Seasonally dry tropical forests (SDTFs) provide a habitat for a diverse number of species and cover significant land areas. Yet, the amount of scientific research they have attracted is minimal. Recently, an international debate on the generality, consequences and forces keeping SDTFs in a position of relative negligence has begun. This paper assesses and compares biodiversity-related knowledge across the major Brazilian ecosystems to verify in which extent the Caatinga vegetation (a mosaic of scrubs and patches of seasonally dry forest) has been scientifically unappreciated. In fact, Caatinga attracted the lowest scores from semi-quantitative indexes describing biodiversity-survey efforts and knowledge status, with a negligible number of papers published internationally. Caatinga also supports fewer research teams and senior researchers as compared to humid tropical forests (Amazonia and Atlantic Forest). Both the knowledge index and number of published papers were explained by a model combining ecosystem area (km2), inventory index plus the current number of research teams or senior researchers assigned to Brazilian ecosystems. These findings reinforce the notion that SDTFs have experienced lower scientific efforts, but also reveal an apparent connection between institutional capacity, production/accumulation of scientific knowledge and conservation efforts. Although the research agenda for reconciling land-use and biodiversity conservation has been launched, current institutional anemia across SDTFs is likely to limit its impacts and achievements.

The analysis on nine inventories on the richness and diversity of galling herbivores in Brazil accounted for 806 gall systems occurring in 443 host-plant species from 74 plant families. This checklist of the Brazilian gall morphotypes proposes seven standardized morphotypes and five additional shapes that group the majority of the three-dimensional shapes reported in literature. Criteria are proposed to standardize the terminology, and a critical analysis is provided aiming to avoid possible inconsistencies in order to generate easily comparable data in future inventories. The morphotypes are herein catalogued in alphabetical order, accompanied by a conceptual definition, an illustration, and examples that best represent the shape. It is proposed that the inventories should present at least the (1) host-plant species, (2) galling herbivore species or its identification to the lowest possible taxonomic level, (3) host-plant galled organ and gall position, (4) gall morphotype, (5) gall color and registration of indumentum when present, (6) gall phenological and developmental data, (7) association with other trophic levels, and (8) additional information, such as dimension, and number of chamber(s).

Diversity of gall-inducing insects in the tropical dry forest (caatinga) of Pernambuco. We report on the richness of galling insects in the vegetation of caatinga of Pernambuco state, Brazil. We recorded 64 different types of galls collected primarily from leaves and stems of 48 species of host plants belonging to 17 families and 31 genera. The most common gall morphological types were spheroid and discoid, glabrous, predominantly green and with one chamber. The main gall inducing taxon was the Cecidomyiidae (Diptera). The results of this study contribute to existing knowledge of galling insect and host-plant diversity in caatinga.
Diversidade de insetos indutores de galhas na floresta tropical seca (caatinga) de Pernambuco. Este artigo reporta sobre a riqueza de insetos galhadores na vegetação de caatinga de Pernambuco, Brasil. Foram registrados 64 diferentes tipos de galhas coletadas principalmente em folhas e caules de 48 espécies de plantas hospedeiras pertencentes a 17 famílias e 31 gêneros. Os tipos morfológicos de galhas mais comuns foram esferóide e discóides, glabro, predominantemente verde e com uma câmara. O principal táxon indutor de galhas foi Cecidomyiidae (Diptera). Os resultados deste estudo contribuem para o conhecimento da diversidade de insetos galhadores e planta-hospedeira na caatinga

The Plant Vigor Hypothesis (PVH) proposes that natural selection on female oviposition choice results from higher fitness of larvae on more vigorous and larger plant modules. For six consecutive years we tested the PVH predictions by investigating the effect of shoot size of Bauhinia brevipes (Fabaceae) on the oviposition preference and offspring survival of the gall-midge Schizomyia macrocapillata (Diptera: Cecidomyiidae). Additionally, we analyzed the effects of bottom-up and top-down mortality forces on the system. The hypersensitive reaction (bottomup effect) accounted for more than 90% larval mortality of S. macrocapillata, making available few galls to be found and killed by natural enemies (top-down effect). Smaller shoots were always more abundant while longer shoots were rare. Nevertheless, the percent number of galls induced by S. macrocapillata was up to 10-fold greater on the largest shoots, corroborating the preference prediction of the PVH. Schizomyia macrocapillata should use over-exploit larger shoots to maximize the preference for, and consequently increase the performance on these shoots. Our results partially support the performance prediction of the PVH: (1) the observed survival was higher than expected on longer shoots, and (2) the ratio of survival per shoot was positively related with shoot length only in 2 years. Thus, we found a link between female preference and larval performance on large-sized shoots, at least in some years. The gall-midge attack pattern in this study might be an evolved response to maximize the female preference and increased larval performance on longer shoots of the host plant.

Amelioration of harsh conditions, manipulation of host plant quality, and protection from natural enemies have all been suggested as potential forces in the evolution and maintenance of concealed feeding in insects. The construction of shelters--either in the form of mines, galls, and leaf rolls--are expected to increase larval survivorship and might influence other organisms of the community through non-trophic direct and indirect effects when shelters are co-occupied or occupied after abandonment, placing leaf and stem shelter-builders within the context of ecosystem engineering. In this review, we evaluate the potential of shelter built by insects to reduce pressure exerted by natural enemies, increase tissue quality, and provide shelter against abiotic conditions experienced during insect development. Through a quantitative analysis, we also examined the effects of insect shelters on patterns of richness and abundance of local communities, reviewing the data published in the last 15 years. We demonstrate strong effects of shelters on several arthropods, with increased richness and abundance when shelters are present in the host plants. These results reinforce the importance of the physical structures created by insects that although subtle, might have important roles in facilitative interactions.