Gall Tissue Research Articles

Plant senescence cues entry into diapause in the gall flyEurosta solidaginis: resulting metabolic depression is critical for water conservation

Mechanisms and possible cues for seasonal increases in desiccation resistance in larvae of the goldenrod gall fly Eurosta solidaginis, were examined before and after natural and premature plant senescence, or after being removed from their gall and placed in either 100, 95 or 75% relative humidity (RH). Rates of water loss were 8.6-fold lower, averaging 0.7+/-0.2 microg mm(-2) h(-1), in larvae from senescent gall tissue and after all RH treatments than in control larvae from pre-senescent plants. Enhanced desiccation resistance occurred quickly, within 3 days of removal from their gall. Contrary to most previous reports, a large majority of the increased desiccation resistance (approximately 85%) was due to reduced respiratory transpiration with the remainder being the result of a lowered cuticular permeability. Rates of cuticular water loss were reduced by the presence of a vapor pressure gradient between the larval hemolymph and environmental water vapor and were probably due to increases in cuticular lipids and/or production of the cryoprotectant glycerol. Metabolic rate was reduced by over fourfold, averaging 0.07+/-0.01 microl CO2 g(-1) h(-1), in larvae from senescent gall tissue and all RH treatments compared to larvae from pre-senescent plants. The magnitude of the reduction in metabolic rates indicated that these larvae had entered diapause. In addition, larvae entered diapause in response to removal from, or degeneration of, the gall tissue they feed, on rather than seasonal changes in temperature or photoperiod. The low metabolic rates of the diapausing larvae probably allowed them to dramatically reduce their respiratory transpiration and total rate of water loss compared with non-diapausing controls. Thus, diapause, with its associated lowered metabolic rate, may be essential for conserving water in overwintering temperate insects, which may be dormant for six or more months of the year.

Distribution of metabolites in galled and non-galled foliar tissues of Tibouchina pulchra

This paper reports the contents of foliar metabolites of Tibouchina pulchra (Melastomataceae) in (a) galls induced by a lepidopteran, (b) remaining parts of the galled leaf after gall removal, (c) leaves opposite to the galled leaf, and (d) leaves of non-infested stem branches (control). The parameters assayed were soluble phenols, flavonoids, tannins, lignins, fibers, soluble carbohydrates, lipids and organic nitrogen. Differences in the parameters assayed were evaluated using Principle Components Analysis. Compared to other tissues, galls showed significantly higher contents of soluble phenols, tannins, lignins, fibers, soluble carbohydrates and lipids, and significantly lower contents of flavonoids and organic nitrogen. Apart from gall tissues, in most cases no significant differences were detected in the quantitative analyses among the leaf tissues assayed. Flavonols and flavones were not detected in galls. Other tissues revealed a similar flavonoid pattern, characterized by 3- O-monoglycosides of kaempferol, myricetin and quercetin. A luteolin glycoside was obtained exclusively from control leaves. Carbohydrate amounts are lower in the foliar tissues closer to the galls than in non-galled tissues. Palmitic acid was essentially the sole fatty acid found in all tissues analysed. The high lipid content of the galls suggests that such substances represent the main energy source for the insect, and suggests that the studied galls could be classified as cynipid galls. The observed metabolic changes taking place in the galls strengthen the hypotheses that galls behave as new organs, operating a metabolic machinery of their own.

The biology, damage and within-tree distribution on the spruce bud midge on black spruce in Newfoundland

The spruce bud midge (Rhabdophaga swainei) has one generation a year on black spruce (Picea mariana) in Newfoundland. Newly hatched larvae enter primordia of flushing buds in late June and early July and larvae mature by fall to overwinter within buds. Pupation occurs within buds the following spring and adults emerge in June. Virgin females averaged 86 eggs upon dissection. Platygaster rhabdophagae, Mesopolobus sp., Torymus sp., and Tetrastichus sp. were responsible for high parasitism levels of spruce bud midge larvae. Terminal buds were attacked significantly more than lateral or uppermost lateral buds. The number of infested buds was significantly higher in the top third of the crown than in the bottom crown third, but was not significantly different among north, east, south and west crown exposures. The apical meristem never developed in infested buds, and these buds did not flush. The growth of bud primordial cells is redirected by R. swainei to produce gall tissues that provide nutrients and an overwintering shelter for the larva. Attack of the terminal leader causes a slight loss in height growth but normal leader growth resumes the following year.

Arthropod-induced neoplastic formations on trees change photosynthetic pigment levels and oxidative enzyme activities

In order to test the hypothesis that arthropod-induced neoplastic formations on trees affect biochemical characteristics of both the newly formed galls and host plant tissues, biochemical characteristics with a possible adaptive role were determined in nine gall-former–host tree combinations. Photosynthetic pigments, extractable protein content, and oxidative enzyme activities were determined in gall tissues, leaf tissues of galled leaves, and leaves on ungalled tree branches. Neoplastic tissues were characterized by a low content of photosynthetic pigments, decreased chlorophyll a/b ratio, lower extractable protein content, and decreased activities of peroxidase and polyphenol oxidase as compared with ungalled host leaf tissues. In galled leaves or in leaves adjacent to galls, increased level of peroxidase activity was found. In several gall-inducer–host plant combinations, galled host plant tissues contained increased activity of polyphenol oxidase as well. The presented data reflect long-term systemic effects of neoplastic formation on host tree physiology suggesting that gall inducers affect potential adaptive responses of host plants.

BIOCHEMICAL RESPONSES OF CHESTNUT OAK TO A GALLING CYNIPID

We characterized the distribution of nutritional and defensive biochemical traits in galls elicited on chestnut oak (Quercus prinus L.) by the gall wasp Andricus petiolicolus Basse (Cynipidae) in comparison with gypsy moth-wounded and unwounded leaves. Gall cortex and epidermis exhibited elevated soluble peroxidase (POX) and soluble invertase activities, and greater condensed tannin concentrations than did nutritive tissues or leaves. Nutritive tissue, on which the insect feeds, contained few polyphenols, and lower POX and invertase activities compared with other gall tissues and leaves. Elevated total POX activity arose from a complex pattern of enhanced and suppressed isoform activities in galls. Invertase enzyme activity decreased in all tissues over the course of the 7-d study, although gypsy moth wounding suppressed this decline slightly in ungalled leaves. Our results indicate that the distribution of biochemical defenses in this typical cynipid gall differs significantly from the leaf tissue from which it is formed and support a role for invertases in establishing the gall as a sink. A. petiolicolus larvae do not induce, and may suppress, plant defense responses in nutritive tissue, while enzymatic activity and phenolic accumulation are enhanced in gall tissues surrounding feeding sites. These patterns suggest that the gall is manipulated by the insect to enhance its food and protective value.

Partial link between the seasonal acquisition of cold-tolerance and desiccation resistance in the goldenrod gall flyEurosta solidaginis(Diptera: Tephritidae)

Possible links between seasonal increases in cold-tolerance and desiccation resistance were examined in field-collected larvae of the goldenrod gall fly, Eurosta solidaginis. From 20 September to 30 October 2001, larvae exhibited a gradual increase in cold-tolerance culminating in 100% survival of freezing at -20 degrees C for 24 h. The increase in cold-tolerance was probably due to a concomitant increase in cryoprotectants as measured by hemolymph osmolality (488-695 mOsmol kg(-1)). In contrast to the gradual increase in cold-tolerance, larvae exhibited two distinct phases of reduced rates of water loss. The first phase was an abrupt sixfold decrease to 0.57 microg mm(-2) h(-1) between 3 and 16 October. The first phase of reduced rates of water loss was not correlated with changes in cold-tolerance; nor was it correlated with hemolymph osmolality and body water content, which remained constant throughout the study. The reduction in rates of water loss during the first phase were probably the result of decreased respiratory water loss as the larvae entered diapause, and possibly reduced cuticular water loss as larvae increased the amount of their cuticular hydrocarbons. Interestingly, the first phase of reduced water loss was associated with, and may have been cued by, a reduction in the water potential of the gall tissues surrounding the larvae. The second phase was a more subtle fourfold reduction in rates of water loss occurring between 16 October and 11 December. In contrast to the first phase, the second phase of increased desiccation resistance correlated closely with increases in hemolymph osmolality (568-870 mOsmol kg(-1)). The correlation between seasonal increases in hemolymph osmolality and reduction in rates of water loss may represent a link between desiccation resistance and cold-tolerance in this species.

Host range and host preference of a flea weevil, Orchestes hustachei, parasitizing aphid galls

Although larvae of flea weevils (Curculioninae: Rhamphini) have been known to be leaf miners, larvae of the rhamphine weevil Orchestes hustachei have been found in aphid galls of four Tetraneura species on Ulmus davidiana and in galls of Paracolopha morissoni on Zelkova serrata. This study clarified the feeding habits of O. hustachei larvae and evaluated gall selection by ovipositing females to test the hypothesis of host race formation on their hosts, Tetraneura and Paracolopha galls. When weevil larvae were placed in half-cut galls, they always fed on aphids rather than on gall tissue. When given gall tissue only, all larvae failed to reach adulthood. The number of aphids surviving in a parasitized gall decreased significantly with the development of the weevil larvae. These results suggest that O. hustachei larvae use aphids as their major food source. In the field, ovipositing females did not discern between four Tetraneura species on U. davidiana, in spite of a large difference in suitability as food. Paracolopha morrisoni was introduced into Hokkaido approximately 100 years ago, together with the host plant Z. serrata. It is probable that P. morrisoni has recently come to be used as a host by O. hustachei in Hokkaido. Host choice experiments using Tetraneura sp. O and P. morrisoni galls indicated that female weevils from Z. serrata preferred P. morrisoni to Tetraneura sp. O galls, while females from U. davidiana selected the two types of gall randomly. On Z. serrata, female weevils selected larger P. morrisoni galls, while on U. davidiana, females did not show a preference for gall size. These results suggest that a host shift to P. morrisoni galls may have led to an initial stage of host race formation between the weevil population using Tetraneura galls on U. davidiana, and that using P. morrisoni galls on Z. serrata.

Weevil Parasitism of Ambrosia Galls

Abstract Gall midge larvae are associated with specific fungal symbionts in ambrosia galls. We found that the weevil Wagnerinus costatus (Hustache) (Coleoptera: Curculionidae: Ceutorhynchinae) frequently attacked ambrosia galls formed by the midge Asphondylia diervillae Felt (Diptera: Cecidomyiidae: Asphondyliini) on the buds of Weigela hortensis (Sieb. et Zucc.) (Caprifoliaceae) in three locations in central Japan. From late April to early May, female weevils laid single eggs in fully developed ambrosia galls, and upon hatching weevil larvae bored into these galls. The rate of parasitism by weevils was consistently high, from 90.2 to 94.5% in each gall midge population. Weevil larvae fed on the hyphae of fungal symbionts as well as on gall tissue. In most cases, parasitism by weevils did not influence the survivorship of A. diervillae or its parasitoids, because oviposition and feeding by the weevil occurred when gall midges had already developed into mature larvae or pupae within hard chambers surrounde...

Differential expression of pine and Cronartium quercuum f. sp. fusiforme genes in fusiform rust galls.

Cronartium quercuum f. sp. fusiforme is the causative agent of fusiform rust disease of southern pines in the United States. This disease is characterized by the formation of woody branch and stem galls. Differential display was used to identify pine genes whose expression is altered by C. quercuum f. sp. fusiforme infection and to identify C. quercuum f. sp. fusiforme genes that are expressed in fusiform rust galls. Six pine cDNAs that appeared to be differentially expressed in galled and healthy stems and 13 C. quercuum f. sp. fusiforme cDNAs expressed in galled tissues were identified. A probe that hybridizes specifically to C. quercuum f. sp. fusiforme 18S rRNA was used to estimate that 14% of the total RNA in fusiform rust galls was from C. quercuum f. sp. fusiforme. This finding was used to calibrate gene expression levels in galls when comparing them to expression levels in uninfected pines or in isolated C. quercuum f. sp. fusiforme cultures. According to Northern analysis and reverse transcriptase PCR analysis, all six of the pine clones were expressed at lower levels in galls than in healthy tissues. Seven of the nine C. quercuum f. sp. fusiforme clones that were assayed were expressed at higher levels in galls than in axenic culture. A number of the cDNAs encode proteins that are similar to those that play roles in plant development, plant defense, or fungal stress responses.

Activation of phenylpropanoid metabolism in sesame by over-expression of carrot calmodulin gene.

Transgenic sesame (Sesamum schinzianum ASCH.) was produced by Agrobacterium-mediated transfection of a carrot calmodulin gene, cam-4, which was specifically expressed upon the contact of carrot cells with oligogalacturonide elicitor. Coding region of cam-4 was ligated to the downstream of 35S promoter of cauliflower mosaic virus and subcloned into pMATGBO-DB3.1. A. tumefaciens 4404 was transformed with the constructed vector, and the crown gall tissues formed in the sesame seedlings were transferred onto appropriate media to obtain the re-differentiated plants. The reverse-transcription polymerase chain reaction followed by Southern blot analysis revealed that cam-4 gene was appreciably expressed in the transgenic plants. Activities of two key enzyme regulating phenylpropanoid metabolisms, phenylalanine ammonia-lyase and caffeic acid O-methyltransferase, and the contents of phenolic compounds in the transformed sesame were markedly elevated as compared with those of the control. These results suggest that the over-expression of cam-4 gene enhances the biosynthetic activities of phenylpropane derivatives in the transformed sesame plants.

Altered matrix polysaccharides in cell walls of pocket galls formed by an aphid on Distylium racemosum leaves

ABSTRACTThe present work reports the results of a study on the isolation and characterization of matrix polysaccharides in the cell walls of galls formed by an aphid (Neothoracaphis yanonis) on Distylium racemosum leaves. Cell walls were isolated from both healthy Distylium leaf and gall tissues and then extracted sequentially with cyclohexane‐trans‐1,2‐diaminetetra‐acetate (CDTA), Na2CO3, 1 m KOH, and 4 m KOH. The amount of pectin solubilized from gall cell walls was approximately 2.6‐fold higher than the pectin solubilized from leaf cell walls, whereas the amount of hemicellulose solubilized from gall cell walls was 1.4‐fold higher than that from normal leaf cell walls. When the polysaccharides were fractionated by anion‐exchange chromatography, considerable increases in arabinose and galactose were observed in CDTA‐soluble pectic polymer (fraction PI‐1) from gall cell walls, whereas the gall cell walls had less xylose in 1 m KOH‐soluble hemicellulosic polymers (fractions HI‐2, HI‐3, and HI‐4) than did the cell walls from the healthy leaf. The hemicellulosic polymers of the gall cell walls exhibited distinctly different patterns of molecular mass, compared with the healthy leaf cell walls. These results suggest that an extensive change occurs in the matrix polysaccharide structure of the cell walls of Distylium galls formed by an aphid. In addition, many glycosylhydrolase activities were detected in the protein fraction solubilized with strong saline solution from the gall cell walls, and the activities of β‐galactosidase, β‐xylosidase and α‐l‐arabinofuranosidase were considerably increased under gall formation.

Complex interactions envolving a gall midge Myrciamyia maricaensis Maia (Diptera, Cecidomyiidae), phytophagous modifiers and parasitoids

Myrciamyia maricaensis Maia, 1995 (Diptera, Cecidomyiidae) induces a gall in lateral and apical shoots in the plant Myrcia lundiana Kiaersk (Myrtaceae) which is used and modified by two eulophid wasps species. In both cases the gall former species suffer high rate of attack exceeding the importance of parasitoid species as mortality factors. In this study these interactions are described and their effects as mortality of gall former. The intensity of occurrence of the two eulophid species as modifiers and of microhymenopteran parasitoids, and the relative importance of these species as mortality agents of the M. maricaensis larvae is compared. This comparison reveals that two modifiers species found in the gall tissue modification causing the death of the M. maricaensis larva and it is a more important factor of mortality than the cecidomyiid larva parasitism. The fluctuation of the number of each type of gall along the year was monitored in the research field and confirmed in numerical and in synchronic terms of occurrence of the galls; the importance of the species of the gall modifier eulophids, particularly one of these species, as factors of mortality of the M. maricaensis larvae and justified our comparing the relationship between these species and M. maricaensis as similar to the parasitoid-host relationship. The gall shape modification by one of the eulophids allows the occurrence of other inquiline insect species, what means that this gall modification becomes it more heterogeneous and allows the increase of the species richness to the system.

Acquisition of freezing tolerance in early autumn and seasonal changes in gall water content influence inoculative freezing of gall fly larvae, Eurosta solidaginis (Diptera, Tephritidae)

We examined seasonal changes in freeze tolerance and the susceptibility of larvae of the gall fly, Eurosta solidaginis to inoculative freezing within the goldenrod gall ( Solidago sp.). In late September, when the water content of the galls was high (~55%), more than half of the larvae froze within their galls when held at –2.5 °C for 24 h, and nearly all larvae froze at –4 or –6 °C. At this time, most larvae survived freezing at ≥ –4 °C. By October plants had senesced, and their water content had decreased to 33%. Correspondingly, the number of larvae that froze by inoculation at –4 and –6 °C also decreased, however the proportion of larvae that survived freezing increased markedly. Gall water content reached its lowest value (10%) in November, when few larvae froze during exposure to subzero temperatures ≥ –6 °C. In winter, rain and melting snow transiently increased gall water content to values as high as 64% causing many larvae to freeze when exposed to temperatures as high as –4 °C. However, in the absence of precipitation, gall tissues dried and, as before, larvae were not likely to freeze by inoculation. Consequently, in nature larvae freeze earlier in the autumn and/or at higher temperatures than would be predicted based on the temperature of crystallization ( T c) of isolated larvae. However, even in early September when environmental temperatures are relatively high, larvae exhibited limited levels of freezing tolerance sufficient to protect them if they did freeze.

Screening for differential gene expression in Atropa belladonna leafy gall induced following Rhodococcus fascians infection

To better characterise at the molecular level the nature of plant responses to infection by Rhodococcus fascians PCR-based differential display patterns of Atropa belladonna leafy gall (LG) and non-infected plant tissues were compared. Six differentially expressed genes were identified and their altered expression was confirmed by RT-PCR. Three of them corresponded to up-regulated genes which encode proteins involved in plant defence. The three remaining cDNA fragments which correspond to down-regulated genes in LG, encoded proteins with similarity to a multicystatin, a miraculin and a methallothionein-like protein, respectively. Upon elimination of the bacteria from infected plant tissue, the expression of up-regulated genes was maintained, whereas expression of down-regulated genes resumed suggesting a potential role of these up-regulated genes in plant growth and development.

Seed Predation inPhilodendron solimoesense(Araceae) by Chalcid Wasps (Hymenoptera)

The relationships between Philodendron solimoesense and the larvae of two chalcid wasp species, inhabiting up to 88% of the infructescences, were studied in French Guiana. Exurus sp. (Chalcidoidea, Eulophidae, Tetrastichinae), is a gall maker and its larvae develop at the expense of seeds which are transformed into galls. We estimate that two seeds are necessary for the development of one eulophid. Their impact on plant reproductive success appears to be important, since parasitized fruits produce 60% fewer seeds than nonparasitized fruits and could explain the reduced seed set observed (53%). The larvae of a Sycophila sp. (Chalcidoidea, Eurytomidae, Eurytominae) are also present in the fruits of P. solimoesense occupied by eulophid larvae. The eurytomid larvae apparently develop at the expense of about one eulophid and are responsible for the death of 39% of them by direct predation or indirectly by consuming the gall tissues. Eulophids are far more abundant than eurytomids, since parasitized fruits contain an average of 11 eulophids but only one eurytomid. As chalcid wasp emergence takes place in a closed cavity and sex ratios are strongly biased in a given gall, local mate competition may occur as observed for fig wasps within figs.

The influence of species identity and herbivore feeding mode on top-down and bottom-up effects in a salt marsh system.

In this study we investigated the potential importance of species identity and herbivore feeding mode in determining the strengths of top-down and bottom-up effects on phytophagous insect densities. In 1998, we conducted two factorial field experiments in which we manipulated host plant quality and intensity of parasitoid attack on three salt marsh herbivores, the planthoppers Prokelisia marginata and Pissonotus quadripustulatus (Homoptera: Delphacidae), which feed only on Spartina alterniflora and Borrichia frutescens, respectively, and the gall fly Asphondylia borrichiae (Diptera: Cecidomyiidae), which feeds only on B. frutescens. We increased plant quality through addition of nitrogen fertilizer, and decreased parasitism by trapping hymenopteran parasitoids continuously throughout the study. Herbivore densities were censused biweekly. Increasing plant quality through fertilization increased the density of all three herbivores within 2weeks of treatment application, and higher densities were maintained for the duration of the study. Reduction of top-down pressure had no effect on either planthopper species, possibly because of compensatory mortality affecting the two species. In contrast, reduction of parasitism significantly increased the density of A. borrichiae galls, perhaps because development within gall tissue reduces the sources of compensatory mortality affecting this species. The results of this study show that the bottom-up effects of plant quality were strong and consistent for all three species, but the strength of top-down effects differed between the two feeding guilds. Thus, even for herbivores feeding on the same host plant, conclusions drawn regarding the relative importance of top-down and bottom-up effects may vary depending upon the feeding mode of the herbivore.

Biological control of invasive golden wattle trees (Acacia pycnantha) by a gall wasp, Trichilogaster sp. (Hymenoptera: Pteromalidae), in South Africa

Abstract An undescribed species of gall wasp, Trichilogaster sp. (Hymenoptera: Pteromalidae), has been introduced to South Africa for biological control of the invasive Australian tree, golden wattle ( Acacia pycnantha ). After a slow start, Trichilogaster sp. is now common and widespread on the weed. The wasps usually lay their eggs in immature inflorescences, although about 10% are laid in meristematic vegetative tissues. The developing larvae induce substantial galls (up to 3 cm in diameter) to develop on the host plant. The gall tissues have calorific values that are comparable with buds and seedpods, but the wasps drain resources from the plants by: (i) developing much earlier in the season than normal flowers and buds; (ii) reaching masses that are almost three times greater than seedpods; and (iii) causing proportionately more inflorescences to become galls than would normally develop into seedpods. This `forced commitment' affects the viability of the host plants and even moderate levels of galling substantially curtail seed production. No impairment of vegetative growth was detected, probably because this study was conducted during the early stages of colonization by the gall wasps. In areas where the wasps are already abundant, branches and trees frequently collapse under the weight of galls and dramatic effects on vegetative growth are still anticipated. All indications are that A. pycnantha is being brought under biological control as successfully as Acacia longifolia was by a congeneric gall wasp, Trichilogaster acaciaelongifoliae .

Applicability of the co-inoculation technique using Agrobacterium tumefaciens shooty-tumour strain 82.139 in silver birch

In the co-inoculation technique, genetic transformation is performed using a mixture of Agrobacterium strains – shoot regeneration is induced by the wild-type strain 82.139, while the transferable genes are provided in a binary plasmid by another, non-oncogenic Agrobacterium strain. The aim of the present work was to study the applicability of co-inoculation under both in vitro and greenhouse conditions for in planta transformation in silver birch (Betula pendula Roth). In addition to the original method, several modifications of the technique including an genetically engineered 82.139 strain harbouring the binary pGUSINT were tested. The co-inoculations resulted in a gall formation frequency of 52–94% with greenhouse seedlings, and 4–63% with tissue-cultured plantlets, the shoot induction percentage varying by 0–13 in the greenhouse and 42–75 in vitro. PCR analysis verified that the majority of the regenerated material was non-transgenic, with a few individuals showing integration of the oncogenic T-DNA. According to the histochemical tests, however, some of the numerous differentiating buds and small shoots on gall tissues were transgenic, and contained the GUS reporter gene. The results show that it would have been necessary to apply selection pressure during differentiation in order to recover shoots transformed with the desired genes from the binary plasmid. The morphology and growth of all the regenerated plantlets was normal, suggesting that the oncogenic T-DNA was not expressed even though it was present. In conclusion, it was possible to obtain transgenic silver birch plantlets using the A. tumefaciens strain 82.139, but the co-inoculation method is not directly applicable as in planta transformation protocol.

Cytokinins in the ball gall of Solidago altissima and in the gall forming larvae of Eurosta solidaginis.

• The identities and concentrations of cytokinins in goldenrod ball galls, normal goldenrod stems, and in the gall-forming larvae of the tephritid fly Eurosta solidaginis were determined in order to gain insight into the mechanism of ball gall formation on Solidago altissima. • Zeatin, zeatin riboside, isopentenyladenine, and isopentenyladenosine were identified and quantified by gas chromatography-mass spectrometry in ball galls, goldenrod stems, and in larvae of E. solidaginis. • Concentrations of the four cytokinins were higher in gall tissues than in stem tissues when expressed on a weight per stem length basis but not when expressed on a weight per weight basis. Isopentenyladenine was the most abundant cytokinin in larvae from developing galls and in larvae from fully formed galls exhibiting 'green islands'. In first instar larvae, isopentenyladenine was present at a much higher concentration (c.50 fold) than in control stem tissues. • The presence of an E. solidaginis larva results in higher cytokinin amounts in a given length of stem than are found in its absence. Larvae of E. solidaginis may act as point sources of isopentenyladenine in developing ball galls. ABBREVIATIONS: BHT, butylated hydroxytoluene; DMSO, dimethylsulphoxide; DMSO- , dimethylsulphoxide anion; GC-MS, gas chromatography mass spectrometry; HPLC, high pressure liquid chromatography; iP, isopentenyladenine; iPA, isopentenyladenosine; Me-dHZ, methyl-dihydrozeatin; Me-dHZR, methyl-dihydrozeatin riboside; Me-iP, methyl-isopentenyladenine; Me-iPA, methyl-isopentenyladenosine; Me-Z, methyl-zeatin; Me-ZOG, methyl-zeatin-O-glucoside; Me-ZR, methyl-zeatin riboside; Me-ZROG, methyl-zeatin riboside-O-glucoside; m/z, mass to charge ratio; PVPP, polyvinylpolypyrrolidone; SIM, selected ion monitoring; TEAB, triethylammonium bicarbonate; Z, zeatin; ZR, zeatin riboside.

Indole-3-acetic acid and ball gall development on Solidago altissima.

• Indole-3-acetic acid (IAA) concentrations are reported in ball galls, stem tissue, and in the gall-forming larvae of the tephritid fly Eurosta solidaginis, to gain insight into the mechanism of ball gall formation on the goldenrod, Solidago altissima. • IAA was identified and quantified by gas chromatography-mass spectrometry, with [13 C6 ]-IAA as an internal standard. • Concentrations of IAA were higher in gall tissues than in stem tissues on a weight per stem length basis, but not on a weight per weight basis. First instar larvae of E. solidaginis contained IAA at 9µg g-1 f. wt or 1.21ng per larva, a concentration 33-times higher than in control stem tissues. Gall development was unaffected by the early removal of the apical bud and leaves from galls, and lateral bud release was inhibited by galls in terminal positions in the absence of the apical bud, indicating that ball galls act as sources of auxin. • The presence of an E. solidaginis larva results in higher amounts of IAA in a given length of stem than are found in its absence. E. solidaginis larvae may act as point sources of IAA in developing ball galls.