Helena C. Morais’s research while affiliated with Instituto de Ciências Farmacêuticas and other places

Herbivory pressure is an important ecological aspect to determine quantitative variation in plant defenses, such as the number of extrafloral nectaries (EFNs) and their nectar amount and quality. Extrafloral nectaries can attract ants, which can be considered a type of induced plant defense. Besides, plants tend to invest more in defense when they are more vulnerable to herbivores. Therefore, we aimed to elucidate if Stryphnodendron adstringens (Fabaceae), a common Cerrado tree species, when subjected to damage (by manual leaf cutting and experimental fire) would produce a greater number of EFNs and changes its nectar quality on newly produced leaves in comparison with plants not subjected to these treatments. Leaf damage was performed artificially directly on the plant branches and at the entire plant canopy (by means of scissors or fire events). Extrafloral nectary density was higher in new leaves produced after the treatment application (artificial herbivory and fire) in comparison with plants under control treatment. The amount of nectar was also higher under treatments in comparison with control, with a significant change on nectar quality in plants subjected to the treatments of artificial herbivory. The results provided support for the hypothesis that EFNs are an inducible defensive strategy in S. adstringens, confirming the existence of phenotypic plasticity given environmental pressures.

This study evaluated whether herbivorous insects can be expected to have particular adaptations to withstand the harsh dry season in tropical dry forests (TDFs). We specifically investigated a possible escape in space, with herbivorous insects moving to the few evergreen trees that occur in this ecosystem; and escape in time, with herbivores presenting an increased nocturnal rather than diurnal activity during the dry season. We determined the variation in the free-feeding herbivorous insects (sap-sucking and leaf chewing) between seasons (beginning and middle of both rainy and dry seasons), plant phenological groups (deciduous and evergreen trees) and diel period (diurnal and nocturnal) in a Brazilian TDF. We sampled a total of 5827 insect herbivores in 72 flight-interception traps. Contrary to our expectations, we found a greater herbivore diversity during the dry season, with low species overlap among seasons. In the dry season, evergreen trees supported greater richness and abundance of herbivores as compared to deciduous trees. Insects were also more active at night during the dry season, but no diel differences in insect abundance were detected during the rainy season. These results indicate that the strategies used by insect herbivores to withstand the severe climatic conditions of TDFs during the dry season include both small-scale escape in space and time, with evergreen trees playing a key role in maintaining resident insect herbivore populations in TDFs. Relatively more nocturnal activity during the dry season may be related to the avoidance of harsh climatic conditions during the day. We suggest that the few evergreen tree species occurring in the TDF landscape should be especially targeted for protection in this threatened ecosystem, given their importance for insect conservation.

ABSTRACT We document the biology and morphology of the egg, caterpillar, and pupa of Strymon crambusa (Hewitson, 1874), a Neotropical Eumaeini. In the Cerrado, the caterpillar feeds on the inflorescences and leaves of Oxalis L. S. crambusa has four larval instars, all of which are illustrated. The density of caterpillars on plants is higher than that recorded for leaf-feeding caterpillars and other flower-feeding Eumaeini, which suggests that the species is a specialist on Oxalidaceae in the Cerrado.

Deciduous and evergreen trees coexist in tropical dry forests, but exhibit distinct leaf syndromes for resource-use efficiency and defenses against herbivores. Moreover, these functional groups may have contrasting patterns of temporal variation in leaf traits and herbivory along leaf ontogeny. We tested these predictions by comparing a set of leaf traits related to water stress and defense, and herbivory levels between young and mature leaves from evergreen leaf-exchanger and deciduous species. We evaluated deciduous and evergreen trees within the same habitat type: a tropical dry forest with 90-100% of leaf deciduousness during the dry season. We sampled 10 individuals of three deciduous and three evergreen species. Evergreen plants had greater leaf thickness and concentration of phenolics and tannins. On the other hand, deciduous plants had higher leaf nitrogen content and specific leaf area. Deciduous plants lost twice as much leaf area by herbivory as evergreen plants (6.48 versus 3.20%), and leaf damage was positively related to both phenolic compounds and nitrogen content. Mature leaves from both phenological groups had higher levels of tannins and phenolic compounds, and lower levels of nitrogen and herbivory increment than young leaves. Our results suggest an adaptive convergence on leaf traits primarily related to water stress for different species within each phenological group. Some of these traits also play a role in leaf palatability, although the fitness consequences of the absolute difference in leaf damage (approximately 3%) between evergreen and deciduous species remain unclear.

Significance Dietary specialization determines an organism’s resource base as well as impacts on host or prey species. There are important basic and applied reasons to ask why some animals have narrow diets and others are more generalized, and if different regions of the Earth support more specialized interactions. We investigated site-specific host records for more than 7,500 species of insect herbivores. Although host specialists predominate, the proportion of specialists is affected by the diversity of hosts and shifts globally, supporting predictions of more exclusive tropical interactions. These results not only affect our understanding of the ecology of food webs, but also have implications for how they respond to environmental change, as well as for ecosystem management and restoration.

This study aimed to elucidate the anatomy and morphology of extrafloral nectaries (EFNs) in Maprounea brasiliensis and whether environmental factors influence their traits of production and morphology. For this reason, we sampled leaves from individuals subjected to distinct fire and water regimes, and the anatomy and ultrastructures of EFNs as well as the chemical constitution of nectar were analyzed. EFN nectar production was associated with immature and recently expanded leaves. EFNs originate from the epidermis. At the end of ontogeny, secretory cells are surrounded by three or more layers of cells with secondary and lignified walls, isolating the EFN of vascular tissue. The ultrastructural analysis revealed mature EFNs with secretory activity. The experiments showed that EFN production was not influenced by the presence of frequent fires. However, during the rainy season, new produced leaves had nectaries in greater quantity and diameter than leaves produced during the dry season. The anatomical and ultrastructural changes demonstrated that nectar production is strongly influenced by the age of the nectaries which influence ant attendance to EFN since no ants were observed on leaves that did not secrete nectar. The seasonality experiment confirmed that EFNs of M. brasiliensis are resource dependent and evolutionary programed to appear in elevated number during the rainy season.

The biology and morphology of the early stages of 22 species of Eumaeini (Lepidoptera: Lycaenidae, Theclinae) are presented. Observations were collected through the inspection of inflorescences in the field and the rearing of 214 larvae in laboratory. Allosmaitia strophius (Godart) associated with Malpighiaceae species and the polyphagous Strymon mulucha (Hewitson) were the most frequently collected species. Detritivory was observed in two species, Electrostrymon endymion (F.) and Kisutam syllis (Godman & Salvin), and myrmecophily in four other species, A. strophius, Ministrymon azia (Hewitson), Parrhasius polibetes (Stoll), and S. mulucha. Cannibalism was observed in A. strophius; in addition, the pupa of this and of three other species produced audible sounds. Paiwarria aphaca (Hewitson) was highlighted because of the great difference observed between its first and last instars, as well as the marked difference between that species and the larvae of Paiwarria umbratus (Geyer) documented in Costa Rica. Larvae of Calycopis mimas (Godman & Salvin) displayed "bungee jumping" behavior when stimulated. Parasitoids (Diptera, Hymenoptera) attacked 21 larvae of eight species, A. strophius, K. syllis, M. azia, Pai. aphaca, P. polibetes, Rekoa marius (Lucas), S. mulucha, and Tmolus venustus (H.H. Druce). Illustrations of immatures and parasitoids are provided.

O Guia de Campo Lagartas do Cerrado é o primeiro do gênero para qualquer bioma do Brasil. Será extremamente útil para profissionais e outros interessados na fauna de insetos, principalmente do Cerrado. Esse guia foi elaborado de forma simples e de maneira adequada para a utilização no campo, contém informações para cada espécie de lagarta e é fartamente ilustrado (lagartas e adultos) para facilitar a identificação das espécies. Contém a diagnose das lagartas de cada família e informações, quando possível, da descrição morfológica e das mudanças durante o seu desenvolvimento, da amplitude de dieta (especialista ou generalista), de espécies de plantas hospedeiras (somente aquelas restritas ao Cerrado de Brasília - DF, Pirenópolis e Chapada dos Veadeiros - GO), da aparência (coloração críptica ou aposemática), do comportamento (solitário ou gregário, desenvolvimento exposto na planta ou em abrigo), da ocorrência temporal e da abundância relativa em plantas do Cerrado de Brasília, Pirenópolis e Chapada dos Veadeiros (rara ou comum).

Caterpillar shelters provide protection against desiccation and natural enemies, whereas extra-floral nectaries (EFNs) may be an anti-herbivore adaptation that reduces herbivore abundance by attracting predators and parasites. We used a large, long-term dataset for caterpillars found in the Brazilian cerrado to examine temporal variations in the relative abundance of shelter-building caterpillars and exposed caterpillars, and to determine how much variation depends on the season and the presence of EFNs on host plants. We also compared the patterns of parasitism between sheltered and exposed caterpillars, between seasons, and between different host plants. The cerrado has a marked dry season, and its vegetation is a mixture of mostly deciduous shrubs and trees. Leaf production occurs mainly during the rainy season, and many plant species bear EFNs. Our results show that 60 % of cerrado caterpillars build shelters. These caterpillars were found to be proportionally more abundant during the dry season and less parasitized than exposed ones. The proportion of caterpillars building shelters was highest on plants with new leaves (functional EFNs), and parasitism of caterpillars on these plants was higher. Even though our study includes a taxonomically diverse suite of caterpillars that build many different types of shelter and a diverse set of plants and EFN types, our results suggest that EFNs play an important role in structuring caterpillar assemblages in the cerrado, and that the prolific use of shelters by caterpillars may be a result of their effectiveness in protecting caterpillars from natural enemies and desiccation.