Euglossine bees are known to be long-distance pollinators in tropical rainforests. But there is controversy concerning to the flight ranges of these bees between forest fragments. In an isolated fragment of Atlantic Rainforest in Pernambuco, NE Brazil, surrounded by sugarcane monocultures, it was examined if euglossine males leave closed rainforest to collect fragrances. In a straight-line transect leading from forest into a sugarcane plantation, euglossine males were simultaneously captured by scent baits at seven distinct points: inside the forest, forest edge, outside the forest in the sugarcane fields at distances of 10 m, 50 m, 100 m, 250 m and 500 m from the forest edge. A total of 945 euglossine bees of 16 species were recorded. The results demonstrate different relations of the Euglossini species to the closed forest. Males of 11 species did not leave the forest. Such species, together with the plants they are linked to, seem to be the most threatened by habitat fragmentation. Only bees of five species were found at the scent baits in the sugarcane fields. Already the 10 m sampling point outside the forest showed a drastic reduction in species richness, indicating that the forest edge functions as a barrier for most euglossine species.

Oligolectic bees collect pollen from only a few related plant taxa, and our understanding of both the bees' innate and learned behavior in host-plant recognition is incomplete. For the oligolectic bee Chelostoma rapunculi, whose host plants are within Campanula, we conducted choice tests on foraging-naïve individuals to investigate the bee's innate preference for visual and olfactory floral cues of its host plants over those of nonhost plants. In addition, we tested both foraging-naïve and foraging-experienced individuals to determine the relative importance of these 2 sensory modalities in the bee's innate and learned host-flower location. Visual and olfactory cues of Campanula trachelium flowers, both separately and combined, attracted significantly more foraging-naïve bees than equivalent cues of nonhost plants. Furthermore, for both foraging-naïve and -experienced bees, the visual cues of host plants were more attractive than the olfactory ones, and the 2 cues combined attracted more bees than either alone. In foraging-naïve bees, visual and olfactory cues alone elicited almost exclusively approaches, whereas after the bees gained foraging experience, landings became more frequent in response to visual cues but not to olfactory cues; in both bee groups, the combination of visual and olfactory cues was most effective in promoting landings. We conclude that Ch. rapunculi has an innate preference for the floral cues of its host plants over those of nonhost species and that both foraging-naïve and foraging-experienced bees integrate visual and olfactory cues to find their host flowers, with a slightly greater reliance on visual cues in bees with foraging experience.

Aedes aegypti is responsible for the transmission of dengue, a disease that infects millions of people each year. Although essential oils are well recognized as sources of compounds with repellent and larvicidal activities against the dengue mosquito, much less is known about their oviposition deterrent effects. Commiphora leptophloeos, a tree native to South America, has important pharmacological properties, but the chemical profile and applicability of its essential oil in controlling the spread of the dengue mosquito have not been investigated. The aim of this study was to determine the composition of C. leptophloeos leaf oil and to evaluate its larvicidal and oviposition deterrent effects against A. aegypti. Fifty-five components of the essential oil were detected by gas chromatography (GC)—mass spectrometry, with α-phellandrene (26.3%), (E)-caryophyllene (18.0%) and β-phellandrene (12.9%) identified as the major constituents. Bioassays showed that the oil exhibited strong oviposition deterrent effects against A. aegypti at concentrations between 25 and 100 ppm, and possessed good larvicidal activity (LC₅₀ = 99.4 ppm). Analysis of the oil by GC coupled with electroantennographic detection established that seven constituents could trigger antennal depolarization in A. aegypti gravid females. Two of these components, namely (E)-caryophyllene and α-humulene, were present in substantial proportions in the oil, and oviposition deterrence assays confirmed that both were significantly active at concentrations equivalent to those present in the oil. It is concluded that these sesquiterpenes are responsible, at least in part, for the deterrent effect of the oil. The oviposition deterrent activity of the leaf oil of C. leptophloeos is one of the most potent reported so far, suggesting that it could represent an interesting alternative to synthetic insecticides. The results of this study highlight the importance of integrating chemical and electrophysiological methods for screening natural compounds for their potential in combating vectors of insect-borne diseases.

Nectar-feeding bats depend mainly on floral nectar to fulfil their energetic requirements. Chiropterophilous flowers generally present strong floral scents and provide conspicuous acoustic echoes to attract bats. While floral scents are assumed to attract bats over long distances, acoustic properties of flower structures may provide detailed information, thus supporting the localization of a flower at close ranges. So far, to our knowledge, there is no study trying to understand the relative importance as well as the combination of these generally coupled cues for detection (presence) and localization (exact position) of open flowers in nature. For a better comprehension of the significance of olfaction and echolocation in the foraging behaviour of nectar-feeding bats, we conducted two-choice experiments with Leptonycteris yerbabuenae . We tested the bats' behaviour in three experimental scenarios with different cues: (i) olfaction versus echolocation, (ii) echolocation versus echolocation and olfaction, and (iii) olfaction versus echolocation and olfaction. We used the floral scent of the bat-pollinated cactus Pachycereus pringlei as olfactory cue and an acrylic paraboloid as acoustic cue. Additionally, we recorded the echolocation behaviour of the bats and analysed the floral scent of P. pringlei . When decoupled cues were offered, bats displayed no preference in choice for any of the two cues. However, bats reacted first to and chose more often the coupled cues. All bats echolocated continuously and broadcast a long terminal group before a successful visit. The floral scent bouquet of P. pringlei is composed of 20 compounds, some of which (e.g. methyl benzoate) were already reported from chiropterophilous plants. Our investigation demonstrates for the first time to our knowledge, that nectar-feeding bats integrate over different sensory modes for detection and precise localization of open flowers. The combined information from olfactory and acoustic cues allows bats to forage more efficiently.