Review of the inquilinous fauna associated with insect galls in Brazilian restingas

Several records of associated fauna, including parasitoids, inquilines, predators, and successors, have been reported by insect gall inventories in Brazilian restingas. Although most guilds are well established, inquilines have frequently been misinterpreted. In this paper, the inquilinous fauna of insect galls is revised based on five criteria: food habit; coexistence with the inducer; modification of gall tissues or production of new tissues; phylogenetic relationship with the inducer; and mobility. Gall inventories dated from 1988 to 2019 were examined, totaling 16 publications, eight of them with inquiline records. This guild was reported in 53 gall morphotypes in 44 plant species and four morphospecies distributed among 36 genera of 24 host families for a total of 65 records. Most inquilines were repositioned into the cecidophage guild and others into the kleptoparasite guild, resulting in a large reduction in the frequency of inquilines (from 65 to five records), and in first reports of cecidophages and kleptoparasites, with 46 and 13 records, respectively. Cecidophage was the most diverse guild with insects of five orders (Diptera, Coleoptera, Lepidoptera, Hemiptera, and Thysanoptera) while kleptoparasites were represented only by two orders (Diptera and Hymenoptera) and inquiline solely by Hymenoptera. Other results indicate that Leptothorax sp. (Formicidae) could be a successor and not an inquiline.

Comparison of Auxin and Cytokinins Concentrations, and the Structure of Bacterial Community between Host Twigs and Lithosaphonecrus arcoverticus Galls

Insect galls are the abnormal growth of plant tissues induced by a wide variety of galling insects and characterized by high concentrations of auxins and cytokinins. It remains unclear whether the auxins and cytokinins affect the bacterial community structure of insect galls. We determined the concentrations of indoleacetic acid (IAA) as an example of auxin, trans-zeatin riboside (tZR) and isopentenyladenine (iP) as cytokinins in Lithosaphonecrus arcoverticus (Hymenoptera: Cynipidae) galls and the galled twigs of Lithocarpus glaber (Fagaceae) using liquid chromatography–tandem mass spectrometry. Moreover, for the first time, we compared the bacterial community structure of L. arcoverticus galls and galled twigs by high-throughput sequencing, and calculated the Spearman correlation and associated degree of significance between the IAA, tZR and iP concentrations and the bacterial community structure. Our results indicated the concentrations of IAA, tZR and iP were higher in L. arcoverticus galls than in galled twigs, and positively correlated with the bacterial community structure of L. arcoverticus galls. We suggest the high concentrations of IAA, tZR and iP may affect the bacterial community structure of L. arcoverticus galls.

Diversity of insect galls associated with Eucalyptus alba & E. urophylla in altitudinal zones in Timor Island, Indonesia

Puspasari LT, Buchori D, Ubaidillah R, Triwidodo H, Hidayat P. 2021. Diversity of insect galls associated with Eucalyptus alba & E. urophylla in altitudinal zones in Timor Island, Indonesia. Biodiversitas 22: 2667-2679. We investigated the galling insects associated with two species of Eucalyptus, namely E. alba Reinw. and E. urophylla S.T. Blake in different altitudinal zones in Timor Island, Indonesia. This is the first report for Indonesia of the diversity patterns and community structures of galling insects in these two species of eucalyptus and the type of galls they produce. Surveys and data collection were carried out between October 2017 and June 2018 at different altitudes of secondary forest in Timor Tengah Selatan district, Timor. We visited five altitudinal zones (± 829 m asl., ± 942 m asl. ± 1,621 m asl., ± 1992 m asl., and ± 2457 m asl.) and selected 25 eucalyptus plants of 3 to 5 m in height in each altitudinal zone from which to collect insect galls. The galls were observed on leaves, upper leaves (shoots), outer leaves, symptomatic twigs and stems. The galls were taken to the laboratory for rearing of the insects they contained. A total number of 12 gall types were found in E. alba and 15 in E. urophylla from which 28 insect morphospecies were identified belonging to 16 families and five orders. The order Hymenoptera was represented by ten families: Bethylidae, Torymidae, Eulophidae, Eupelmidae Eurytomidae, Pteromalidae, Encyrtidae, Mymaridae, Braconidae and Scelinonidae while the order Diptera was represented by three families: Fergusoninidae, Cecidomyiidae and Chaoboridae. Galling species diversity ranged from 1.71 to 2.38 on the Shannon-Wiener index and 0.75 to 0.87 on the Simpson index and showed that the galling-insect communities were species-rich and composed of galling formers and very few inquilines. In the study, communities are categorized and structured according to different types of galling insects, including those that induce galling, those that are parasitoid, and those that are inquiline. Within the category of gall-forming insects in the two species of eucalyptus, Eulophidae is found to be the dominant family. Our field data makes an important contribution to basic knowledge of insect galling patterns in eucalyptus forests and constitutes baseline data for the implementation of pest control.

The Diversity and Dynamics of Fungi in Dryocosmus kuriphilus Community

Dryocosmus kuriphilus (Hymenoptera: Cynipidae) is a gall wasp that induces insect galls on chestnut trees and results in massive yield losses worldwide. Fungi can cause the necrosis of chestnut trees and the death of gall wasps. The aim of this research was to investigate the potential role of D. kuriphilus in the transmission of fungi. We sequenced the ribosomal RNA internal transcribed spacer region 1 of fungi in D. kuriphilus adults, associated insect galls and the galled twigs of Castanea mollissima, using high-throughput sequencing. We compared the species richness, α-diversity and community structure of fungi in D. kuriphilus adults, insect galls and the galled twigs. We provide the first evidence that D. kuriphilus adults shared most fungal species with associated insect galls and the galled twigs, and were dominated by Botryosphaeria sp., Aspergillus sp. and Diaporthe sp. We suggest D. kuriphilus adults may be potential vectors of plant pathogens and may facilitate the transmission of fungi between chestnut trees. Furthermore, the fungi may horizontally transmit among D. kuriphilus adults, associated insect galls and the galled twigs.

Microbiomes of willow-galling sawflies: effects of host plant, gall type, and phylogeny on community structure and function

While free-living herbivorous insects are thought to harbor microbial communities composed of transient bacteria derived from their diet, recent studies indicate that insects that induce galls on plants may be involved in more intimate host–microbe relationships. We used 16S rDNA metabarcoding to survey larval microbiomes of 20 nematine sawfly species that induce bud or leaf galls on 13 Salix species. The 391 amplicon sequence variants (ASVs) detected represented 69 bacterial genera in six phyla. Multi-variate statistical analyses showed that the structure of larval microbiomes is influenced by willow host species as well as by gall type. Nevertheless, a “core” microbiome composed of 58 ASVs is shared widely across the focal galler species. Within the core community, the presence of many abundant, related ASVs representing multiple distantly related bacterial taxa is reflected as a statistically significant effect of bacterial phylogeny on galler–microbe associations. Members of the core community have a variety of inferred functions, including degradation of phenolic compounds, nutrient supplementation, and production of plant hormones. Hence, our results support suggestions of intimate and diverse interactions between galling insects and microbes and add to a growing body of evidence that microbes may play a role in the induction of insect galls on plants.

Insect galls of the Brazilian Cerrado: associated fauna

Insect galls host a rich and diverse fauna of secondary dwellers, which compose the associated fauna. In Brazil, many inventories of insect galls in Cerrado areas have recorded secondary dwellers. These records were scattered in several papers. This study gathered literature data to provide an overview of the arthropod fauna associated with insect galls in the Brazilian Cerrado. We searched for scientific publications in online academic databases and retrieved 16 papers with data on the secondary dwellers. We limited our search to the period from 1988 to 2020. We updated the name of plant species and verified endemism and geographic distribution in Flora do Brasil 2020. We provided plant species uses based on the Tropical Useful Plants 2014. We found 163 gall morphotypes with secondary dwellers (16.8% of the total of gall morphotypes of the Brazilian Cerrado) on 94 plant species in 37 families. Asteraceae, Fabaceae, Myrtaceae, and Malpighiaceae exhibited the greatest number of records. These are the richest families in insect galls in the Brazilian Cerrado. Most arthropod fauna were recorded in galls of Cecidomyiidae (Diptera). Most records were in leaf galls, the predominant galled organ. Parasitoids were more frequent than successors, inquilines, and predators. Eulophidae and Eurytomidae were the most frequent parasitoid families. Inquilines were represented by Coleoptera, Diplopoda, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Psocoptera, and Thysanoptera; successors by Acari, Araneae, Cecidomyiidae (Diptera), Coleoptera, Collembola, and Formicidae (Hymenoptera), whereas predators by Pseudoscorpiones and Diptera. Most records were presented in suprageneric categories, showing that the taxonomic knowledge is very deficient. 29 plant species are endemic to Brazil and totaled 45 gall morphotypes with secondary dwellers; 46 plant species are useful and host secondary dwellers in 62 gall morphotypes. These data add ecological and economic importance to these arthropods.

Diversity of insect galls from Mato Grosso State, Brazil: Cerrado

The Midwest region of Brazil possesses large areas dominated by the Cerrado that is poorly known concerning insect gall and their interactions. In this study, we inventory the gall morphology, host plants, and the gall makers from Parque Nacional da Chapada dos Guimarães, Mato Grosso State, in areas of natural vegetation from Cerrado, for the first time. Samplings occurred in two expeditions, July 2012 and January 2013. We characterized 295 morphotypes of insect galls in 140 host plant species, with 89 gall makers; the richest family in host plants was Fabaceae (16.7%), and the species was Protium heptaphyllum (Aubl.) Marchand (Burseraceae, 3.7%). Parque Nacional da Chapada dos Guimarães is the richest Brazilian cerrado area in gall morphotypes (295) and the second in average morphotypes/host plant species (2.1). Additionally, six genera and 38 species are new records as host plants; two of them, Bernardia similis Pax and K.Hoffm and Ormosia macrophylla Benth., are new occurrences for Mato Grosso State, and other two, Vochysia petraea Warm. and Talisia subalbens (Mart.) Radlk. are listed in the Red List of Threatened Species IUCN. This inventory data represents a testimony of insect-plant interactions in a Brazilian Cerrado area that was consumed by an unprecedented fire in the dry season of 2020.

Diversity of insect galls from Mato Grosso State, Brazil: North Pantanal

The Pantanal Biome occupies 20% of the Brazilian territory extending its distribution over two Brazilian States, Mato Grosso and Mato Grosso do Sul. This Biome is one of Brazil's poorly known regions concerning insect gall and their interactions with host plants. In this study, we characterized for the first time the gall morphology, identified host plants and the gall makers from an area of Brazilian wetlands from Mato Grosso State, known as Pantanal Matogrossense. We sampled Pantanal Biome areas in Poconé municipality, along the Transpantaneira Road, Mato Grosso State, Brazil, in two expeditions, July 2012 and January 2013, with a total effort of 2 hours. We characterized 91 morphotypes of insect galls in 54 host plant species; 28 gall makers in 24 host plant species; the richest host plant families are Fabaceae, Myrtaceae, and Sapindaceae. Psidium guineense Sw. is the super host species. This area in Pantanal Matogrossense is the second in the richness of gall morphotypes (N=91) and average morphotypes/plant species (1.7), comparing phytophysiognomies. Additionally, 15 plant species are new record as host in galler-host plant interaction in the world. This number represents 30% of the total of host plant species sampled in Poconé. This inventory is new knowledge to the Pantanal Matogrossense and representing a unique testimony of insect-plant interactions consumed by the unprecedented fire that occurred in Pantanal Biome in the dry season of 2020.