijven van gedrag. Waarom gedragen dieren zich zoals ze zich gedragen? Dat waarom kende vier dimensies: het werkingsmechanisme, de ecologische functie, de ontwikkeling van gedrag en de evolutie van gedrag. Marcel Dicke doet veel onderzoek aan twee andere sluipwespen, Cotesia glomerate en C. rubecula