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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.

Many pollinators specialize on a few plants as food sources and rely on flower scents to recognize their hosts. However, the specific compounds mediating this recognition are mostly unknown. We investigated the chemical basis of host location/recognition in the Campanula-specialist bee Chelostoma rapunculi using chemical, electrophysiological, and behavioral approaches. Our findings show that Ca. trachelium flowers emit a weak scent consisting of both widespread and rare (i.e., spiroacetals) volatiles. In electroantennographic analyses, the antennae of bees responded to aliphatics, terpenes, aromatics, and spiroacetals; however, the bioassays revealed a more complex response picture. Spiroacetals attracted host-naive bees, whereas spiroacetals together with aliphatics and terpenes were used for host finding by host-experienced bees. On the intrafloral level, different flower parts of Ca. trachelium showed differences in the absolute and relative amounts of scent, including spiroacetals. Scent from pollen-presenting flower parts elicited more feeding responses in host-naive bees as compared to a scentless control, whereas host-experienced bees responded more to the nectar-presenting parts. Our study demonstrates the occurrence of learning (i.e., change in the bee's innate chemical search-image) after bees gain foraging experience on host flowers. We conclude that highly specific floral volatiles play a key role in host-flower recognition by this pollen-specialist bee, and discuss our findings into the broader context of host-recognition in oligolectic bees.

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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.

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The South American fruit fly is one of the most destructive polyphagous pests in South America. In this species, males gathered in aggregations emit volatiles that attract females; however, the compounds involved in this task remain unknown. In this study, we investigated the chemical composition of the volatile blend emitted by males aiming to identify the specific compounds within this blend that elicit behavioral responses in conspecific females. For this purpose, we performed chemical and electrophysiological analyses and bioassays. The chemical analyses revealed the presence of 29 compounds in headspace samples of A. fraterculus males, of which six compounds, i.e. a-pinene, limonene, (Z)-3-nonen-1-ol, (E,Z)-3,6-nonadien-1-ol, a-farnesene and (S,S)-(-)-epianastrephin, triggered antennal depolarization in conspecific females. In laboratory bioassays, five out of eight synthetic compounds tested individually elicited more behavioral responses than a hexane control, but only the synthetic mixture composed of all EAD-active compounds triggered behavioral responses in females similar to the responses to the headspace samples of conspecific males. In an experiment under semi-natural conditions, the synthetic mixture was more attractive to females than a hexane control and equally attractive to headspace extracts of males. This study reports the identification of male volatile compounds that act as attractant for A. fraterculus females, which may be useful for the control of this pest in infested orchards.