Mosquito Anopheles Quadrimaculatus Research Articles

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).

The effects of certain cations and antibiotics on blood digestion in two species of mosquitoes

Immediately after emergence as adults, female Aedes aegypti and Anopheles quadrimaculatus mosquitoes were fed on sugar solutions containing the chlorides of either calcium, magnesium, manganese, or iron in various concentrations, the antibiotics oxytetracycline, neomycin, streptomycin, and penicillin, or the antibiotics in combination with each other or in combination with the cations. After feeding on these solutions for approximately 4 days, the mosquitoes were allowed to take a blood meal, and either 72 or 96 hr later, when normally digestion would have been completed, the stomachs were examined microscopically for evidences of blood residues. It was found that calcium, magnesium, manganese, and iron all inhibited blood digestion to varying degrees in both A. aegypti and A. quadrimaculatus. The antibiotics, however, acted in a more complicated manner and produced a variety of effects. Thus, oxytetracycline, for example, had scarcely any inhibitory effect in Aedes, yet when fed to the mosquitoes in combination with either calcium, magnesium, or manganese it produced a substantial potentiation of the cation effect, whereas in combination with iron it suppressed almost entirely the effect of the latter. In the anophelines oxytetracycline had a marked inhibitory effect yet its potentiating effect was apparent only in combination with manganese, although it still suppressed the effect of iron. In Aedes, penicillin suppressed the inhibitory effects of calcium, manganese as well as oxytetracycline and neomycin, whereas in Anopheles it had instead a limited inhibitory effect, although again in this species it also acted to suppress the inhibition produced by oxytetracycline and neomycin. Whereas in Aedes the inhibition produced by neomycin was suppressed by iron, in the anophelines neomycin and iron together had an additive inhibitory effect. These results indicate that the in vivo effect of a particular antibiotic on a given physiological system is a function of the animal species, and that this effect is further modified by the presence of certain cations or other antibiotics.

The Infectivity of Native Malarias in South Carolina to Anopheles Quadrimaculatus 1

Summary and Conclusions In a field study in South Carolina, Anopheles quadrimaculatus mosquitoes were applied to native cases of malaria in Negroes to determine the infectivity of such malaria cases. Of 142 feedings upon Plasmodium falciparum patients, 21 showed infections. Of 12,606 mosquitoes dissected, 2.5 per cent were infected. These infections developed normally in the mosquito and in one out of two trials transmission was successful. The majority of the mosquito infections occurred during the months of October through January. Mosquitoes kept at outside temperatures during October and November became infected. One patient remained infective to mosquitoes over an 8-month period. Of the 25 patients showing gametocytes, 64 per cent infected mosquitoes. The gametocyte densities resulting in infections were relatively low, none being over 90 per cmm. Thirteen of the infections resulted when the gametocytes were fewer than 10 per cmm. Patients with asymptomatic parasitemias infected mosquitoes at about the same rate as did those who were symptomatic. As the asymptomatic group is considerably larger than the other, it is concluded that the former is mainly responsible for the transmission of malaria. There were 14 feedings upon P. malariae. Four cases showed gametocytes of a low density at feeding and three lots of mosquitoes were infected. Of 586 mosquitoes dissected, 1.7 per cent were infected. Of nine feedings upon P. vivax, none became infected nor were gametocytes present. It is concluded that the patient with an asymptomatic parasitemia, usually with a relatively low gametocyte density, is the important factor in the transmission and maintenance of P. falciparum and P. malariae malaria in the area studied.

The Importance of Coverage in DDT Residual House Spraying for Control of Anopheles quadrimaculatus Mosquitoes

The Importance of Coverage in DDT Residual House Spraying for Control of Anopheles quadrimaculatus Mosquitoes

Strains of Anopheles Quadrimaculatus

Summary and Conclusions 1. By mass selection it was possible to obtain two separate colonies of Anopheles quadrimaculatus mosquitoes which appeared morphologically identical but whose larval and pupal offspring maintained distinctly different color patterns. 2. The color pattern which was selected as a character and proved to be inheritable was a broad white stripe on the dorsal surfaces of larvae and pupae. 3. Experiments showed that the ratio of striped to nonstriped larvae and pupae was not influenced by alterations in light, food, or temperature. 4. Preliminary experiments to determine if the two strains of artificially selected A. quadrimaculatus could be separated on the basis of their susceptibility to experimental malaria were negative in that they seem equally susceptible.

EXPERIMENTAL STUDIES ON ENCEPHALITIS

Anopheles quadrimaculatus mosquitoes, fed on mice in which encephalitis virus (St. Louis type) is present in the blood stream, take up and retain the virus for the duration of their lives. The titre of the virus in mosquitoes 4 hours after engorging on mice with a maximum blood stream infection represents about 10,000 lethal mouse intracerebral doses per mosquito. This titre drops during the following 2 weeks to about 100 lethal doses per mosquito, but from the 3rd week to the death of the mosquito, usually increases to approximately the original level and remains there. The titre of virus in mosquitoes which have engorged on mouse blood containing smaller quantities of virus exhibits the same drop and subsequent rise to the original level. The virus-containing mosquitoes did not infect mice or monkeys by biting.