Igor Abba Arriola

Bio: Igor Abba Arriola is an academic researcher from Universidade Federal de Minas Gerais. The author has contributed to research in topics: Gall & Cecidomyiidae. The author has an hindex of 4, co-authored 12 publications receiving 39 citations.

Questioning the environmental stress hypothesis for gall diversity of restinga vegetation on dunes

Abstract: The Atlantic Coast Restinga is a mosaic of plant communities with a distinct floristic and phytophysi- ognomy, exposed to luminous, thermal, and saline stresses. Plants of the restinga must have special features commonly associated to xeric environments, and are expected to host a high diversity of galling herbivores. We studied gall morphotypes, and recorded the diversity of galls on plants growing in sand dunes in a remnant area of restinga (Acarai State Park) in Sao Francisco do Sul, Santa Catarina State, Brazil. The sampling was done in four plots (250 x 5 m), constituting a total area of 5 000 m², during April, May and June. Plant branches (n ≥ 5) with galls were sampled, identified, and the galls were photographed. The galls were classified into eight morphotypes, associated to eight host plants constituting 15 host plants - galling herbivores systems. The identification of the gall - inducers was based on literature, and on the species-specific feature of this kind of host plant-gall inducers interaction. There was a predominance of leaf galls, green in color. The most common morphotypes were the globoid, lenticular, conical, rosette, marginal, and fusiform galls, similarly to the inven- tories performed on other Brazilian biomes. Despite the environmental stresses, the xeric features of the dunes of the ASP, and the high local plant diversity, the diversity of galling herbivores were low. Varronia curassavica (Boraginaceae), Smilax campestris (Smilacaceae), and Guapira opposita (Nyctaginaceae) were superhosts of galling herbivores in the dunes, with about 70 % of the total associated parasites. The environmental effect seems to be neutral, either for the host plants or for the generation of gall morphotypes. Alternatively, the scarce nutritional resources could be restrictive for the establishment of the galling herbivores inside plant tissues. Rev. Biol. Trop. 63 (4): 959-970. Epub 2015 December 01.

Where host plant goes, galls go too: new records of the Neotropical galling Cecidomyiidae (Diptera) associated with Calophyllum brasiliense Cambess. (Calophyllaceae)

Abstract: Calophyllum brasiliense , a Neotropical species, hosts seven galling Cecidomyiidae reported only for Brazil. Our hypothesis is the distribution of the galling insects associated with C. brasiliense is similar to that of the host plant. We checked gall occurrence by field sampling and by searching data in literature and herbaria. Current results indicate that the occurrence of galling Cecidomyiidae associated with C. brasiliense extends to 13 Brazilian states, as well as to 11 countries of Neotropical America.

Galls on Smilax campestris Griseb. (Smilacaceae) protect the insects against restinga constraints, but do not provide enriched nutrition

Abstract: Smilax campestris Griseb. (Smilacaceae) is a superhost of galling insects, adapted to xeric environments such as those of the restingas of the Parque Estadual do Acarai, Santa Catarina, Brazil. Currently, we evaluate the structural and histochemical changes induced by a Cecidomyiidae on S. campestris leaves, originating globoid midrib galls. We hypothesized that the macroenvironmental constraints of the restingas should reflect in gall developmental sites, resulting in enhanced xeromorphic anatomical features. The mesophyll of S. campestris non-galled leaves is dorsiventral, hypostomatic, with an adaxial homogeneous parenchyma, some cells with invagination in the walls, and an abaxial ordinary spongy parenchyma. In galls, the cells of leaf mesophyll redifferentiate into a homogenous parenchyma, with polygonal cells and straight cell walls. Few intercellular spaces are observed. Galls have uniseriate epidermis, without stomata, an outer parenchymatic cortex, a mechanical layer, and a nutritive tissue, limiting a diminutive central larval chamber. The histochemical profile reveals an increment in lignified cell walls, and accumulation of polyphenols, tannins, and alkaloids from non-galled leaves toward the galls. The absence of any special type of reserve in nutritive cells, and the occurrence of secondary metabolites in outer cortical layers, indicate reduction or absence of photosynthesis in gall tissues. Gall structure is redirected to a protective shelter against UV and oxidative damages imposed by the excessive light and water deficiency of the restingas, but do not provide enriched nutrition to the gall inducer. Current results contrast with common observations in insect-induced galls and reveal an alternative adaptive morphogenetic pathway for xeric environments induced on Smilax campestris by the gall inducer.

Diversidade de galhadores nas restingas do ecossistema Babitonga, Santa Catarina, Brasil

Abstract: Galhas sao estruturas cujo desenvolvimento envolve hipertrofia celular e hiperplasia no orgao vegetal onde sao induzidas. Esta inducao se da, principalmente, por insetos que, tem como resultado dessa interacao, abrigo e fonte de recursos alimentares que lhes garantem completar em parte ou em sua totalidade o seu ciclo de vida. Como se trata de uma interacao especie-especifica, os morfotipos de galhas representam a diversidade de organismos galhadores. O presente estudo objetivou compilar o conhecimento produzido sobre esse tema na area de abrangencia do ecossistema Babitonga. Sao registradas 86 morfoespecies de galhas associadas a flora das formacoes de restinga da baia. A alta riqueza especifica de organismos galhadores parece estar relacionada a maior riqueza de plantas nas comunidades de restinga. O conhecimento sobre este grupo ainda e escasso devido a dificuldade de obtencao de especimes e estima-se que apenas 50% dos organismos galhadores tenha sido descrito. Os resultados sugerem a necessidade de se ampliar os investimentos para subsidiar pesquisas sobre a biologia de galhadores que fazem do ecossistema Babitonga uma importante area para a conservacao da biodiversidade.

Dynamics of limited neoplastic growth on Pongamia pinnata (L.) (Fabaceae) leaf, induced by Aceria pongamiae (Acari: Eriophyidae).

Abstract: Galls or the neoplastic growth on plants result from a complex type of interaction between the inducers (Acari, Insects, Microbes and Nematodes) and plants. The present study sheds light on the gall inducing habit of a highly host specific eriophyid mite, Aceria pongamiae, on the leaves of Pongamia pinnata leading to the production of abnormal pouch like outgrowths on the adaxial and abaxial surfaces of the foliage. Each leaf gall is a highly complex, irregular massive structure, and the formation of which often leads to complete destruction of leaves, especially during heavy mite infestation, and thereby adversely affecting the physiology and growth of the host plant. The study was carried out by making comparative observations on FE-SEM histological sections of galls representing four different growth stages categorized on the basis of difference in age groups. Apart from variations in cell metaplasia, a dramatic change was observed in the abaxial-adaxial polarity of the laminar surfaces also throughout the developmental sequence of galls, in all the four growth stages. Significant variations could be observed in the anti-oxidative potency as well as elemental composition in the all the four age groups of galls, and also revealed ATR-FTIR pattern of gall formation. Being the first attempt to unravel the mystery of gall induction by eriophyids in general and by A. pongamiae in particular, on its host plant P.pinnata, by shedding light on the structural and histological alterations taking place during leaf gall formation under the influence of the mite, the current study is to be treated as the model of plant-animal interactive system.

30 years of research on insect galls in Brazil: a scientometric review

Abstract: The first systematic studies on insect galls in Brazil date to the early 20th century, after which research on insect galls remained dormant in the country, with interest not reviving until the 1980s. The aim of this study was is to document historical trends in publications about insect galls in Brazil over the last 30 years. Papers about insect galls and galling species in Brazil published in peer-reviewed journals from 1988 to 2017 were compiled. A total of 1,378 papers were analyzed, of which 182 addressed insect galls in Brazil. The results showed that the number of publications on the subject has been increasing over the last 30 years, and especially in the last decade. The diversity of journals that published on the subject has also been increasing. The studies were concentrated on the following topics: ecology (94 papers), inventory (29) and taxonomy (27). Most of the insect gall inventories in Brazil took place in the Southeast Region (29 papers), followed by the Central-West and Northeast regions, with eight papers each. This study documents a trend toward increasing scientific production on insect galls in Brazil, but with significant geographical bias: the researchers involved are concentrated in the Southeast Brazilian region.

Community structure of gall-inducing insects associated with a tropical shrub: regional, local and individual patterns

Abstract: The organization of gall-inducing insect communities can be affected by environmental factors and host plant traits that may operate at different spatial scales. Using Copaifera oblongifolia (Fabaceae), we evaluated the organization of their associated gall-inducing insect species in different spatial scales considering the following hypotheses: (i) the community of gall-inducing insects will be different between different populations of C. oblongifolia; (ii) plant individuals with a greater number of neighbours (host plant density) will have a greater diversity of gall-inducing insects; (iii) and more structurally complex plants will support a greater diversity of gall-inducing insects. Data were collected from the three different populations of C. oblongifolia located in abandoned pastures of three different municipalities in northern Minas Gerais, Brazil. We recorded a total of 17,843 galls belonging to 15 different gall-inducing insect species associated to 60 C. oblongifolia plants sampled in the three populations (20 individuals per population). Abundance, richness and composition of gall-inducing insect species were different between the populations, suggesting that local environmental conditions influenced the gall-inducing insect community at a regional scale. Host plant density negatively affected the richness and abundance of gall-inducing insects per plant. Our data did not corroborate the hypothesis of resource concentration, perhaps due to the effect of resource dilution. The biomass of the host plant positively influenced the abundance of gall-inducing insects per plant. However, the interaction between plant density and biomass of the plant suggests that plants with greater structural complexity are more attacked by gall-inducing insects in plots with lower number of neighbours.