Gall Species Research Articles

Galls in Schinus polygamus (Anacardiaceae): effects of forest structure on infestation intensity

Diverse ecological factors (top-down and bottom-up) act on the richness and abundance patterns of insect galls. Host plant density is a kind of bottom-up factor and is related to “resource concentration hypothesis.” In this study, we analyzed forest patches that differ in vegetational structure and host plant abundance: homogeneous forest patches (Schinus-dominated) and more complex forest patches, to determine whether there are differences in the intensity of gall infestation among individual trees. Insect galls were sampled from 15 Schinus polygamus trees along five transects in each forest (150 trees in total). Two galler species, a psyllid leaf galler and cecidomyiid shoot galler, were recorded. We found that Psyllidae gall infestation in S. polygamus presents higher values of galls per individual tree in Schinus-dominated forest patches than forest patches that are more diverse in plant species. Cecidomyiidae galls did not differ between areas and were not related to host plant abundance. We did not observe any variation in gall infestation within individual. Our study demonstrated that density-dependence effect could be more important for some galls species than others. The results suggest that biological attributes of galling insects’ infestation could be associated with susceptibility to host plant density.

Exeristes roborator (Fabricius, 1793) (Hymenoptera: Ichneumonidae) in the parasitoid community of Diplolepis galls in the Carpathian Basin

Exeristes roborator (Fabricius, 1793) is usually known as the parasitoid of lepidopteran pupae, but was also recorded as the parasitoid of diff erent Cynipidae species in the southern parts of Europe and parts of Middle East. In samples of Diplolepis rosae (Linnaeus, 1758) and D. mayri (Schlechtendal, 1876) galls collected in the eastern Carpathian Basin after 2010 E. roborator appeared in large numbers compared to those collected before 2010, when the species was not present in the gall communities. Here we report the diff erential presence of Exeristes roborator in the two rose gall species, which points out the host shift of the ichneumonid parasitoid spreading towards north. With 3 figures.

Modeling the potential distribution and conservation status of three species of oak gall wasps (Hymenoptera: Cynipidae) in the Iberian range

Cynipids (Hymenoptera: Cynipidae) induce a wide variety of complex galls on plants of different botanical families, particularly on Quercus species. Cynipid galls are well known to host large communities of insects, providing fundamental ecological niches for different animal taxa, which are organized in structured and relatively isolated communities at the microhabitat level. Gall communities of Quercus woodlands could be a conservation concern considering some risks, which affect several species of the Parasitica group of Hymenoptera, within which gall wasps and their parasitoids and inquilines are included. These risks concerning Parasitica species are mainly due to three causes: their high trophic level, high host specialization and the lack of knowledge of their biology. In this paper, a preliminary approach to this issue is presented for the Iberian–Balearic range. We model and study the ecological niche of three cynipid gall species that induce galls on Quercus species (Andricus quercustozae, Biorhiza pallida and Plagiotrochus quercusilicis). The cynipid gall species were selected for their different sets of host species and life cycle. The Ecological Niche Factor Analysis and two niche models built for each species (MAXENT and Mahalanobis Distances) support the interpretation that the bioclimatic variables considered have effects on cynipids through their respective sets of host plants. In addition, the results regarding A. quercustozae are consistent with the hypothetical existence of cryptic sexual generation (exposed in other works) parasitizing cork oak (Quercus suber), which could have another key role in its conservation.

Gall‐forming insects in a lowland tropical rainforest: low species diversity in an extremely specialised guild

1. Gall‐forming insects are a guild of endophages that exhibit a high level of fidelity to their host plants, however, their level of host specificity is seldom explicitly tested.2. Gall‐forming insect taxa from 32 species of woody tropical plants with resolved phylogenetic relationships were collected and reared, representing 15 families from all the major clades of angiosperms, at three lowland rainforest locations in Madang, Papua New Guinea (PNG).3. More than 8800 galled plant parts were collected from 78 gall morphospecies at an average of 2.4 per host plant. Total species richness at the sampling sites was estimated to be 83–89. All but one morphospecies were monophagous resulting in an effective specialisation of 0.98.4. Specific leaf weight, foliar nitrogen, the presence of latex, and the successional preference of plant species all gave a phylogenetic signal, but only plant successional preference influenced the species richness of galls on analysis of phylogenetically independent contrasts. Gall species were distributed randomly among host plant species and showed no preference for any particular plant lineage. Furthermore, most gall‐forming taxa were evenly dispersed across the host plant phylogeny.5. In the tropical rainforests of New Guinea, gall‐forming insects are ubiquitous but occur in species‐poor assemblages. Local species richness is closely tied to the diversity of angiosperms owing to very high host specificity.6. Finally, galler species richness data from the literature across habitats and latitudes were compared and suggest that tropical rainforests may be richer in galls than previously acknowledged.

Gall wasp community response to fragmentation of oak tree species: importance of fragment size and isolated trees

We explore the impact of habitat fragmentation on interactions between keystone resources of forest trees—oaks, genus Quercus (Fagaceae)—and an associated radiation of specialist cynipid gall wasps. Habitat fragmentation is predicted to have bottom‐up impacts on cynipid communities through impacts on host plant quality (plant vigor hypothesis). We explored the bottom‐up impacts on cynipid communities of habitat fragment size, fragment edge effects and presence of isolated oaks. We quantified temporal and spatial variation of leaves produced in the canopy to quantify plant vigor, and surveyed cynipid gall species abundance and richness over three years using 15 permanent forest patches and 25 isolated oaks in a fragmented oak woodland landscape in central Mexico. Cynipid gall abundance and species richness were higher in isolated oaks and small woodland fragments than in larger ones. Cynipid abundance and species richness were also higher along fragment edges in comparison with fragment interiors. This contrasts with patterns observed in other taxa. In addition, host plant quality was higher in isolated trees, in smaller fragments and along fragment edges. We therefore hypothesize that observed patterns in cynipid abundance and species richness are driven by changes in host plant quality due to forest fragmentation. Our data represent a baseline for longer‐term monitoring of fragmentation effects at a landscape scale. Further work is required to explore alternative potential explanations for observed patterns, including the estimation of potential top‐down impacts of fragmentation mediated by natural enemies.

Communities of Galling Insects onNeoboutonia macrocalyxTrees in Continuous Forests and Remnants of Forest Fragments in Kibale, Uganda

The responses of Afrotropical galling insects to habitat fragmentation are poorly understood. We studied the influence of fragmentation and fragment characteristics on communities of galling insects on Neoboutonia macrocalyx trees, in six forest fragments around Kibale National Park, Uganda. Insect galls were collected from six randomly cut tips of branches from each of 10 randomly selected trees in every forest five times over a 10-month period.Atotal of 6090 individuals representing five galler species were recorded. The species richness, density and community composition of gallers were significantly different among the forests. Continuous forest areas showed similar community characteristics but some fragments were similar to continuous forests and others differed from them. None of the fragment characteristics measured (size, host-tree density, distance from continuous forest boundary and from nearest neighbour) explained differences in community measures (species richness and density) of gallers. Our results indicate that habitat fragmentation can lead to a decline in the galler species richness and to changes in the density and composition of galling insects, emphasizing the need to maintain large continuous forested areas as a long-termstrategy for their conservation. However, the similarity of community measures of gallers of some fragments and continuous forests suggest that the preservation of fragments might provide an important complement to the conservation of galling insects, highlighting the need to include also these habitats in management and conservation priorities. However, our study did not identify habitat characteristics to predict which fragments have a high value for gallers, indicating that processes that produced high-value fragments might have been stochastic. Our results caution against making generalizations on the use of easily measureable fragment characteristics (e.g. size and distance of isolation) when designing and planning conservation areas.

High resilience of galling insect communities to selective and clear-cut logging in a tropical rainforest

Increasing anthropogenic disturbance in tropical rainforests is a major challenge to biodiversity conservation. The responses of herbivorous insect communities to habitat changes are not well understood. In this study, we investigated the resilience of galling insect communities associated with Neoboutonia macrocalyx (Euphorbiaceae) trees to logging in Kibale National Park, Uganda. Resilience was measured by comparing the species density, abundance and community structure of gallers in nine differently aged successional forests with those in adjacent primary forests. Insect galls were sampled from the canopy of 10 randomly selected trees in each successional stage, five times in a 10-month period. A total of 7219 individuals representing five galler species were recorded. No significant differences were found in the species density and overall density of gallers between the regenerating and primary forests. The mean tree height was positively correlated with the overall density of gallers. The community structure of gallers differed significantly among the successional stages, but exhibited no clear directional recovery trend. In addition, remarkable seasonal variations were observed in galler communities, with peak abundance being found in the wettest months. The results of the preset study indicate that specialist galling insects whose hosts are pioneer trees can recolonize successional sites rapidly and are resilient to the effects of selective and clear-cut logging in case primary or secondary forests with an established population of Neoboutonia host trees (source populations) are close by. Thus, recovering tropical forests can provide important habitats for galling insect biodiversity, highlighting the need to include them in management and conservation priority plans.

Bottom-up impact on the cecidomyiid leaf galler and its parasitism in a tropical rainforest.

The relative importance of host-plant resources, natural enemies or their interactions in controlling the population of galling insects and their parasitism is poorly known for tropical gallers. In this study, we assessed the impacts of plant quality and density of host trees in regulating the densities of a galler species, the cecidomyiid leaf galler (Cecidomyiini sp. 1EJV) and its parasitoids and inquilines on Neoboutonia macrocalyx trees in Uganda. We manipulated the nutritional quality (or vigour)and the resource concentration with four levels each of fertilization and the group size of host tree. We then recorded the effects of these treatments on the growth rate and total leaf area of host plants, the density of gallers and their mortality by parasitoids and inquilines. Higher levels of fertilization and host density resulted in significantly higher total leaf area than did ambient nutrient levels, and lowest tree densities, respectively. Fertilization also caused significant change in the growth rate of leaf area. Both higher fertilization and host density caused higher density of gallers. Total leaf area was positively associated with galler density, but within galled replicates, the galled leaves were larger than the ungalled leaves. Although highest levels of fertilization and density of host trees caused significant change in the densities of parasitoids, the rate of parasitism did not change. However, tree-density manipulations increased the rate of inquilinism, but on a very low level. Our results demonstrate a trophic cascade in the tropical galler and its parasitoids as a response to bottom-up effects.

Bottom‐up manipulations alter the community structures of galling insects and gall morphs on Neoboutonia macrocalyx trees in a moist tropical rainforest

Abstract The effects of bottom‐up forces on the community structure of tropical insect gallers and within species variation in gall morphotype assemblages are not well understood. We tested the roles of increased nutritional quality and density of host plants with respect to structuring the galling insect communities and gall morphotype assemblages on Neoboutonia macrocalyx trees in Uganda. Plant nutritional quality and resource concentration were manipulated with four levels of fertilization and the group size of trees, respectively. After applying these treatments in May 2011, gallers established naturally on experimental replicates. Five months later, we sampled gallers and recorded their numbers and the different morphotypes. We analyzed the effects of treatments on the structures of galler communities and gall morphotype assemblages. We recorded 5237 individuals, representing four galler species. One species, Cecidomyiid leaf galler, was represented by three morphologically distinct galls. Fertilization, host tree density and their interactions significantly changed the structures of galler species communities and gall morphotype assemblages. The results of the present study demonstrate the important role of bottom‐up factors in structuring galler communities and the gall morphotype assemblages. These changes are likely caused by differential responses of different galler species and gall morphs to plant quality or quantity changes.

Effects of Roads onCastanopsis carlesiiSeedlings and Their Leaf Herbivory in a Subtropical Forest in China

The effects of a forest road on Castanopsis carlesii (Hemsley) Hayata (Fagales: Fagaceae) seedlings and their leaf herbivory were investigated in a subtropical forest at Jiulianshan National Nature Reserve, Jiangxi, China. A total of 1124 seedlings, 33949 leaves, 468 leaf mines, and 205 leaf galls were found. Generally, individual numbers, tree heights, and leaf numbers of C. carlesii seedlings became lower with increasing distances from the road. These results might indicate that old seedlings were fewer and survival rate of seedlings was lower in forest interiors. Leaf miners preferred the seedlings close to the forest road, while leaf gallers preferred the seedlings about 2 m from the road. Species diversity of leaf miners was higher in the forest interior area, while species diversity of leaf gallers was higher near the road. However, both leaf miners and leaf gallers decreased in general from the road to the interior forest. There were interspecific differences in the effects of roads on leaf miner species and leaf galler species. The effects of the road on seedlings and insects could be explained by varying microhabitat conditions and different ecological strategies.

Effects of roads on Castanopsis carlesii seedlings and their leaf herbivory in a subtropical forest in China.

The effects of a forest road on Castanopsis carlesii (Hemsley) Hayata (Fagales: Fagaceae) seedlings and their leaf herbivory were investigated in a subtropical forest at Jiulianshan National Nature Reserve, Jiangxi, China. A total of 1124 seedlings, 33949 leaves, 468 leaf mines, and 205 leaf galls were found. Generally, individual numbers, tree heights, and leaf numbers of C. carlesii seedlings became lower with increasing distances from the road. These results might indicate that old seedlings were fewer and survival rate of seedlings was lower in forest interiors. Leaf miners preferred the seedlings close to the forest road, while leaf gallers preferred the seedlings about 2 m from the road. Species diversity of leaf miners was higher in the forest interior area, while species diversity of leaf gallers was higher near the road. However, both leaf miners and leaf gallers decreased in general from the road to the interior forest. There were interspecific differences in the effects of roads on leaf miner species and leaf galler species. The effects of the road on seedlings and insects could be explained by varying microhabitat conditions and different ecological strategies. 摘要

Gall-inducing insects from Campos de Altitude, Brazil

Gall-inducing insects are very specious in vegetations of southeastern Brazil. Our goal was describe the gall richness by characterizing their external forms and their patterns of occurrence on host plants. Samples were collected from Campos de Altitude at four regions of the Mantiqueira Range: 1) Parque Estadual da Serra do Brigadeiro, 2) Parque Nacional do Caparaó, 3) Parque Estadual do Ibitipoca, 4) Parque Nacional do Itatiaia. We found 93 gall species within 13 families, 30 genera and 50 host plant species. We recorded 38 gall species in Parque Estadual da Serra do Brigadeiro, 21 in Parque Nacional do Caparaó, 23 in Parque Estadual do Ibitipoca and 20 in Parque Nacional do Itatiaia. Asteraceae represented 33% of the species collected, followed by Melastomataceae at 17%; with each one concentrating 56% and 18% of the galling insects, respectively. 98% of galls were Cecydomiidae (Diptera). The most attacked organ was the stem (56%), followed by the leaf (23%). Only 12% of the galls described in our study had been already recorded in previous studies, thus reinforcing the need to increase the sampling effort toward a better understanding of the richness and the natural history of gall-inducing insects from Brazil.

Interspecific competition influences the organization of a diverse sessile insect community

Interspecific competition has played a major role in determining the effects of species interactions in terrestrial communities and the perception of its role on shaping population dynamics and community structure has changed throughout the years. In this study, we evaluated the existence of interspecific competition in the herbivore community of the dioecious plant Baccharis pseudomyriocephala (Asteraceae), which holds a diverse community of gall-forming insects. Sixty plants were studied and gall richness and abundance among plants were evaluated. To address whether a plant already occupied by a gall species is preferred or avoided by another gall species, null models were used for all 60 plants combined and for male and female plants separately. Our results have shown that the 11 species of gall-formers found on B. pseudomyriocephala co-occur less than expected by chance alone, indicating that interspecific competition might be an important force structuring the insect community in this tropical host plant, regardless of plant gender.

Plantas hospedeiras e galhas entomógenas em sub-bosques de florestas tropicais do Pará, Brasil

In this study we recorded the occurrence of galls and host plants in understory areas of Floresta Ombrofila Densa, in the Floresta Nacional de Saraca-Taquera in Porto Trombetas, north of Para, Brazil. We recorded 112 gall morphotypes distributed in 65 families and 33 species of host plants, being Cecidomyiidae (Diptera) the most important group of galling insects. The plant families that showed more gall richness were Fabaceae with 18 morphotypes, Bignoniaceae with 14, Lauraceae and Sapotaceae with 12, and Burseraceae with 10 galling species. The genera Adenocalymma (Bignoniaceae), Pouteria (Sapotaceae), Inga (Fabaceae) and Protium (Burseraceae) and the species Adenocalymma neoflavidum (Bignoniaceae) and Ocotea sp. (Lauraceae) were the most diverse host plant taxa. Gall richness in the studied forest is high when compared to others Brazilian biomes, as Cerrado and Mata Atlântica. These results show the importance of Amazon region to diversity of entomogenous galls in the Brazil.

A new genus of gall-dwelling thrips from Costa Rica (Thysanoptera: Phlaeothripidae: Phlaeothripinae)

A new genus and species of thrips, Fourbethrips fiorella, inhabiting stems, petioles and leaf vein galls of a Melastomataceae from Costa Rica is described. The galls are induced by an unidentified gall midge larva (Cecidomyiidae). This new thrips can be distinguished from other genus and species of Phlaeothripinae by the shape of the pelta, the position of maxillary stylets in the head, the reduced and acute anterior pair of postocular setae, the long and capitate posterior pair of postocular setae, the presence of a group of minute setae, and a pair of short ventral setae in the middle area of the abdominal sternites II-VII. The tergites II-VII have a pair of campaniform sensillae.

Herbarium BUNS: Plant gall collection

The plant gall collection is part of the Herbarium BUNS collection, University of Novi Sad. Collection began with the formation in 1976, and as a unique type of collection in Serbia, it has existed for 35 years. Today?s collection Herbarium cecidologicum is made of two units - Plant gall collection (dried specimens) and database, and includes 438 data: 294 data for dried specimens and 144 collected literature data about the distribution plant galls. Galls collection has multiple significances: assessment biodiversity (diversity of plants and diversity of causers), estimate the population status of certain causers taxa, primarily invertebrates, monitoring the spread of pests, which usually occurs in population of the cultivated species. Collecting data in one database, providing data on new plant gall species and distribution on both challengers as well as host plants is one of the main tasks of this collection.

Size, age and composition: characteristics of plant taxa as diversity predictors of gall-midges (Diptera: Cecidomyiidae)

Many hypotheses have been proposed to explain the diversity of gall-midge insects (Diptera: Cecidomyiidae), some of them taking into account plant diversity. This study aims to test the importance of size, age and composition of host plant taxa in the diversity of Cecidomyiidae. For this we used inventories data on the diversity of galling and host plants in Brazil. We found that Asterales, Myrtales and Malpighiales, were the most important orders, with 34, 33 and 25, gall morphotypes, respectively. The most representative host families were Asteraceae (34 morphotypes), Myrtaceae (23) and Fabaceae (22). In general, the order size and the plant family were good predictors of the galling diversity, but not the taxon age. The most diverse host genera for gall-midges were Mikania, Eugenia and Styrax, with 15, 13 and nine galler species, respectively. The size of plant genera showed no significant relationship with the richness of Cecidomyiidae, contrary to the prediction of the plant taxon size hypothesis. The plant genera with the greatest diversity of galling insects are not necessarily those with the greatest number of species. These results indicate that some plant taxa have a high intrinsic richness of galling insects, suggesting that the plant species composition may be equally or more important for the diversity of gall-midges than the size or age of the host taxon.

Leaf miner and plant galler species richness on Acacia: relative importance of plant traits and climate

Diversity patterns of herbivores have been related to climate, host plant traits, host plant distribution and evolutionary relationships individually. However, few studies have assessed the relative contributions of a range of variables to explain these diversity patterns across large geographical and host plant species gradients. Here we assess the relative influence that climate and host plant traits have on endophagous species (leaf miners and plant gallers) diversity across a suite of host species from a genus that is widely distributed and morphologically variable. Forty-six species of Acacia were sampled to encapsulate the diversity of species across four taxonomic sections and a range of habitats along a 950 km climatic gradient: from subtropical forest habitats to semi-arid habitats. Plant traits, climatic variables, leaf miner and plant galler diversity were all quantified on each plant species. In total, 97 leaf mining species and 84 plant galling species were recorded from all host plants. Factors that best explained leaf miner richness across the climatic gradient (using AIC model selection) included specific leaf area (SLA), foliage thickness and mean annual rainfall. The factor that best explained plant galler richness across the climatic gradient was C:N ratio. In terms of the influence of plant and climatic traits on species composition, leaf miner assemblages were best explained by SLA, foliage thickness, mean minimum temperature and mean annual rainfall, whilst plant gall assemblages were explained by C:N ratio, %P, foliage thickness, mean minimum temperature and mean annual rainfall. This work is the first to assess diversity and structure across a broad environmental gradient and a wide range of potential key climatic and plant trait determinants simultaneously. Such methods provide key insights into endophage diversity and provide a solid basis for assessing their responses to a changing climate.

Comparative life‐history traits in a fig wasp community: implications for community structure

1. Whether life‐history traits can determine community composition and structure is an important question that has been well explored theoretically, but has received scant empirical attention. Life‐history traits of a seven‐member community of galler and parasitoid fig wasp species (Chalcidoidea), developing within the inflorescences (syconia) ofFicus racemosa(Moraceae) in India, were determined and used to examine community structure and ecology.2. Gallers were pro‐ovigenic (all eggs are mature upon adult emergence) whereas parasitoids were synovigenic (eggs mature progressively during adult lifespan). Initial egg load was correlated with body size for some species, and there was a trade‐off between egg number and egg size across all species. Although all species completed their development and left the syconium concurrently, they differed in their adult and pre‐adult lifespans. Providing sucrose solutions increased parasitoid lifespan but had no effect on the longevity of some galler species. While feeding regimes and body size affected longevity in most species, an interaction effect between these variables was detected for only one species.3. Life‐history traits of wasp species exhibited a continuum in relation to their arrival sequence at syconia for oviposition during syconium development, and therefore reflected their ecology. The largest number of eggs, smallest egg sizes, and shortest longevities were characteristic of the earliest‐arriving galling wasps at the smallest, immature syconia; the converse characterised the later‐arriving parasitoids at the larger, already parasitised syconia. Thus life history is an important correlate of community resource partitioning and can be used to understand community structure.4. This is the first comprehensive study of life‐history traits in a fig wasp community. The comparative approach revealed constraints and flexibility in trait evolution.

Insetos indutores de galhas da porção sul da Cadeia do Espinhaço, Minas Gerais, Brasil

A riqueza de insetos galhadores e maior nas latitudes intermediarias em habitats quentes e com vegetacao esclerofila sob estresse hidrico e de nutrientes. Em regioes tropicais, os campos rupestres sao indicados como habitats ricos em especies de insetos galhadores. Neste trabalho, foram descritas as galhas induzidas por insetos e suas plantas hospedeiras na porcao sul da Cadeia do Espinhaco, sudeste do Brasil. Foram selecionados 60 sitios em seis regioes ao longo na porcao sul da Cadeia do Espinhaco no estado de Minas Gerais. Em cada sitio 100 plantas foram amostradas totalizando 6.000 plantas censuradas ao longo de um gradiente altitudinal de 668 a 1860m. Foram encontrados 241 morfotipos de galhas em 142 especies de plantas distribuidas em 29 familias e de um total de 384 especies de plantas amostradas. As familias mais ricas em especies de insetos galhadores foram Asteraceae (42%), principalmente especies do genero Baccharis. A maior parte das galhas (85%) foi induzida por insetos da familia Cecidomyiidae seguidos por Lepidoptera (4%) e Homoptera (3%). Os ramos foram os orgaos mais frequentemente atacados (72%) enquanto que os morfotipos mais comuns foram o eliptico (37%) e o globoide (36%). A especie de planta hospedeira que apresentou mais morfotipos de galhas foi Baccharis pseudomyriocephala com 10 galhas distintas. Este estudo sustenta a afirmativa que campos rupestres apresentam uma elevada riqueza em especies de insetos galhadores.