Anopheline Mosquito Species Research Articles

Factors Influencing Larval Color in the Simulium vittatum Complex (Diptera: Simuliidae)

We investigated factors that influence larval color in black flies of the Simulium vittatum complex. In the laboratory, larvae were exposed to different light sources (ultraviolet and fluorescent cool background colors (black and white), and diets (periphyton, Spirulina, and fish food). Larvae were significantly darker when exposed to ultraviolet radiation, when reared in black containers, and when fed periphyton. Larval color was independent of sex. In the field, larvae on rocks were significantly darker than those on in-stream vegetation. Larval color also varied among seasons. Pigment analyses suggested that field-collected larvae contain a carotenoid. To investigate the adaptive significance of larval color, visual predators (Gambusia holbrooki) were introduced to a recirculating flume that contained dark larvae on black and white backgrounds. The predatory fish consumed significantly more dark larvae on white squares than expected by chance. Larvae, however, did not select a background that matched their body color. Our investigations show that a significant component of color is under environmental control. Additional key words: black flies, pigments, aquatic insects, stream The ability of immature and adult insects to change color has been investigated frequently in terrestrial environments (Raabe 1983) but rarely in aquatic habitats. The larval odonates Leucorrhinia dubia (VAN DER LIND) and Ischnura verticalis (SAY) can change color to match green or brown backgrounds (Moum & Baker 1990; Henrikson 1993). Air sacs of the phantom midge Corethra plumicornis change color in response to background (Wemhoner & Weber 1973), and larvae of two species of anopheline mosquitoes undergo color change when exposed to different backgrounds (Benedict & Seawright 1987). In each of these cases, predator avoidance is suggested as the evolutionary significance of color change, along with avoidance of detection by prey in the case of the odonates. Black fly larvae are stream-dwelling filter feeders common throughout the world (Crosskey 1990). Larvae of the Simulium (Psilozia) vittatum ZETTERSTEDT complex show a strong correlation between larval pigmentation and the color of the background to which they attach; larvae on green vegetation are pale with distinct head spots, whereas those on rocks are dark with confluent head spots (Adler & Kim 1984). This apresent address and author for correspondence: Department of Biology, Clemson University, Clemson, SC 296341903. E-mail: jzettle@clemson.edu relation holds for all members of the subgenus Psilozia and might be a defining synapotypy for the taxon (Adler, unpubl. data). The implication is that these larvae might have the ability to change their color. To gain insight into the relation between larval color and substrate in the S. vittatum complex, we designed our study to address two basic questions. At the proximate level, we asked what factors influence larval color. To address this question, we tested the hypotheses that larval color is influenced by food, by background color, by ultraviolet (UV) radiation, and by sex, and that larval color is seasonal. At the ultimate level, we asked whether larval color provides a selective advantage against predators, and tested two hypotheses: (1) risk of predation for larvae on a light or dark background depends on body color, and (2) larvae select a background matching their body color.

Mitochondrial DNA variation within and between two species of neotropical anopheline mosquitoes (Diptera:Culicidae).

We analyzed variation in mitochondrial DNA (mtDNA) of two neotropical mosquitoes, Anopheles rangeli (n = 181) and A. trinkae (n = 45), with very different distribution patterns in Latin America, to assess species boundaries for these putative sister taxa and to examine population genetic structure. Phylogenetic analyses revealed (1) support for the monophyletic origin of each species; (2) diagnostic restriction site differences between the species; (3) geographic partitioning of haplotypes by country in A. rangeli from Bolivia, Ecuador, and Venezuela compared with considerable overlap in haplotypes of A. trinkae from Bolivia and Ecuador; and (4) similar levels of mean haplotype and nucleotide diversity in both species, but lower levels of mean nucleotide divergence in A. trinkae compared with A. rangeli. We hypothesize that higher maternal gene flow and lower divergence in A. trinkae are most likely due either to a distinctive matrilineal history or to a smaller effective population size, which may have been influenced by a smaller, essentially linear geographic range along the eastern flank of the Andes. In the cladistic analysis of A. rangell, the Bolivian haplotypes appear to be more derived than those from Ecuador or Venezuela, yet there is no evidence to support the hypothesis of a recent range expansion from Ecuador into Bolivia.

Rule-based system for the fast identification of species of Indian Anopheline mosquitoes.

In a developing country like India, classification and identification of the species of Anopheline mosquitoes in control operations of mosquito-borne diseases is of paramount importance. The WHO monograph, which describes the taxonomic data in the form of a pictorial key is generally difficult to understand by a non-taxonomist. Utilizing the principles of ID3 algorithm, a novel rule-based system, for the fast identification of unknown species of Indian Anopheline mosquitoes, is developed. The rule-based system is user-friendly, menu-driven and even a novice can make use of it in the identification of the unknown species with little practice. The above software is available on floppy disk and can be obtained with a minimum cost. This program can be ported on 5 1/4" or 3 1/2" floppy disk.

ハマダラカ属数種に対する殺虫剤および昆虫成長制御剤の効力評価

ハマダラカ属数種に対する殺虫剤および昆虫成長制御剤の効力評価

Electrophoretic Method for Recognition of Sibling Species of Anopheline Mosquitoes. A Practical Approach

Laboratory hybridization tests, comparative study of the banding patterns of polytene chromosomes, and electrophroetic techniques for isozyme analysis are the methods that are usually employed for the recognition of sibling species of anopheline and some other mosquitoes. Hybridization tests under laboratory conditions are sufficient for measuring postmating reproductive isolation, but premating mechanisms are generally undetectable. Difficulty in obtaining good quality preparations tends to limit the usefulness of the chromosomal approach for the identification of sibling species. Generally, isozyme analysis is more accurate and reliable in uncovering cryptic variation, providing meaningful information on genetic relatedness, and in the identification of sibling species. We have presented a step-by-step analysis of electrophoretic data for the identification of both allopatric and sympatric sibling species.

Changes in Pigmentation in Mosquitoes (Diptera: Culicidae) in Response to Color of Environment

In laboratory experiments, coloration of larvae of two species of anopheline mosquitoes was modified significantly by color of the rearing background. Larvae of Anopheles albimanus Wiedemann, Anopheles quadrimaculatus Say, Culex quinquefasciatus Say, Culex salinarius Coquillett, Aedes aegypti (L.), and Aedes taeniorhynchus Wiedemann were reared in darkness and on either black, white, or green backgrounds, illuminated by either fluorescent lighting or sunlight. Normal strains of Anopheles and Culex larvae reared in black containers developed darker larval pigmentation than larvae reared on the other backgrounds or in darkness. Response of anophelines was more intense than that of culicines. Larval body-color mutants of A. albimanus responded similarly to wild-type on black background, but eye-color mutants of A. albimanus and A. quadrimaculatus did not respond to color of the rearing container. No changes in pigmentation were noted in either Aedes species under any of the test conditions. When normal fourth-instar A. albimanus were introduced into a bicolored (half white, half black) container, a significant majority of larvae selectively moved onto the color, either black or white, of their original rearing container.

RNA synthesis in two species of anopheline mosquitoes

. 1. 1. A method is described for the extraction of adult mosquito nuclear RNA. The RNA is tightly bound to nuclear components. The nuclei were dispersed by the use of sodium chloride and urea of high ionic strength. 2. 2. Deproteinization of the cytoplasmic minus mitochondria fraction resulted in the separation of a high molecular weight RNA. The RNA is derived from a polynucleotide precursor in the nucleus and transported to the cytoplasm. 3. 3. The rate of RNA synthesis in Anopheles quadrimaculatus and A. albimanus was measured by the incorporation of radiolabelled adenine into RNA. The radioactive precursor was presumably converted to the adenine nucleotide by adenine phosphoribosyltransferase. 4. 4. The conversion of adenine nucleotides to guanine nucleotides was essentially the same in the two species, however, differences were found in the specific activities of RNA purines. 5. 5. Cellulose powder and DEAE profiles of nuclear and cytoplasmic RNAs from the two species were compared.

Malaria of the orang-utan (Pongo pygmaeus) in Borneo.

The primary objective of this project was to study the life cycle and ecology of Plasmodium pitheci, a malaria parasite of the orang-utan. The field work was based on the orang-utan rehabilitation centre in the Sepilok Forest Reserve of eastern Sabah. Two visits were made to Sepilok, the first in February and March, 1972, and the second (by W.P.) in January 1974. On the first visit two species of "surrogate host" were taken to Sabah, i.e. chimpanzees and Aotus monkeys for experimental work. The arboreal habitat of the orang-utan in the dipterocarp forests of eastern Sabah is described. In the Sepilok Forest Reserve dwell gibbons and leaf-monkeys, in addition to a small population of semi-domesticated and wild, free-ranging orang-utans of various ages. Although numerous species of anopheline mosquitoes have been collected in eastern Sabah, longitudinal studies are not available. Anopheles balabacensis was caught both attracted to orang-utans and to man at Sepilok. This species which is the main vector of human malaria in the north of Borneo, is suspected also of transmitting orang-utan malaria in this part of Sabah. Repeated blood examinations have been made on a number of orang-utans in the centre since 1966 and a high prevalence of infection was recorded with Plasmodium pitheci. In 1966 10 out of 19 animals had demonstrable parasitaemia. Detailed case histories are presented to show the course of parasitaemia in several orang-utans. Infections of P. pitheci were found to run a very chronic course. During the 1972 expedition a second, previously undescribed malaria parasite of the orang-utan was discovered, and was named P. silvaticum. The new parasite was successfully transmitted both by blood inoculation and, later, by sporozoite inoculation, into splenectomized chimpanzees. Although both species of malaria parasite may cause transitory signs of illness, orang-utans in general appear to be little discomforted by the infection. The animals do however suffer from other infectious diseases such as amoebic and balantidial dysentery, and melioidosis is a serious natural hazard which may have accounted for several deaths of wild orang-utans. An unidentified, intraerythrocytic structure that appeared in the blood of one chimpanzee, which had been inoculated with blood from an orang-utan, may have contributed to its death. Detailed descriptions and illustrations of P. pitheci and P. silvaticum are given. All stages of the life cycle of P. silvaticum are known (the tissue stages having been described in the liver of a "surrogate host", the chimpanzee) but only the blood and sporogonic stages of P. pitheci have been seen. This species was not infective to a chimpanzee, although there is an earlier report of a transient infection in this host by other workers. In the blood both parasites showed a tertian periodicity. From the appearance of the tissue schizonts on the seventh day it was estimated that the complete pre-erythrocytic cycle of P. silvaticum in the chimpanzee would occupy 8 days. P...

Lack of Gene Flow Among Three Species of Anopheline Mosquitoes

Lack of Gene Flow Among Three Species of Anopheline Mosquitoes

Lack of Gene Flow among Three Species of Anopheline Mosquitoes

Lack of Gene Flow among Three Species of Anopheline Mosquitoes

Homologous alkaline phosphatases and homologous loci in two sibling species of European anopheline mosquitoes.

Anopheles atroparvus and Anopheles labranchiae are two sibling species belonging to the maculipennis group of European anopheline mosquitoes. They may be considered the most closely related species of the group; their gene pools are probably the most similar. By the definition of Lorkovic they could be termed “semispecies”, showing some of the characteristics of the species and some of subspecies1. Individuals of A. atroparvus and A. labranchiae are not clearly distinguishable by cytogenetic analysis of the banding pattern of the salivary chromosomes. They can be distinguished on the basis of slight differences in the micromorphology of the eggs, and also on the basis of hybridization data: the interspecific hybrid males are sterile, but introgressive hybridization is possible, for the females can be backcrossed to A. atroparvus and A. labranchiae males, and again produce normal females and several normal males.

Studies on the Transmission of Simian Malarias II. Transmission of the H Strain of Plasmodium knowlesi by Anopheles balabacensis balabacensis

Five species of anopheline mosquitoes were examined in regards to their susceptibility to infection with the strain of Plasmodium knowlesi. Anopheles balabacensis balabacensis, Anopheles freeborni, Anopheles maculatus, and Anopheles stephensi were readily infected to the oocyst stage but only in the first-named species were salivary glands heavily infected. Only A. quadrimaculatus failed to become infected. Transmission of this parasite to Alacaca mulatta monkeys was obtained by the bites of A. b. balabacensis mosquitoes on two occasions. The extrinsic incubation periods in these lots of mosquitoes were 12 and 13 days and the prepatent periods in the infected monkeys were 8 and 7 days, respectively. The usefulness of the malaria parasites of nonhuman primates as laboratory models for the study of pathology, physiology, immunity, and drug response has been well established. Some of these species have been easily adapted to laboratory transmission with a variety of anophelines while considerable difficulty has been encountered in finding a suitable laboratory vector for others. Plasmodium knowlesi is one of the monkey parasites which has proven most difficult to adapt to routine laboratory transmission. The development of this parasite in mosquitoes to the point of sporozoite-positive salivary glands has been demonstrated in Anopheles annularis (Singh et al., 1949), in A. atroparvus (Weyer, 1937; Hawking et al., 1957), in A. aztecus (Gamrnham et al., 1957), and in A. stephensi (Singh et al., 1949; Hawking and Mellanby, 1953; Hawking et al., 1957; Garnham et al., 1957). The parasite has been passaged through mosquitoes to susceptible monkeys by the intravenous inoculation of dissected infected salivary glands and/or guts by several workers. The mosquitoes used for this purpose included A. stephensi (Singh et al., 1949; Garnham et al., 1957; Hawking and Mellanby, 1953; Hawking et al., 1957), A. annularis (Singh et al., 1949), A. aztecus (Gamham et al., 1957), and A. atroparvus (Hawking et al., 1957). None of these investigators reported attempts to transmit the infection through the bite of infected mosquitoes, and to our knowledge such natural transmission has not been reported elsewhere. The present report is concerned with the Received for publication 20 March 1967. susceptibility of five species of Anopheles to Plasmodium knowlesi and the transmission of this parasite by the bite of Anopheles balabacensis balabacensis. MATERIALS AND METHODS The P. knowlesi used was isolated from a naturally acquired human infection (Chin et al., 1965) and had been passaged by blood to humans and Macaca mulatta monkeys. It has been designated by us as the H strain. Malaria-free M. mulatta monkeys from North India were used throughout the course of these experiments. In Al. mulatta monkeys parasitemias of P. knowlesi develop to extremely high levels and the infection is usually fatal if not treated. The Anopheles quadrimaculatus mosquitoes were the Q-1 strain which was obtained from Technical Development Laboratories, CDC, Savannah, Georgia. The A. freeborni (F-1 strain) were from Marysville, California and have been maintained in the laboratory since 1944. The A. stephensi were from Delhi, India and were obtained from the London School of Hygiene and Tropical Medicine, London, England in 1963. The A. maculatus were obtained from the Institute for Medical Reearch, Kuala Lumpur, Malaysia in 1964 and have been maintained in our laboratory since then. The A. balabacensis balabacensis colony was originally from Thailand and was recently obtained from the Walter Reed Army Institute of Research, Washington, D. C. through the courtesy of Col. W. D. Tigertt and Major J. E. Scanlon. The mosquitoes most often used in the experiments were A. freeborni and the susceptibility of the others was, in each case, compared with this species. After the infective feeding, six to 43 specimens of each species were examined for oocysts. Only when A. freeborni was found to be infected were the results used in determination of the comparative susceptibility of the anopheline species. The details of the procedures used in this study are presented in the first report in this series (Collins et al., 1966).

Normal susceptibility levels of Anopheles pharoensis Theobald to DDT and dieldrin.

HOUSE spraying with residual insecticides, particularly with DDT and dieldrin, plays an important part in modern anti-malaria campaigns. The tolerance of malaria vectors to these toxicants is therefore of special interest. Assessments of the susceptibility of many different species of anopheline mosquitoes before and during spraying operations have been carried out in many parts of the world1. However, nothing seems to have been published on the normal resistance-level of A. pharoensis, a vector of malaria in several countries of Africa.

Factors influencing infection of the mosquito with Dirofilaria immitis (Leidy, 1856)

Factors influencing infection of the mosquito with Dirofilaria immitis (Leidy, 1856)

Complete Sporogonic Development of Plasmodium berghei in Experimentally Infected Anopheles spp.

SINCE the discovery of Plasmodium berghei by Vincke and Lips1, repeated attempts have been made to infect various anopheline and culicine mosquito species with this plasmodium in the laboratory. Oocysts and sporozoites have been observed in naturally infected Anopheles dureni2; but apart from the finding on two occasions of small numbers of young oocysts in experimentally infected A. maculipennis var. atroparvus3, no sporogonic development of P. berghei under experimental conditions has hitherto been described.

Malaria Reconnaissance of the Province of Pinar Del Rio in Cuba 1

Summary 1. The malaria survey in Cuba, which is planned eventually to include the whole island, has been completed now in Pinar del Rio Province and the data are reported here. 2. In the Province of Pinar del Rio 16,855 children have been examined for splenomegaly and 7,407 for malaria parasites. The results of the latter examinations show a significantly higher frequency of children with malaria parasites among those with splenomegaly than in the spleen negative group. 3. Plasmodium vivax and Plasmodium falciparum are well distributed throughout the area. The former occurs almost twice as frequently as the latter. 4. The endemicity of malaria is moderate in those portions of the counties of Mantua, Guane, Consolacion del Sur, San Luis, and Vinales which lie in the low coastal plain. In the remainder of the province the malaria problem is one of light endemicity, with recurring epidemics when conditions are unusually favorable to the breeding of anophelines capable of transmitting the disease. 5. Five species of anopheline mosquitoes have been encountered in the area. These are: A. albimanus, A. crucians, A. grabhami, A. vestitipennis, and A. atropos. 6. A study of the distribution of these anophelines in the area confirms the fact that A. albimanus is present in far greater numbers in the coastal plain area, where most malaria was encountered. The season of maximum prevalence of this mosquito coincides with the malaria transmission season. It is known to be a malaria vector, and it is reasonable to conclude that it is the important malaria vector in Pinar del Rio Province.

The factors which determine the varying degrees of malarial incidence in Assam Tea Estates and the fundamental principles governing mosquito control of malaria in Assam

Twenty species of anopheline mosquitoes have been found in the Cachar District of Assam. The two species which should be added to the eighteen species already published by the writer in 1927 are A. theobaldi Giles and A. annandalei Baini Prashad. From an Infectivity Survey extending to over 27,000 dissections of anopheline mosquitoes caught in nature, the only species which have been found with sporozoites in the salivary glands, i.e., carriers of malaria in nature, are A. minimus Theobald, and A. ramsayi Covell. The importance of these species has been proved by the results of anti-larval measures directed against their breeding-areas, i.e., decrease in malarial incidence. A. ramsayi was only of sanitary importance in one estate. A. minimus is an extremely efficient natural carrier, and is practically entirely responsible for the incidence of malaria in Assam. The period of infectivity of A. minimus in nature is from about the middle of April until practically the end of the year. The efficient control of malaria in Assam is dependant on the control by anti-larval measures of the summer breeding-areas of A. minimus, i.e., during the period of the year when A. minimus can become infected and transmit malaria in nature. Control only of the winter resorts of A. minimus, at any rate over a limited area of country, will not control the incidence of malaria owing to migration of A. minimus from winter to summer resorts. The migration of A. minimus in Assam is dependant on rainfall which is practically confined to the warm monsoon seasons. Destruction of A. minimus larv˦ in their monsoon or summer resorts by oiling is a highly efficient method of malaria control. An Anti-malaria Organisation by carefully locating the breeding-areas of A. minimus can greatly reduce expenditure in oiling and add to efficiency in control. Nature's methods of controlling the breeding-areas of A. minimus are by flooding, flushing and heavy shade. Flooding and flushing account for the healthiness of low-lying land (rice land) and low-lying tea estates as A. minimus migrates to higher and safer levels away from the dangers of flooding and flushing. Land at higher levels when under virgin jungle, i.e., under heavy shade, is invariably healthy. When the jungle is cut and certain types of streamlets or streams are exposed, or partially exposed, or indifferently constructed drains are cut, appropriate breeding-areas are created as summer resorts for A. minimus. This accounts for the high degree of malarial endemicity on certain types of plateau land also in hill foot areas, i.e., the areas above flood level. Investigations and observations are at present being carried out in the practical application of nature's methods of control by various artificial means to reduce recurring expenditure and to meet the requirements of commerce and civilisation. Finally, we consider from our investigations and the results of malaria control by anti-larval measures that much needless loss of life, ill-health, suffering and misery can be obviated if Assam malaria problems are properly investigated and appropriate measures applied.