Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Response of the zoophytophagous predators Macrolophus pygmaeus and Nesidiocoris tenuis to volatiles of uninfested plants and to plants infested by prey or conspecifics
Lins, J.C. ; Loon, J.J.A. van; Bueno, V.H.P. ; Lucas-Barbosa, D. ; Dicke, M. ; Lenteren, J.C. van - \ 2014
BioControl 59 (2014)6. - ISSN 1386-6141 - p. 707 - 718.
borer tuta-absoluta - carnivorous arthropods - heteroptera miridae - biological-control - infochemical use - spider-mites - tomato - herbivores - bug - caliginosus
Knowledge about the orientation mechanisms used by two important predaceous mirids (Macrolophus pygmaeus Rambour and Nesidiocoris tenuis (Reuter)) in finding their prey (whitefly Bemisia tabaci (Gennadius) and the tomato borer Tuta absoluta (Meyrick)) is limited. In a Y-tube olfactometer, we tested the behavioral responses of naïve and experienced predators to uninfested plants, herbivore-induced plant volatiles (HIPVs) from plants infested with T. absoluta and/or B. tabaci, the sex pheromone of T. absoluta, and volatiles produced by plants injured by the predators. Nesidiocoris tenuis responds to volatiles produced by uninfested plants only after experience with the plant, whereas naïve and experienced M. pygmaeus show positive chemotaxis. Both predators are attracted to volatiles from prey-infested plants, and we provide the first evidence that experience affects this response in M. pygmaeus. Infestation of the same plant by both prey species elicited similar responses by the two predators as plants infested by either herbivore singly. Neither predator responded to sex pheromones of T. absoluta. Macrolophus pygmaeus avoided plants injured by conspecifics, while N. tenuis females were attracted by such plants. The implications of these results for augmentative biological control are discussed.
Effect of belowground herbivory on parasitoid associative learning of plant odours
Kruidhof, H.M. ; Rijk, M. de; Hoffmann, D. ; Harvey, J.A. ; Vet, L.E.M. ; Soler Gamborena, R. - \ 2013
Oikos 122 (2013)7. - ISSN 0030-1299 - p. 1094 - 1100.
aboveground multitrophic interactions - infochemical use - natural enemies - root herbivores - quality - behavior - wasps - performance - preference - volatiles
Root herbivores can influence both the performance and the behaviour of parasitoids of aboveground insect herbivores through changes in aboveground plant quality and in the composition of the plant's odour blend. Here we show that root herbivory by Delia radicum larvae did not influence the innate preferences for plant odours of the two closely related parasitoid species Cotesia glomerata and C. rubecula, but did affect their learned preferences, and did so in an opposite direction. While C. glomerata learned to prefer the odour of plants with intact roots, C. rubecula learned to prefer the odour of root-infested plants. The learned preference of C. glomerata for the odour of plants with intact roots matches our previously published result of its better performance when developing in P. brassicae hosts feeding on this plant type. In contrast, the relatively stronger learned preference of C. rubecula for the odour of root-infested plants cannot be merely explained by its performance, as the results of our present study indicate that D. radicum root herbivory did not influence the performance of C. rubecula nor of its host P. rapae. Our results stress the importance of assessing the influence of root herbivores on both innate and learned responses of parasitoids to plant odours.
Variation in the specificity of plant volatiles and their use by a specialist and a generalist parasitoid
Gols, R. ; Veenemans, C. ; Potting, R.P.J. ; Smid, H.M. ; Dicke, M. ; Harvey, J.A. ; Bukovinszky, T. - \ 2012
Animal Behaviour 83 (2012)5. - ISSN 0003-3472 - p. 1231 - 1242.
plutella-xylostella lepidoptera - diadegma species hymenoptera - host-selection principle - diamondback moth - headspace volatiles - semiclausum hellen - indirect defenses - natural variation - infochemical use - memory dynamics
Herbivore-induced plant volatiles (HIPV) provide important information that influences host location behaviour for insect natural enemies, such as parasitoid wasps, that develop in the bodies of herbivorous insects. The dietary breadth of both the parasitoid and its host may affect the extent to which a searching parasitoid relies on HIPV. Specialist species are expected to rely on specific volatile cues to which they respond innately, whereas generalists are expected to show a higher degree of phenotypic plasticity that depends on foraging experience in the parasitoid. We compared the response to HIPV emitted by different plant species damaged by host and nonhost caterpillars for two congeneric parasitoid species, the specialist Diadegma semiclausum and the generalist Diadegma fenestrale, attacking caterpillars of the diamondback moth, Plutella xylostella. For the three tested plant species, Brassica oleracea, a feral Brassica population and Sinapis alba, both parasitoid species preferred volatiles from host-infested plants over those produced by undamaged plants. However, both parasitoid species only distinguished between volatiles induced by host and nonhosts when the caterpillars had been feeding on B. oleracea, the plant on which they had been reared. Chemical analysis of the volatile blends could not explain volatile preferences of the parasitoids. Despite the difference in their dietary breadth, the two parasitoids responded similarly to HIPV and experience treatments. A flexible response to a wide array of volatile blends by parasitoids is probably important in nature, given that different generations of the host and the parasitoid probably develop on different food plants.
Root and shoot jasmonic acid induction differently affects the foraging behavior of under semi-field conditions
Qiu, B.L. ; Dam, N.M. van; Harvey, J.A. ; Vet, L.E.M. - \ 2012
BioControl 57 (2012). - ISSN 1386-6141 - p. 387 - 395.
induced plant volatiles - planthopper nilaparvata-lugens - carnivorous arthropods - anagrus-nilaparvatae - pieris-brassicae - beta-glucosidase - infochemical use - parasitic wasps - rice volatiles - zea-mays
Plants can accumulate and release defensive chemicals by activating various signaling pathways when they are damaged by herbivores or pathogens. The jasmonic acid pathway is activated after damage by chewing herbivores. Here we used jasmonic acid (JA) as an exogenous elicitor to induce feral cabbage plants. In this study, the effects of root JA (RJA) and shoot JA (SJA) induction on the foraging behavior of , a parasitoid of the large cabbage white butterfly , was investigated under semi-field conditions. In all combinations of differently induced plants (RJA, SJA and control plants), the percentages of shoot induced plants that were visited by at least one wasp were significantly higher than those of controls or root induced plants during 3 h of foraging. Consequently, parasitism rates of on shoot-JA induced plants were significantly higher than on plants induced with JA to the roots or control plants in all tests. However, this behavioral preference was not reflected in the allocation of offspring. The clutch sizes of eggs on control, root induced and shoot induced plants were not significantly different from each other in two-choice or three-choice experiments, but did differ with clutch size in the two-choice experiment of uninduced control plants versus SJA. This semi-field study helps to further understand the choice behavior and preferences of parasitoids in natural multitrophic communities in which plants induced with root or shoot herbivores occur together.
Demonstration of long-term memory in the parasitic wasp Nasonia vitripennis
Schurmann, D. ; Sommer, C. ; Schinko, A.P.B. ; Greschista, M. ; Smid, H.M. ; Steidle, J.L.M. - \ 2012
Entomologia Experimentalis et Applicata 143 (2012)2. - ISSN 0013-8703 - p. 199 - 206.
male sex-pheromone - lariophagus-distinguendus - microplitis-croceipes - host discrimination - natural variation - infochemical use - learning rate - dynamics - pteromalidae - hymenoptera
We studied the formation of protein synthesis-dependent long-term memory (LTM) in the parasitic wasp Nasonia vitripennis Walker (Hymenoptera: Pteromalidae), a parasitoid of fly pupae. Female wasps were trained in one of five different training procedures in the presence of hosts and the odour cinnamon. Six days later the reaction of the wasps towards the odour was tested in a static four-chamber olfactometer. When wasps were trained by a single drilling experience we could not find any reaction to cinnamon after 6 days. In contrast, when wasps were trained either via drilling plus host feeding, three drilling events (spaced training), 1 h training, or 24 h training including oviposition, they significantly preferred cinnamon 6 days later. Wasps which were injected the transcription inhibitor actinomycin D after a 1-h training to block protein synthesis showed normal memory retention up to 3 days, but did not react to cinnamon after 4 and 6 days. Control experiments showed no influence of actinomycin D on the natural behaviour and the general odour discrimination ability of N. vitripennis. This demonstrates that protein synthesis-dependent LTM has been formed. To our knowledge this is the first time that LTM formation after drilling plus host feeding but without oviposition is demonstrated in a parasitic wasp. These results were combined with additional findings about anaesthesia-sensitive memory, anaesthesia-resistant memory, and intermediate memory to develop a multiphase model of memory dynamics in N. vitripennis and to discuss ecological adaptations of memory formation in N. vitripennis and other parasitic wasp species.
Natural variation in learning rate and memory dynamics in parasitoid wasps: opportunities for converging ecology and neuroscience
Hoedjes, K.M. ; Kruidhof, H.M. ; Huigens, M.E. ; Dicke, M. ; Vet, L.E.M. ; Smid, H.M. - \ 2011
Proceedings of the Royal Society. B: Biological Sciences 278 (2011)1707. - ISSN 0962-8452 - p. 889 - 897.
long-term-memory - cotesia-glomerata - drosophila-melanogaster - leptopilina-heterotoma - microplitis-croceipes - phytophagous insects - foraging success - infochemical use - apis-mellifera - c-rubecula
Although the neural and genetic pathways underlying learning and memory formation seem strikingly similar among species of distant animal phyla, several more subtle inter- and intraspecific differences become evident from studies on model organisms. The true significance of such variation can only be understood when integrating this with information on the ecological relevance. Here, we argue that parasitoid wasps provide an excellent opportunity for multi-disciplinary studies that integrate ultimate and proximate approaches. These insects display interspecific variation in learning rate and memory dynamics that reflects natural variation in a daunting foraging task that largely determines their fitness: finding the inconspicuous hosts to which they will assign their offspring to develop. We review bioassays used for oviposition learning, the ecological factors that are considered to underlie the observed differences in learning rate and memory dynamics, and the opportunities for convergence of ecology and neuroscience that are offered by using parasitoid wasps as model species. We advocate that variation in learning and memory traits has evolved to suit an insect's lifestyle within its ecological niche.
Smelling the Wood from the Trees: Non-Linear Parasitoid Responses to Volatile Attractants Produced by Wild and Cultivated Cabbage
Gols, R. ; Bullock, J.M. ; Dicke, M. ; Bukovinszky, T. ; Harvey, J.A. - \ 2011
Journal of Chemical Ecology 37 (2011)8. - ISSN 0098-0331 - p. 795 - 807.
indirect plant defense - natural enemies - diaeretiella-rapae - infochemical use - damaged plants - jasmonic acid - food plants - herbivores - specialist - brassica
Despite a large number of studies on herbivoreinduced plant volatiles (HIPVs), little is known about which specific compounds are used by natural enemies to locate prey- or host- infested plants. In addition, the role of HIPVs in attracting natural enemies has been restricted largely to agricultural systems. Differences in volatile blends emitted by cultivars and plants that originate from wild populations may be attributed to potentially contrasting selection regimes: natural selection among the wild types and artificial selection among cultivars. A more realistic understanding of these interactions in a broader ecological and evolutionary framework should include studies that involve insect herbivores, parasitoids, and wild plants on which they naturally interact in the field. We compared the attractiveness of HIPVs emitted by wild and cultivated cabbage to the parasitoid Cotesia rubecula, and determined the chemical composition of the HIPV blends to elucidate which compounds are involved in parasitoid attraction. Wild and cultivated cabbage differed significantly in their volatile emissions. Cotesia rubecula was differentially attracted to the wild cabbage populations and preferred wild over cultivated cabbage. Isothiocyanates, which were only emitted by the wild cabbages, may be the key components that explain the preference for wild over cultivated cabbage, whereas terpenes may be important for the differential attraction among the wild populations. Volatile analysis revealed that parasitoid attraction cannot be explained by simple linear relationships. Our results suggest that unraveling which compound(s) are innately attractive to parasitoids of cabbage pests should include wild Brassicaceae
Aboveground herbivory affects indirect defences of brassicaceous plants against the root feeder Delia radicum Linnaeus: laboratory and field evidence
Pierre, P.S. ; Dugravot, S. ; Ferry, A. ; Soler, R. ; Dam, N.M. van; Cortesero, A.M. - \ 2011
Ecological Entomology 36 (2011)3. - ISSN 0307-6946 - p. 326 - 334.
natural enemies - entomopathogenic nematodes - specialist herbivore - insect herbivores - induced volatiles - infochemical use - cabbage plants - host-plant - performance - attraction
1. Belowground herbivory has recently been shown to disrupt the host location behaviour of aboveground parasitoids and thereby impact plants indirect defences. Reverse interactions, on the other hand, have received little attention so far. 2. Lab and field studies were conducted to examine whether the presence of the leaf herbivore Pieris brassicae Linnaeus on brassicaceous plants influences the response of Trybliographa rapae Westwood, a specialist parasitoid of the root feeder Delia radicum Linnaeus. 3. The present results show that the attraction of the parasitoid towards host-infested plants disappeared when these plants were also infested by P. brassicae. This absence of attraction was observed both when the complete odour blend or only undamaged leaves from damaged plants were offered, emphasising the role of systemically induced volatiles for host location in T. rapae. 4. Furthermore, the field study revealed that parasitism levels dropped from 30% on root-infested plants to 4% on double-infested plants. 5. The present study is the first to confirm that reduced attraction to host-infested plants as a result of simultaneous attack by below- and aboveground herbivores translates into lower levels of parasitism in the field.
Chemical espionage on species-specific butterfly anti-aphrodisiacs by hitchhiking Trichogramma wasps
Huigens, M.E. ; Woelke, J.B. ; Pashalidou, F.G. ; Bukovinszky, T. ; Smid, H.M. ; Fatouros, N.E. - \ 2010
Behavioral Ecology 21 (2010). - ISSN 1045-2249 - p. 470 - 478.
podisus-maculiventris hemiptera - weevil ceutorhynchus-assimilis - rape brassica-napus - sex-pheromone - oilseed rape - entomophagous insects - parasitic wasps - egg parasitoids - foraging behavior - infochemical use
Parasitic wasps employ a wide range of chemical cues to find their hosts. Very recently, we discovered how 2 closely related egg parasitoids, Trichogramma brassicae and Trichogramma evanescens, exploit the anti-aphrodisiac pheromone benzyl cyanide of one of their hosts, the gregarious large cabbage white butterfly Pieris brassicae that deposits a clutch of more than 20 eggs per oviposition bout. The pheromone is transferred by male butterflies to females during mating to enforce female monogamy. On detecting the anti-aphrodisiac, the tiny parasitic wasps ride on a mated female butterfly to a host plant and then parasitize her freshly laid eggs. The present study demonstrates that both wasp species similarly exploit the anti-aphrodisiac mixture of methyl salicylate and indole of another host, the more common solitary small cabbage white butterfly Pieris rapae that deposits only one egg at a time. Interestingly, this behavior is innate in T. brassicae, whereas T. evanescens learns it after one successful ride on a mated female butterfly. Moreover, we show that the wasps only respond to the anti-aphrodisiacs of the 2 cabbage white butterflies when the ubiquitous compounds are part of a complete mated female odor blend. Obviously, parasitic wasps use the sophisticated espionage-and-ride strategy to find eggs of different gregarious and solitary host species. From the wasps’ perspective there seems to be a trade-off between the abundance and egg-laying behavior of the butterflies. Our findings suggest that Pieris butterflies are under strong selective pressure to minimize the use of an anti-aphrodisiac.
Nonlinear effects of plant root and shoot jasmonic acid application on the performance of Pieris brassicae and its parasitoid Cotesia glomerata
Qiu, B.L. ; Harvey, J.A. ; Raaijmakers, C.E. ; Vet, L.E.M. ; Dam, N.M. van - \ 2009
Functional Ecology 23 (2009)3. - ISSN 0269-8463 - p. 496 - 505.
host-plant - food-web - solitary specialist - insect parasitoids - signaling pathways - induced resistance - ecological costs - infochemical use - feeding insect - herbivore
1. Plant species employ several direct and indirect defence strategies to protect themselves against insect herbivores. Most studies, however, have focused on shoot-induced responses. Much less is known about interactions between below- and above-ground herbivores and how these may affect their respective parasitoids. 2. Here, we quantify the impact of below-ground induced responses vs. that of above-ground induced responses in a feral Brassica on the performance of Pieris brassicae and its endoparasitoid Cotesia glomerata. Jasmonic acid (JA) was applied to induce the plants above- or below-ground. The glucosinolate, sugar and amino acid levels of the leaves were analysed. 3. Pieris brassicae larvae grew significantly slower on shoot JA-induced (SJA) plants than on root JA-induced (RJA) and control plants, which were treated with acidic water. On RJA and control plants they showed similar developmental trajectories. Pupal masses, survival till eclosion and egg load, however, were similar on all plants. 4. The development of C. glomerata larvae on SJA plants was significantly longer than that on RJA and control plants. In contrast, the parasitoid's pupal stage lasted longer in hosts feeding on control plants. The total developmental times eventually were similar in all groups. However, the masses of male and female C. glomerata adults that developed hosts on control and RJA plants were significantly larger than those from hosts on SJA plants. JA application increased total glucosinolate contents and decreased the sugars and total amino acids levels independent of whether JA was applied. However, the trajectories of herbivore-induced glucosinolate levels differed between RJA and SJA plants. 5. These results show that the differential effects of above- and below-ground-induced responses on herbivores also affect higher trophic levels in a nonlinear fashion via differential changes in host plant quality. In particular, the indirect effects that below-ground herbivores have on the performance of above-ground parasitoids may exceed the direct effects of plant chemistry on herbivore performance. Consequently, above-ground and below-ground interactions mediated by induced plant responses have the potential to mediate insect community structure and function in complex ways
Species-specific acquisition and consolidation of long-term memory in parasitic wasps
Smid, H.M. ; Bukovinszky, T. ; Wang, G. ; Steidle, J.L.M. ; Bleeker, M.A.K. ; Loon, J.J.A. van; Vet, L.E.M. - \ 2007
Proceedings of the Royal Society. B: Biological Sciences 274 (2007)1617. - ISSN 0962-8452 - p. 1539 - 1546.
cotesia-glomerata - infochemical use - messenger-rna - c-rubecula - drosophila - host - honeybee - dissection - evolution - dynamics
Long-term memory (LTM) formation usually requires repeated, spaced learning events and is achieved by the synthesis of specific proteins. Other memory forms require a single learning experience and are independent of protein synthesis. We investigated in two closely related parasitic wasp species, Cotesia glomerata and Cotesia rubecula, whether natural differences in foraging behaviour are correlated with differences in LTM acquisition and formation. These parasitic wasp species lay their eggs in young caterpillars of pierid butterflies and can learn to associate plant odours with a successful egg laying experience on caterpillars on the odour-producing plant. We used a classical conditioning set-up, while interfering with LTM formation through translation or transcription inhibitors. We show here that C. rubecula formed LTM after three spaced learning trials, whereas C. glomerata required only a single trial for LTM formation. After three spaced learning trials, LTM formation was complete within 4h in C. glomerata, whereas in C. rubecula, LTM formation took 3 days. Linking neurobiology with ecology, we argue that this species-specific difference in LTM acquisition and formation is adaptive given the extreme differences in both the number of foraging decisions of the two wasp species and in the spatial distributions of their respective hosts in nature.
Root herbivores influence the behaviour of an aboveground parasitoid through changes in plant-volatile signals
Soler, R. ; Harvey, J.A. ; Kamp, A.F.D. ; Vet, L.E.M. ; Putten, W.H. van der; Dam, N.M. van; Stuefer, J.F. ; Gols, R. ; Hordijk, C.A. ; Bezemer, T.M. - \ 2007
Oikos 116 (2007)3. - ISSN 0030-1299 - p. 367 - 376.
cotesia-glomerata - natural enemies - evolutionary context - plutella-xylostella - insect parasitoids - infochemical use - trophic levels - host-plant - performance - responses
It is widely reported that plants emit volatile compounds when they are attacked by herbivorous insects, which may be used by parasitoids and predators to locate their host or prey. The study of herbivore-induced plant volatiles and their role in mediating interactions between plants, herbivores and their natural enemies have been primarily based on aboveground systems, generally ignoring the potential interactions between above and belowground infochemical- and food webs. This study examines whether herbivory by Delia radicum feeding on roots of Brassica nigra (black mustard) affects the behaviour of Cotesia glomerata, a parasitoid of the leaf herbivore Pieris brassicae, mediated by changes in plant volatiles. In a semi-field experiment with root-damaged and root-undamaged plants C. glomerata prefers to oviposit in hosts feeding on root-undamaged plants. In addition, in a flight-cage experiment the parasitoid also prefers to search for hosts on plants without root herbivores. Plants exposed to root herbivory were shown to emit a volatile blend characterized by high levels of specific sulphur volatile compounds, which are reported to be highly toxic for insects, combined with low levels of several compounds, i.e. beta-farnesene, reported to act as attractants for herbivorous and carnivorous insects. Our results provide evidence that the foraging behaviour of a parasitoid of an aboveground herbivore can be influenced by belowground herbivores through changes in the plant volatile blend. Such indirect interactions may have profound consequences for the evolution of host selection behaviour in parasitoids, and may play an important role in the structuring and functioning of communities.
Flexible use of patch-leaving mechanisms in a parasitoid wasp
Burger, J.M.S. ; Huang, Y. ; Hemerik, L. ; Lenteren, J.C. van; Vet, L.E.M. - \ 2006
Journal of Insect Behavior 19 (2006)2. - ISSN 0892-7553 - p. 155 - 170.
encarsia-formosa hymenoptera - vaporariorum homoptera-aleyrodidae - time allocation - trialeurodes-vaporariorum - host relationship - infochemical use - commercial glasshouse - population-dynamics - volatile emissions - venturia-canescens
Classical optimal-foraging theory predicts that a parasitoid is less likely to leave a patch after a host encounter when the host distribution is aggregated, whereas a parasitoid is more likely to leave after a host encounter when the host distribution is regular. Field data on host distributions in the area of origin of the whitefly parasitoid Encarsia formosa showed that whiteflies aggregate at several spatial scales. However, infested leaves most likely contained a single host. This suggests that a host encounter is not enough to decide when to leave. We therefore tested the effect of host distribution and parasitoid experience on patch-leaving behavior. Each parasitoid was observed for several consecutive days in a three-dimensional arena with leaflets containing on average one host per leaflet in an either regular or aggregated host distribution. A proportional hazards model showed that a host encounter decreased the leaving tendency on a leaflet with one host when the time since the latest host encounter was short, but increased the leaving tendency when the time since the latest host encounter was long, independent of host distribution. We conclude that a parasitoid can switch from decreasing to increasing its tendency to leave a patch after a host encounter. We propose two hypotheses that may explain the evolution of such a switching mechanism.
Herbivore-induced plant volatiles mediate in-flight host discrimination by parasitoids
Fatouros, N.E. ; Loon, J.J.A. van; Hordijk, K.A. ; Smid, H.M. ; Dicke, M. - \ 2005
Journal of Chemical Ecology 31 (2005)9. - ISSN 0098-0331 - p. 2033 - 2047.
brussels-sprouts plants - pieris-brassicae - cotesia-rubecula - cabbage plants - c-rubecula - carnivorous arthropods - infochemical use - damaged plants - hymenoptera - braconidae
Herbivore feeding induces plants to emit volatiles that are detectable and reliable cues for foraging parasitoids, which allows them to perform oriented host searching. We investigated whether these plant volatiles play a role in avoiding parasitoid competition by discriminating parasitized from unparasitized hosts in flight. In a wind tunnel set-up, we used mechanically damaged plants treated with regurgitant containing elicitors to simulate and standardize herbivore feeding. The solitary parasitoid Cotesia rubecula discriminated among volatile blends from Brussels sprouts plants treated with regurgitant of unparasitized Pieris rapae or P. brassicae caterpillars over blends emitted by plants treated with regurgitant of parasitized caterpillars. The gregarious Cotesia glomerata discriminated between volatiles induced by regurgitant from parasitized and unparasitized caterpillars of its major host species, P. brassicae. Gas chromatography-mass spectrometry analysis of headspace odors revealed that cabbage plants treated with regurgitant of parasitized P. brassicae caterpillars emitted lower amounts of volatiles than plants treated with unparasitized caterpillars. We demonstrate (1) that parasitoids can detect, in flight, whether their hosts contain competitors, and (2) that plants reduce the production of specific herbivore-induced volatiles after a successful recruitment of their bodyguards. As the induced volatiles bear biosynthetic and ecological costs to plants, downregulation of their production has adaptive value. These findings add a new level of intricacy to plant¿parasitoid interactions
Choosy egg parasitoids: specificity of oviposition-induced pine volatiles exploited by an egg parasitoid of pine sawflies
Mumm, R. ; Tiemann, T. ; Varama, M. ; Hilker, M. - \ 2005
Entomologia Experimentalis et Applicata 115 (2005)1. - ISSN 0013-8703 - p. 217 - 225.
plant-carnivore mutualism - diprion-pini - dietary specialization - infochemical use - natural enemies - apis-mellifera - complex odors - host location - genus pinus - black pine
Generalist parasitoids are well-known to be able to cope with the high genotypic and phenotypic plasticity of plant volatiles by learning odours during their host encounters. In contrast, specialised parasitoids often respond innately to host-specific cues. Previous studies have shown that females of the specialised egg parasitoid Chrysonotomyia ruforum Krausse (Hymenoptera: Eulophidae) are attracted to volatiles from Pinus sylvestris L. induced by the egg deposition of its host Diprion pini L. (Hymenoptera: Diprionidae), when they have previously experienced pine twigs with host eggs. In this study we investigated by olfactometer bioassays how specifically C. ruforum responded to oviposition-induced plant volatiles. Furthermore, we studied whether parasitoids show an innate response to oviposition-induced pine volatiles. Naïve parasitoids were not attracted to oviposition-induced pine volatiles. The attractiveness of volatiles from pines carrying eggs was shown to be specific for the pine and herbivore species, respectively (species specificity). We also tested whether not only oviposition, but also larval feeding, induces attractive volatiles (developmental stage specificity). The feeding of D. pini larvae did not induce the emission of P. sylvestris volatiles attractive to the egg parasitoid. Our results show that a specialist egg parasitoid does not innately show a positive response to oviposition-induced plant volatiles, but needs to learn them. Furthermore, the results show that C. ruforum as a specialist does not learn a wide range of volatiles as some generalists do, but instead learns only a very specific oviposition-induced plant volatile pattern, i.e., a pattern induced by the most preferred host species laying eggs on the most preferred food plant
Evolutionary ecology of communication signals that induce aggregative behaviour
Wertheim, B. - \ 2005
Oikos 109 (2005)1. - ISSN 0030-1299 - p. 117 - 124.
cis-vaccenyl acetate - drosophila-melanogaster females - accessory-gland products - infochemical use - natural enemies - sexual conflict - pheromone - responses - exploitation - context
Communication signals inducing aggregative behaviour profoundly affect a variety of ecological interactions, partly because they can be exploited by every member of the foodweb. To develop an evolutionary argument for the use of signals inducing aggregative behaviour in animals, the intricate role of aggregation pheromones in the ecology of Drosophila is discussed as a case study. Costs and benefits for the use of aggregation pheromone depend largely on the local characteristics of the environment, they involve various multitrophic interactions, and payoffs and penalties are density dependent. Plasticity in the use of pheromone is predicted and indeed found. For every ecological system, informational cues accompany food web interactions, and this affects the optimal strategy for individuals in their release of and response to such cues.
Oviposition-induced plant cues: do they arrest Trichogramma wasps during host location?
Fatouros, N.E. ; Bukovinszkine-Kiss, G. ; Kalkers, L.A. ; Soler Gamborena, R. ; Dicke, M. ; Hilker, M. - \ 2005
Entomologia Experimentalis et Applicata 115 (2005)1. - ISSN 0013-8703 - p. 207 - 215.
pieris-brassicae - carnivorous arthropods - insect oviposition - pinus-sylvestris - infochemical use - natural enemies - egg parasitoids - sex-pheromone - tussock moth - volatiles
Plants can defend themselves against herbivorous insects before the larvae hatch from eggs and start feeding. One of these preventive defence strategies is to produce plant volatiles, in response to egg deposition, which attract egg parasitoids that subsequently kill the herbivore eggs. Here, we studied whether egg deposition by Pieris brassicae L. (Lepidoptera: Pieridae) induces Brussels sprouts plants to produce cues that attract or arrest Trichogramma brassicae Bezdeko (Hymenoptera: Trichogrammatidae). Olfactometer bioassays revealed that odours from plants with eggs did not attract or arrest parasitoids. However, contact bioassays showed that T. brassicae females were arrested on egg-free leaf squares excised from leaves with 72 h-old egg masses, which are highly suitable for parasitisation. We tested the hypothesis that this arresting activity is due to scales and chemicals deposited by the butterflies during oviposition and which are thus present on the leaf surface in the vicinity of the eggs. Indeed, leaf squares excised from egg-free leaves, but contaminated with butterfly deposits, arrested the wasps when the squares were tested 1 day after contamination. However, squares from egg-free leaves with 72 h-old butterfly deposits had no arresting activity. Thus, we exclude that the arresting activity of the leaf area near 72 h-old egg masses was elicited by cues from scales and other butterfly deposits. We suggest that egg deposition of P. brassicae induces a change in the leaf surface chemicals in leaves with egg masses. A systemic induction extending to an egg-free leaf neighbouring an egg-carrying leaf could not be detected. Our data suggest that a local, oviposition-induced change of leaf surface chemicals arrests T. brassicae in the vicinity of host eggs
The role of methyl salicylate in prey searching behavior of the predatory mite Phytoseiulus persimilis
Boer, J.G. de; Dicke, M. - \ 2004
Journal of Chemical Ecology 30 (2004)2. - ISSN 0098-0331 - p. 255 - 271.
induced plant volatiles - evolutionary context - infochemical use - natural enemies - abiotic factors - corn plants - identification - emissions - involvement - information
The profiles of pyrrolizidine alkaloids (PAs) in the two highly polyphagous arctiids Estigmene acrea and Grammia geneura and their potential PA sources in southeastern Arizona were compiled. One of four species of Boraginaceae, Plagiobothrys arizonicus, contained PAs; this is the first PA record for this plant species. The principle PA sources are Senecio longilobus (Asteraceae) and Crotalaria pumila (Fabaceae). The known PA pattern of S. longilobus was extended; the species was found to contain six closely related PAs of the senecionine type. Three novel PAs of the monocrotaline type, named pumilines A–C, were isolated and characterized from C. pumila, a species not studied before. The pumilines are the major PAs in the seeds, while in the vegetative organs they are accompanied by the simple necine derivatives supinidine and as the dominant compound subulacine (1,2-epoxytrachelanthamidine). In both plant species, the PAs are stored as N-oxides, except C. pumila seeds, which accumulate the free bases. Great variation in PA composition was observed between local populations of C. pumila. The PA profiles were established for larvae and adults of E. acrea that as larvae had fed on an artificial diet supplemented with crotalaria-powder and of G. geneura fed with S. longilobus. In both experiments, the larvae had a free choice between the respective PA source and diet or food plants free of PAs. The profiles compiled for the two species reflect the alkaloid profiles of their PA sources with one exception, subulacine could never be detected in E. acrea. Besides acquired PAs, insect PAs synthesized from acquired necine bases and necic acids of insect origin were detected in the two arctiid species. These insect PAs that do not occur in the larval food sources accounted for some 40–70% (E. acrea) and 17–37% (G. geneura) of total PAs extracted from the insects. A number of novel insect PAs were identified. Plant-acquired and insect PAs were found to accumulate as N-oxides. The results are discussed in relation to specific biochemical, electrophysiological, and behavioral mechanisms involved in PA sequestration by arctiids.
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