No abstract

In the Brazilian savanna many plant species bear regular associations with patrolling ants that are aggressive towards insect herbivores. However, not only ants but also several species of predatory wasps are attracted to plants due to the extrafloral nectaries (EFNs). Such wasps feed on both herbivores and plant exudates. In this study we describe the foraging behavior of the social Polistinae wasp Brachygastra lecheguana in the extrafloral nectaried shrub Banisteriopsis malifolia, and investigated the influence of patrolling ants Camponotus blandus on the activity of the wasp. Brachygastra lecheguana fed on the endophytic larvae of Anthonomus (Curculionidae) beetles that developed inside flower buds. The wasp lacerated the bud layers to reach the beetle larvae located at the bud core. The wasp visits to Ba. malifolia were statistically related to the abundance of flower buds and beetles. Ant exclusion experiments revealed that the hunting behavior of B. lecheguana on beetles was not related to the absence of C. blandus. However we found that wasps spent more time consuming extrafloral nectar on branches where ants were excluded. This is the first study reporting extrafloral nectar consumption by B. lecheguana, as well as the predation on herbivores in natural areas. In cerrado vegetation, ants benefit the plant by reducing insect herbivores, and our study provides evidence that the B. lecheguana -Ba. malifolia system represents a potential interaction where the wasp may also benefit the host plant. The value of this wasp species as a plant-guard is discussed.

No abstract

In the Brazilian savanna, myrmecophilous lycaenids are often found in many shrubs feeding on plant reproductive structures while are tended by ants, but only recently the role of both ants and food on the occurrence of lycaenids have received attention. In this study, we investigated the influence of Camponotus blandus (Formicinae) and flower bud abundance on the occurrence of Parrhasius polibetes, a florivorous lycaenid species that occurs in Banisteriopsis malifolia (Malpighiaceae). We also examined to what extent larval florivory was deleterious to plant reproductive outputs. Ant-exclusion experiments revealed that most P. polibetes individuals were found on branches with free C. blandus access. Nonetheless, the occurrence of larvae was not related to the abundance of ants and flower buds, indicating that the presence, rather than the abundance of mutualistic ants and food, influenced the occurrence of P. polibetes. Larvae were attended by C. blandus, which antennated frequently the dorsal nectary organ of larvae. Larval florivory was not deleterious to the plant. Banisteriopsis malifolia produces thousands of buds simultaneously and larvae feed only on a small portion of flower buds. The occurrence of P. polibetes in B. malifolia is advantageous for the larvae, since this plant supports mutualistic ants and plenty of food resources.

The presence of aggregates of A. reticulatum on Bauhinia has been reported, but the insects were mainly attended by ants of the genus Camponotus, and stingless bees were not regularly recorded in aggregations. We observed a colony of thetreehopper A. reticulatum and stingless bees, Trigona branneri, interacting on Bauhinia forficata (Fabaceae). Agonistic behavior was observed in bees when another individual of the same species or ants approached. Although this is not proof that the interaction between stingless bees and treehoppers is mutualistic, the interactions between ants and this insect are common and mutualistic. Thus, if T. branneri effectively provides protection for the aphids, a new mutualism can be the focus of future research to determine if the bee-aphid interactions have same ecological functions as the ant-aphid interactions.

No abstract

Spatial and temporal limited resource and niche overlap studies have been widely used to explain resource-sharing in community ecology. Furthermore, morphological and behavioral differences among species are relevant to predict how they may share niche availabilities. We evaluated temporal niche overlap and the ability of visitors to collect floral resources on three Malpighiaceae species in the Brazilian savannah. We hypothesized: (I) an overlap between the temporal niches due the similarities between their floral resources requirements and the temporal limitation of flowering; and (II) a differential ability of bee species in resource harvesting. The 31 floral visitor species exhibited a higher niche overlap than expected by chance, confirming our first hypothesis. Furthermore, according to our second hypothesis, we observed that floral visitors showed a different efficiency in resource collection, depending on bee size and behavior. We believe that this may be a proxy of pollination efficiency. Our discussion is based on the distinct specialization of oil-collecting abilities and the specific requirements of each bee tribe.

Galls are specific interactions between specialist herbivores and their host plants. They are considered neoformed plant organs developed from cellular hypertrophy, tissue hyperplasia and cellular redifferentiation of the host tissues. Among several organisms capable of inducing galls, insects induce them with high morphological complexity. The induction and development of galls depend on the availability of responsive sites in the host plant that react to the chemical and/or mechanical stimuli of galling insects. The synchronization between the timing of availability of these responsive sites and the galling insect life cycle is essential for the establishment of the interaction. Galling insects are subject to several chemical, physiological and phenological changes in their host plant. Thus, changes in the host cycle may alter the insect's life cycle, distribution and abundance. This study focused on the morphological aspects and phenological relationship of the Matayba guianensis Aubl. (Sapindaceae)-Bystracoccus mataybae Hodgson, Isaias & Oliveira (Eriococcidae) system, carried out in a semi-deciduous forest located at the Estação Ecológica do Panga (EEP), Uberlândia, MG, Brazil. We monitored the host plant phenology monthly from April 2015 to April 2016, and galls were sampled throughout the year to determine the stage of development of the galling insect. During leaf flushing, galling insects were collected every two days. The second-instar nymph induced leaf galls during leaf sprouting (peaks in September and October). The growth, development and maturation of the gall and of the galling insect occur concomitant to leaf maturation (peaks from February to May). Before the first leaves fall (August), the first-instar nymph moves from the senescent leaflet gall to branches and induces a stem gall, where it remains during part of the dry season until the next leaf flush. The synchrony between the life cycle of the galling insect and the host plant phenology maintains the univoltine cycle.