The cyclopoid copepods of a wet campo marsh in central Brazil

Eight species of cyclopoid copepods were recorded from 1979–1983 in the complex microhabitats of a wet campo (campo úmido) marsh in central Brazil. Ectocyclops herbsti and Paracyclops fimbriatus occurred most often in areas with water covering the soil; Muscocyclops therasiae n. sp. occurred mainly in soils with no surface water; while Metacyclops campestris n. sp. showed no distinct microhabitat preference. Occurrence of the remaining four species was too sporadic to determine microhabitat preference. Paracyclops carectum n. sp., Metacyclops campestris n. sp., Muscocyclops therasiae n. sp., Muscocyclops bidentatus n. sp. and Ponticyclops boscoi n. g. n. sp. are described. A key to the New World species of Metacyclops s. str. is provided.     

Giselinidae fam. nov., a new monophyletic group of cyclopoid copepods (Copepoda, Crustacea) from the Atlantic deep sea

Four new species of Cyclopoida from deep-sea waters are described and placed in two new genera: Giselina gen. n. and Sensogiselina gen. n. The new genera and species belong to a new monophyletic group within the cyclopinid cyclopoids. A new name, Giselinidae, is proposed for this monophylum. The new family is characterised by the combination of the following characters: (1) tergite of leg 1 fused to cephalosome dorsally, but incompletely fused laterally, (2) absence of aesthetascs on ancestral antennulary segments XVI, XXI and XXV, (3) absence of antennary exopodal setae, (4) presence of only three spines on distal exopodal segment of leg 1, (5) absence of inner setae on first endopodal segments of legs 1–4, (6) outer terminal and distal inner elements of distal endopodal segment of leg 4 transformed into spines, (7) distal outer element of leg 5 exopod transformed into a spine, (8) leg 6 with only one seta, and (9) furcal setae I and III located on dorsal margin. Received in revised form: 16 June 2000 Electronic Publication     

Species assemblages of cyclopoid Copepoda from Mantecal,Venezuela

A 14 year monitoring of species composition and abundance of cyclopoid copepods throughout the rainy and dry seasons in a flooded savanna at Mantecal, Apure State, Venezuela, is presented. Two characteristic habitats within these water bodies were selected: the open center of small ponds free of emergent vegetation and the surrounding flooded grassland. In total, 13 species were registered, all of which appeared in the flooded grassland and 11 of which occurred in the open water. Ten species were common for the two habitats during the dry season. The highest abundance was found in flooded grassland during the dry season. Eight species showed abundances greater than 1.0 individual per liter in flooded grassland during both seasons; 3 and 7 species were this abundant in the open water during rainy and dry seasons, respectively. Mesocyclops meridianus and Microcyclops varicans were the most abundant species in both habitats and seasons, while Thermocyclops decipiens was the dominant species during rainy season in open water. Principal component analysis indicates that the important species were positively correlated between them (sharing habitat and season).     

A laboratory evaluation of the microsporidian Vavraia culicis as an agent for mosquito control

The susceptibility of the mosquitoes Aedes aegypti, Aedes taeniorhynchus, Anopheles albimanus, Culex pipiens quinquefasciatus, Culex salinarius, and Culex tarsalis to infection by the microsporidian Vavraia culicis was determined. Using 18-hr exposures to 5 × 10³, 1 × 10⁴, 5 × 10⁴, and 1 × 10⁵ spores/ml, C. salinarius, C. tarsalis, and A. albimanus were found to be significantly more susceptible than A. aegypti. The most severe infections were observed in C. salinarius and C. tarsalis, although heavy infections of approximately 1 million spores per adult were recorded at the higher dosages in all species tested except A. aegypti. Production trials indicated that up to 5.4 × 10⁸ spores could be routinely produced in individual corn earworms, Heliothis zea. Inactivation of the spores by sunlight was measured by observing the subsequent incidence of infection and spore production in A. albimanus. These two measurements provided an LT₉₀ of 5.5 and 3.3 hr, respectively.     

Origin and evolution of the parasitic cyclopoid copepods

Six of the 10 recognised families of the order Cyclopoida are parasitic, with 4 of them occurring on marine invertebrates and the remaining 2 on freshwater gastropods and fishes, respectively. A cladistic analysis of the 10 families indicates that evolution of parasitism occurred twice in the history of the cyclopoids. The first attempt was made by the marine epibenthic ancestors seeking food and shelter in sessile tunicates — the ascidians. This event led to the evolution of 2 ascidicolous families: Archinotodelphyidae and Notodelphyidae. The descendant of this lineage had also invaded the mantle cavity of marine bivalve molluscs, eventually leading to the evolution of the Mantridae. The second attempt for the parasitic mode of life was launched by the ancestor which was the sister group of the ancestral cyclopoids — the most successful family of freshwater copepods. This ancestral stock, while living in the coastal zone, split into 2 groups: one group stayed behind in the ocean and colonised again the ascidians; the other groups invaded freshwater and evolved into the fish-parasitising Lernaeidae and the gastropod-parasitising Ozmanidae.     

In vitro production of zoospores by the mosquito pathogen Lagenidium giganteum (Oomycetes: Lagenidiales) on solid media

Reliable, large-scale production of Lagenidium giganteum zoospores was obtained on solid media. The fungus was grown for 7 days in a liquid medium of wheat germ, hemp seed, yeast extract, and glucose, then placed onto hemp-seed agar. Zoosporogenesis was induced on agar by immersing the fungal cultures into water. Zoospore production began 10 hr postimmersion, peaked at 18 hr, and ceased by 36 hr. A single, 10-cm Petri dish of fungus on hemp-seed agar produced 1.7?3.8 × 10⁷ zoospores during the 26 hr of zoosporogenesis. Optimal zoospore production occurred with 4- to 7-day-old cultures; cultures older than 10 days produced few zoospores. The temperature range for zoosporogenesis was 15–35°C. The extent of zoosporogenesis was directly related to the volume of water used to induce zoospore formation and inversely proportional to agar thickness. Bioassay of zoospores against second instar Culex quinquefasciatus larvae yielded an LD₅₀ of 400 zoospores/ml.     

Implications of guppy (Poecilia reticulata) life‐history phenotype for mosquito control

Guppies (Poecilia reticulata) are frequently introduced to both natural and artificial water bodies as a mosquito control. Laboratory studies have demonstrated that guppies can consume large numbers of larval mosquitoes. Our study investigates how intraspecific variability in guppy phenotype affects their importance as a mosquito biocontrol and how habitat conditions (natural ponds vs. water storage containers) may influence insect biomass and guppy feeding. Using a blocked experimental design, we established stream‐side mesocosm ponds with half receiving gravel substrate to simulate pond‐bottom habitat. To provide realistic diet choices and insect abundances, we allowed the mesocosms to colonize naturally with aquatic insect larvae for 1 month before introducing guppies. We tested two distinct guppy phenotypes (from high‐ and low‐predation streams) alongside fish‐free controls. After 1 month, we measured insect biomass in the mesocosms and examined guppy gut contents to document direct predation. While overall insect biomass was not significantly different across the three fish treatments, we observed a significant reduction in mosquito biomass in fish treatments compared to fish‐free controls, as well as intraspecific differences in feeding. Overall insect biomass was significantly higher in mesocosms without gravel, while habitat condition had no effect on mosquito biomass. As guppy phenotype responds to changes in their environments, it is an important consideration for biocontrol policy to anticipate potential ecosystem effects. We close by relating our findings to other studies and by discussing the implications and potential risks of using guppies to control mosquitoes.     

Field evaluation of Tilapia zilli (Gervais) as a biological control agent for mosquito control

Tilapia zilli (Gervais), a larvivorous fish identified in the Mwea Rice Irrigation System (Kenya), was evaluated in the field to assess its potential for biological control of mosquito larvae. The study was conducted from October 1991 to April 1992 in experimental ponds constructed at Mbui-Njeru, which is one of the 36 villages in the irrigation scheme. T. zilli was found to be extremely effective in controlling mosquito breeding that persisted throughout the study period. However, the presence of vegetation and turbidity significantly reduced its efficiency in predation. The negative effects of vegetation could be averted by combining T. zilli with an herbivorous fish to control weeds. Similarly, breeding of other larvivorous organisms, including frogs, should be encouraged to enhance mosquito control efficiency. It is suggested that positive measures should be taken to deter colonization of catfish whose presence aggravates the turbidity problem and also depletes the fish population due to its substrate feeding and carnivorous behaviour.     

雌蚊翅振音及其在蚊虫防治中的应用

蚊虫飞翔时 ,翅上下拍打会形成连续的翅振音。雌蚊翅振音频率会随蚊种、蚊体长和日龄及环境温度而变化 ,一般在 3 0 0～ 5 0 0Hz之间。同种个体间翅振音频率变化较小 ,常在平均频率± 5 0Hz范围内。雄蚊只对基本频率的雌蚊翅振音起反应 ,雌蚊翅振音的偶然变化不会降低其对雄蚊的引诱力。雄蚊对雌蚊翅振音具有敏感反应的主要原因是其听觉器官对雌蚊翅振音形成了良好的适应性。因此 ,许多蚊虫研究者希望利用雌蚊翅振音来防治蚊虫。因该方法对环境安全 ,在今后蚊虫防治中其重要性将会日益显现。     

Comparison of the predation rate of freshwater cyclopoid copepod species on larvae of the mosquito Culex pipiens

The predation rates of six copepod species: Acanthocyclops robustus G.O. Sars, Eucyclops neumani Pesta, Macrocyclops albidus Jurine, Mesocyclops longisetus Thibaud, Metacyclops grandis Kiefer and Metacyclops mendocinus Wierzejski (Copepoda: Cyclopidae) on mosquito larvae, Culex pipiens Linnaeus (Diptera: Culicidae) were assessed. Experiments consisted of 24-h incubations of one copepod and 10 larvae without extra food at 16 degrees C and 26 degrees C. Nine replicates were considered for each species and temperature. Predation rates (larvae per copepod per day) were: M. mendocinus (1.8), M. grandis (3.1), E. neumani (3.8), A. robustus (3.8), Ma. albidus (6.1) and Me. longisetus (7.0). There was a significant effect of both species and temperature on predation: all species experienced higher predation at 26 degrees C than at 16 degrees C, except for A. robustus whose predation rate was similar at both temperatures. These observations are consistent with previous results that point to Macrocyclops and Mesocyclops genera as important larval predators and suggest the need for field trials to evaluate the response of Ma. albidus and Me. longisetus under natural conditions in Uruguay.     

Two new genera of cyclopinid copepods (Crustacea) from anchihaline caves on western Mediterranean and eastern Atlantic islands

Troglocyclopina balearica gen nov. ap. nov. and Muceddina multispinosa gen nov. sp. nov. are described from the flooded coastal karst of the Balearic Islands, and from caves on Sardinia, the Balearics, and Lanzarote (Canaries), respectively. Both taxa seem to prefer anchihaline habitats with water salinities in excess of 18%, although Troglocyclopina has also been found in more reduced salinity cave lakes located some distance from the coast. These new taxa are the first cyclopinids to be reported from caves, all previous citations of cyclopinids from hypogean environments relate only to the marine interstitial. The small clutch-size exhibited by Troglocyclopina balearica (two eggs per sac) and the absence of the exopodal seta on the antenna at Muceddina multispinosa are interpreted as troglomorphic features, in addition to the absence of the nauplius eye and the lack of body pigmentation in both taxa. The derivation of both taxa from shallow-water, hyperbenthic marine ancestors is proposed.     

The freeliving freshwater cyclopoid copepoda (crustacea) of Malaysia and Singapore

A study of freeliving freshwater Cyclopoida of Malaysia and Singapore yielded 15 species. Some remarks are made on the morphology including a species belonging to the schmeili group of Thermocyclops. Shallow and vegetation-bearing habitats had the largest numbers of species. Most of the species are cosmopolitan. The three common species, Mesocyclops leuckarti, Thermocyclops crassus and Microcyclops varicans are eurytopic. M. leuckarti and T. crassus are the only species occurring commonly in limnetic situations in contrast to a much wider limnetic Cyclopoida species spectrum in temperate lakes. There appears to be a reduction in Cyclopoida from temperate to tropical latitudes, but the data on which this are based are at present fragmentary.     

Comparative evaluation of the larvivorous fish Gambusia affinis and Aphanius dispar as mosquito control agents

Under laboratory conditions Aphanius was more successful than Gambusia in preying upon the 3rd, 4th and pupal stages of mosquitoes. The reverse was found for the first two instars. However. Aphanius consumed more 2nd instar larvae under the cover of vegetation when larger fish were able to penetrate shallow water and feed on the mosquito larvae.The two species showed a similar prey-size selection except for Aphanius of the medium size (31–35 mm) which ate larger larvae than Gambusia of the same size range.When provided access to the surface, neither fish species showed any adverse effect at oxygen levels as low as 0.5 mg l^-1 (6% saturation). When denied access to the surface, both species behaved normally at oxygen levels as low as 1.3 mg l^-1 (15% saturation).This study suggests that Gambusia affinis and Aphanius dispar can complement each other as mosquito control agents in different habitat conditions. We suggest that in mosquito infested situation which are characterized by high organic matter and low oxygen levels biological control could best be achieved by introduction of a range of sizes of both fish species. Repeated introductions of the fish, in large enough numbers, may be required for ad-hoc alleviation of a mosquito problem. Best results are thus to be expected in relatively small water bodies such as oxidation ponds.     

食蚊鱼昼夜摄食节律观察

以分时段采样法研究入侵物种食蚊鱼的夏季昼夜摄食节律。食蚊鱼夏季种群内有雌鱼、雄鱼和幼鱼三个不同的摄食类群,这三个类群的摄食节律差异明显。雌鱼摄食节律成双峰型,第一高峰在10:00,而最高峰在22:00,此时肠道食物团平均重量11.70±11.60mg,饱满指数为190.22±155.61。幼鱼也成双峰型,分别在6:00和18:00有两个摄食高峰,以清晨6:00为最高,肠道食物团平均重1.08±1.09mg,饱满指数为128.44±105.49。雄鱼则成单峰型,摄食高峰出现午后14:00左右,肠道食物团平均重0.71±0.96mg,饱满指数为71.80±107.65。食蚊鱼不同摄食类群间的摄食高峰交错出现,是其协调种内关系,降低种内竞争的一种有效行为机制。     

Predation on the invasive mosquito Aedes japonicus (Diptera: Culicidae) by native copepod species in Germany

Some limnic copepod species are predators of mosquito larvae. Seven species belonging to the order Cyclopoida, family Cyclopidae, were collected in the field in Germany and tested for the first time in laboratory bioassays for their potential to serve as biological control agents of the invasive Asian bush mosquito Aedes japonicus (Theobald), a vector of various pathogens causing disease. Females of Diacyclops bicuspidatus (Claus) did not attack 1^st instar larvae of Ae. japonicus, but Macrocyclops distinctus (Richard), Cyclops divergens Lindberg, and C. heberti Einsle predated a mean of 14, 18, or 19 1^st instar larvae, respectively. Acanthocyclops einslei Mirabdullayev and Defaye killed 30 larvae, and high predation rates with a mean of 39 or 46 larvae, respectively, were obtained by Megacyclops viridis (Jurine) and M. gigas (Claus). In regression analyses, predation rates by M. viridis correlated with body size, with specimens of 1.8 mm length being more effective than smaller or bigger ones. Based on the presented data, the two Megacyclops species seem to be promising candidates for use in field studies on the biological control of Ae. japonicus.     

Habitat modification for mosquito control in the Ilparpa Swamp, Northern Territory, Australia

Habitat modification is an established method of effective long-term mosquito management, particularly in salt-marsh environments. It is especially pertinent when mosquitoes are known vectors of life-threatening disease and their larval breeding habitat is in close proximity to residential areas. The Ilparpa Swamp is located less than 10 km from Alice Springs, Northern Territory. Wet season rainfall, often followed by effluent discharges to the swamp from the adjacent sewage treatment plant, create ideal sites for the immature stages of the common banded mosquito Culex annulirostris (Skuse), a major vector of Murray Valley encephalitis (MVEV) and Kunjin (KUNV) viruses. Subsequent to increases in notifications of MVEV disease cases in 2000 and 2001, a drainage system was established in the Ilparpa Swamp in early 2002. This paper evaluates the drainage intervention effects. Results indicate a significant reduction in mosquito numbers following habitat modification, which remain low. There have been no seroconversions in sentinel chickens to MVEV or KUNV and no human infections from these viruses in the Alice Springs urban region since the drains were completed. Habitat modification has successfully reduced mosquito numbers and minimized the risk for mosquito-borne disease to residents in Alice Springs urban and surrounding areas, which has never before been documented in Australia.     

Evaluating perceptions of risk in mosquito experts and identifying undocumented pathways for the introduction of invasive mosquito species into Europe

In several reported cases of the entry of invasive mosquito species (IMSs) into Europe, the introduction was associated with a specific pathway of introduction or dispersal. The identification of potential pathways for the introduction of IMSs and evaluations of the importance of the different pathways are key to designing proper surveillance strategies to promptly detect and control introductions in non‐infested areas. The main goals of the present study were to identify other, previously undocumented, pathways of introduction into Europe, and to identify mosquito experts' perceptions regarding control measures against IMS introductions via different documented pathways. At the European Mosquito Control Association (EMCA) conference in Montenegro in March 2017, a questionnaire was distributed among meeting participants to collect expert data. Results showed that ground transportation (by cars, trucks, etc.), passive natural dispersal and the shipping of used tyres are perceived as the most likely pathways. Introduction via aircraft did not appear to be well known and was not perceived as probable. This study shows that there were no pathways unknown to European experts that could lead to cryptic introductions into the experts' countries. Furthermore, the findings demonstrated that the perceived efficacy of surveillance and control is key to overcoming the constraints experienced and to supporting the implementation of actions against introductions.