Diversity of insect galls associated with coastal shrub vegetation in Rio de Janeiro, Brazil

Surveys in the coastal sandy plains (restingas) of Rio de Janeiro have shown a great richness of galls. We investigated the galling insects in two preserved restingas areas of Rio de Janeiro state: Parque Estadual da Costa do Sol and Reserva Particular do Patrimônio Natural Fazenda Caruara. The collections were done each two months, from June 2011 to May 2012. We investigated 38 points during 45 minutes each per collection. The galls were taken to the laboratory for rearing the insects. A total number of 151 insect galls were found in 82 plant species distributed into 34 botanic families. Most of the galls occurred on leaves and the plant families with the highest richness of galls were Myrtaceae and Fabaceae. All the six insect orders with galling species were found in this survey, where Cecidomyiidae (Diptera) was the main galler group. Hymenoptera and Thysanoptera were found as parasitoids and inquilines in 29 galls. The richness of galls in the surveyed areas reveals the importance of restinga for the composition and diversity of gallinducing insect fauna.


inTRoDuCTion
Galls are abnormal modifications in plant tissue induced by insects or mites (Raman 2007).Among the insects, six orders have been recorded by having gall-inducing species, Diptera, Hymenoptera, Lepidoptera, Coleoptera, Hemiptera, and Thysanoptera.The family Cecidomyiidae (Diptera) is the main taxa of galling insect within the arthropods (Gagné and Jaschhof 2014).
Brazil shows a rich fauna of galling insects, but the taxonomic knowledge of them is poorly known.Cerrado, Atlantic Forest, Amazon Forest, Caatinga, and Pantanal are among the studied biomes and they have shown a high number of insect galls.Some studies have correlated this rich fauna to the flora of these areas, mainly the most diverse ones, such as Amazon, Atlantic Forest, and Cerrado (Maia 2001, Araújo 2013, Santos et al. 2013).
The surveys of galls in Brazil are concentrated in the southeastern region, and these contributions have been corroborating with the high diversity of insect galls in this region.Most of the records are related to surveys in sandy coastal plains, also called restinga (Maia 2001, Oliveira and Maia 2005, Maia and Oliveira 2010, Rodrigues et al. 2014).
Restinga areas were investigated in Espírito Santo, São Paulo, and Rio de Janeiro states, being SHEILA P. CARVALHO-FERNANDES, SHARLENE ASCENDINO, VALéRIA C. MAIA and MáRCIA S. COuRI the last one the most studied (Maia 2013, Maia et al. 2014).The Atlantic forest, biome where the restinga vegetation is inserted, is known by the high plant diversity and endemism level.Considering the high specificity degree of this guild to their host plants, we expect a high diversity of these insects even in areas where there are some available data.
To the present contribution we investigated the galling insects associated with coastal shrub vegetation in two preserved areas of Rio de Janeiro state.

MaTeRial anD MeThoDS
Surveys were conducted in two preserved areas: Parque Estadual da Costa do Sol (PECS) and Reserva Particular do Patrimônio Natural Fazenda Caruara (RPPNFC).The PECS was created in 2011 and has about 9,800 ha, being the surveys done in the municipalities of Saquarema, Araruama, Arraial do Cabo, and Cabo Frio.The RPPNFC has 3,800 ha of area and is a private reserve located in the municipality of São João da Barra.
The collections were made each two months, from June 2011 to May 2012.38 points were chosen and distributed along the restinga vegetation from each Municipality, proportionally to the restinga area (Fig. 1).In each point we investigated the plants during 45 minutes.All the galls were photographed and separated in morphotypes following the classification proposed by Isaias et al. (2013), where the authors standardized the most common galls shapes found in Brazil.The host plants were pressed, dried and sent for identification to botanist of Museu Nacional, universidade Federal do Rio de Janeiro (MNRJ).The plant species names were updated using the Flora do Brasil website (Flora do Brasil 2015).
The galls were taken to the Diptera laboratory of Museu Nacional, for rearing the insects and obtain the adults for identification.Each gall morphotype was kept individually in plastic pots layered at the bottom with damp cotton and covered by fine screening.The pots were checked daily for adult emergence (gallers, parasitoids, inquilines and predators).Immature insects were obtained by dissecting some galls.All specimens were preserved in 70% ethanol.The Cecidomyiidae specimens were mounted in slides following Gagné (1994), except by using butyl acetate instead of creosote oil.These specimens were identified using taxonomic keys (Gagné 1994) and comparisons with original descriptions.All insect and plant specimens were deposited in the Entomological collection and Herbarium of Museu Nacional, Rio de Janeiro (MNRJ), respectively.
The super host families were Myrtaceae with 36 gall morphotypes on 11 species followed by Fabaceae with 14 galls on 11 species and Rubiaceae with nine galls on seven species.Eugenia L. (Myrtaceae) was the super host genera, with a total number of 21 gall morphotypes, which corresponded to 60% of the galls found on Myrtaceae.
Eugenia copacabanensis Kiaersk (Myrtaceae) was the species with the highest gall richness, with nine gall morphotypes.
Forty five Cecidomyiidae were determined at species level, and they are distributed into 22 genera.The remaining specimens were identified at genus level or higher categories, totalizing 29 genera, because the material collected was insufficient for a more accurate identification.The most representative genera were Dasineura Rondani, 1840 with seven species, Lopesia Rübsaamen, 1908 with six species, Stephomyia Tavares, 1916, with four species, Asphondylia Loew, 1850, Bruggmannia Tavares, 1906, Clinodiplosis Kieffer, 1894 (each with three species).70% of the remaining genera were represented only by one species (n=19).

DiSCuSSion
In restinga areas a total number of 480 gall morphotypes in 229 plant species and 60 botanic families have been recorded in São Paulo, Espírito Santo, and Rio de Janeiro states (Maia et al. 2014).Most of the gall inducers are identified only on family level or superior categories.Cecidomyiidae is the best known family among the gall inducers in Brazil, but the gall midge taxonomy is far to reach all the species that probably may exist.
Cecidomyiidae is a family with many different feeding habits, but about 75% of the species are plant feeders.The majority are gall-inducing insects, being this family the most important taxon among this herbivore guild.About 60% of the galls occurring in restingas from Southeast of Brazil are induced by Cecidomyiidae (Maia 2013, Gagné andJaschhof 2014, Maia et al. 2014).
Tephritidae is the second family of Diptera in importance among the galling species, being the cecidogenous represented by about 5% of all described species, most of them associated with Asteraceae (Freidberg 1998).This is the second record of Tephritidae galls in restingas from Rio de Janeiro, the other previous species was associated with another Asteraceae species, Vernonia rufrogisea St.-Hill. in Ilha da Marambaia (Mangaratiba, Rio de Janeiro state), and another record on Vernonia beyrichii Less.from Bertioga, São Paulo (Maia et al. 2008, Rodrigues et al. 2014).
Agromyzidae are mainly known as leaf miners, but so far the galling species are known from seven genera.They usually induce galls on Salicaceae, Asteraceae and Fabaceae (Spencer 1990).The gall of Japanagromyza inferna was previously recorded in restingas from Arraial do Cabo, Marambaia, and Saquarema (Rio de Janeiro state) associated with the same host plant found in this work (Sousa and Couri 2014).
Galls of Lepidoptera, Coleoptera, Hemiptera, Hymenoptera and Thysanoptera were previously recorded in Brazilian restingas.They comprise about 10% of all galls found in coastal shrub vegetation, with Hemiptera and Lepidoptera the most abundant (Maia et al. 2014).
Leaves are the main affected organ by the galling insects (Mani 1964) probably because this is the most abundant organ and, in most of the case, in restingas vegetation is available during all the year, unlike other dry forests, as caatinga in Brazil, where trees lose their leaves during the dry season.Leaf galls in restingas correspond to about 60% of all galls, but as recorded in this survey, galls are also present in other organs, such as stems, buds, fruits, and flowers (Maia 2013, Maia et al. 2014).
Despite in this inventory the most common gall shape found was fusiform, globoid galls are the most common shape in the Neotropical region (Isaias et al. 2013), the same pattern is observed in various ecosystems in Brazil, such as Cerrado, Amazon forest and also in restingas (Carvalho-Fernandes et al. 2012, Santos et al. 2012, Maia 2013, Maia et al. 2014).
The two most galled plant families recorded in this study are well reported in restingas as the super host families.Myrtaceae can be considered the main host family in coastal shrub vegetation in Southeastern Brazil, due to its great representativeness in all insect galls inventories.Other families, such as Fabaceae, Asteraceae, and Nyctaginaceae are also pointed as important hosts, nonetheless they vary in their importance according to the survey, probably because the diversity of vegetation physiognomies presented in the distinct areas (Bregonci et al. 2010, Maia 2001, Maia et al. 2008, Maia and Oliveira 2010, Rodrigues et al. 2014).In other Brazilian biomes, such as Araucaria Forest, Cerrado, Amazon Forest, Caatinga, and Caatinga-Cerrado transition these families also present the role of main gall hosts (Coelho et al. 2009, Almada and Fernandes 2011, Santos et al. 2011, Costa et al. 2014, Toma and Mendonça Jr 2013).
The identified gall midges of the present study comprise about 35% of species and 50% of genera that are known from Rio de Janeiro state.The recorded richest genera are also among the most speciose in the state (Maia and Barros 2009).
Parasitoidism is the main mortality factor affecting the survival rate of cedidomyiids.The Hymenoptera families represented in this study are frequent in galls in restingas of Rio de Janeiro, and Eulophidae and Eupelmidae are among the most common families associated with many galls in a great variety of plant families and species (Maia and Azevedo 2009).
The restingas of the State of Rio de Janeiro can be considered the most studied when we compare with other Brazilian restingas.Even so, we still have a great diversity to be discovered, as shown with the new records presented here and a high number of new species to be named in these areas.