Rodent Trapping Research Articles

Life history of Ixodes (Ixodes) jellisoni (Acari: Ixodidae) and its vector competence for Borrelia burgdorferi sensu lato.

Ixodes (Ixodes) jellisoni Cooley & Kohls, a nonhuman biting and little known tick, is one of 4 members of the I. ricinus complex in the United States. A localized population of I. jellisoni inhabiting a grassland biotope in Mendocino County, CA, was studied from 1993 to 1997. Rodent trapping in all seasons revealed that the only host of both immature and adult I. jellisoni was the heteromyid rodent Dipodomys californicus Merriam. Field investigations suggested that I. jellisoni is nidicolous in habit, and laboratory findings demonstrated that it reproduces parthenogenetically. Known parthenogenetic females (n = 4) produced an average of 530 eggs of which 74% hatched, which was comparable to the fecundity and fertility of wild-caught females (n = 8). After the transstadial molt, 57 F1 or F2 nymphs derived from 2 wild-caught or 4 laboratory-reared, unmated females produced only females. Ixodes jellisoni males were not found on 112 wild-caught D. californicus individuals that were captured an average of 2 times. Collectively, these findings suggest that I. jellisoni may be obligatorily parthenogenetic. Borrelial isolates were obtained from 85% of 58 D. californicus and 33% of 21 I. jellisoni females removed from this rodent. None of the 7 infected female ticks passed borreliae ovarially to its F1 larval progeny. Eight D. californicus and 5 I. jellisoni-derived isolates that were genetically characterized belonged to 2 restriction pattern groups of Borrelia burgdorferi s.l. Neither restriction pattern group has been assigned to a particular genospecies yet. After placement on naturally infected D. californicus, noninfected larval ticks acquired and transstadially passed spirochetes as efficiently as (group 1 borreliae) or 6 times more efficiently (group 2 borreliae) than Ixodes pacificus Cooley & Kohls. As few as 1-4 infected I. jellisoni nymphs were capable of transmitting group 1 or group 2 borreliae to naive D. californicus. We conclude that I. jellisoni is a competent vector of both restriction fragment groups when D. californicus is used as the animal model.

Short report: Decrease in seroprevalence of antibodies to hantavirus in rodents from 1993-1994 hantavirus pulmonary syndrome case sites.

Rodent trapping was conducted at seven hantavirus pulmonary syndrome (HPS) case sites from June 1993 to March 1994 during the HPS outbreak in the southwestern United States. To determine if there were changes in the rodent population or the hantavirus seroprevalence in rodents since the HPS outbreak, rodents were trapped at the same sites three years later using the same trapping protocol. The trap success decreased from the numbers trapped during the outbreak, however, the number of Peromyscus, as a percentage of the total rodents captured, did not noticeably decrease. In addition, the seroprevalence of hantavirus antibodies in Peromyscus decreased significantly (P < 0.0001).

Deer ticks (Ixodes scapularis) and the agents of Lyme disease and human granulocytic ehrlichiosis in a New York City park.

Rodent trapping and drag sampling in Van Cortlandt Park, New York City, yielded all stages of Ixodes scapularis, the deer tick vector of Lyme disease and human granulocytic ehrlichiosis (HGE). Polymerase chain reaction analyses of the ticks showed Borrelia burgdorferi and the Ehrlichia sp. that causes HGE.

Rodent cycles in relation to biomass and productivity of ground vegetation and predation in the Palearctic

Authors have synthesized the data on population dynamics and densites of rodents in seven biomes of the Palearctic (mainly western parts), and related them to the data on standing crop of biomass and the net productivity of ground vegetation (as rough indicators of food availability to rodents). Analysis of 44 long-term (≥ 5 years) series of rodent trapping showed that there was a continuum from highly cyclic to non-cyclic populations. Rodents inhabiting tundra, taiga, steppe, and farmlands (wintercrops) in the temperate zone have highest cyclicity indices. Definetely non-cyclic are rodents in the temperate forests (mixed and deciduous forests, steppe woodland) and desert.

A household-based, case-control study of environmental factors associated with hantavirus pulmonary syndrome in the southwestern United States.

During an outbreak of hantavirus pulmonary syndrome (HPS) in the southwestern United States, trained environmental assessment teams conducted surveys at 17 case-patient homes and matched controls from June through August 1993. Variables related to rodent abundance were quantified and standardized rodent trapping was conducted around and within households. The majority of households were located in pinon-juniper vegetation zones, and there were no significant differences in the type of house in which cases and controls lived. The only environmental factor that distinguished case households from controls was significantly higher small rodent densities (median trap success for case sites = 17.3%, 12.7% for near controls, and 8.3% for far controls). Frequency of hantaviral infection in deer mice (Peromyscus maniculatus) did not vary significantly among households of cases and controls, with a range of 27.5-32.5% antibody-positive. Indices of rodent fecal contamination were slightly higher in case houses. The data indicate that higher rodent densities were associated with households in which HPS cases occurred. Strategies that control rodent numbers and decrease rodent access to dwellings may reduce risk of human infection.

HABITAT PREFERENCES, POPULATION SIZE, FOOD AND BREEDING OF SIX OWL SPECIES IN THE SPRINGBOK FLATS, SOUTH AFRICA

Summary MENDELSOHN, J. M. 1989. Habitat preferences, population size, food and breeding of six owl species in the Springbok Flats, South Africa. Ostrich 60:183-190. Information on the habitat preferences, population size, food and breeding of Barn, Grass, Whitefaced, Marsh, Pearlspotted and Spotted Eagle Owls was obtained in a 6900-ha area in the Springbok Flats, South Africa. Seventy-two per cent of the area consisted of cultivated fields not usually used by owls. Hunting, roosting and nesting requirements were largely met in 1930 ha of verges, farmyards and patches of wood land ant grassland, here was an estimated total population of 303 owls in the area, giving an overall density of 22,7 ho/owl for the whole area or 6.4 ha/owl for those areas used by owls. These high densities were attributed to an abundance of Mastomys natalensis, the most important prey item for all except Pearlspotted Owls. Rates of predation on M. natalensis varied in relation to their population density, as indicated by rodent trapping results. Marsh Owls ate more insects in summer than at other times. Barn and Marsh Owls usuall laid in March-April and August-September, while other species started breeding in July-October. de timing of breeding of some owls may be related to changes in rates of recruitment of juvenile M. natalensis. Most Marsh Owl nests were placed on the southwestern sides of grass clumps or shrubs.

Small Rodent Populations in Selectively Felled and Mature Tracts of Kibale Forest, Uganda

Live trapping of small rodents was conducted in two adjacent tracts of tropical evergreen forests, selectively felled (K14) and relatively undisturbed mature forest (K30). Small rodents representing 14 species were examined. With the exception of Hybomys univittatus Peters in K14, two species, Praomys (Hylomyscus) stella Waterhouse and Praomys jacksoni de Winton, were the most abundant species in both types of forest during 1977-1978. Most rodent species were represented in both K14 and K30, but those normally associated with forest edges and Savanna habitats such as Lophuromys flavopunctatus Thomas were more abundant in selectively felled than in mature forest. Rodent density ranged from 0.7 to 26 rodents/ha in K14 and from 0.7 to 21.3 rodents/ ha in K30. Both rodent species richness and diversity were higher for plots located in selectively felled than in uncut mature forest. Furthermore, rodent species diversity was positively highly correlated with the estimated percent ground vegetation cover (which was also significantly higher in K14 than K30), whereas rodent species richness was inversely correlated with tree species richness. Seasonal fluctuations in rodent populations were similar in both types of forest but were of greater magnitude in the selectively felled forest than in the mature one. MOST STUDIES ON THE ECOLOGY of small African rodents have concentrated on communities in savanna, secondary bush, or formerly cultivated land. Delany (1972) and Fleming (1975) have summarized most of these studies. Those few studies on forest-inhabiting rodents were mostly of short duration (e.g., Delany 1964; Dieterlen 1966, 1967). Recently information on long-term studies of small forest rodents has become available (e.g., Delaney 1971, Cole 1975,Jeffrey 1977, Happold 1978, Emmons 1980). Some of these studies indicate that a simplification of the tropical forest ecosystem leads to changes in small rodent communities, allowing both population increases by formerly rare species and invasion of forest by species normally associated with forest edges and savanna (e.g., Jeffrey 1977). It has also been suggested that, since most of these small rodents are also seed and seedling predators (Synnott 1975; Genest-Villard 1980; Kasenene and Isabirye-Basuta, in press), their increase in numbers in the wake of forest degradation could affect tree regeneration and possibly the future floristic composition of the forest. This paper reports the results of two studies that investigated long-term trends in the numbers and species composition of small rodents in a relatively undisturbed mature forest and in an adjacent selectively felled forest. We were particularly interested in the effects of selective logging on rodent species richness and diversity.

Small mammals and stored food losses in farm households in Bangladesh

Small-mammal activity indices were obtained with inked tracking tiles before and after 3 nights of removal trapping in farmers' households in Bangladesh. This procedure was followed for 12 months, using 12 different households during each monthly cycle. From the change in proportion of positive tracking tiles before and after trapping, and the number of animals removed, it was possible to estimate the pretrapping population of small mammals: house mice ( Mus musculus) constituted 53% of total captures, and the Asiatic house shrew ( Suncus murinus) accounted for 34%; of lesser importance were bandicoot rats ( Bandicota bengalensis) and roof rats ( Rattus rattus). The estimated small-mammal population varied from 170 in December 1982 to 40 and 34 in March and August 1983, respectively. The rodent population estimated in the farmers' households averaged 8·3 mice and 2·0 rats per household. These rodents were estimated to consume and hoard about 53 kg of rice per farm family per year. Because tracking tiles and traps were placed only on the floors of the structures, data collected on rodent activity and trap captures underestimated the small-mammal populations; consequently, stored food loss estimates represent a minimum per year.

Case-control study of Mastomys natalensis and humans in Lassa virus-infected households in Sierra Leone.

Lassa virus infection and antibodies were studied in households where Lassa fever cases occurred, and compared to those in nearest neighbor houses and "far" houses located across the village from case houses. Seventy-nine percent of all rodents caught in the houses were Mastomys, the natural reservoir of Lassa virus. Rodent infection was not randomly distributed, but rather focal. Thirty-nine percent of the Mastomys in case houses were viremic, compared to 3.7% in control houses. Human antibody prevalence in case houses was 30%, compared to 20% in non-case houses (P less than 0.05, chi-square test, df = 2). Neither seroconversions nor antibody prevalence rates were associated with household size or number of persons per room. Trapping of rodents in half of the case and control houses resulted in a Mastomys reduction ranging from 2.2- to 3.3-fold. This reduction failed to significantly reduce the seroconversion rate to Lassa virus in the people of trapped houses compared to those in untrapped ones. More complete trapping will be needed in order to better evaluate this procedure as a means of interruption of Lassa virus transmission in endemic villages.

Laboratory-acquired infections with Hantaan virus, the etiologic agent of Korean hemorrhagic fever.

Clinically apparent infections with Hantaan virus, the etiologic agent of Korean hemorrhagic fever, occurred in nine persons exposed to the virus at the Korea University Virus Institute (Seoul) between 1971 and 1979. All were directly related to trapping of wild rodents or work with naturally or experimentally infected wild and laboratory rodents in a designated animal suite. All infections were acquired during the months of November-April, and none was associated with accidental parenteral inoculations. These facts suggested that aerosols produced by chronically infected rodents were the infectious vehicles and that limited air circulation and lowered humidity in the animal rooms during winter months increased the probability of viral transmission. Four persons, including two casual visitors, became ill within four months after the initiation of experimental studies of infections in Wistar rats with Hantaan virus, an occurrence suggesting that this rodent may be a highly infectious host for Hantaan virus.

Studies of the epidemiology of arthropod-borne virus infections at Mitchell River Mission, Cape York Peninsula, North Queensland IV. Arbovirus infections of mosquitoes and mammals, 1967–1969

Studies of arbovirus epidemiology at Mitchell River were continued in 1967–1969 by further mosquito collections in February–March 1967 (wet season), by collections of mosquitoes, trapping of rodents, shooting of other mammals and exposure of sentinel mice and chickens in November 1967-January 1968 (late dry season and early wet season), by further collections of mammals in December 1968 and by trapping of rodents and other vertebrates in April 1969. Ross River virus was isolated from Culex annulirostris collected in February and March 1967 and January 1968, and from Wallabia agilis shot in January 1968; Kokobera virus was isolated from Ae. vigilax trapped in early 1967. Inhibitors (tentatively viewed as antibody) of Ross River and Kokobera viruses were common in wallabies. Inhibitors of other group B viruses, reacting to highest titre with members of the Murray Valley encephalitis virus subgroup, were found in fruit bats (Pteropus), pigs, dogs and cattle. The low isolation rate from mosquitoes in the wet season of early 1967, when rainfall was heavy, is at variance with previous observations which suggested that arbovirus activity was correlated with rainfall. The study adds to previous evidence that wallabies and kangaroos may be important vertebrate hosts for Ross River virus. It has not shown how Murray Valley encephalitis and related viruses survive the dry season but has indicated several hosts (fruit bats, dogs and cattle) as worthy of further study.

Quelques données sur les Lézards (Lacerta viridis et L. agilis) marques à la pointe d’Arçay (Vendée)

In a tidal marsh along the Vendee coast, a programme of rodent trapping enabled the study of a Lizard community comprising two species : Lacerta viridis and L. agilis. Individuals were weighed, marked and released. The two species were active from April to August. They shared, without apparent competition, a common hunting area ; this seems referable to a slight difference in activity hours and preferential activity zones. A narrow barrier beach, always above sea-level, is used as a wintering area and, at least by L. viridis, for night resting places during summer. There is a tendency among recaptured individuals to use a restricted (20-30 m diameter) activity range. Some individuals of the two species have been recaptured in two successive summers.

Range of Movement of Some Malayan Rats

Although accounts of experiments involving the trapping and retrapping of marked rodents are now numerous, no such studies seem to have been made of the many species of rats in Southeast Asia. Experiments of this sort have recently been carried out in Malaya on rats which are the hosts of the chiggers which transmit mite-typhus (scrub-typhus). Unlike most such studies, interest was centered rather on differences between species than on differences between individuals of the same species, and a method was sought of expressing an “average” home range for such species. In attempting to do this it became clear that the customary methods of estimating home range, such as those summarized by Stickel (1954), were not in fact applicable to the problem, since the “ home range,” as usually understood, could not be exactly delimited. The concept of the home range has, therefore, been replaced, for this purpose, by the concept of a series of probability contours surrounding a center of activity, and what appears to be a new way of calculating and expressing the result has been evolved. The major hosts of the trombiculid mites which convey mite-typhus are, in Malaysia, rats of the genus Rattus . Some account of the various mammals involved has previously been given in these pages (Harrison and Traub, 1950) and elsewhere (Audy and Harrison, 1954), while a detailed study of their habitat preferences has been published recently (Harrison, 1957). The species involved in the present account are: Rattus jalorensis (Bonhote), Malaysian wood rat. A member of the white-bellied Rattus rattus group, confined to cleared land and secondary forest, with a decided preference for the edges of woodland. Rattus argentiventer (Robinson & Kloss), ricefield rat. Also a member of the Rattus rattus group, confined to grassland and ricefields. Rattus exulans (Peale) = R. …

A New Live-Catch Rodent Trap and Comparison with Two Other Traps

Journal Article A New Live-Catch Rodent Trap and Comparison with Two Other Traps Get access Robebt Holdenried Robebt Holdenried St. Michael's College, Santa Fe, New Mexico Search for other works by this author on: Oxford Academic Google Scholar Journal of Mammalogy, Volume 35, Issue 2, May 1954, Pages 267–268, https://doi.org/10.2307/1376055 Published: 01 May 1954 Article history Published: 01 May 1954 Received: 02 February 1958

A Vacuum Tube Amplifier Model

The model of a vacuum tube power amplifier described here is very simple and, seemingly, very obvious. Yet the author has found it to be very effective in making clear some of the funadamental characteristics of the amplifier. A small rodent trap A is mounted on a stout board above a larger trap. A string passing through eyelets is fastened between the spring of the small trap to the trigger of the larger trap B. The spring of the latter trap is connected by a stout cord to a five-kilogram weight W resting on the edge of some near-by chair. The operation consists in setting both traps. A small weight w attached to a string is allowed to rest on the trigger of trap A, thus releasing the spring. The movement of this spring is transferred by means of the string to the trigger of the larger trap B. The heavy spring, upon being released, drags the fivekilogram weight from the chair. It falls to the floor. Basically, the model shows how a small impulse or signal voltage w, applied to the grid of the input tube, may release or control a large amount of energy in the output of a power tube W. The trigger of each trap is the grid of the tube, while the energy in the plate circuit is represented by the energy in the spring. The output of the first trap must excite the input or trigger of the second stage or larger trap. To do this the following points are in evidence: (1) There is a minimum grid voltage input to an amplifier that will cause it to function as such. Thus, w can be made so small that trap A is not sprung. The first trigger, if too sensitive, would be released by the vibrations of footsteps approaching it. In an amplifier, the sensitivity must be no less than several microvolts. Otherwise, the shot effect and thermal effects would produce a background of noise. (2) The coupling between the stages is represented by the string S. Thus, the slack in S can be so great that trap B is unaffected or only partially affected so that the spring of the second trap is not released. (3) In a power amplifier, the first tubes need only be, essentially, voltage amplifying tubes which are to provide the large grid swing in the power tube. This large grid swing causes energy to be dissipated in the load. Here, the first trap is a light trap to provide a large swing to the second larger trap. Since the large trap is really quite sensitive, requiring a very small displacement of the trigger to release the spring, the trigger here has been loaded to make it more analagous to the amplifier.