A comparative study of cleaning activity of two reef fishes at Fernando de Noronha Archipelago, tropical West Atlantic

Cleaner fishes are usually classified as obligate or facultative cleaners according to their diet and the extent to which their nutritional requirements in the different ontogenetic stages are gained from cleaning. While obligate cleaners clean throughout their lives and ingest mainly food taken from the clients` body surface, facultative cleaners clean only as juveniles and have a broader diet. In addition, some facultative cleaners may experience a relatively higher predation risk, and thus rarely interact with piscivorous fishes. Despite these acknowledged differences, there are very few studies that compare cleaning activity of obligate and facultative cleaners within the same area. Cleaning activity of the obligate cleaner goby Elacatinus cf. randalli and the facultative cleaner wrasse Thalassoma noronhanum were comparatively examined at Fernando de Noronha Archipelago, tropical West Atlantic. The client assemblage attended by the two cleaners differed, as the goby attended a slightly greater diversity of species (22), mostly piscivores and zoobenthivores, and the wrasse attended fewer species (19), mostly planktivores. Chromis multilineata was the most common client species of both cleaners, although body size (which is expected to be positively correlated to clients` ectoparasite load) of C. multilineata individuals attended by the goby was larger than that of the individuals attended by the wrasse. Despite such differences, T. noronhanum showed a surprisingly species-rich client assemblage when compared with other cleaners of the genus Thalassoma. In addition, the frequency and time spent on cleaning interactions, as well as the number of client species attended per 10-min period, was similar for both cleaner species, which indicate that they have important yet complimentary ecological roles in the reef community at Fernando de Noronha Archipelago.

Arginine vasotocin regulation of interspecific cooperative behaviour in a cleaner fish

In an interspecific cooperative context, individuals must be prepared to tolerate close interactive proximity to other species but also need to be able to respond to relevant social stimuli in the most appropriate manner. The neuropeptides vasopressin and oxytocin and their non-mammalian homologues have been implicated in the evolution of sociality and in the regulation of social behaviour across vertebrates. However, little is known about the underlying physiological mechanisms of interspecific cooperative interactions. In interspecific cleaning mutualisms, interactions functionally resemble most intraspecific social interactions. Here we provide the first empirical evidence that arginine vasotocin (AVT), a non-mammalian homologue of arginine vasopressin (AVP), plays a critical role as moderator of interspecific behaviour in the best studied and ubiquitous marine cleaning mutualism involving the Indo-Pacific bluestreak cleaner wrasse Labroides dimidiatus. Exogenous administration of AVT caused a substantial decrease of most interspecific cleaning activities, without similarly affecting the expression of conspecific directed behaviour, which suggests a differential effect of AVT on cleaning behaviour and not a general effect on social behaviour. Furthermore, the AVP-V1a receptor antagonist (manning compound) induced a higher likelihood for cleaners to engage in cleaning interactions and also to increase their levels of dishonesty towards clients. The present findings extend the knowledge of neuropeptide effects on social interactions beyond the study of their influence on conspecific social behaviour. Our evidence demonstrates that AVT pathways might play a pivotal role in the regulation of interspecific cooperative behaviour and conspecific social behaviour among stabilized pairs of cleaner fish. Moreover, our results suggest that the role of AVT as a neurochemical regulator of social behaviour may have been co-opted in the evolution of cooperative behaviour in an interspecific context, a hypothesis that is amenable to further testing on the potential direct central mechanism involved.

Cleaner wrasse prefer client mucus: support for partner control mechanisms in cleaning interactions

Recent studies on cleaning behaviour suggest that there are conflicts between cleaners and their clients over what cleaners eat. The diet of cleaners usually contains ectoparasites and some client tissue. It is unclear, however, whether cleaners prefer client tissue over ectoparasites or whether they include client tissue in their diet only when searching for parasites alone is not profitable. To distinguish between these two hypotheses, we trained cleaner fish Labroides dimidiatus to feed from plates and offered them client mucus from the parrotfish Chlorurus sordidus, parasitic monogenean flat-worms, parasitic gnathiid isopods and boiled flour glue as a control. We found that cleaners ate more mucus and monogeneans than gnathiids, with gnathiids eaten slightly more often than the control substance. Because gnathiids are the most abundant ectoparasites, our results suggest a potential for conflict between cleaners and clients over what the cleaner should eat, and support studies emphasizing the importance of partner control in keeping cleaning interactions mutualistic.

Cleaner fish use tactile dancing behavior as a preconflict management strategy

The most commonly asked question about cooperative interactions is how they are maintained when cheating is theoretically more profitable [1]. In cleaning interactions, where cleaners remove parasites from apparently cooperating clients, the classical question asked is why cleaner fish can clean piscivorous client fish without being eaten, a problem Trivers [2] used to explain reciprocal altruism. Trivers [2] suggested that predators refrain from eating cleaners only when the repeated removal of parasites by a particular cleaner results in a greater benefit than eating the cleaner. Although several theoretical models have examined cheating behavior in clients [3,4], no empirical tests have been done (but see Darcy [5]). It has been observed that cleaners are susceptible to predation [6, 7]. Thus, cleaners should have evolved strategies to avoid conflict or being eaten. In primates, conflicts are often resolved with conflict or preconflict management behavior [8]. Here, I show that cleaner fish tactically stimulate clients while swimming in an oscillating dancing manner (tactile dancing) more when exposed to hungry piscivorous clients than satiated ones, regardless of the client's parasite load. Tactile dancing thus may function as a preconflict management strategy that enables cleaner fish to avoid conflict with potentially dangerous clients.

Cleaner shrimp do clean

Apart from cleaner fish, there are many reports on cleaning by shrimps, yet whether shrimps actually 'clean', i.e. eat parasites in the wild, has not been demonstrated. For the first time, we show that, conclusively, cleaner shrimp in the wild do clean. We found crustacean ectoparasites from the Family Gnathiidae and the Class Copepoda in the gut contents of wild cleaner shrimp, Urocaridella sp. and Periclimenes holthuisi. In addition, they ate parasitic monogenean flatworms, Benedenia sp., offered to them in the laboratory. Finally, P. holthuisi, significantly reduced monogenean, Benedenia sp., loads by 74.5% on captive surgeonfish Ctenochaetus striatus within 48 h. Such large reductions in parasite loads are likely to benefit individual fish. These results emphasise the need for more information on the ecological role of cleaner shrimp on coral reefs.

Cleaner fish become hosts: a novel form of parasite transmission

Adult bucephalid trematodes (Digenea) generally only occur in piscivorous fish. Within labrid fishes they are very rare, however, we have found them in labrid cleaner fish that feed on the ectoparasites of fish. We surveyed 969 labrid fishes from the tropical Pacific and found bucephalids only in cleaners (Lahroides dimidiatus, L. bicolor, and Bodianus axillaris) and none in piscivores. The prevalences of bucephalids in L. dimidiatus at Lizard Island, Heron Island, Orpheus Island (all on the Great Barrier Reef), New Caledonia, and Moorea (French Polynesia) were 51, 47, 67, 56, and 67%, respectively. All of the L. bicolor examined from Moorea were infected. Bucephalids were highly prevalent in all size classes of L. dimidiatus from Lizard Island. Bucephalids were found in a 1.6-cm long juvenile L. dimidiatus, in which, piscivory is highly unlikely. We examined the literature on the worldwide bucephalid fauna in labrids and all hosts were found to be cleaners (Symphodus tinca, S. mediterraneus, L. dimidiatus, L. bicolor, and Bodianus axillaris) except Notolabrus parilus, whose ecology is unknown. We suggest that cleaners eat bucephalid metacercariae directly from the exterior surface of client fish during cleaning interactions. This is the first evidence of digeneans in the diet of L. dimidiatus, and the first study to show this novel form of parasite transmission where infective stages are eaten as a result of cleaning behaviour. Cleaning-mediated parasite transmission may result in behavioural modification of second intermediate hosts because clients and parasites both benefit from transmission. If the infection is costly to cleaners and acquired during cheating behaviour, then this parasite might regulate mutualism. Alternatively, if infective stages are targeted, infection by these bucephalids may be a negative consequence of an honest foraging strategy.

Does client size affect cleaner fish choice of client? An empirical test using client fish models

To determine whether the choice of client fishes in the cleaner fish Labroides dimidiatus was influenced by client size, cleaner fish were given a choice of equal amount of food spread on large and small client redfin butterflyfish Chaetodon trifasciatus models. All large models received bites from cleaners compared to 27% for small models. Seventy-nine per cent of cleaners took their first bite from the large fish model. The results suggest that client size may affect cleaner fish choice.

Image scoring and cooperation in a cleaner fish mutualism

Humans are highly social animals and often help unrelated individuals that may never reciprocate the altruist's favour(1-5). This apparent evolutionary puzzle may be explained by the altruist's gain in social image: image-scoring bystanders, also known as eavesdroppers, notice the altruistic act and therefore are more likely to help the altruist in the future(5-7). Such complex indirect reciprocity based on altruistic acts may evolve only after simple indirect reciprocity has been established, which requires two steps. First, image scoring evolves when bystanders gain personal benefits from information gathered, for example, by finding cooperative partners(8-10). Second, altruistic behaviour in the presence of such bystanders may evolve if altruists benefit from access to the bystanders. Here, we provide experimental evidence for both of the requirements in a cleaning mutualism involving the cleaner fish Labroides dimidiatus. These cleaners may cooperate and remove ectoparasites from clients or they may cheat by feeding on client mucus(11,12). As mucus may be preferred over typical client ectoparasites(13), clients must make cleaners feed against their preference to obtain a cooperative service. We found that eavesdropping clients spent more time next to 'cooperative' than 'unknown cooperative level' cleaners, which shows that clients engage in image-scoring behaviour. Furthermore, trained cleaners learned to feed more cooperatively when in an `image-scoring' than in a 'non-image-scoring' situation.

Emergence rates from the benthos of the parasitic juveniles of gnathiid isopods

Variation in the rate at which parasitic gnathiid isopod juveniles emerged from the benthos at Lizard Island, Great Barrier Reef, Australia, was examined (I) every 4 or 8 h throughout the day and night over a 24 h period, (2) over a 12 h period during the day or night, and (3) during different lunar phases (weeks). The number of gnathiids sampled per 4 or 8 h was low, with only 30% of the traps containing gnathiids and the abundance ranging from 0 to 3 gnathiids m(-2). The number of gnathiids that emerged over 12 h, in contrast, ranged from 0 to 36 m(-2). During the third and fifth weeks sampled, more gnathiids emerged during the day than at night. This coincided with the full moon and new moon. Most gnathiids that emerged from the reef during the day (98 %) had not fed, in contrast to those sampled at night (71%). Of the gnathiids with no engorged gut, most (97 %) of those collected during the day were small (II. mm) compared to those collected at night (19%), the latter being mostly >1 mm. Of the gnathiids with an engorged gut, most were sampled at night (83 %) and 97 % were >1 mm in size. These percentages suggest differences in the emergence behaviour among Life stages or species of gnathiids. This study, which shows that gnathiids do emerge during the day and supports other studies showing that gnathiids also attack fishes during the day, has important implications for understanding the role of cleaner fish and their main food source, gnathiids, as it shows there is a constant source of gnathiids emerging from the reef during the day and night in search of hosts.

Revisão do gênero Euhybus Coquillett (Diptera, Empididae, Hybotinae) da região Neotropical. Grupo dimidiatus

As espécies de Euhybus Coquillett do grupo dimidiatus são revisadas, cinco espécies novas da região amazônica são descritas, E. amazonicus (Santiago, Sierra de Cutucu, Ecuador), Ε. dubius (Parque Nacional do Jaú, Amazonas, Brasil), E. ikedai (Novo Aripuanã, Amazonas, Brasil), E. setulosus (Mocoa, Puntamayo, Colômbia) e E. symmetricus (Parque Nacional do Jaú, Amazonas, Brasil), novos registros geográficos são feitos, novas sinonímias estabelecidas e uma chave para os grupos de espécies de Euhybus é apresentada.

Leishmaniose tegumentar alviericana na Ilha Grande, Rio de Janeiro: III. reservatórios silvestres e comensais

Em 203 animais silvestres e comensais examinados na Praia Vermelha, Ilha Grande, município de Angra dos fíeis, RJ, durante o estudo de um surto de Leishmaniose Tegumentar Americana, foram encontrados 2 exemplares de Proechimys dimidiatus, com lesões hipocrômicas nas extremidades das orelhas, e 1 exemplar de Rattus norvegicus norvegicus, com úlcera de dorso, cuja histopatologia revelou a presença de Leishmania sp. nos 3 exemplares.

Observations on helminth infections of free-living and captive rheas (Rhea americana) in Brazil

The present work describes helminth infection of eight free-living and 12 captive rheas (Rhea americana) from, respectively, Pantanal of Mato Grosso do Sul State, and Jaboticabal, São Paulo State, Brazil. Captive birds were young and had a high mortality rate, while free-living birds were adult and apparently healthy. Infections were evaluated by post-mortem examination of internal organs and recovery of helminths using standard parasitological procedures. Seven species of nematodes (Sicarius uncinipenis, Torquatoides crotophaga, Deletrocephalus dimidiatus, D. cesarpintoi, Paradeletrocephalus minor, Capillaria venteli and Dicheilonema rheae) and two species of cestodes (Houttuynia struthionis and Chapmania tauricolis) were identified. P. minor, which inhabits the large intestine, was the most common helminth in free-living birds (63.9%). In captive rheas, a mean parasitic load of 173 helminths per host was found. The gizzard of these birds was the most parasitized organ and S. uncinipenis was most common (92.5%). Parasitism of free-living and captive birds and associated pathology are discussed. (c) 2005 Published by Elsevier B. V.

Evolutionary chromosomal differentiation among four species of Conoderus Eschscholtz, 1829 (Coleoptera, Elateridae, Agrypninae, Conoderini) detected by standard staining, C-banding, silver nitrate impregnation, and CMA(3)/DA/DAPI staining

The speciose Brazilian Elateridae fauna is characterized by high karyotypic diversity, including one species (Chalcolepidius zonatus Eschscholtz, 1829) with the lowest diploid number within any Coleoptera order. Cytogenetic analysis of Conoderus dimidiatus Germar, 1839, C. scalaris (Germar, 1824,) C. ternarius Germar, 1839, and C. stigmosus Germar, 1839 by standard and differential staining was performed with the aim of establishing mechanisms of karyotypic differentiation in these species. Conoderus dimidiatus, C. scalaris, and C. ternarius have diploid numbers of 2n(male) = 17 and 2n(female) = 18, and a X0/XX sex determination system, similar to that encountered in the majority of Conoderini species. The karyotype of C. stigmosus was characterized by a diploid number of 2n=16 and a neoXY/neoXX sex determination system that was highly differentiated from other species of the genus. Some features of the mitotic and meiotic chromosomes suggest an autosome/ancestral X chromosome fusion as the cause of the neoXY system origin in C. stigmosus. C-banding and silver impregnation techniques showed that the four Conoderus species possess similar chromosomal characteristics to those registered in most Polyphaga species, including pericentromeric C band and autosomal NORs. Triple staining techniques including CMA(3)/DA/DAPI also provided useful information for differentiating these Conoderus species. These techniques revealed unique GC-rich heterochromatin associated with NORs in C. scalaris and C. stigmosus and CMA(3)-heteromorphism in C. scalaris and C. ternarius.

Mecanismos de diferenciação cromossômica em 13 espécies de Elateridae (Coleoptera, polyphaga) estabelecidos através da análise de células mitóticas e meióticas

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