Evaluation of Mesocyclops annulatus (Copepoda: Cyclopoidea) as a control agent of Aedes aegypti (Diptera: Culicidae) in Argentina

We evaluated the potential of Mesocyclops annulatus as a control agent of Aedes aegypti in La Plata city (Argentina). Mosquito larval survivorship due to predation by these copepods was estimated at weekly intervals during the oviposition period of A. aegypti. Mean weekly A. aegypti larval survivorship in cylindrical plastic containers (12 cm height and 11 cm diameter) with copepods was significantly lower than in control containers. Furthermore, weekly larval survival was negatively correlated with M. annulatus adult density, and approximately 23 adult copepods/container would be a threshold density over which the weekly mosquito larval survivorship approached zero. The copepods were able to persist in all containers during approximately 100 days (in three of them until the end of the experiment: 155 days) without the resource represented by A. aegypti larvae. The predation and persistence observed suggest that M. annulatus is a potential control agent to be considered in biological control programs.     

Sur quelques Mesocyclops (Crustacea,Copepoda)

Resumé Après un rappel des critères morphologiques qu'il faut considérer en taxonomie des Copépodes du genre Mesocyclops, 14 espèces de ce genre sont décrites our redécrites, à savoir: M. granulatus nov.sp., M. thermocyclopoides, M. isabellae nov.sp., M. Kieferi, M. pehpeiensis, M. ogunnus, M. splendidus, M. brevisetosus, M. borneoensis nov.sp., M. tobae, M. pseudospinosus nov.sp., M. darwini nov.sp., M. notius, et M. australiensis, toutes formes des régions tropicales de l'Asie méridionale ou de l'Australasie.     

A new Oriental species of Mesocyclops (Copepoda: Cyclopidae)

Mesocyclops ferjemurami sp. nov. is described from Central Vietnam, North India and Sri Lanka. It differs from all congeners in having a unique spinule ornamentation on the caudal surface of the antennary basipodite: the `leuckarti-type' spinule pattern is supplemented with a group of spinules at the height of implantation of the medial setae, and proximal to this group a triangular spinule field occurs, the longest side of which runs more or less parallel to the oblique row of tiny spinules starting at distal half of the medial rim. It is suggested that Mesocyclops ferjemurami is closely related to Mesocyclops pehpeiensis Hu, 1943 and Mesocyclops papuensis Van de Velde, 1987.     

Epizootiological studies of Amblyospora albifasciati (Microsporidiida: Amblyosporidae) in natural populations of Aedes albifasciatus (Diptera: Culicidae) and Mesocyclops annulatus (Copepoda: Cyclopidae) in a transient floodwater habitat

The epizootiology of the microsporidium Amblyospora albifasciati was studied in natural populations of its definitive host, a multivoltine, neotropical, floodwater mosquito, Aedes albifasciatus, and its intermediate copepod host, Mesocyclops annulatus, in an ephemeral floodwater habitat during a 12-month period. A. albifasciati was enzootic in mosquitoes. Vertically (transovarially) transmitted meiospore infections occurred regularly and were detected in five of eight larval broods but the prevalence of infection was always low, ranging from 0.5 to 6.9% with an overall average of 0.7%. Horizontal transmission of A. albifasciati infection from copepods to mosquitoes was nominal and limited. It was detected at levels of 6.4 to 20% in larval Ae. albifasciatus populations on two occasions, the month of August and late September through early October. The low levels of horizontal transmission of infection to mosquito larvae appeared to be the principal limiting factor that prevented the proliferation of A. albifasciati in Ae. albifasciatus populations. Copepod populations were abundant from May through September and weekly prevalence rates of A. albifasciati averaged over 50% (range = 5.8 to 100%). The moderately high infection rates in M. annulatus copepods were inconsistent with the low prevalence of meiospore infection in Ae. albifasciatus mosquito larvae. Results suggest that either meiospores of A. albifasciati produced in the mosquito host are highly infectious to copepods or they are long-lived and remain viable within the pool as long as some standing water is present. Observations further indicate that A. albifasciati has a significant detrimental impact on M. annulatus copepod populations but minimal impact on larval populations of Ae. albifasciatus at this site.     

Phylogeny of Mesocyclops (Copepoda: Cyclopidae) inferred from morphological characters

Evolutionary relationships were investigated in the genus Mesocyclops, a pantropical freshwater cyclopid group. In the phylogenetic analyses that involved all 71 known species, and used 81 morphological characters (265 character states) mainly of the adult females, two different approaches were applied: global parsimony, and a new distance method based upon the recognition of sister‐groups on the basis of minimal distances iteratively corrected for unique character states (MICSEQ). In coding of the characters, half of which showed intraspecific variation, the ‘scaled’ method was employed, which assumes that any trait between its absence and fixed presence passes through a polymorphic stage. Impact of the reference points on topology of the trees generated by the parsimony method was tested in three ways where the outgroups comprised: (1) nine species representing six genera of two subfamilies; (2) three species from two genera supposedly not distant from Mesocyclops; and (3) one presumably close and one distant relative of Mesocyclops. The trees generated by the parsimony‐based and corrected distance methods agreed as to the monophyly of the following groups: reidae‐clade (M. reidae, M. chaci, M. yutsil); rarus‐clade (Mesocyclops annae, M. pseudoannae, M. splendidus, M. rarus, M. paludosus, M. darwini, M. dayakorum); annulatus‐clade (Mesocyclops intermedius, M. ellipticus, M. paranaensis, M. annulatus, M. tenuisaccus); meridianus‐clade (Mesocyclops meridionalis, M. varius, M. venezolanus, M. brasilianus, M. pseudomeridianus, M. meridianus); major‐clade (Mesocyclops major, M. pilosus, M. insulensis); dussarti‐clade (M. dussarti, M. dadayi, M. isabellae, M. thermocyclopoides); pubiventris‐clade (M. pubiventris, M. medialis, M. brooksi, M. notius). A majority of the analyses support a clade of the ‘true’Mesocyclops including all ingroup species except the reidae‐group, and point to monophyly of the Old World species lacking medial spine on P1 basipodite. There were, however, some components for which the two procedures, regardless of the outgroup choice and/or character set, suggested different relationships. Basal relationships of Mesocyclops[between M. edax (North and Central America), the Neotropical species (M. longisetus, M. araucanus, M. evadomingoi, meridianus‐ and annulatus‐clade), Old World group (P1 basipodite without medial spine) and the rarus‐clade (Old World; P1 basipodite with medial spine)] remained unresolved. © 2006 The Linnean Society of London, Zoological Journal of the Linnean Society, 2006, 147 , 1–70.     

Redescription of Mesocyclops aspericornis (Daday, 1906) (Copepoda: Cyclopoida) from an Indian pond

The morphology of a cyclopoid copepod, Mesocyclops aspericornis(Daday, 1906), from a tropical pond is redescribed in detail.This species is clearly distinguished from Mesocyclops leuckarti.New diagnostic characters, such as the distribution of featheredand non-feathered outgrowths on the antennule, the presenceof aesthetascs in both genders, circular groups of spinulesalong the dorsal and ventral surface of caudal rami, a groupof 14 spinules on the coxa of P2 and P3 and eight spinules onP1 and P4, are described. In the case of males, a stouter firstendopodite segment of the antennae and an upwardly bent spineon the first exopodite segment of P2 and spinules on the genitalsegment are described for the first time. The taxonomy of M.aspericornis is discussed.     

On Neodiaptomus schmackeri (Poppe & Richard, 1892) (Crustacea,Copepoda)

Neodiaptomus schmackeri and related species are redescribed. The synonymy of this species with N. strigilipes and N. handeli is discussed.     

Carnivorous and detritivorous feeding of Mesocyclops leuckarti Claus (Cyclopoida Copepoda)

Food preference of M. leuckarti was experimentally analysed in relation to different species of live and dead crustaceans. Also their possibility of using detritus from bottom sediments as a source of food was tested.It has been found that M. leuckarti readily feed on dead organisms, and detritus from bottom sediments is sufficient for their survival.On the basis of experimental results the feeding strategy of M. leuckarti in lakes is discussed. It seems that the availability of different species of live prey depends on the mode of their swimming and on their body cover, while the availability of dead prey depends only on the body cover. Detritus may be an important source of food, particularly when the live prey are scarce in the pelagic zone, or not easily available.     

Revision of the African species of the genus Mesocyclops Sars, 1914 (Copepoda: Cyclopidae)

A revision is made of the African Mesocyclops species, based on type material (when extant) and on collections from various parts in Africa.Diagnostic characteristics are: presence or absence of spinule patterns on antennular segments, structure of the hyaline membrane of the 17th antennular segment, spine pattern on the basipodite of the antenna, armature of the maxillulary palp, presence or absence of a spine on the basipodite of P₁, armature of the connecting lamella, coxopodite and basipodite of P₄, armature of the apical spines of Enp₃P₄, armature of the last thoracic segment, genital segment and the other abdominal segments, armature of the furcal rami and structure of the receptaculum seminis.First, the taxonomical status of M. leuckarti (Claus) is redefined; this species does not occur in Africa and its geographical range is restricted to Europe and the western part of Northern Asia. On the African continent, twelve other taxa are found. Four are described as new to science: M. kieferi sp.n., M. dussarti sp.n., M. spinosus sp.n. and M. aequatorialis similis subsp.n. The remainder are: M. major Sars, M. tenuisaccus (Sars), M. paludosus Lindberg, M. salinus Onabamiro, M. ogunnus Onabamiro, M. aspericornis (Daday), M. rarus Kiefer and M. aequatorialis aequatorialis (Kiefer).Their geographical distribution is discussed. Eleven taxa are restricted to the African continent (including the Arabian Peninsula and the Canary Islands). One taxon is also found in the Oriental Region. Madagascan representatives are briefly mentioned.The importance of breeding and cross-breeding experiments should be stressed in copepod taxonomy. Experiments were performed on African species and M. leuckarti to evaluate the morphological characters used in the present study, and intraspecific morphological variability was examined up to and including the third generation (Van de Velde, in press).In future one should critically reconsider the so-called cosmopolitan species; they may indeed represent a complex of related taxa, each with a geographical range more restricted than that of the species-complex itself.Abstracted from the author's Ph.D. thesis, State University of Ghent, 1982.Abstracted from the author's Ph.D. thesis, State University of Ghent, 1982.     

Morfologia y taxonomia de los Mesocyclops (Crustacea: Copepoda: Cyclopoida) de Mexico

A fundamental review of all species and subspecies of Mesocyclopsencountered in the territory of Mexico, a biogeographical transitionzone where the Neotropical Region bounds the Nearctic Regionin the south. The book begins with a sketch of the history of     

Life history traits of the tropical freshwater copepod Mesocyclops longisetus (Crustacea: Copepoda)

The life history traits of a tropical copepod population of Mesocyclops longisetus were measured in the laboratory under defined and controlled culture conditions. Egg duration times at 25 and 30 °C were 42.1 and 29.6 hours, respectively. Development times from nauplius I to adult females and males were 22.3 and 18.3 days, respectively. Body sizes (cephalothorax length) of adult females and males were 1.00 and 0.60 mm, respectively. Clutch size averaged 70.2 eggs. Comparison of these traits with those of its congeners reveals considerable life history variation in the genus Mesocyclops. Lipid analyses of early stage eggs showed that the percent composition of triglycerides to total lipid in M. longisetus (22%) is similar to that of Mesocyclops edax (17%) and daphniid cladocerans, but only half that of a marine calanoid copepod. We suggest that zooplankton may adapt to different resource environments by either adjusting their egg size or altering the proportion of lipid that is readily available for metabolic energy of embryos and nauplii. The diverse arrays of zooplankton life histories may be explained in part by adaptations in lipid metabolism in response to the level and predictability of resources.     

Experimental and Field Studies of Mesocyclops notius (Copepoda: Cyclopoida) from a Subtropical Chinese Lake, Lake Donghu

This paper reports experimental and field studies on the cyclopoidMesocyclops notius from subtropical Lake Donghu close to theYangtze river. Mesocyclops notius, a dominant crustacean zooplankterthroughout tropical Australia, was previously considered tobe endemic to Australia, but recently, Mesocyclops leuckartiin Lake Donghu was re-identified as M. notius. Laboratory cultureexperiments were conducted to reveal the effect of temperature(15, 20, 25 and 30°C) on the development, growth and reproductionof M. notius. Temperature was inversely related to developmenttimes of eggs, nauplii and copepodites, body length and physiologicallongevity of adults, and brood size. Body length and physiologicallongevity of females were greater than those of males at thesame temperature. No reproduction took place at 15°C. Productionand seasonal cycles of M. notius during 1980–1982 werestudied at two sampling stations of Lake Donghu. At the mid-lakestation, the annual production and production/biomass (P/B)ratio of M. notius varied between 6.0 and18.0 g dry wt m^–2year^–1 and 74.6 and 95.5, respectively. Mesocyclops notiusreached their highest density peaks in the warm months (July–October),with a maximum density of 1256 individuals l^–1 at a littoralsite. No reproduction and recruitment by M. notius took placeduring the cold months (December–March) when the temperatureof the lake water was <15°C. Mesocyclops notius weremore abundant at a littoral station than at a pelagic station,possibly due to different food availability. The higher male:femalesex ratio of M. notius at the littoral station was most likelycaused by size-selective fish predation on larger females.     

Mesocyclops dissimilis n. sp. from Lake Biwa,Japan (Copepoda,Cyclopoida)

The status of the Mesocyclops from lake Biwa is reexamined and a new species, Mesocyclops dissimilis n. sp., distinct from M. thermocyclopoides Harada, 1931, is described.     

Revision of the Genus Mesocyclops Sars 1914 (Copepoda,Cyclopidae) of the World Fauna

Biology Bulletin - The genus Mesocyclops Sars 1914, which has hitherto contained too many nominal species, is divided into four subgenera based on the morphological and habitat characteristics. The...     

Redescription of Mesocyclops leuckarti (Copepoda,Cyclopoida), Including a Study of its Naupliar Development

The female and male of Mesocyclops leuckarti (CLAUS , 1857) from a European population are redescribed in detail. New diagnostic characters are described which have passed unnoticed so far. All six naupliar stages of this species are studied as well. Characters of the adult and naupliar external morphology are discussed with respect to previous studies.     

中国中剑水蚤属种类记述

记录了目前分布在中国的中剑水蚤属共计10个种：刘氏中剑水蚤Mesocyclops leuckarti（Claus,1857）、温中剑水蚤M．thermocyclopoides Harada,1931、特异中剑水蚤M．dissimilis Defaye＆Kawabata,1993、北碚中剑水蚤M．pehpeiensis Hu,1943、奥贡中剑水蚤M.ogunnus Onabamiro,1957、邬氏中剑水蚤M．woutersi Van de Velde,1987、糙角中剑水蚤M．aspericornis（Daday,1906）、玛丽中剑水蚤M．mariae Guo,2000、深圳中剑水蚤M．shenzhenensis Guo,2000、蒙古中剑水蚤M．mongoliensis Kiefer,1981。对每一种的主要形态特征和地理分布分别做了详尽描述,给出了如何鉴定这10个种的检索表。同时还讨论和更正了过去一些学者对分布在中国的中剑水蚤属个别种诸如同物异名或同名异物的错误。     

Laboratory and field studies of Macrocyclops albidus (Crustacea: Copepoda) for biological control of mosquitoes in artificial containers in a subtropical environment.

The cyclopoid copepod Macrocyclops albidus (Jurine) was tested as a potential biological control agent of mosquitoes in laboratory microcosms, in controlled field conditions, and in a 22-mo field experiment using discarded tires. The predator was highly efficient in controlling mosquitoes in all three settings, reaching close to 90% reduction in larval survival under field conditions and exceeding the recommended predation rates for effective mosquito control in laboratory experiments. The predator was most effective on 1-4-d-old larvae. Alternate food and habitat structure significantly influenced the predation rates on mosquito larvae. Once established, the copepod was able to maintain reproducing populations in the field for the duration of the experiments. However, the predator failed to establish populations at four of the experimental field sites. Two of the failures can be attributed to characteristics of the individual tires, such as leaching chemicals, whereas the other two were probably due to site-specific factors. This copepod species is a promising candidate for control of mosquito larvae because it is a widespread and highly effective predator that is capable of establishing and maintaining populations under a wide variety of field conditions. Additionally, M. albidus is relatively easy to culture, maintain, and deliver to the target areas.