Trade‐offs in oviposition choice? Food‐dependent performance and defence against predators of a herbivorous sawfly

The sawfly Athalia rosae L. (Hymenoptera: Tenthredinidae) is a feeding specialist on plant species of the Brassicaceae, which are characterised by secondary metabolites, called glucosinolates. The larvae can take up the respective glucosinolates of their hosts and concentrate them in their haemolymph to protect themselves against predators. Oviposition preferences of naïve females were tested for three species, Sinapis alba L., Brassica nigra (L.) Koch, and Barbarea stricta Andrz., and were related to larval performance patterns. Larvae were reared on either one of these plants and it was investigated how host‐plant quality influences both the developmental times and growth of larvae (bottom‐up) and the defence efficiency against predators (top‐down). Innately, almost all adult females avoided B. stricta for oviposition and clearly preferred B. nigra over S. alba. On average, larvae developed best on B. nigra. Female larvae reached similar final body masses on all host‐plant species, but males reared on S. alba were slightly lighter. The developmental time of larvae reared on B. stricta was significantly longer than on the other two plants. However, larvae reared on B. stricta were best protected against the predatory wasp Polistes dominulus Christ (Hymenoptera: Vespidae). The wasps rejected these larvae most often, while they attacked larvae reared on S. alba most frequently. Thus, larvae feeding on B. stricta theoretically run a higher risk of predation due to a prolonged developmental time, but in practice they are better protected against predators. Overall, oviposition preferences of A. rosae seem to be more influenced by bottom‐up effects on larval performance than by top‐down effects.     

Metal contamination and human health risk associated with the consumption of Labeo rosae from the Olifants River system,South Africa

The Olifants River, a tributary of the Limpopo River system, is one of the most polluted rivers in South Africa. In May 2011 the concentrations of metals in fish muscle tissue from two impoundments, Loskop and Flag Boshielo dams, on the Olifants River were measured and a human health risk assessment conducted to investigate whether it was safe to consume Labeo rosae from these impoundments. Labeo rosae is one of the most common pan fish in these impoundments and is readily available to rural communities. Metals are accumulating in the muscle tissue of L. rosae even although the fish populations appear to be healthy. At Loskop Dam all L. rosae analysed exceeded the recommended hazard quotient (HQ) of 1 for antimony, and less than 50% exceeded that for lead. At Flag Boshielo Dam, the recommended HQ was exceeded for lead in less than 50% of L. rosae analysed, and more than 50% exceeded that for antimony. The weekly consumption of 150?g of L. rosae muscle tissue from these impoundments may pose an unacceptable health risk to rural communities.     

Adaptive accuracy of temperature oviposition preferences in newts

Oviposition-site choice has profound fitness consequences for both a mother and her offspring. The adaptive significance of oviposition behaviour for both generations depends on two rarely considered assumptions: (1) the fit of maternal oviposition preferences with local phenotypic optimum (adaptive accuracy) and (2) the predictability of future conditions for developing offspring based on conditions at the time of oviposition. We examined both assumptions using temperature oviposition preferences (T _p,o) previously measured under laboratory conditions in the alpine newt, Ichthyosaura (formerly Triturus) alpestris. Analyses of temperature time series in the newt natural environment revealed, in agreement with oviposition-site choice of female newts, that T _p,o were closer to phenotypic optima at the water surface than at the maximal depth (bottom). Temperature time series in both depths contained a high proportion of predictable variation, though bottom thermal conditions were more predictable than those at the water surface. We concluded that female newts have to trade the adaptive accuracy of T _p,o for the predictability of future thermal conditions at the time of oviposition.     

Temporal changes in olfactory and oviposition responses of the diamondback moth to herbivore‐induced host plants

Temporal changes in the pre‐ and post‐alighting responses of mated female diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), to two species of Brassica (Brassicaceae) host plants induced by larval feeding were studied using olfactometer and oviposition assays. Females displayed strong olfactory and oviposition preferences for herbivore‐induced common cabbage (Brassica oleracea var. capitata L. cv. sugarloaf) plants over intact plants; these preferences decreased with time and disappeared by the 7th day after induction. In herbivore‐induced common cabbage plants, eggs were clustered near feeding damage on the younger leaves (leaves 5–7), whereas in intact plants, eggs were clustered on the stem and lower leaves (leaves 1–4) . However, as the time interval between larval feeding and oviposition increased, more eggs were laid on the lower leaves of induced plants. This demonstrates a change in egg distribution from the pattern associated with induced plants to that associated with intact plants. In contrast, females displayed strong olfactory and oviposition preferences for intact Chinese cabbage [Brassica rapa ssp. pekinensis (Lour.) Hanelt cv. Wombok] plants over induced plants; these preferences decreased with time and disappeared by the 5th day after induction. More eggs were laid on the upper leaves (leaves 4–6) than on the lower leaves (leaves 1–3) of intact Chinese cabbage plants at first, but the distribution changed over time until there were no significant differences in the egg count between upper and lower leaves by the 4th day post induction. For both host plant species, pre‐alighting responses of moths were reliable indicators of post‐alighting responses on the first 2 days post induction. The results suggest that temporal changes in a plant's profile (chemical or otherwise) following herbivory may influence attractiveness to an insect herbivore and be accompanied by changes in olfactory and oviposition preferences.     

Searching at different spatial scales: the foraging behaviour of the aphid parasitoid Aphidius rosae in rose bushes

The searching patterns of the aphid parasitoid Aphidius rosae were analysed at three different spatial scales: leaves, shoots and bushes. Parasitoid females searched aphid-infested leaves and shoots intensively and remained on average more than twice as long on infested than on uninfested shoots. Patch times and oviposition numbers per shoot were highly variable both between females and for different shoot visits within females. However, at the shoot and bush level low oviposition numbers were generally found. The time spent on different behavioural patterns (searching, resting, feeding, host handling) changed significantly during subsequent shoot visits of individual females but oviposition success was not influenced by this change. Parasitoids searched individual leaves and shoots mainly by walking, while moving between shoots occurred exclusively by flight. The travel time between shoots (i.e. flight time) accounted for less than 1% of the residence time in a bush. At the bush level foraging was characterized by a high ability to localize infested shoots and consequently little time was wasted in searching on uninfested shoots. The pattern of resource exploitation of individual females was consistent with the distribution of A. rosae larvae in field samples taken from individual rose bushes.     

Natal insect experience with Arabidopsis thaliana plant genotypes influences plasticity in oviposition behavior

Previous studies have shown that insect experience with secondary chemicals present in different plant species can induce behavioral changes in female oviposition preferences. However, there is a lack of information on whether insect experience with intraspecific plant variation may influence oviposition behavior. The prediction that experience with plant genotypes would affect the oviposition behavior of two crucifer insect pests was tested using a wild ecotype of Arabidopsis thaliana (L.) Heynh. (Brassicaceae) (Col‐0) and two of its genetically modified lines (35S:ESP and tgg1 tgg2), which differ in their glucosinolate hydrolysis profiles. Choice oviposition assays were performed using both naïve and experienced females of the specialist Plutella xylostella (L.) (Lepidoptera: Plutellidae) and the generalist Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae). In addition to oviposition preferences, the effect of plant genetic lines was assessed on insect traits related to development, growth, survival, and fecundity. Experience with different natal treatments (i.e., artificial diet and plant genotypes) led to changes in oviposition behavior of the diamondback moth P. xylostella; however, this effect was dependent on the specific genetic lines included in dual‐choice oviposition assays. In addition, for both moth species, experience led to female oviposition choices that would have maximized fitness of their offspring. In summary, this article suggests that insect experience with plant genotypes varying in their secondary metabolites can influence subsequent oviposition behavior. This outcome may have implications for plant‐insect coevolution and integrated pest management.     

GENETIC VARIATION IN CACTOPHILIC DROSOPHILA FOR OVIPOSITION ON NATURAL YEAST SUBSTRATES

Theory predicts that environmental heterogeneity in space or in time can maintain genetic polymorphism. Stable polymorphisms are expected to be more readily maintained if there are genotype specific habitat preferences. Genotype specific preferences for oviposition sites in Drosophila could be a major factor promoting habitat selection, and thus the maintenance of genetic variation. This hypothesis is being tested using the cactophilic species, D. buzzatii and D. aldrichi, where available evidence indicates a potential for such habitat selection, the habitats (oviposition sites) being yeast species found in the natural environment of these flies (cactus rots). Genetic variation for oviposition preferences was tested using isofemale lines—for D. buzzatii, a total of 60 lines from seven localities widely distributed through the species range in Australia, and for D. aldrichi, 21 lines from three of these localities. Females were given a choice of five yeast species as oviposition sites. Genetic variation for oviposition preferences on these natural substrates was demonstrated. There was significant variation among isofemale lines within populations in their patterns of preferences for oviposition on the five yeast species. However, analyses of preferences for each yeast species separately showed that the genetic variation for preferences relates to only three of the five species. Heritabilities of individual female preferences for these three species were low, ranging up to 9%. Little geographic differentiation was apparent among populations, most likely due to similar selection regimes within each population. Within populations, this kind of habitat selection could act to maintain polymorphisms, both at loci determining the habitat preferences and at other loci in linkage disequilibrium with them.     

Why does only Athalia Japonica enter summer diapause among three sympatric Athalia sawflies feeding on crucifers?

This report assesses the primary factor for the evolution of summer diapause of the three species of sawfly, Athalia japonica, A. rosae and A. infumata that feed on cruciferous plants and coexist in the same area. A. japonica has two discrete spring and autumn generations, but A. rosae and A. infumata 5–6 generations. Only A. japonica enters summer diapause in response to the long daylengths in spring. Although these three sawflies usually feed on the same cultivated crucifers, they differ markedly in the utilization of wild crucifers. They oviposit only on young leaves. A. japonica mainly uses Cardamine plants which sprout in spring and autumn. A. rosae and A. infumata primarily use hosts with new leaves all the year round, i.e. cultivated crucifers and Rorippa indica, respectively. The thermal threshold for development is lower in A. japonica than in the other two species. The low heat tolerance of A. japonica is adapted only to cool shady habitats where Cardamine grows. Presumably, summer diapause of A. japonica is adaptation to the deterioration of the primary host plants rather than unfavorable climatic conditions. This interpretation is supported by the movement patterns of the three Athalia sawflies, alternative means to escape from deteriorated habitat conditions.     

Morphological and molecular studies of <Emphasis Type="Italic">Hyphodermella</Emphasis> in the Western Mediterranean area

The genus Hyphodermella was studied based on material from the western Mediterranean area (France, Italy, Spain, Portugal and Morocco) where the following three species have been recognized: H. corrugata (Fr.) J. Erikss. & Ryvarden, widely distributed, H. densa Melo & Hjortstam, only known from Portugal, and H. rosae (Bres.) Nakasone described from Italy. Twenty-one new ITS nrDNA sequences from these species, including the holotype collection of H. rosae and the paratype of H. densa, were aligned with one obtained from GenBank. The molecular results show that these collections are distributed in two highly supported monophyletic clades: one corresponds to H. corrugata, and the other one with H. densa and H. rosae collections. Morphological studies, including the type collections of the three taxa, show significant differences between the clades if we take into account the size of basidia and spores. The present study confirms H. corrugata as an independent species of H. rosae and H. densa, and that H. densa and H. rosae are conspecific; consequently, H. densa is a synonym of H. rosae. This last species is widely distributed in the Mediterranean area (France, Italy, Spain and Portugal) and as frequent as H. corrugata. Comments are offered on sequencing the barcode from types and well-annotated specimens.     

Oviposition preference and larval performance of North American monarch butterflies on four Asclepias species

Monarch butterflies, Danaus plexippus L. (Lepidoptera: Nymphalidae), occur world‐wide and are specialist herbivores of plants in the milkweed family (Asclepiadaceae). In North America, two monarch populations breed east and west of the continental divide in areas populated by different host plant species. To examine the population variation in monarch responses to different Asclepias species, we measured oviposition preference and larval performance among captive progeny reared from adult butterflies collected in eastern and western North America. Host plant use was evaluated using two milkweed species widely distributed in eastern North America (A. incarnata and A. syriaca), and two species common to western North America (A. fascicularis and A. speciosa). We predicted that exposure to different host plant species in their respective breeding ranges could select for divergent host use traits, so that monarchs should preferentially lay more eggs on, and larvae should perform better on, milkweed species common to their native habitats. Results showed that across all adult female butterflies, oviposition preferences were highest for A. incarnata and lowest for A. fascicularis, but mean preferences did not differ significantly between eastern and western monarch populations. Larvae from both populations experienced the highest survival and growth rates on A. incarnata and A. fascicularis, and we again found no significant interactions between monarch source population and milkweed species. Moreover, the average rank order of larval performance did not correspond directly to mean female oviposition preferences, suggesting that additional factors beyond larval performance influence monarch oviposition behavior. Finally, significant family level variation was observed for both preference and performance responses within populations, suggesting an underlying genetic variation or maternal effects governing these traits.     

Taste sensitivity and divergence in host plant acceptance between adult females and larvae of Papilio hospiton

On the island of Sardinia the lepidopteran Papilio hospiton uses Ferula communis as exclusive host plant. However, on the small island of Tavolara, adult females lay eggs on Seseli tortuosum, a plant confined to the island. When raised in captivity on Seseli only few larvae grew beyond the first–second instar. Host specificity of lepidopterans is determined by female oviposition preferences, but also by larval food acceptance, and adult and larval taste sensitivity may be related to host selection in both cases. Aim of this work was: (i) to study the taste sensitivity of larvae and ovipositing females to saps of Ferula and Seseli; (ii) to cross‐compare the spike activity of gustatory receptor neurons (GRNs) to both taste stimuli; (iii) to evaluate the discriminating capability between the two saps and determine which neural code/s is/are used. The results show that: (i) the spike responses of the tarsal GRNs of adult females to both plant saps are not different and therefore they cannot discriminate the two plants; (ii) larval L‐lat GRN shows a higher activity in response to Seseli than Ferula, while the opposite occurs for the phagostimulant neurons, and larvae may discriminate between the two saps by means of multiple neural codes; (iii) the number of eggs laid on the two plants is the same, but the larval growth performance is better on Ferula than Seseli. Taste sensitivity differences may explain the absence of a positive relationship between oviposition preferences by adult females and plant acceptance and growth performance by larvae.     

No host‐associated differentiation in the gall wasp Diplolepis rosae (Hymenoptera: Cynipidae) on three dog rose species

Differences in quality and quantity of secondary compounds, as well as in leaf traits of host plants, may influence the host choice of herbivores. Different host preferences could lead to host‐associated differentiation, the first step of sympatric speciation. In the present study, we investigated whether the rose gall wasp Diplolepis rosae L. (Hymenoptera: Cynipidae) shows genetic differentiation related to its host plants (Rosa canina L., Rosa corymbifera Borkh., and Rosa rubiginosa L.). These three host species radiated recently and subsequently expanded their range. Therefore, we expected a diversification within the closely‐associated phytophagous insects. The process of genetic differentiation should be intensified in D. rosae by its close relationship to the host plant, as well as by its parthenogenetic reproduction (infection rate by Wolbachia sp. of almost 100%). However, using 106 polymorphic amplified fragment length polymorphism markers, we found no genetic differentiation among the wasps from different host plants. The population structuring between geographical localities was also low, suggesting considerable gene flow between sites. In part, the low genetic differentiation between sites is explained by the wide distribution of host species and hybrids between host plants. Hybrids with intermediate traits may facilitate the gene flow between wasp populations exploiting different host species. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 369–377.     

Effect of mixed cropping on some insect pests of carrots and onions

Mixed cropping carrots with onions reduced attacks by carrot fly,Psila rosae Fab., on carrots andThrips tabaci Lind. on onions, compared with those on carrots and onions inmonoculture. Increased plant density also reduced the numbers of carrot-willow aphid,Cavariella aegopodii Scop., Carabid and staphylinid predators ofP. rosae eggs were trapped in higher numbers on the intercropped plots with higher onion:carrot plant density ratios (PDR) over bothP. rosae generations but losses of exposed markedP. rosae eggs were not consistent with these differences. In addition, the PDR treatment effect was greatest when the carrots were intercropped with young onions and virtually ineffective once the onions began to bulb.Over 90% of adultP. rosae trapped entering carrot plots were female and the majority approached the plots upwind at a height of <40 cm above the ground possibly in response to the carrot odour. Row-intercropping with onions caused fewer flies to enter the plots. Mixed cropping of carrots with onions probably reducedP. rosae attack by the onion volatiles disturbing host-plant finding particularly when the onions were young. Mixed cropping with the French marigold,Tagetes patula L. was ineffective. C. aegopodii was not directly affected by intercropping as wasT. tabaci, the latter being reduced in numbers by increased PDR possibly due to reduced apparancy of the onion plants.

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Effet de l'association culturale sur quelques insectes attaquant carottes et oignons

Résumé L'association culturale des carrottes et des oignons réduit les attaques dePsila rosae Fab sur carottes et deThrips tabaci Lind sur oignons, par rapport aux monocultures. L'accroissement de la densité végétale réduit de même le nombre de pucerons de la carotte,Cavariella aegopodii Scop. Les carabes et staphylins prédateurs d'oeufs dePsila rosae sont piégés en plus grand nombre en culture alternée avec une densité élevée (PDR) d'oignons et de carottes, pendant les 2 générations deP. rosae; mais les pertes d'oeufs marqués exposés deP. rosae ne confirment pas ces différences. De plus, l'effet du PDR est plus important quand les carottes alternent avec de jeunes oignons et virtuellement sans effet quand les bulbes des oignons commencent à se former. Plus de 90% des adultes deP. rosae piégés en entrant dans les parcelles de carottes étaient des femelles, et la majorité se dirigeait face au vent à moins de 40 cm au dessus du sol, vraisemblablement en réponse à l'odeur de carotte. L'alternance avec des rangs d'oignons limite le nombre de mouches pénétrant dans les parcelles. L'association de carottes et d'oignons a réduit probablement les attaques deP. rosae par l'action de substances volatiles des oignons, en perturbant la découverte de la plante hôte, particulièrement quand les oignons étaient jeunes. L'association avecTagetes patula L. n'a pas eu d'effet. C. aegopodii n'a pas été directement affecté par l'association comme l'étaitT. tabaci, l'effectif de ce dernier ayant pu être limité par un PDR élevé qui aurait réduit l'individualisation des pieds d'oignons.

     

Oviposition habitat selection by container‐dwelling mosquitoes: responses to cues of larval and detritus abundances in the field

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Choosy egg parasitoids: Specificity of oviposition-induced pine volatiles exploited by an egg parasitoid of pine sawflies

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.     

Larval development of Empoasca vitis and Edwardsiana rosae (Homoptera: Cicadellidae) at different temperatures on grapevine leaves

The grape leafhopper Empoasca vitis (Homoptera: Cicadellidae) is regarded as a major insect pest in many European grapevine growing areas, with an increasing importance realized in recent years maybe as a result of climatic change. Both larvae and adults feed on the phloem vessels of the leaves, causing characteristic symptoms also referred to as hopperburn. Phenology of adult leafhoppers was monitored in one vineyard in three successive years and indicated that immigration of a few hibernated E. vitis individuals into vineyards might take place already quite early in the year depending on winter temperatures and starts to progress in substantial numbers right at grapevine bud burst. In addition, these monitoring studies have shown that there are several other leafhopper species occurring on grapevine plants besides E. vitis, such as the rose leafhopper Edwardsiana rosae (Homoptera: Cicadellidae). Here, we report on the development of larval instars of both leafhopper species, E. vitis and E. rosae on grapevine leaves under different temperature regimes in the laboratory. Shortest larval developmental time was observed at night temperatures of 13–15°C and day temperatures of 23–25°C, which was in agreement with predicted optimal temperatures for both species. At the temperature regime of 20°C night and 30°C day temperature, either no egg hatch was observed or early development of first‐instar larvae was not successful for both species. These results suggest that warm (18°C) nights and moderately warm (28°C) days are representing the upper thermal threshold for development of both E. vitis and E. rosae embryonic stages on grapevine leaves, questioning current assumptions of an increasing importance of E. vitis as a grapevine pest under future climate change.     

The effect of abiotic factors on foraging and oviposition success of the aphid parasitoid,Aphidius rosae

Searching patterns and oviposition success of the aphid parasitoid Aphidius rosae were analysed in different abiotic conditions (simulated wind, simulated drizzling rain, simulated shower, high temperature, low humidity, standard conditions) in the laboratory. Residence times, time allocation and oviposition success did not differ significantly between females foraging on rose shoots during periods with high temperature (>33°C) and low humidity (35%–40% relative humidity) and females searching under standard laboratory conditions (20°C, 65%–70% relative humidity, no wind). A wind speed of 2 m/s reduced the oviposition numbers significantly, and females spent much more time resting than searching for hosts. Females did not leave a shoot during wind, but departed quickly after wind had ceased. Simulated drizzling rain or simulated showers had the strongest effects on A. rosae foraging. Both types of rain prevented all foraging activities including departure from the shoot, and females laid no eggs during rain. After rain had stopped, females were mainly engaged with cleaning themselves and laid relatively few eggs compared to standard conditions. The impact of unfavourable abiotic environmental factors like wind or rain may help to explain why many parasitoids lay only a small proportion of their available eggs when foraging in the field.     

Micro‐climate determines oviposition site selection and abundance in the butterfly Pyrgus armoricanus at its northern range margin

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The role of olfactory cues in the sequential radiation of a gall‐boring beetle,Mordellistena convicta

1. Herbivorous insects often have close associations with specific host plants, and their preferences for mating and ovipositing on a specific host‐plant species can reproductively isolate populations, facilitating ecological speciation. Volatile emissions from host plants can play a major role in assisting herbivores to locate their natal host plants and thus facilitate assortative mating and host‐specific oviposition. 2. The present study investigated the role of host‐plant volatiles in host fidelity and oviposition preference of the gall‐boring, inquiline beetle, Mordellistena convicta LeConte (Coleoptera: Mordellidae), using Y‐tube olfactometers. Previous studies suggest that the gall‐boring beetle is undergoing sequential host‐associated divergence by utilising the resources that are created by the diverging populations of the gall fly, Eurosta solidaginis Fitch (Diptera: Tephritidae), which induces galls on the stems of goldenrods including Solidago altissima L. (Asteraceae) and Solidago gigantea Ait. 3. Our results show that M. convicta adults are attracted to galls on their natal host plant, avoid the alternate host galls, and do not respond to volatile emissions from their host‐plant stems. 4. These findings suggest that the gall‐boring beetles can orient to the volatile chemicals from host galls, and that beetles can use them to identify suitable sites for mating and/or oviposition. Host‐associated mating and oviposition likely play a role in the sequential radiation of the gall‐boring beetle.     

Interactions between glucosinolate- and myrosinase-containing plants and the sawfly Athalia rosae

Several insects have specialised on using Brassicaceae as host plants. Therefore, they evolved metabolic pathways to cope with the defensive glucosinolate–myrosinase system of their diet. Larvae of the turnip sawfly, Athalia rosae L. (Hymenoptera: Tenthredinidae), incorporate various glucosinolates from their hosts into their haemolymph. The ability to sequester these metabolites makes A. rosae a useful model system to study mechanisms of glucosinolate metabolism in this species compared to other specialists, and to study effects of sawfly feeding on levels of glucosinolates and their hydrolysing enzymes in plants. The levels of plant metabolites might in turn directly affect the performance of the insect. On the one hand, costs for glucosinolate uptake and avoidance of myrosinase activity were postulated. On the other hand, sequestration of glucosinolates can be part of the insect’s defence against several predators. Here, the findings on glucosinolate metabolic pathways are compared between different herbivores and the sawfly. The impact of different glucosinolate levels and myrosinase activities on the performance of A. rosae is discussed. Furthermore, effects of feeding by A. rosae larvae on the chemical composition and enzyme activities of various Brassicaceae species are summarised. Induction patterns vary not only between different plant species and cultivars but also due to the inducing agent. Finally, the plant–herbivore interactions are discussed with regard to the sawflies’ defence abilities against different carnivore guilds.