Food spectrum of the deepwater squid Moroteuthis ingens (Cephalopoda: Onychoteuthidae) in New Zealand waters

Prey species of the deepwater squid Moroteuthis ingens were examined for 37 large specimens captured in New Zealand waters. Caecum contents were predominantly less than 80% full and covered a range of digestion stages. The diet consisted of fish (at least seven species, of which four were myctophids) and squid. The most abundant prey was the myctophid Lampanyctodes hectoris, which was represented by 1323 otoliths from 22 caeca. The second most abundant prey was viperfish (Chauliodus sloani) and/or dragonfish (Stomias boa), represented by 537 otoliths from 17 caeca. Individual squid appeared to ingest surprisingly large numbers of fish (up to 100) during a single feeding period and could achieve feeding rates greater than 10% of their body weight per day. While some males appeared to ingest larger numbers of L. hectoris, females targeted significantly larger individuals of L. hectoris thereby ingesting a greater biomass of fish. Received: 31 July 1997 / Accepted: 15 January 1998     

A standard photomap of ovarian nurse cell chromosomes in the European malaria vector Anopheles atroparvus

Anopheles atroparvus (Diptera: Culicidae) is one of the main malaria vectors of the Maculipennis group in Europe. Cytogenetic analysis based on salivary gland chromosomes has been used in taxonomic and population genetic studies of mosquitoes from this group. However, a high‐resolution cytogenetic map that could be used in physical genome mapping in An. atroparvus is still lacking. In the present study, a high‐quality photomap of the polytene chromosomes from ovarian nurse cells of An. atroparvus was developed. Using fluorescent in situ hybridization, 10 genes from the five largest genomic supercontigs on the polytene chromosome were localized and 28% of the genome was anchored to the cytogenetic map. The study established chromosome arm homology between An. atroparvus and the major African malaria vector Anopheles gambiae, suggesting a whole‐arm translocation between autosomes of these two species. The standard photomap constructed for ovarian nurse cell chromosomes of An. atroparvus will be useful for routine physical mapping. This map will assist in the development of a fine‐scale chromosome‐based genome assembly for this species and will also facilitate comparative and evolutionary genomics studies in the genus Anopheles.     

The mosquito Anopheles (Cellia) oreios sp. n., formerly species 6 of the Australasian Anopheles farauti complex,and a critical review of its biology and relation to disease

Species 6 of the Australasian Anopheles farauti sibling species complex (Diptera: Culicidae) is described and formally named Anopheles oreios Bangs & Harbach, sp. n. Adult, pupal and fourth‐instar larval specimens collected in the Baliem Valley, Papua Province, Indonesia, are characterized and compared with those of Anopheles farauti, Anopheles hinesorum, Anopheles irenicus and Anopheles torresiensis (formerly informally denoted as species 1, 2, 7 and 3, respectively). The variable wings of adult females, the male genitalia, the pupa and the fourth‐instar larva of An. oreios are illustrated and DNA sequence data are included for regions coding for sections of the mitochondrial COI and COII genes. The biology of An. oreios and its relation to malaria transmission are discussed in detail and contrasted with the biology and disease relations of some members of the An. farauti and Anopheles punctulatus sibling species complexes.     

Spatio-temporal variability of ichthyoplankton and its relationship with oceanographic conditions at the shelf break off Chilean Patagonia (43°S–51°S)

Larval fish composition and abundance have been studied in fjords of south Patagonia. However, the ichthyoplankton of the adjacent shelf and slope waters of the Pacific Ocean, which is an important spawning and nursery ground for demersal fishery species (e.g. austral hake and Patagonian grenadier), remains largely unknown. To compare ichthyoplankton occurrence with environmental conditions in August 2013 and 2014 (austral winter), two bio-oceanographic cruises were carried out between 43° and 51°S. Conductivity, temperature and depth (CTD) data and ichthyoplankton samples were collected. The highest frequency of occurrence (FO) was observed for eggs of lightfish Maurolicus parvipinnis (84 and 91% FO in 2013 and 2014, respectively) and larvae of the myctophid Lampanyctodes hectoris (60 and 94% FO, respectively). Ichthyoplankton composition and abundance varied significantly between years, and richness varied from 10 (2013) to 18 taxa (2014). Only larval L. hectoris showed a significant increase in abundance during the winter of 2014. Water column temperature and salinity were significantly different between years; the water was warmer and saltier in 2013. Canonical Correspondence Analysis detected positive relationships between temperature and salinity with egg abundance and larval distribution of Merluccius australis. The highest abundance of eggs of M. australis was found at ～6–10°C, mainly off south Guafo Island. Additionally, ichthyoplankton from the shelf-break area off south Patagonia showed a wider latitudinal distribution in the winter of 2014 than in 2013.     

The selection of resting positions by Anopheles gambiae and Culex pipiens fatigans and the function of the metathoracic legs

Anopheles gambiae were shown to prefer a rough textured to a more smooth textured surface, but this preference was lost after amputation of the metathoracic legs. Culex pipiens fatigans showed no preference for rough or smooth textured surface either when intact or after amputation of metathoracic legs. It is suggested that leg-waving, on landing, which is shown by Anopheles gambiae, but not Culex pipiens is used to determine the texture of the substrate.

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zusammenfassung Im Sudan findet man Anopheles gambiae oft in Nomadenzelten an den rauhen Flächen aus Ziegenwolle. Culex pipiens fatigans sitzt dagegen bevorzugt in Häusern an den Wänden. In einem Wahlexperiment wurde gezeigt, daß Anopheles gambiae einer grobstrukturierten Oberfläche gegenüber einer glatten den Vorzug gab. Amputation der Hinterbeine beseitigte diese Präferenz. Culex pipiens fatigans zeigte weder vor noch nach Hinterbeinamputation eine Bevorzugung rauher oder glatter Oberfläche. Als Erklärung wird vorgeschlagen, daß wirbelnde Bewegungen der Hinterbeine, die bei Anopheles gambiae, aber nicht bei Culex pipiens unmittelbar nach dem Landen zu sehen sind, dazu dienen, die Substratbeschaffenheit festzustellen.

     

Biting activity and host preference of the malaria vectors Anopheles maculatus and Anopheles sawadwongporni (Diptera: Culicidae) in Thailand

Adult mosquitoes in the Anopheles maculatus group were surveyed from different regions of Thailand and five different species were morphologically identified, including Anopheles maculatus, Anopheles sawadwongporni, Anopheles notanandai, Anopheles dravidicus, and Anopheles willmori. Blood‐feeding activity and host preference of two species, Anopheles maculatus and Anopheles sawadwongporni, were observed during a one‐year period at Pu Teuy Village, Sai Yok District, Kanchanaburi Province, west‐central Thailand. Both species were more prevalent during the wetter period of the year and each had a greater predilection to feed on cattle than humans. Primary feeding activity occurred between 20:00‐23:00 and a smaller peak at 01:00‐03:00. Findings are discussed relative to the importance of these two vectors for malaria transmission in Pu Teuy.     

DNA probes for species identification of mosquitoes in the Anopheles gambiae complex

Abstract. Identification of species within the Anopheles gambiae Giles species complex is essential for the correct evaluation of malaria vector ecology studies and control programmes. The development of DNA probes to distinguish species of the An.gambiae complex is described. Genomic libraries were prepared for four members of the An.gambiae complex. These were screened using radiolabeled DNA from different species of An. gambiae sensu lato and a number of clones selected on the basis of their species specificity. These clones could be divided into two groups, each containing homologous sequences. Sequences homologous to group 1 inserts are highly reiterated in the genomes of Anopheles arabiensis Patton and Anopheles merus Dönitz, present in low copy number in Anopheles melas Theobald, but were not detected in Anopheles gambiae sensu stricto. Studies on the organization of this sequence in the genome of An.arabiensis show that homologous sequences are male specific and interspersed within the chromatin. Sequences homologous to group 2 inserts are highly repeated in the genomes of An.merus and An.melas, but present in low copy number in An.gambiae s.s. and An.arabiensis. Group 2 homologous sequences are not sex-specific in the species tested and appear to be tandemly repeated. When used as hybridization probes, these sequences provide a sensitive means for the identification of species within the Anopheles gambiae complex.     

Estimated resistance of the malaria mosquito Anopheles messeae s.l. to the insecticide malathion

Resistance to agricultural pesticides is an important and insufficiently studied concern for pest and disease vector research. We determined the malathion resistance of species in the Anopheles maculipennis mosquito group in a habitat near Novosibirsk, Russia. Most of the 851 individuals we measured were members of the Anopheles messeae s.l. complex (An. messeae and An. daciae species). The LC₅₀ value for malathion was 0.052 mg/L for the mixed specimens, and we failed to find any differences between species. The LC₅₀ value was within the range of values for malathion resistance of Anopheles stephensi and Culex quinquefasciatus. As the main resistance mechanism to organophosphate and carbamate insecticides is a single mononucleotide substitution in the ace‐1 gene, we searched for this mutation in An. messeae s.l. and An. beklemishevi by restriction analysis. This mutation was not found in 347 of the specimens. We sequenced the ace‐1 gene fragment for 24 specimens from four species of the Anopheles maculipennis group, including An. messeae, An. daciae, An. atroparvus, and An. beklemishevi. These specimens harbored a nucleotide substitution in the triplet where a mutation can lead to insecticide resistance, but this substitution would make it difficult for the resistance to develop. Since the studied specimens belong to branches of the Palearctic portion of the Anopheles maculipennis group, we suspect that all other Palearctic species of this group would have difficulties harboring the ace‐1 mutation that would lead to organophosphate and carbamate resistance.     

DNA content in nine species of Nematocera with special reference to the sibling species of the Anopheles maculipennis group and the Culex pipiens group

DNA values were determined for the nine species: Telmatoscopus meridionalis (family Psychodidae), Dixa obscura (family Dixidae), and Culiseta litorea, Culex pipiens, Aedes caspius, Anopheles labranchiae, Anopheles atroparvus, Anopheles stephensi, and Anopheles freeborni (family Culicidae). The DNA content indicated that the species could be divided into three categories: The Culex group with Culex pipiens, Culiseta litorea and Aedes caspius containing 1.02, 0.92 and 0.99 pg DNA in the haploid set, the Anopheles group including the four Anopheles species A. labranchiae, A. atroparvus, A. stephensi, A. freeborni and Telmatoscopus meridionalis with 0.23, 0.24, 0.24, 0.29 and 0.24 pg DNA and the third group with Dixa obscura containing 0.16 pg DNA. Within the sibling species of the Anopheles maculipennis group DNA differences were found to be present between the palaearctic and the nearctic populations. No deviations could be found between two Culex pipiens populations which were reproductively isolated.This work was supported by a grant of the Volkswagenstiftung (Germany) and by grant No. 70.1146.04 from C.N.R. (Italian Centre of Researches).     

Geometric morphometrics for the taxonomy of 11 species of Anopheles (Nyssorhynchus) mosquitoes

The subgenus Anopheles (Nyssorhynchus) (Diptera: Culicidae) includes the primary vectors of Plasmodium spp. in Colombia. Most adult females of this subgenus are difficult to identify in the field using the available keys. With the objective of further investigating the discriminatory power of modern morphometrics, both landmark‐based and outline‐based approaches were explored using the wing venation geometry of 11 Anopheles (Nyssorhynchus) species. Wing shape was able to separate the closest species of the subgenus. When the 11 species were analysed together, validated classification scores on average 5.3–8.6 times higher than those expected by chance were observed. These scores computed from the total sample of 11 species were not satisfactory for the recognition of Anopheles benarrochi B, Anopheles oswaldoi s.l. and Anopheles strodei. These sibling species were captured in sympatry. To improve the identification power of the morphometric tool, it was necessary to analyse these species separately from the remaining species. The best classification scores were obtained using a combination of 12 landmarks collected not only on the intersections of wing veins, but also on spots. An outline approach also gave excellent reclassification scores. Another pair of sibling species, collected in allopatry, Anopheles nuneztovari and Anopheles rangeli, also showed high classification scores.     

Larval salinity tolerance of two members of the Anopheles funestus group

The Anopheles funestus group (Diptera: Culicidae) is one of the main species groups involved in malaria transmission in the Afrotropical regions. Basic research into this group has been limited because its members are eurygamic (they tend not to mate in confined spaces), which makes laboratory colonization difficult. Currently, only a few An. funestus Giles colonies are available and no colonies of other members of the group have been established. As information on the larval biology of members of the An. funestus group is limited, the present study aims to determine the effects of different salt concentrations on survival rates of the aquatic stages of two members of the An. funestus group, Anopheles funestus and Anopheles rivulorum Leeson. There were statistically significant negative trends in hatch rate and larval survival rate in An. funestus with increasing salt concentrations, with no larvae surviving to pupae at concentrations that included > 15% seawater. Anopheles rivulorum, by contrast, showed no significant trends in hatch rate or larval survival with increasing salt concentrations. This is the first report on salinity tolerance in An. rivulorum. A basic understanding of these variations in salinity tolerance provides vital information on the biology, ecology and colony rearing of members of the An. funestus group.     

Bionomics of Anopheles spp. (Diptera: Culicidae) in a malaria endemic region of Sukabumi,West Java,Indonesia

A 15‐month bionomic study of Anopheles species was conducted in two ecologically distinct villages (coastal and upland) of Sukabumi District, West Java, Indonesia from June 2006 to September 2007. Mosquitoes were captured using human‐landing collections at both sites. During the study, a total of 17,100 Anopheles mosquitoes comprising 13 Anopheles species were caught: 9,151 at the coastal site and 7,949 at the upland site. Anopheles barbirostris, Anopheles maculatus, and Anopheles vagus were the predominant species caught at the coastal site, and Anopheles aconitus, Anopheles barbirostris, and An. maculatus predominated in the upland site. Overall, species were exophagic at both sites, but there was variation between species. Anopheles aconitus was endophagic at the coastal site, exophagic at the upland site, collected most often in April 2007 and had a peak landing time between 22:00 and 23:00. Anopheles sundaicus was only collected at the coastal site, exophagic, collected most often in October 2006, and had a peak landing time between 19:00 and 20:00. Potential malaria vector species such An. aconitus, An. maculatus, and An. sundaicus were present throughout the year. None of the 7,770 Anopheles tested using CSP‐ELISA were positive for malaria, although the risk for malaria outbreaks in Sukabumi district remains high.     

Isolation and characterization of microsatellite DNA markers in the malaria vector Anopheles maculipennis

The Anopheles maculipennis complex includes the most important malaria vectors of the western Palearctic. Anopheles maculipennis s.s., one member of this complex, is a reported vector in the Middle East. Here we describe the isolation of 15 microsatellite polymorphic loci from the An. maculipennis s.s. genome, displaying a high among individual diversity (0.37–0.77) in a sample from France. Three loci displayed a significant departure from Hardy–Weinberg proportions, suggesting a substantial frequency of null alleles. The remaining 12 loci are good candidates for further genetic studies in this species.     

Biting patterns and host preference of Anopheles epiroticus in Chang Island,Trat Province,eastern Thailand

A study of species diversity of Anopheles mosquitoes, biting patterns, and seasonal abundance of important mosquito vectors was conducted in two villages of Chang Island, Trat Province, in eastern Thailand, one located along the coast and the other in the low hills of the central interior of the island. Of 5,399 captured female anophelines, 70.25% belong to the subgenus Cellia and remaining specimens to the subgenus Anopheles. Five important putative malaria vectors were molecularly identified, including Anopheles epiroticus, Anopheles dirus, Anopheles sawadwongporni, Anopheles maculatus, and Anopheles minimus. Anopheles epiroticus was the most commonly collected species in the coastal site, whereas An. dirus was found to be most abundant in the forest‐hill site. From both locations, a greater number of mosquitoes was collected during the dry season compared to the wet. Anopheles epiroticus showed greater exophagic and zoophilic behavior with the highest blood feeding densities occurring between 18:00 and 19:00. In contrast, An. dirus demonstrated an activity peak between midnight and 01:00. We conclude that An. epiroticus and An. dirus, in coastal and inland areas, respectively, appear to be the most epidemiologically important malaria vectors on Chang Island. As no studies of vector competency specific to Chang Island have been conducted, our conclusions that these two species play a primary role in malaria transmission are based on evidence from other localities in Thailand and mainland Southeast Asia. This information serves as a basis for designing improved vector control programs that target specific species, and if integrated with other interventions could result in the elimination of malaria transmission on the island.     

Shift in species composition in the Anopheles gambiae complex after implementation of long‐lasting insecticidal nets in Dielmo,Senegal

Long‐lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) are the cornerstones of malaria vector control. However, the effectiveness of these control tools depends on vector ecology and behaviour, which also largely determine the efficacy of certain Anopheles mosquitoes (Diptera: Culicidae) as vectors. Malaria vectors in sub‐Saharan Africa are primarily species of the Anopheles gambiae complex, which present intraspecific differences in behaviour that affect how they respond to vector control tools. The focus of this study is the change in species composition in the An. gambiae complex after the implementation of LLINs in Dielmo, Senegal. The main findings referred to dramatic decreases in the proportions of Anopheles coluzzii and An. gambiae after the introduction of LLINs, and an increase in the proportion of Anopheles arabiensis. Two years after LLINs were first introduced, An. arabiensis remained the most prevalent species and An. gambiae had begun to rebound. This indicated a need to develop additional vector control tools that can target the full range of malaria vectors.     

Gene cloning,bacterial expression,and purification of calreticulin from Anopheles stephensi (AsCRT)

During the invasion of Plasmodium ookinetes to the mosquito midgut epithelium, several proteins or glycoproteins are involved. Recent study has shown that the calreticulin (CRT) of the midgut from Anopheles albimanus can bind to the protein receptor Pvs25 on surface of Plasmodium vivax ookinetes. Thus, in order to get more insight into the potential roles of Anopheles stephensi calreticulin (AsCRT) in the midgut, we amplified and cloned the full‐length of calreticulin coding sequence from Anopheles stephensi. The AsCRT consists of 1221 bp nucleic acids with one open reading frame (ORF) encoding 406 amino acids and an apparent molecular weight around 46 KDa. Subsequently, the recombinant calreticulin as Glutathione S‐transferase (GST) fusion in pGEX ?6p‐1 expression vector (GST‐AsCRT) was produced in the prokaryotic system under optimum conditions. GST‐AsCRT fusion protein has a molecular weight around 73 KDa. The recombinant protein was detected by Western blotting using a rabbit anti‐GST polyclonal antibody. Here, we report via single protein purification procedure using MagneGST beads, 25 mg of the recombinant protein was obtained per liter of bacterial culture. This is the first report describing the heterologous expression of Anopheles stephensi calreticulin in the prokaryotic system. The production of this recombinant protein will now allow us to further investigate AsCRT molecular protein analyses, characterization of physiochemical properties, as well as interaction between calreticulin and plasmodium protein surface.     

Occurrence and host preferences of Anopheles maculipennis group mosquitoes in England and Wales

Mosquitoes of the Anopheles maculipennis Meigen (Diptera: Culicidae) group are of public health concern: five of the 11 morphologically indistinct species have been historically considered as vectors of malaria in Europe. Three members of the An. maculipennis group have been reported in the U.K.: Anopheles atroparvus van Thiel; Anopheles messeae Falleroni, and Anopheles daciae Linton, Nicolescu & Harbach. To study the distribution of the three U.K. species, particularly that of An. daciae, we developed a polymerase chain reaction–Restriction fragment length polymorphism (PCR‐RFLP) assay using the nuclear ribosomal internal transcribed spacer 2 (ITS‐2) gene. Anopheles daciae was found to be widespread, occurring in four of the five counties surveyed in southern England and on the Welsh island of Anglesey, often in sympatry with the closely related species An. messeae. The host preferences of 237 blood‐fed females were determined using either direct sequencing or PCR‐based fragment analysis of the mitochondrial cytochrome oxidase b gene with DNA from females' abdomens. All three species were found to be opportunistic, having fed on at least three different hosts. Seventeen individuals contained multiple bloodmeals, including two An. daciae that had fed on humans and birds. Our results show that An. daciae is widespread in England and Wales, occurs in sympatry with other members of the An. maculipennis group, and feeds on humans, which suggests it is a potential vector of disease in the U.K.     

Recombinant Enterobacter amnigenus Highly Toxic to Anopheles dirus Mosquito Larvae

The mosquito-larvicidal binary toxin of Bacillus sphaericus 2297 was expressed in Enterobacter amnigenus, a Gram-negative bacterium isolated from Anopheles dirus larvae gut. The toxin was placed under the regulation of various promoters in order to improve the expression level of the toxin. Amongst the recombinants obtained, E. amnigenus harboring pBS373, a plasmid which contains the toxin genes under the control of the native B. sphaericus promoter, expressed a significant amount of protein, comparable to that found in B. sphaericus 2297. In addition, this recombinant provided approximately twenty times higher toxicity against second-instar Anopheles dirus larvae when compared to B. sphaericus 2297. The procedure of obtaining this environmentally isolated bacterium from larvae gut and introducing the system for mosquito-larvicidal toxin synthesis is noteworthy. The promising result presented here provides a substantial degree of confidence for further field studies.     

Longitudinal follow‐up of malaria transmission dynamics in two villages in a Sahelian area of Niger during a nationwide insecticide‐treated bednet distribution programme

Malaria transmission was monitored in two villages in the Sahel zone of Niger over 4 years. During this period, a nationwide vector control programme was carried out in which insecticide‐treated bednets were distributed free to mothers of children aged <5 years. Anopheles gambiae and Anopheles arabiensis (Diptera: Culicidae) were found to be the major malaria vectors. The dynamics of An. gambiae s.l. did not vary dramatically over the study period although the proportion of female mosquitoes found resting indoors decreased in both villages and, in one village, the parity rate and sporozoite index were significantly reduced after bednet distribution. By contrast with An. gambiae, the dynamics of Anopheles funestus altered greatly after the bednet distribution period, when adult density, endophagous rate and sporozoite rates decreased dramatically. Our observations highlight the importance of quantifying and monitoring the dynamics and infections of malaria vectors during large‐scale vector control interventions.     

Estimation of divergence time between two sibling species of the <Emphasis Type="Italic">Anopheles (Kerteszia) cruzii</Emphasis>complex using a multilocus approach

Background  

Anopheles cruzii is the primary human Plasmodium vector in southern and southeastern Brazil. The distribution of this mosquito follows the coast of the Brazilian Atlantic Forest. Previous studies indicated that An. cruzii is a complex of cryptic species.