The evolution of host plant manipulation by insects: molecular and ecological evidence from gall-forming aphids on Pistacia

One of the most striking characteristics of gall-forming insects is the variability in gall position, morphology, and complexity. Our knowledge of the driving forces behind the evolutionary divergence of gall types is limited. Natural enemies, competition, and behavioral constraints might be involved. We present a cladogram, based on sequences of COI and COII (1952bp), of mitochondrial DNA for the evolution of 14 species of gall-forming aphids (Fordinae). These insects induce five gall types with remarkable morphological variation on Pistacia spp. hosts. The parsimony cladogram divides the Fordinae into three lineages, Fordini and Baizongiini, and a third (new) sister group including the previously Fordini member, Smynthurodes betae (West). We then use ecological data to trace and explain the evolution of gall morphology. The aphids seem to have evolved gradually towards better ability to manipulate their host plant, induce stronger sinks, and gain higher reproductive success. We suggest that the ancestral gall type was a simple, open, "pea"-sized gall located on the leaflet midvein. Some Fordini and S. betae evolved a two-gall life cycle, inducing a new gall type on the leaflet margin. The Baizongiini improved the manipulation of their host by inducing larger galls near the midvein, with stronger sinks supporting thousands of aphids. Similar gall types are induced at similar sites on different Pistacia hosts suggesting control of the aphids on gall morphology and frequent host shifts. Thus, even extreme specialization (specific gall and host) is flexible.     

Cladistic analysis and biogeography of the cicadas of the Indo-Pacific subtribe Cosmopsaltriina (Hemiptera: Cicadoidea: Cicadidae)

Abstract A consensus cladogram is presented for ninety-seven of the ninety-nine (sub)species of the cicada subtribe Cosmopsaltriina on the basis of a cladistic analysis of forty-nine characters. The consensus cladogram confirms the monophyly of the eight genera constituting the subtribe, and the monophyly of the subtribe as a whole. Cosmopsaltriina occur in Sulawesi, the Moluccas, New Guinea, Cape York, the Solomon Islands, Vanuatu, Fiji, Tonga and Samoa. The subtribe demonstrates a high rate of endemism on genus, species group and species level. The taxon-area and consensus-area cladograms resulting from Brooks parsimony analysis are discussed in relation to the palaeogeography of the area.     

Phylogeny,Evolution and Classification of Gall Wasps: The Plot Thickens

Gall wasps (Cynipidae) represent the most spectacular radiation of gall-inducing insects. In addition to true gall formers, gall wasps also include phytophagous inquilines, which live inside the galls induced by gall wasps or other insects. Here we present the first comprehensive molecular and total-evidence analyses of higher-level gall wasp relationships. We studied more than 100 taxa representing a rich selection of outgroups and the majority of described cynipid genera outside the diverse oak gall wasps (Cynipini), which were more sparsely sampled. About 5 kb of nucleotide data from one mitochondrial (COI) and four nuclear (28S, LWRh, EF1alpha F1, and EF1alpha F2) markers were analyzed separately and in combination with morphological and life-history data. According to previous morphology-based studies, gall wasps evolved in the Northern Hemisphere and were initially herb gallers. Inquilines originated once from gall inducers that lost the ability to initiate galls. Our results, albeit not conclusive, suggest a different scenario. The first gall wasps were more likely associated with woody host plants, and there must have been multiple origins of gall inducers, inquilines or both. One possibility is that gall inducers arose independently from inquilines in several lineages. Except for these surprising results, our analyses are largely consistent with previous studies. They confirm that gall wasps are conservative in their host-plant preferences, and that herb-galling lineages have radiated repeatedly onto the same set of unrelated host plants. We propose a revised classification of the family into twelve tribes, which are strongly supported as monophyletic across independent datasets. Four are new: Aulacideini, Phanacidini, Diastrophini and Ceroptresini. We present a key to the tribes and discuss their morphological and biological diversity. Until the relationships among the tribes are resolved, the origin and early evolution of gall wasps will remain elusive.     

Western Palaearctic phylogeography of an inquiline oak gall wasp,Synergus umbraculus

Insect‐induced galls on plants comprise species‐rich but self‐contained communities of herbivores and natural enemies. In the present study, we focus on galls induced by cynipid gall wasps on oaks, and on the least‐known trophic level that these galls contain: inquilines. These insects, also cynipids, feed on gall tissue and are an abundant but taxonomically poorly understood part of an otherwise well‐studied system. We used DNA sequence data to examine spatial patterns in the genetic diversity of Synergus umbraculus Olivier 1791 (Hymenoptera: Cynipidae: Synergini), a widespread species attacking many host galls across the Western Palaearctic. Analysis of 239 cytochrome b sequences revealed eight haplogroups showing significant phylogeographic pattern across the Western Palaearctic, corresponding to putative glacial refugia in Iberia, Central Europe, Turkey, and Iran. There were significant genetic discontinuities across the Pyrenees and the Anatolian diagonal but no impact of the Alps, suggesting that significant discontinuities have biotic rather than physical causes. Detailed analysis of sites in the Carpathian Basin reveal a high diversity and low spatial structure, and identify Central Europe as the source of colonists for Quaternary colonization of Germany, France, and Britain. We found no evidence for host‐associated differentiation of S. umbraculus lineages associated with the most common cynipid host galls, suggesting frequent shifts within the host gall assemblage by inquiline lineages. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 102 , 750–764.     

Sequential radiation of unrelated organisms: the gall fly Eurosta solidaginis and the tumbling flower beetle Mordellistena convicta

Host shifts and the formation of insect-host races are likely common processes in the speciation of herbivorous insects. The interactions of goldenrods Solidago (Compositae), the gall fly Eurosta solidaginis (Diptera: Tephritidae) and the beetle Mordellistena convicta (Coleoptera: Mordellidae) provide behavioural, ecological and genetic evidence of host races that may represent incipient species forming via sympatric speciation. We summarize evidence for Eurosta host races and show that M. convicta has radiated from goldenrod stems to Eurosta galls to form host-part races and, having exploited the galler's host shift, has begun to differentiate into host races within galls. Thus, host-race formation has occurred in two interacting, but unrelated organisms representing two trophic levels, resulting in 'sequential radiation' (escalation of biodiversity up the trophic system). Distributions of host races and their behavioural isolating mechanisms suggest sympatric differentiation. Such differentiation suggests host-race formation and subsequent speciation may be an important source of biodiversity.     

The impact of kleptoparasitic invasions on the evolution of gall-size in social and solitary Australian Acacia thrips

Many species of gall-inducing Acacia thrips are attacked by kleptoparasitic thrips who enter the gall, destroy the occupants, and then use the gall for producing their own offspring. The hypothesis tested here is that pressure exerted by ldeptoparasites （genus Koptothrips） not only provoked the evolution of soldiers in the gall-inducing clade, but have also influenced the evolution of gall size and morphology. Various size dimensions of invaded galls were compared to those of uninvaded galls using data from six gall-inducing species and their kleptoparasites. For the non-social gall-inducing species （K. ellobus and K. nicholsoni） invaded galls showed no significant size differences from galls that had not been invaded. For the four social gall-inducingspecies （K. habrus, K. intermedius, K. waterhousei and K. morrisi） invaded galls were significantly narrower and/or shorter than uninvaded galls. Galls of social species that had not been invaded and contained adult soldiers were significantly larger than galls where soldiers were still at a larval stage, suggesting that gall size is related to gall age in these species. An hypothesis is proposed that links the timing of invasion by kleptoparasites to size of the host gall： induction of a smaller gall by host founders will reduce the period of vulnerability to invasion （before soldiers become adults） for social thrips by allowing foundresses in these smaller galls to begin laying soldierdestined eggs relatively sooner.     

Detection of two new cryptic species of Kiefferia (Diptera: Cecidomyiidae) by means of morphological,molecular and ecological studies

Morphological, molecular and ecological studies revealed that Kiefferia Mik, 1985 (Diptera: Cecidomyiidae) is not a monotypic genus. Two new species, Kiefferia ezoensis sp. nov. and K. olla sp. nov. from Japan and Korea are added to the known European species, Kiefferia pericarpiicola. The new and known species are distinguishable from each other mainly by the shape of the larval sternal spatula. Molecular data support the results of morphological classification. Species of Kiefferia induce fruit galls on various plant species of Apiaceae. We found that K. ezoensis and K. olla utilized exclusively Angelica ursina and Oenanthe javanica, respectively. In contrast, we listed 37 apiaceous species belonging to 23 genera as hosts for K. pericarpiicola from previously published reports, suggesting the existence of additional undescribed species. Life history patterns of the three species are distinctly different from each other. Mature larvae of K. ezoensis and K. olla drop to the ground with the fruit gall in October and September, respectively, whereas mature larvae of K. pericarpiicola quit the galls and drop to the ground in August. A key to the Kiefferia species is provided based on morphological features and information on life history patterns and host ranges.     

Systematic status of the genus Formosaphis Takahashi and the evolution of galls based on the molecular phylogeny of Pemphigini (Hemiptera: Aphididae: Eriosomatinae)

Abstract.  Aphids of the tribe Pemphigini (Hemiptera: Aphididae: Eriosomatinae) can induce pseudo-galls or galls on their primary host plants. Those belonging to subtribe Prociphilina often produce pseudo-galls, and those of the other subtribe, Pemphigina, can form not only pseudo-galls but also true galls. Pseudo-galls are all formed on the leaves, whereas true galls, although all similar in shape, can be located on the joint of the leaf blade and the petiole, the middle of the petiole and the branches of the host plant. From a first phylogenetic analysis of Pemphigini based on nuclear elongation factor-1α (EF-1α) sequences, no support was found for the monophyly of Pemphigini, but subtribe Pemphigina was monophyletic with robust support. Formosaphis obviously clusters with Pemphigina which has Populus as a primary host. Formosaphis belongs to Pemphigini and its unknown primary host is probably Populus. The evolution of galls in Pemphigina is discussed based on the phylogenetic tree drawn from EF-1α sequences and mitochondrial cytochrome oxidase subunit I (COI) sequences. The results suggest that, in this subtribe, the closed gall is preceded by an open pseudo-gall, and the galls move their locations from the joint of the leaf blade and the petiole to the middle of the petiole and, eventually, to the branch of the host plant. Such an evolutionary tendency may provide aphids with more protection and nutrition.     

Polymorphism of axillary bud galls induced by Rhopalomyia longitubifex (Diptera: Cecidomyiidae) on Artemisia princeps and A. montana (Asteraceae) in Japan and Korea, with designation of new synonyms

In the past, Rhopalomyia longitubifex, Rhopalomyia shinjii, and Rhopalomyia sp. (Diptera: Cecidomyiidae) have been regarded as independent species based on differences in the sizes and shapes of axillary bud galls induced on Artemisia montana (Asteraceae) in Japan and A. princeps in Japan and Korea. However, comparison of morphological features and molecular sequencing data indicate that these Rhopalomyia gall midges are identical and that the differences in gall shape are polymorphisms, although the measurements of gall height and diameter overlap slightly. This finding suggests that although galls have frequently been regarded as extensions of the phenotype of a species, differences in gall shape may not always be reliable for identifying gall‐inducing cecidomyiids. The older name, R. longitubifex, is applied to these gall midges, and the names that were applied to this species on later occasions are revised or synonymized. The mature and immature stages of R. longitubifex are redescribed and information on the distribution, host range, and gall size of this species is provided. We also discuss the role of gall polymorphism in the early stages of speciation.     

Eriophyoid Mites (Acariformes,Eriophyoidea) from Rosaceae: Taxonomic Diversity,Host-Parasite Relationships,and Ability to Cause Galls

A review on the complex of species of eriophyoid mites associated with Rosaceae is given, focused on the phylogeny, biology, and distribution of their host plants and galls induced by these mites. About 200 species of 39 genera from 3 families ofEriophyoidea are known from Rosaceae. Among them, 6 species from 2 genera belong to Phytoptidae, 178 species from 27 genera, to Eriophyidae, and 28 species from 10 genera, to Diptilomiopidae; 7 genera of the latter family are represented on Rosaceae by a single species each. The ability to induce galls is discussed using the example of the most widespread and numerous genera of the family Eriophyidae from Rosaceae. Mites of two large subfamilies, Eriophyinae and Phyllocoptinae, include both vagrant and concealed forms. The types of galls caused by mites are related to the systematic position of mites and the distribution of mites and their host plants. The hypothesis of host shifts of eriophyoid mites from other plant families to Rosaceae is considered. Most of the species which presumably switched to Rosaceae have been described from Southeast Asia. Morphological similarity between vagrant and concealed forms from the paraphyletic tribes Eriophyini and Phyllocoptini, and also Aceriini and Anthocoptini is discussed. Their pairwise similarity might be the result of evolution (Eriophyini → Phyllocoptini and Aceriini → Anthocoptini) connected with change oflife style.     

Gall Flies, Inquilines, and Goldenrods: A Model for Host-race Formation and Sympatric Speciation

Host shifts and subsequent host-race formation likely play amore common role in the speciation of herbivorous insects thanhas generally been recognized. Our studies of the interactionsof goldenrod host plants (Solidago: Compositae), the gall flyEurosta solidaginis (Diptera: Tephritidae), and the stem- andgall-boring Mordellistena convicta (Coleoptera: Mordellidae)provide behavioral, ecological, and genetic evidence of insecthost races that may represent incipient species formed via sympatricspeciation. Eurosta solidaginis has developed genetically differentiatedand reproductively isolated host races that are associated withthe ancestral host Solidago altissima and the derived host S.gigantea. Conventional wisdom suggests that shifts even to closelyrelated host plants are limited by host preferences or the inabilityto utilize a chemically and developmentally distinct host. However,our preliminary work with Eurosta from S. gigantea implies thathost choice and gall induction do not deter a shift to S. canadensis.The galling of Solidago by Eurosta created a new resource thathas led to a subsequent host range expansion by the stem-boringbeetle. Mordellistena convicta from stems and galls are geneticallydistinct and likely shifted from stems to galls. Beetles fromS. altissima versus S. gigantea galls exhibit assortative matingand higher preference for and/or performance on their natalhost. The present-day distributions of the Eurosta host racesand their behavioral isolating mechanisms do not suggest thatgeographic isolation was required for their formation; ratherthese characteristics suggest a sympatric mode of differentiation.Our findings lend credence to recent assertions that sympatricspeciation may be an important source of biodiversity.     

Evolution of the gall wasp-host plant association

Gall wasps, or cynipids, form the second largest radiation of galling insects with more than 1300 described species. According to current views, the first cynipids were phytophagous and developed in herb stems of the Asteraceae without modifying plant growth or development. The first galls were supposedly multichambered stem swellings, and subsequent trends involved increase in gall complexity and reduction in the number of larval chambers. Gall wasps also have many of the features believed to be characteristic for phytophagous insects radiating in parallel with their host plants. We tested these hypotheses by mapping characters onto a recent estimate of higher cynipid relationships from a morphology-based analysis of exemplar taxa, controlling for phylogenetic uncertainty using bootstrapping. Characters were also mapped onto a metatree including all gall wasps, assembled from phylogenetic analyses as well as recent classifications. The results contradict many of the current hypotheses. The first cynipids with extant descendants were not Asteraceae stem feeders but induced distinct single-chambered galls in reproductive organs of herbaceous Papaveraceae, or possibly Lamiaceae. There has been a general trend toward more complex galls but the herb-stem feeders evolved from ancestors inducing distinct galls and their larval chambers are best understood as cryptic galls. Woody hosts have been colonized only three times, making the apparently irreversible transition from herbs to woody hosts one of the most conservative features of the gall wasp-host plant association. The evolution of host plant preferences is characterized by colonization of preexisting host-plant lineages rather than by parallel cladogenesis. Cynipids are mono- or oligophagous and host-plant choice is strongly phylogenetically conserved. Yet, the few major host shifts have involved remarkably distantly related plants. Many shifts have been onto plant species already exploited by other gall wasps, suggesting that interspecific parasitism among cynipids facilitates colonization of novel host plants.     

Partitioning of herbivore hosts across time and food plants promotes diversification in the Megastigmus dorsalis oak gall parasitoid complex

Communities of insect herbivores and their natural enemies are rich and ecologically crucial components of terrestrial biodiversity. Understanding the processes that promote their origin and maintenance is thus of considerable interest. One major proposed mechanism is ecological speciation through host‐associated differentiation (HAD), the divergence of a polyphagous species first into ecological host races and eventually into more specialized daughter species. The rich chalcid parasitoid communities attacking cynipid oak gall wasp hosts are structured by multiple host traits, including food plant taxon, host gall phenology, and gall structure. Here, we ask whether the same traits structure genetic diversity within supposedly generalist parasitoid morphospecies. We use mitochondrial DNA sequences and microsatellite genotypes to quantify HAD for Megastigmus (Bootanomyia) dorsalis, a complex of two apparently generalist cryptic parasitoid species attacking oak galls. Ancient Balkan refugial populations showed phenological separation between the cryptic species, one primarily attacking spring galls, and the other mainly attacking autumn galls. The spring species also contained host races specializing on galls developing on different host‐plant lineages (sections Cerris vs. Quercus) within the oak genus Quercus. These results indicate more significant host‐associated structuring within oak gall parasitoid communities than previously thought and support ecological theory predicting the evolution of specialist lineages within generalist parasitoids. In contrast, UK populations of the autumn cryptic species associated with both native and recently invading oak gall wasps showed no evidence of population differentiation, implying rapid recruitment of native parasitoid populations onto invading hosts, and hence potential for natural biological control. This is of significance given recent rapid range expansion of the economically damaging chestnut gall wasp, Dryocosmus kuriphilus, in Europe.     

Molecular and ecological evidence for species specificity and coevolution in a group of marine algal-bacterial symbioses

The phylogenetic relationships of bacterial symbionts from three gall-bearing species in the marine red algal genus Prionitis (Rhodophyta) were inferred from 16S rDNA sequence analysis and compared to host phylogeny also inferred from sequence comparisons (nuclear ribosomal internal-transcribed-spacer region). Gall formation has been described previously on two species of Prionitis, P. lanceolata (from central California) and P. decipiens (from Peru). This investigation reports gall formation on a third related host, Prionitis filiformis. Phylogenetic analyses based on sequence comparisons place the bacteria as a single lineage within the Roseobacter grouping of the alpha subclass of the division Proteobacteria (99.4 to 98.25% sequence identity among phylotypes). Comparison of symbiont and host molecular phylogenies confirms the presence of three gall-bearing algal lineages and is consistent with the hypothesis that these red seaweeds and their bacterial symbionts are coevolving. The species specificity of these associations was investigated in nature by whole-cell hybridization of gall bacteria and in the laboratory by using cross-inoculation trials. Whole-cell in situ hybridization confirmed that a single bacterial symbiont phylotype is present in galls on each host. In laboratory trials, bacterial symbionts were incapable of inducing galls on alternate hosts (including two non-gall-bearing species). Symbiont-host specificity in Prionitis gall formation indicates an effective ecological separation between these closely related symbiont phylotypes and provides an example of a biological context in which to consider the organismic significance of 16S rDNA sequence variation.     

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.     

Biology of Asphondyliini (Diptera: Cecidomyiidae)

The family Cecidomyiidae (Diptera) including about 6100 described species displays diverse feeding habits. The tribe Asphondyliini is a well‐circumscribed monophyletic group of Cecidomyiidae and all species are known as gall inducers. Species belonging to this tribe exhibit fascinating ecological traits such as host alternation, polyphagy, extended diapause, induction of dimorphic galls and association with fungal symbionts. For these reasons, biogeographical and phylogenetic studies of Asphondyliini are of interest in elucidating the evolution of these traits, and particularly the processes of host‐range expansion, host‐plant shift and shifts in gall‐bearing organs. In order to facilitate further evolutionary studies of Asphondyliini, I review studies of systematics, biogeography, phylogeny, speciation, cytology, behavior, ecology, physiology, biological interaction and economic importance in this tribe.     

基于形态特征和mtDNA COI序列的北美五倍子蚜分类和系统发育地位研究

五倍子蚜共6属12种, 除北美分布1属1种外, 其余分布东亚。本研究采用数值分类和分子系统发育分析方法对北美五倍子蚜Melaphis rhois的形态特点和分类地位进行研究, 以倍蚜6属8种179个有翅孤雌蚜为研究对象, 对其头部、胸部、腹部的直接测量特征48个、量度间比例特征31个及转化为数值的描述特征29个共108个特征进行分析。基于欧氏距离的聚类结果显示, 北美倍蚜M. rhois与倍蚜属关系较近, 五倍子蚜8个种共形成3个大的聚类簇, 北美倍蚜M. rhois与倍蚜属的倍蛋蚜Schlechtendalia peitan和角倍蚜S. chinensis聚为一支; 铁倍蚜属的肚倍蚜蛋铁亚种Kaburagia rhusicola ovogallis和肚倍蚜枣铁亚种K. rhusicola ensigallis与小铁枣蚜属的红小铁枣蚜Meitanaphis elongallis、圆角倍蚜属的倍花蚜Nurudea shiraii和红倍花蚜N. yanoiella与铁倍花蚜属的铁倍花蚜Floraphis meitanensis分别聚为一支。另外, 测定五倍子蚜8个种共16个样本的mtDNA COI基因序列（约1.2 kb）, 最大简约法(maximum parsimony, MP)和最大似然法(maximum likelihood, ML)分子系统发育分析结果均显示北美倍蚜M. rhois与倍蚜属的关系密切, 和形态数据得到的结果一致; 但倍蚜8个种之间的聚类总体上与形态学研究结果不太一致, 铁倍花蚜属的铁倍花蚜和小铁枣蚜属的红小铁枣蚜、铁倍蚜属的肚倍蚜枣铁亚种和肚倍蚜蛋铁亚种与圆角倍蚜属的倍花蚜和红倍花蚜分别聚为一支, 彼此之间的关系尚需深入研究。     

Ecological divergence among morphologically and genetically related Asphondylia species (Diptera: Cecidomyiidae), with new life history data for three congeners including the Alpinia fruit gall midge

Ecological data is crucial for determining the degree of reproductive isolation among closely related species, and in identifying the factors that have produced this divergence. We studied life history traits for three Asphondylia (Diptera: Cecidomyiidae) species that induce fruit galls either on Alpinia, Ligustrum or Aucuba, and we compared the traits with those published for three other closely related Japanese Asphondylia species. We found that the six species were significantly differentiated in important life history traits, such as host range, voltinism, lower developmental threshold temperature, thermal constant and diapausing season. The data indicate that divergence in the assessed life history traits evolves before morphological divergence, and such ecological divergence could strengthen isolating barriers among the taxa. We present scenarios on how host range expansion, host plant shift and host organ shift for galling initiate the early stages of speciation. We also highlight the importance of ecological data in identifying cryptic species. Specifically, we confirm that Alpinia intermedia (Zingiberaceae) is not an autumn–spring host of the soybean pod gall midge Asphondylia yushimai based on many differences in the life history traits between the Alpinia fruit gall midge Asphondylia sp. and A. yushimai.     

Phenotypic plasticity and similarity among gall morphotypes on a superhost,Baccharis reticularia (Asteraceae)

Understanding factors that modulate plant development is still a challenging task in plant biology. Although research has highlighted the role of abiotic and biotic factors in determining final plant structure, we know little of how these factors combine to produce specific developmental patterns. Here, we studied patterns of cell and tissue organisation in galled and non‐galled organs of Baccharis reticularia, a Neotropical shrub that hosts over ten species of galling insects. We employed qualitative and quantitative approaches to understand patterns of growth and differentiation in its four most abundant gall morphotypes. We compared two leaf galls induced by sap‐sucking Hemiptera and stem galls induced by a Lepidopteran and a Dipteran, Cecidomyiidae. The hypotheses tested were: (i) the more complex the galls, the more distinct they are from their non‐galled host; (ii) galls induced on less plastic host organs, e.g. stems, develop under more morphogenetic constraints and, therefore, should be more similar among themselves than galls induced on more plastic organs. We also evaluated the plant sex preference of gall‐inducing insects for oviposition. Simple galls were qualitative and quantitatively more similar to non‐galled organs than complex galls, thereby supporting the first hypothesis. Unexpectedly, stem galls had more similarities between them than to their host organ, hence only partially supporting the second hypothesis. Similarity among stem galls may be caused by the restrictive pattern of host stems. The opposite trend was observed for host leaves, which generate either similar or distinct gall morphotypes due to their higher phenotypic plasticity. The Relative Distance of Plasticity Index for non‐galled stems and stem galls ranged from 0.02 to 0.42. Our results strongly suggest that both tissue plasticity and gall inducer identity interact to determine plant developmental patterns, and therefore, final gall structure.