Artur Campos Dália Maia

The Key Role of 4-methyl-5-vinylthiazole in the Attraction of Scarab Beetle Pollinators: a Unique Olfactory Floral Signal Shared by Annonaceae and Araceae

Cyclocephaline scarabs are specialised scent-driven pollinators, implicated with the reproductive success of several Neotropical plant taxa. Night-blooming flowers pollinated by these beetles are thermogenic and release intense fragrances synchronized to pollinator activity. However, data on floral scent composition within such mutualistic interactions are scarce, and the identity of behaviorally active compounds involved is largely unknown. We performed GC-MS analyses of floral scents of four species of Annona (magnoliids, Annonaceae) and Caladium bicolor (monocots, Araceae), and demonstrated the chemical basis for the attraction of their effective pollinators. 4-Methyl-5-vinylthiazole, a nitrogen and sulphur-containing heterocyclic compound previously unreported in flowers, was found as a prominent constituent in all studied species. Field biotests confirmed that it is highly attractive to both male and female beetles of three species of the genus Cyclocephala, pollinators of the studied plant taxa. The origin of 4-methyl-5-vinylthiazole in plants might be associated with the metabolism of thiamine (vitamin B1), and we hypothesize that the presence of this compound in unrelated lineages of angiosperms is either linked to selective expression of a plesiomorphic biosynthetic pathway or to parallel evolution.

POLLINATION OF PHILODENDRON ACUTATUM (ARACEAE) IN THE ATLANTIC FOREST OF NORTHEASTERN BRAZIL: A SINGLE SCARAB BEETLE SPECIES GUARANTEES HIGH FRUIT SET

Philodendron acutatum (Araceae) is a hemiepiphyte common to the Atlantic Forest of northeastern Brazil. In two localities, we studied the species’ breeding system and associations with flower‐visiting insects, along with an analysis of its floral scent composition. The fruit set of self‐incompatible P. acutatum was high, more than 90%, and inflorescences were exclusively pollinated by one species of scarab beetle, Cyclocephala celata (Scarabaeidae, Dynastinae). Pollinators are drawn toward the inflorescences at dusk by strong floral fragrances given off during the female phase of anthesis, along with endogenous heating of the spadix, whose temperatures were recorded at more than 11°C above ambient air. Two other species of flower‐visiting Cyclocephala were also consistently recovered in blacklight trappings during the flowering period of P. acutatum. The fact that only C. celata was found in association with P. acutatum suggests a local reproductive dependence of the plant to this scarab beetle species. Dihydro‐β‐ionone and 2‐hydroxy‐5‐methyl‐3‐hexanone, a rare volatile molecule so far unreported as a floral compound, together accounted for more than 97% of the unique scent composition of P. acutatum and might be involved in specific attraction of C. celata.

The floral scent of Taccarum ulei (Araceae) : attraction of scarab beetle pollinators to an unusual aliphatic acyloin

The strongly fragrant thermogenic inflorescences of Taccarum ulei (Araceae) are highly attractive to night-active scarab beetles of Cyclocephala celata and C. cearae (Scarabaeidae, Cyclocephalini), which are effective pollinators of plants in the wild in northeastern Brazil. GC-MS analysis of headspace floral scent samples of T. ulei established that two constituents, (S)-2-hydroxy-5-methyl-3-hexanone (an aliphatic acyloin rarely detected in flowers) and dihydro-β-ionone (an irregular terpene) accounted for over 96% of the total scent discharge. Behavioral tests (in both field and cages) showed that male and female C. celata and C. cearae were attracted to traps baited with a synthetic mixture of both compounds; however, they were also responsive to (S)-2-hydroxy-5-methyl-3-hexanone alone, which thus functions as a specific attractive cue. These findings support other recent research in suggesting that angiosperms pollinated by cyclocephaline scarab beetles release floral odors of limited complexity in terms of numbers of compounds, but often dominated by unusual compounds that may ensure attraction of specific pollinator species.

The floral scents of Nymphaea subg. Hydrocallis (Nymphaeaceae), the New World night-blooming water lilies, and their relation with putative pollinators

Night-blooming water lilies are characterized by intense emission of floral VOCs. Their unique scent-oriented pollinators, cyclocephaline scarabs (Scarabaeidae, Cyclocephalini), are attracted to flowers that they use as reliable sources of food and as mating aggregation sites. Chemical analysis of floral scent samples of seven species of Nymphaea subg. Hydrocallis established remarkably simple fragrant blends, each of which was dominated by one or two prominent compounds that alone accounted for over 95% of total scent emission. A total of 22 VOCs were identified: aliphatics (9), C5-branched chain compounds (5) and aromatics (8). Anisole was the dominant constituent in the floral scents of Nymphaea amazonum subsp. amazonum, N. amazonum subsp. pedersenii and N. tenerinervia, whereas (methoxymethyl)benzene was the most abundant VOC in samples of N. lasiophylla and N. lingulata. Flowers of N. rudgeana and N. gardneriana emitted high amounts of methyl hexanoate and methyl 2-methylbutanoate. Comparisons of floral VOC composition including other day- and night-blooming species of Nymphaea and Victoria obtained from the literature evidenced disparities related to habitus. While flowers of day-blooming species mostly emit aromatic alcohols and ethers, nocturnal species are particularly rich in aromatic ethers, aliphatic esters and C5-branched chain esters. These findings strongly suggest that the floral scent composition within closely related Nymphaea and Victoria is linked to pollinator selection, and the putative role of floral VOCs in pollinator attractiveness is discussed.

The life of Cyclocephala celata Dechambre, 1980 (Coleoptera: Scarabaeidae: Dynastinae) in captivity with descriptions of the immature stages

We collected 76 specimens of the Cyclocephala celata Dechambre in Igarassu, Pernambuco, Brazil, in March 2008 for captive breeding and rearing to document its life cycle and to describe the immatures. A total of 98 eggs was obtained from captive-reared insects, each individually enclosed in an egg chamber assembled with the surrounding substrate. Viability was highest in the egg phase (92.8%). Pupae were enclosed in pupal cells. The duration of the life cycle was 164 days (n = 2), and only 2% of the eggs developed into adults. Third instar characters documented for the first time in the genus are: epitorma on the epipharynx, three dorsolongitudinal striae on the right mandible and one fringe of setae on the hypopharynx. Our data support the possibility of captive rearing and breeding of C. celata, contributing to the formulation of accurate management and conservation plans for native pollinators.

Nocturnal Bees are Attracted by Widespread Floral Scents

Flower localization in darkness is a challenging task for nocturnal pollinators. Floral scents often play a crucial role in guiding them towards their hosts. Using common volatile compounds of floral scents, we trapped female nocturnal Megalopta-bees (Halictidae), thus uncovering olfactory cues involved in their search for floral resources. Applying a new sampling method hereby described, we offer novel perspectives on the investigation of nocturnal bees.

New Biological and Immature Morphological Records of the Masked Chafer, Cyclocephala paraguayensis

Abstract In order to obtain information on the biology of the masked chafer, Cyclocephala paraguayensis Arrow (Scarabaeidae: Dynastinae: Cyclocephalini), and its immature morphology, the beetle life cycle was studied under laboratory conditions. After field collection, adults were placed inside containers filled with soil obtained in the original capture to provide an oviposition site after mating ocurred. Eggs were collected daily and isolated for manipulation experiments and life cycle observations. Detailed information about the eggs, instars and life cycle duration, and morphological features of immature stages were noted and examined. Egg viability was higher in the “nonmanipulated” batch. The complete ontogenic cycle of C. paraguayensis was 171 ± 11 days (n = 7). Despite the records of Cyclocephala being crop pests, reared larvae of C. paraguayensis thrived and developed into well-formed, fertile adults on an entirely saprophagous diet, indicating that they are not rhizophagous in the wild. The third instar can be distinguished from the other species mainly by the following unique characters: maximum width of the head capsule, distal antennal setae, and bifurcated setae on the raster.

Description of Cyclocephala distincta Burmeister (Coleoptera: Scarabaeidae: Dynastinae: Cyclocephalini) immatures and identification key for third instars of some Cyclocephala species

The larval instars and pupa of Cyclocephala distincta Burmeister (Coleoptera: Scarabaeidae: Dynastinae: Cyclocephalini) are described and compared to those of other known congenerics. Adult C. distincta, specialized flower visitors of Neotropical palms (Arecaceae), were collected in an area of native Atlantic Forest cover in the northeastern coast of Brazil and reared in captivity. The larvae of C. distincta diff---er from those of the other congenerics because of a distinctive pattern and arrangement of the setae on the raster.

2-Alkyl-3-methoxypyrazines are potent attractants of florivorous scarabs (Melolonthidae, Cyclocephalini) associated with economically exploitable Neotropical palms (Arecaceae): Florivorous scarab pests are attracted to 2-alkyl-3-methoxypyrazines

BACKGROUND 2-Alkyl-3-methoxypyrazines (MPs) are naturally occurring aromatic compounds involved in insect chemical communication as both pheromones and allelochemicals. Although rarely characterized in floral scents, they have been identified as major constituents in headspace samples from palm inflorescences and evidence pointed towards their function as attractive cues for scent-oriented pollinators, as well as florivores. In this study, we investigated the occurrence of MPs in economically exploitable palms belonging to Acrocomia and Attalea through headspace floral scent analysis and assessed their role in the selective attraction of flower-feeding cyclocephaline scarabs (Melolonthidae, Cyclocephalini) in field bioassays conducted in Brazil and Colombia. RESULTS Three different MPs were identified among floral headspace samples of Acrocomia aculeata, Acr. intumescens, Attalea butyracea and Att. insignis: 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP) and 2-(sec-butyl)-3-methoxypyrazine (SBMP). Their combined estimated total scent emissions per inflorescence ranged from 246 μg h-1 to 6.2 mg h-1 . Scented traps, individually baited with either IPMP or SBMP, resulted in species-selective and high yield captures of Cyclocephala amazona and C. distincta, known florivores associated with over 20 different species of Neotropical palms. CONCLUSIONS The identification of MPs as potent kairomones could prove instrumental in integrated pest management plans for these insects in emerging oil-yielding crops in South America, including those of the wine palm (Att. butyracea) and macaw palms (Acrocomia spp.).

A new species of Beebeomyia Curran (Diptera: Richardiidae) from Brazil, with description of immature stages and notes on their association with Taccarum ulei (Araceae)

A new species of the genus Beebeomyia Curran found in the northern coastal region of the state of Pernambuco, northeastern Brazil is described and illustrated, including characteristics of the male and female terminalia, third instar larva and puparium. This new species is only the second record for the genus in Brazil and broadens its occurrence to the Atlantic Forest ecoregion. Beebeomyia taccarivora sp. nov. is straightforwardly distinguishable from all other known species of Beebeomyia for exhibiting an entirely yellowish orange thorax with a central brown-colored stripe on the scutum, and a brownish orange abdomen with a central brown stripe on tergites 1-4. Similarly to what had been previously described for congenerics, female B. taccarivora flies exclusively use the inflorescences of their host plant, Taccarum ulei, as oviposition and brooding sites. Developing larvae feed on living floral tissue and pollen, and pupariation occurs within the inner surface of the spathe.