Areas Of Panama Research Articles

Spatial and temporal variation in shell crushing by fishes on rocky shores of Pacific Panama

Variation in consumer pressure has been invoked to explain differences in some marine communities on both large (latitudinal) and small (among areas or microhabitats) scales. On the Pacific coast of Panama, it has been hypothesized that (1) intertidal molluscs are active on ebbing and flowing tides in part to avoid predaceous fishes and (2) areas or microhabitats where fishes cannot forage effectively are likely to have a greater abundance of sessile organisms. However, fish predation has been experimentally measured only in short-term experiments at a single locale. We here examine variation in the effects of shell-crushing fishes along the rocky Pacific coast of Panama. The hypothesis that predaceous fishes are always present and active was tested by exposing gastropod shells to predaceous fishes at several sites within different regions of Panama's coast. If the hypothesis were valid, rates of shell crushing should show little temporal or spatial variation. In contrast with this prediction, our results show strong variation in rates of crushing among: (1) geographical areas of Panama, (2) sites within a single geographical area, (3) samples at different times at the same site, and (4) successive days within sites. Variation in consumer pressure is a potentially important factor and should be addressed in further studies of tropical rocky shores.

New Taxa of Caladium, Chlorospatha, and Xanthosoma (Araceae: Colocasioideae) from Southern Central America and Northwestern Colombia

Six new infrageneric taxa of Araceae, subfamily Colocasioideae, are described. Chlorospatha hammeliana is described from a restricted area of Panama, C. croatiana ssp. croatiana from Costa Rica and Panama, and Caladium lindeni (Andr6) Madison var. sylvestre from Panama and Colombia. These represent the first reported indigenous occurrences of the genera Caladium and Chlorospatha outside of South America. In addition, Chlorospatha gentryi and C. croatiana ssp. enneaphylla are described from northwestern Colombia. Chlorospatha croatiana and C. gentryi are the fourth and fifth species of their genus known to have compound leaves; a key is provided to all five. A brief review of generic distinctions within the tribe Caladieae precedes the description of the second known peltateleaved species of Xanthosoma, X. caladioides, from eastern Panama. The tribe Caladieae (sensu Madison, 1981), belonging to the subfamily Colocasioideae of the overwhelmingly tropical family Araceae, consists of six genera and 70-7 5 species, all confined to the New World. Three of the genera, Aphyllarum, Jasarum, and Scaphispatha, are monotypic and of restricted distribution in South America and will not be considered further in this paper. The remaining three genera, Caladium, Chlorospatha, and Xanthosoma, comprise the bulk of the species and range more widely, though only Xanthosoma has been heretofore reported to extend beyond South America (Croat, 1979; Madison, 1981). The Caladieae appear to be especially diverse in the Andean regions of northern South America, and recent work on newly available collections from that area (Madison, 1981) has led to the clarification of generic concepts in the group. These refined concepts have, in turn, facilitated the placement of new taxa collected in South America and other regions, including those described below. CALADIUM Caladium lin-denii (Andr6) Madison is well known in cultivation as an ornamental plant with whitish or silvery leaf venation. This species is more commonly, but improperly, known as Xanthosoma lindenii (Andr6) Engl., the transfer to Caladium having been made only recently (Madison, 1981). It was first described, as Phyllotaenium lindenii Andr6, in 1872, from plants supposedly collected in Colombia; although persisting in cultivation, the species was not found again in the wild until 1939, when a form with plain green leaves was collected in Choc6 Department, Colombia (Killip 35140, COL). Subsequent collections have extended the known natural range of this species-and consequently of the genus Caladium-into central Panama. All collections of the plain-leaved form have, until recently, either been misidentified or left

Why Are Seeds of the Central American Guanacaste Tree, Enterolobium cyclocarpum , 1 Not Attacked by Bruchids 2 Except in Panam?

The ranges of most other bruchids are usually contiguous with their hosts, but Stator generalis (Coleoptera: Bruchidae) is known to feed only in exposed seeds of guanacaste, Enterolobium cyclocarpum (Leguminosae: Mimosoideae),in a restricted area of central Panama. Because this tree is widespread in the neotropics and yet is not preyed upon by seed beetles throughout the rest of its range, we fed seeds from Mexico, Guatemala, El Salvador, Honduras, and Costa Rica, and from other areas of Panama, to S. generalis . They were able to develop normally in all these seeds; thus, we rejected the hypothesis that seeds from central Panama were chemically unique. We hypothesize that S. generalis has not spread northward, because guanacaste seeds are not available in amounts or a pattern appropriate for S. generalis to survive. This is because cattle and horses eat nearly all the fruits, thereby widely scattering the cleaned seeds. Small rodents which have access to horse and cattle dung remove the seeds even farther from a state accessible to bruchids. Further, variability in the number of seeds set and available in a specific locality may also reduce the pool of bruchids available for emigration and raise the chance for local extinction. Probably a pool of fruit-free seeds exposed on the surface of the ground only accumulates in sufficient quantity to maintain a population of S. generalis in localities such as city parks, gardens, corrals, and other areas where there is considerable human traffic. The possible effects of Pleistocene large mammals on this system are also discussed.

Population fluctuations of mosquitoes in the non‐seasonal tropics

Abstract. Seasonal and annual fluctuations in abundance of a number of species of mosquitoes were studied in a relatively non‐seasonal climate near Almirante, Panama. The fluctuations observed were large, but did not have a period of 1 year and should be classified as non‐seasonal. At each site the various species were not synchronous in their fluctuation pattern, but the fluctuations of each species were synchronous over an area of at least 4 km long, in spite of large differences in habitat. Changes in abundance from year to year observed in these mosquitoes are large compared with those of insects, including mosquitoes, in other areas of Panama. The importance of such large and unpredictable fluctuations in abundance for planning control measures is discussed.

Host Feeding Profiles of Rhodnius Pallescens (Hemiptera: Reduviidae) in Rural Villages of Central Panama *

Rhodnius pallescens, reported to be the principal vector of Chagas' disease in central Panama, has been shown to feed on opossums, anteaters, sloths, rodents, birds and, rarely, lizards in sylvatic habitats in this country; however, the extent of its anthropophagic affinities in rural areas has never been determined. The host selections of 1,340 R. pallescens from domestic and peridomestic habitats of three Panamanian villages were determined by microcapillary precipitin tests. Slightly more than half of the triatomines collected in houses and nearby palm trees and bird nests had fed on humans. Opossums, which are important reservoirs of Trypanosoma cruzi in Panama, were the second most frequently selected host. The importance for the transmission of Chagas' disease to humans of the close relationship between the principal vector and reservoir in sylvatic and peridomestic environments and the anthropophagy of the former is discussed. Pigeons and chickens were the dominant bloodmeal sources of triatomines collected in their respective shelters. The roof rat, Rattus rattus, was the third most common mammalian host, and may represent an ancillary reservoir in the transmission of Chagas' diseases in rural areas of Panama.

Additions to the Ericaceae of Panama

The following taxa of Ericaceae are newly described from Panama: Cavendishia aberrans Luteyn, C. arizonensis Luteyn, C. chiriquiensis var. bullata Luteyn, C. fortunensis Luteyn, Didonica panamensis Luteyn & Wilbur, Disterigma hammelii Wilbur & Luteyn, Lateropora tubulifera Wilbur & Luteyn, Macleania megabracteata Wilbur & Luteyn and Themistoclesia revoluta Wilbur & Luteyn. Cavendishia quereme (H.B.K.) Bentham & Hooker is reported for the first time from Panama, being previously known only from Costa Rica and Colombia. Vaccinium dissimile Blake is now known from Col6n Province and the range of Vaccinium jefense Luteyn & Wilbur is extended to include Cock6 Province. Keys to the Central American representatives of the genera Disterigma, Lateropora, and Themistoclesia are provided. It may be surprising to many that, although an account of the Ericaceae of Panama was published only recently (Wilbur & Luteyn, 1978) based upon a study of all collections available in the American herbaria with significant holdings of Panamanian plants, a paper would be published so soon increasing by 15% the known ericad flora of that small county. All of these additions are based upon collections previously unavailable to us, and almost all are from collections made in only recently explored areas. It is safe to predict that many additional species await discovery in the extensive areas of Panama that are botanically either unexplored or little explored, and it is to be hoped that funds for continued exploration will be forthcoming. Obviously the botanical exploration of this biogeographically critical area is far from completed.

Polychaetes from intertidal areas in Panama, with a review of previous shallow-water records

Polychaetes from intertidal areas in Panama, with a review of previous shallow-water records

Production of Phlebotomine Sandflies 1 on the Open Forest Floor in Panama: The Species Complement

Breeding populations of phlebotomine sandflies (Diptera, Psychodidae) on the floor of a rain forest in Panama were studied with soil emergence traps. The species Lutzomyia trapidoi (Fairchild and Hertig) was predominant. L. panamensis (Shannon), L. gomezi (Nitzulescu), L. pessoana (Barretto), L. rorotaensis (Floch and Abonnenc), and L. insolita (Fairchild and Hertig) were regularly collected. The overall mean emergence rate was estimated at 24 sandflies/100 m2 of forest soil per day. Data are given on the sex ratios, local and seasonal effects, and associated animal taxa. The ecology and medical importance of the species complement of the forest floor habitat and the implications of the study with regard to sand fly control are discussed. It was concluded that the availability of vector sandflies is probably not the primary limiting factor in the distribution of leishmaniasis in forested areas of Panama.

Additional Panamanian Myristicaceae

Recent collections from wet forest areas of Panama include several species of Myristicaceae new to science or to the North American continent. The two new species described below are of special interest as having the largest fruits in their respective genera.

The venomous coral snakes (genus Micrurus) of Costa Rica.

Four species of venomous coral snakes ( Micrurus ) occur in Costa Rica. The single bicolor species, M. mipartitus has previously been defined as two subspecies; however, variations in diagnostic characters clemonstrate dinal shift that precludes recognition of geographic races. Presence of the tricolor M. clarki is concluded from but a single Costa Rican specimen, although the species is otherwise definitely known from adjacent areas in Panama. Variation among tricolor coral snakes allied to M. nigrocinctus suggests the presence of three populations that occupy southwestern Pacific Costa Rica, northwestern Pacific Costa Rica and western Nicaragua, and Atlantic lowland Costa Rica. Gradual intergradation in the Pacific lowlanels, as well as more complex intergrading patterns in the Meseta Central and Arenal regions and over a broad arca of Nicaragua, eliminate the value of subspecific designations. Where M. nigrocinctus occurs sympatrically with populations of the closely related M. alleni , they can be constently distinguished by differences in head cap patterns and segmental counts. Micrurus alleni is composed of three allopatric populations in the Atlantic lowlands of Costa Rica anel Nicaragua, the southwestern Pacific lowlands of Costa Rica and adjacent southwestern Panama, and Pacific lowland Darien in eastern Panama. Becaust of limited information on variation among these populations we prefer not to apply the trinomials.

A New Species of Cissus (Vitaceae) for Central and South America

Cissus pseudosicyoides is described as new. The species ranges from Costa Rica to Colombia. Though it has been confused in the herbarium with C. sicyoides L., it is probably more closely related to C. biformifolia Standley with which it shares dimorphic leaves and appressed T-shaped trichomes. It is most easily distinguished from C. sicyoides by having minute puberulence on most parts with occasional T-shaped trichomes and by having pubescent pedicels. It is distinguished from C. biformifolia by being densely puberulent and by having smaller greenish flower buds and smaller fruits. Two unifoliate species of Cissus, C. sicyoides L. and C. biformifolia Standley, were reported in the Flora of Panama (Elias, 1968). In the course of my work on the Barro Colorado Island (Panama) flora, another species has been discovered. Cissus pseudosicyoides, sp. nov. Herba scandens cirrhosa; rami parvi et nervi foliorum trichomatibus brevibus inconspicuis, approximatisque necnon trichomatibus T-formibus, sparsis, adpressisque. Folia alterna, sicco nigrescentes; limbo foliorum majorum ovato-cordato, 9-15 cm longo, 9-12 cm lato, nervis lateralibus utroque latere 3-6; petiolis foliorum majorum 7-11 cm longis; limbo foliorum parviorum anguste ovatis, basi truncato aut obtuso aut acutato, 3-10 cm longo, 2-8 cm lato. Inflorescentia 1-4 cm longa; pedunculo florenti 2-10 mm longo, trichomatibus T-formibus densis adpressis; calyx expansus, + crateriformis, 4-lobatus remote, alabastro latiorus; alabastrum ovoideum, 1.5-2 cm longum; petalum album aut cremeum (ruber aliquando). Fructus + globosus, ad 6 mm diametro, viridis. Flores per initium tempus sicci. Tendrilled herbaceous vine, probably ultimately arising from a woody stem; at least smaller stems, petioles, and veins of leaf blades (especially below) closely and inconspicuously puberulent; the same parts but also the axes of the inflorescence, pedicels, and leaf surfaces often sparsely pubescent with flattened, + appressed T-shaped trichomes; stems of juvenile parts often white-speckled; leaves alternate, thin, usually drying dark, the larger ones borne below the inflorescence, ovate-cordate, as broad or nearly as broad as long, 9-15 cm long and 9-12 cm wide, with 3-6 pairs of lateral veins above sinus, with a single strong trunk vein extending into each basal lobe, the veins extending into apiculate teeth along the margin of the blade, the sinus about as deep as broad; petioles mostly 7-11 cm long; leaves higher on the stem and opposite the inflorescences usually narrowly ovate, smaller and with the base truncate to obtuse or acute at base (rarely cordate at base), mostly 3-10 cm long and 2-8 cm wide with petioles mostly 2-8 cm long, otherwise as the larger leaves. Inflorescences terminal or opposite upper leaves, small, congested, branched, umbelliform cymes 1-4 cm long, about as broad as long; peduncles mostly 2-10 mm long at anthesis (somewhat longer in fruit), densely appressed-pubescent with T-shaped trichomes, densely bracteate at apex, the bracts minute with margins glabrous or very in' Curator of Phanerogams, Missouri Botanical Garden, 2315 Tower Grove Avenue, St. Louis, Missouri 63110. ANN. MISSOURI BOT. GARD. 60: 564-567. This content downloaded from 157.55.39.243 on Thu, 06 Oct 2016 04:54:34 UTC All use subject to http://about.jstor.org/terms 1973] CROAT-A NEW CISSUS 565 conspicuously ciliate; pedicels terete, 1.5-3.5 mm long, sparsely pubescent, the trichomes as on peduncles but usually smaller; calyx spreading, + bowl-shaped, inconspicuously 4-lobed, narrower than the buds, nearly glabrous; buds ovoid, 1.5-2 mm long, drying with ridges along the margins of the petals; corolla of 4 free, broadly oblong petals, these obtuse and cucullate at apex inside, usually white or cream (rarely red); stamens opposite petals; filaments to ca. 1 mm long, equalling or longer than anthers; anthers nearly as broad as long, dehiscing laterally; stigma simple, to ca. 1.5 mm long. Fruits ? globose, to 6 mm in diameter, apparently green at maturity; pericarp and mesocarp thin; seed 1, round, only slightly smaller than the dimensions of the fruit. HOLOTYPE: Panama. Canal Zone: Barro Colorado Island, Clearing at laboratory; vine; fruits green; flowers greenish. 9 January 1969. Croat 7017 (MO). Flowers at the beginning of the dry season in December and January on Barro Colorado Island (rarely elsewhere as late as March) or in the rainy season (late July-October). Individual plants may flower for one month or more. The fruits develop promptly, usually are present with flowers, and are usually gone by March. They are probably dispersed by smallto mid-sized birds. It is not known whether the fruits become brightly colored or not. Observations on Barro Colorado Island indicate that the fruits are probably removed before turning color. Cissus pseudosicyoides ranges from Guanacaste Province of Costa Rica to northern Colombia. It is widespread in lowland areas of Panama, principally from the Pacific slope in drier areas of tropical moist forest but is also known from premontane wet forest at Chiman and premontane dry forest at Juan Diaz

Elemental and Hydrologic Budgets of the Panamanian Tropical Moist Forest

Humid tropical forest ecosystems are among the most complex terrestrial systems on earth in terms of their biotic and abiotic interactions and have a great diversity of taxonomic groups. It is easier to study the whole tropical forest system rather than its component individuals (Feibleman, 1965; Van Dyne, 1966) and its processes of production, decomposition, herbivory, carnivory, parasitism, and symbiosis (Evans, 1956; Odum, 1963) rather than its structure. The structure and composition of forests in eastern Panama, northwestern Colombia, and related areas have been studied extensively by Richards (1952), Cain (1963), Holdridge (1963), Beard (1955), Ruinen (1961), Golley et al. (1962), Espinal and Montenegro (1953), and specifically for this area by Golley et al. in this symposium. The University of Georgia Institute of Ecology, supported by Battelle Memorial Institute, authorized under Public Law 88-609, 88th Congress, performed terrestrial ecology studies in the areas of Panama and Colombia as a part of the Interoceanic Sea-Level Canal Feasibility Study. This report describes some aspects of the movement and storage of stable elements through hydrologic and elemental functions of the Tropical moist forest ecosystem.

Epidemiologic studies of Venezuelan equine encephalitis virus in Almirante, Panama.

Grayson, M. A. and P. Galindo (Gorgas Memorial Laboratory, Panama, Re-public of Panama). Epidemiologic studies of Venezuelan equine encephalitis virus in Almirante, Panama.Amer. J. Epid., 1968, 88: 80–96. —Forty-three isolations of Venezuelan equine encephalitis (VEE) virus were made from specimens collected or exposed in a tropical rainforest area of Panama during 1961 and 1962. Six isolates were recovered from febrile patients, seven from field rodents and nine from at least six species of wild birds. Twelve strains of VEE virus were obtained from at least four species of mosquitoes, and nine litters of sentinel mice exposed to the bites of bloodsucking insects also yielded the virus. Serologic evidence of VEE virus activity in the area before 1961 was acquired. Antibodies to VEE virus were detected in 25 species of vertebrates including humans, equines, bovines, canines and domestic fowl as well as several species of wild mammals, birds and reptiles. Human infections with VEE virus were widespread, occurred nearly uniformly in both sexes and were associated with length and place of residence in Almirante. The accumulated evidence suggests that VEE is endemic in Almirante, Panama; that rodents, especially the cotton rat (Sigmodon hispidus), are important reservoirs; and that Culex (Melanoconion) mosquitoes, in particular, C. (M.) taeniopus, are the most efficient vectors of this virus in the area.

New Species of Lisianthus (Gentianaceae) From Panama

Study of collections of Lisianthus L. from hitherto uncollected areas in Panama, viz. Cerro Jefe in the Province of Panama and the mouth of Rio Concepcion in the Province of Veraguas, yielded the following two new species: L. jefensis and L. scopulinus. During the December 1967 Missouri Botanical Garden's expedition to Panama under the direction of Walter H. Lewis (in which the senior author took part), collecting along the mouth of Rio Concepcion and in other inaccessible areas was made possible through a grant from the U.S. Air Force Office of Scientific Research (Grant No. F44620-67-C-0055). This included transportation by helicopter from Albrook Air Force Base in the Canal Zone to sites in the Provinces of Colon, Darien, Los Santos, Panama, Veraguas, and in the Comarca de San Blas.

Echinococcus oligarthrus (Diesing, 1863) from a Panamanian Jaguar (Felis onca L.)

FIGURES 1, 2. Echinococcus oligarthrus from a Panamanian jaguar. 1. Maturing proglottid showing position of genital pore and cirrus sac X 100. 2. Hooks from scolex; two large and one small X 500. redescribed the species on the basis of a collection from a jaguarundi (Felis yagouaroundi Geoffroy) that had died at the London Zoo. Recently Thatcher and Sousa (1966, Ann. Trop. Med. Parasit. 60: 405-416) presented a redescription of E. oligarthrus based on Panamanian material from both the previously known felid definitive hosts, and implicated man as a possible intermediate host. The present report supplements the previous paper in that it records E. oligarthrus from the jaguar (Felis onca L.) for the first time. In February 1967, a 75-lb female jaguar was shot near Achiote, Colon Province, Republic of Panama. Examinations of the upper intestinal tract revealed the presence of about 6,000 specimens of Echinococcus. The parasites occurred throughout the small intestine, but were more concentrated in the anterior portion. The worms showed development of the reproductive structures, but they were not gravid. That the worms belong to the species E. oligarthrus is shown by the limited number of testes and the anterior position of the genital pore (Fig. 1). The hook morphology is typical of young specimens of E. oligarthrus. Although the small hooks are almost completely developed, the large hooks lack well-developed handles (Fig. 2). The jaguar was obtained in an area of Panama that Thatcher and Sousa (loc. cit.) had reported to be endemic for E. oligarthrus. To date, infections have been found in four wild felids (two pumas, one jaguarundi, and one jaguar) from the Achiote area. Two young jaguars from the same area were negative.

An ecological survey for arboviruses in Almirante, Panama, 1959-1962.

SummaryA three-year survey was conducted to determine the arboviruses active in a tropical rainforest area of Panama. Materials for virus isolation attempts consisted of blood specimens from febrile patients, sera and tissues from domestic and wild vertebrates, blood-sucking insects taken on a variety of baits and sentinel mice exposed in the field. These specimens were collected or exposed in a variety of habitats which included upland tropical rainforest, swamp forest, open freshwater marsh and domestic and peridomestic habitats. Following is a list of the arboviruses isolated and the sources from which they were obtained: Venezuelan equine encephalomyelitis: human blood, wild rodents, sentinel mice, adult birds, nestling birds, mosquitoes; Una: mosquitoes; Mayaro: mosquitoes; Bussuquara: sentinel mice, mosquitoes; Ilhéus: adult birds, mosquitoes, Phlebotomus sandflies; Caraparu: sentinel mice; Nepuyo: wild rodents; Ossa: human blood; Madrid: human blood, sentinel mice; BT 4971 (new group C agent): wild rodents, sentinel mice; BT 5012 (new group C agent): wild rodents, sentinel mice; Guama group: sentinel mice, mosquitoes; Cache Valley: mosquitoes; Guaroa: mosquitoes; Wyeomyia: mosquitoes; Vesicular stomatitis (Indiana): Phlebotomus sandflies; BT 436 (new arbovirus type): human blood, Phlebotomus sandflies.The report concludes with a discussion of annual cycles of virus activity and considerations on the habitat in relation to arbovirus activity.

SURVEILLANCE FOR SYLVAN YELLOW FEVER ACTIVITY IN PANAMA (1957-1961).

Summary A surveillance report on sylvan yellow fever in Panama from 1957 to 1961 is presented. The last known outbreak of yellow fever in this country occurred in June 1957 near the town of Buena Vista, located along the Transisthmian Highway a few miles east of the Panama Canal. During the outbreak, yellow fever virus was isolated from the blood of an acutely ill human and from forest, day-flying, arboreal mosquitoes. Failure to isolate yellow fever virus from forest mosquitoes and vertebrates captured in various areas of Panama and results of neutralization tests on the blood of numerous primates and other vertebrates lead the authors to the conclusion that yellow fever virus has not been active in Panama since 1957.

Notes on Sarcosporidia of Birds in Panama

in the present study. These infected birds were found in a lot of 36 specimens, representing 21 species, examined for Sarcocystis. They were collected in 1952-53 from areas of Panama near the Canal Zone, while the writer was at the Gorgas Hospital Laboratory. Each bird was examined for intestinal and blood parasites. Blocks of tissue routinely were cut from the vital organs and muscle and preserved in 10% formalin for the later preparation of sections which were stained with hematoxylin and eosin. Generally, Sarcocystis infection was noted only during the microscopic examination of striated muscle sections. However, the sarcocysts in the collared aricari were seen while the bird was being skinned. In the one infected aricari of the 4 examined, the back, breast, thigh, and neck nmuscles of the bird contained numerous elongated yellow capsules which were 1 to 1.5 mm long and about half as wide. Some of the capsules were removed, ruptured, and the contents stained with Giemsa's stain after heat fixation. Bananashaped sporozoites, 3 to 4.5 microns long and about 1 micron wide, with subterminal nuclei were demonstrated. In longitudinal sections, the largest sarcocyst was 1.23 mm long and 0.339 mm wide at the point of greatest diameter. The cysts were oval in shape and bounded by a thin membranous wall. Many sarcocysts were measured which ranged from 0.462 to 0.678 mm long and 0.123 to 0.354 mm wide. There was also a large number of very much smaller cysts ranging from 0.046 to 0.154 mm in length and 0.031 to 0.092 mm in width. The large cysts, those over 0.3 mm in diameter, were divided into numerous honeycomb-like chambers at the central portion of the cyst, the Kammerung of Miescher. The central chambers were free of sporozoites and contained only a few scattered ovoid bodies, 2.2 to 4.5 microns in diameter which stained pale pink with eosin. Sporozoites were densely packed into similar chambers in the peripheral portions of the sarcocysts. The Sarcocystis parasitizing the aricari produced marked distortion of the infected muscle fibers. There was no evidence of tissue reaction to the parasites in

Fifty Years of Malaria Control in the Panama Area

Summary The efforts to control malaria in the vicinity of the Panama Canal during a half century were progressively more successful as new methods developed. Sanitary engineering works of a permanent type have controlled mosquito breeding in the vicinity of communities in the Canal Zone. A battery of chemicals are in use for destroying mosquitoes in all phases of their life cycle and new drugs for effectively attacking the malaria parasite in the human carrier and patient are now at our disposal. Malaria has been reduced to an uncommon disease in the Canal Zone and urban communities of the Republic of Panama enjoy a considerable degree of freedom from infection, but rural communities and hamlets continue to lose much of their economic production potential due to malaria. Aggressive antimalaria programs temporarily reduce the disease but eradication has not been achieved in Panama. Temporary inactivity of malaria in a community may delude the inhabitants but the disease is unlikely to remain quiescent for long. Continuing and unremittent application of control measures by the individual and the community aimed at reducing the vector and treating the carriers is the solution to this problem in the Panama area. Once initiated, the control should be integrated into the community functions and become a permanent part of the community routine.

The Residual Spraying of Dwellings with DDT in the Control of Malaria Transmission in Panama, with Special Reference to Anopheles Albimanus 1

Summary and Conclusions This paper reports the results of the first fifteen months study of the DDT residual house spray method in the middle Chagres River area of Panama, where the principal malaria vector is Anopheles albimanus. Houses of cane wall and palm-thatch roof construction at the village of Gatuncillo were sprayed, inside and out, with a 5% solution of DDT in kerosene at fourmonth intervals (excepting one trial period of six months). Entomological observations were made at this treated village and two adjacent villages used as controls. It is demonstrated that with this technique anophelines visiting the dwellings are affected in three ways: 1. There is a large reduction in numbers of mosquitoes. 2. Among the mosquitoes which are taken in treated dwellings there is a marked reduction in the per cent engorged, since DDT activates the insects and they lose interest in feeding. 3. Among the engorged mosquitoes the twenty-four hour survival rate is low for three months after treatment. It is thus indicated that the technique tends selectively to reduce the malaria transmission potential by affecting principally those mosquitoes concerned in transmission. Four months is established as the optimum time for retreatment in the area studied. It is demonstrated that with each successive treatment the degree of control improves. (For the period following the third treatment the malaria transmission potential is reduced 99.9%.) Treatment of houses alone was found to produce marked reduction of mosquitoes in the village area outside the houses, and even to some measure in the forest adjacent to the village (for at least three hundred feet), for several weeks. There is evidence of reduction of malaria in the fourteen-month period following the first treatment. The cost of the treatment under conditions of this experiment is calculated as $1.31 per house. Factors affecting the cost of applying the method elsewhere in tropical America are discussed. The place of this method in relation to other malaria control procedures and to the economy of the area is discussed.