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PubMed1989

Rat leucocyte response to the bites of rat fleas (Siphonaptera: Pulicidae).

The host response to bites of the oriental rat flea, Xenopyslla cheopis Rothschild, was investigated by examining rat blood leucocyte kinetics, histopathology, and the effect that the host response had upon subsequent flea feeding and longevity. Test rats were subjected to controlled exposures of fleas, and leucocyte data from test rats were compared to those of unexposed controls. Of the five leucocyte types examined, only the basophil appeared to play a role in the host blood response to flea bites. Significant increases in blood basophil levels occurred 2-3 d after exposure but subsided to control levels within a week. However, flea feeding did not produce histopathology at the flea feeding sites nor did the basophilic blood response of rats affect subsequent feeding or longevity of the fleas.

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PubMed1990

Ovicidal and larvicidal modes of action of fenoxycarb against the cat flea (Siphonaptera: Pulicidae).

The mode of action of the insect growth regulator, fenoxycarb, on embryogenesis of cat flea eggs, Ctenocephalides felis (Bouché), was evaluated biologically and morphologically. Newly oviposited flea eggs were aged for 0, 3, 6, 12, 24, 48, or 72 h and exposed to fenoxycarb (1.1 micrograms/cm2) on filter paper disks for 0 (60 s), 2, 4, 8, 12, or 24 h at 23 +/- 1 degree C and 70 +/- 3% RH. Following exposure, samples of flea eggs were processed for microscopic examination and seeded onto carpet swatches containing flea-rearing medium in order to assess egg hatch, and larval, pupal, and adult development. Fenoxycarb exhibited embryocidal activity against eggs in early blastoderm formation, blastokinesis, and advanced larval development up to hatching. The ovicidal effect of fenoxycarb was not restricted to any specific developmental stage of embryogenesis, and no significant relationship was found between duration of exposure and lethal or inhibitory effects. Indeed, exposure for as little as 60 s produced a lethal inhibition of embryonic development. Conventional microscopy and ultrastructural observations of flea eggs exposed to fenoxycarb showed extensive cellular and tissue damage of the developing embryos, including membrane lysis, burst cells, pycnotic nuclei with coalesced and clumped heterochromatin, swollen and ruptured mitochondria, cellular autolysis, and collapse and discoloration of the eggshell. Fenoxycarb also exhibited larvicidal activity against newly emerged and 24-h-old flea larvae. The midguts of larvae exposed to fenoxybarb appeared disrupted and distorted with large gaps. These data document the ovicidal and larvicidal modes of action of fenoxycarb against the cat flea.

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PubMed1990

Field evaluation of Nylar for control of cat fleas (Siphonaptera: Pulicidae) in home yards.

Procedures were developed to evaluate juvenoid insect growth regulators in home yards as part of an ongoing program to identify photostable insecticides for control of the cat flea, Ctenocephalides felis (Bouché). Nylar, an emulsifiable concentrate formulation of pyriproxyfen, was selected as the experimental insect growth regulator. Efficacy studies, yard survey, and pretreatment sampling techniques are described. Soil samples collected from the yards at intervals after treatment were taken to the laboratory, infested with flea larvae, and tested for juvenoid activity. Results indicated that Nylar applied at a concentration of 32 mg/m2 in 0.82 liter of water/m2 (20 gal/1,000 ft2) prevented development of approximately 80% of the fleas for a period of 3 wk.

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PubMed1990

Prevalence and biology of endosymbionts of fleas (Siphonaptera: Pulicidae) from dogs and cats in Alachua County, Florida.

A study was conducted to determine the prevalence and biology of endosymbionts in local populations of fleas collected from dogs and cats in Alachua Co., Florida. Four hundred three Ctenocephalides felis (Bouché), 194 Pulex simulans Baker, and 44 Echidnophaga gallinacea (Westwood) were examined. Fleas were collected from 52 dogs and 51 cats. From 1 to 20 fleas were dissected from each host. A variety of microorganisms and metazoa was observed, including a baculovirus, gram-negative bacteria, rickettsia-like organisms, amoebae, trypanosomatid flagellates, cephaline gregarines, and microsporidia. Microfilariae of the dog heartworm, Dirofilaria immitis, entomophilic nematodes, and metacestodes of the tapeworm Dipylidium caninum were also observed.

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PubMed1991

Blood consumption by the cat flea, Ctenocephalides felis (Siphonaptera: Pulicidae).

The volume of blood consumed by actively reproducing female cat fleas, Ctenocephalides felis (Bouché), while feeding in confinement feeding chambers on cats for 3 h, was investigated using two radionuclide blood tags (51Cr-erythrocyte and 125I-albumin) and the gravimetric method. Female fleas consumed an average of 0.110 ml (+/- 0.026 ml) of blood per 100 females in 3 h as determined using the dual radionuclide system. The single 51Cr-erythrocyte tag overestimated blood consumption by 11.3% and the single 125I-albumin tag underestimated blood consumption by 6.4%. The gravimetric method underestimated blood consumption by 72.2% compared with the dual radionuclide value. Investigations of blood consumption of nonconfined female fleas were conducted with cats housed in metabolic cages and restricted from grooming. These investigations were conducted using the single 51Cr-erythrocyte tag, and the data obtained were corrected to compensate for using a single erythrocyte tag. Female cat fleas consumed an average of 13.6 microliters (+/- 2.7 microliters) of blood per day, which was equivalent to 15.15 times their body weight. In an additional study, direct exposure to 40 kHz ultrasound did not reduce blood consumption by the fleas.

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PubMed1991

Effect of an experimental systemic compound, CGA-184699, on life stages of the cat flea (Siphonaptera: Pulicidae).

The experimental drug CGA-184699 (N-[2,5-dichloro-4-(1,1,2,3,3,3-hexafluoropropoxy)-phenylaminoc arbonyl]-2,6-difluorobenzamide) was evaluated for efficacy against cat fleas, Ctenocephalides felis (Bouché), held in flea cages on cats. When administered orally, the compound acts systemically and prevents development of the next generation of fleas. There was no effect on adults, but eggs from adults that fed on treated cats had reduced viability. Most larvae that emerged from surviving eggs died. Within the first 2 wk after treatment of cats with CGA-184699, most death of progeny occurred in the egg stage, but as time passed, more eggs hatched but larval mortality prevented development to adults. A single oral dose of CGA-184699 virtually eliminated the next generation of adult fleas for a period of 44 d.

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PubMed1991

Apparent incompetence of Dermacentor variabilis (Acari: Ixodidae) and fleas (Insecta: Siphonaptera) as vectors of Borrelia burgdorferi in an Ixodes dammini endemic area of Ontario, Canada.

From April to October 1990, white-footed mice, Peromyscus leucopus (Rafinesque), were examined for ectoparasites on Long Point, Ontario, the only endemic area for Ixodes dammini Clifford, Spielman, Piesman & Corwin and Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner known in Canada. Larval and nymphal I. dammini and Dermacentor variabilis (Packard), and adult fleas Orchopeas leucopus (Baker), Epitedia wenmanni (Rothschild), and Ctenophthalamus pseudagrytes Baker were common on trapped mice. Questing ticks were collected by dragging, near the sites of mouse trapping, from April to November 1990. Indirect immunofluorescent assay established that 58.3% of adult, 17.3% of nymphal, and 0.15% of larval I. dammini questing at Long Point were infected with B. burgdorferi, indicating that infected mammalian reservoir hosts are common. None of 593 adult, 2 nymphal, and 4 larval D. variabilis collected while questing were infected; and only 1 of 322 fleas (O. leucopus) removed from white-footed mice was infected. The fact that no unfed adult D. variabilis and only one flea were infected, in a situation where the probability of exposure of hematophagous ectoparasites is moderately high, suggests that this species of tick and the fleas examined are poor vectors for the Lyme disease spirochete.

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PubMed1991

Studies on the control of plague in the western United States: laboratory trials of six insecticide dust formulations applied to soil for the control of the plague vector Oropsylla montana (Siphonaptera: Ceratophyllidae).

In this study, six insecticide dust formulations were laboratory-tested in soil mixtures ranging in concentration from 40 to 1,280 parts per million (ppm) against a proven vector of bubonic plague, Oropsylla montana (Baker). Pulicidal effects of the six insecticides, which included three organophosphates, two carbamates, and a pyrethroid, were compared by LD(50) values at both ambient and 75% RH. Permethrin (Pyraperm 455 dust), a pyrethroid with a LD(50) less than 40 ppm, demonstrated the most effective pulicidal action for the 13-wk trial period, followed in order by chlorpyrifos, bendiocarb, propetamphos, diazinon, and carbaryl.

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PubMed1992

Diel patterns of cat flea (Siphonaptera: Pulicidae) egg and fecal deposition.

The quantity of eggs and feces deposited by replicate populations of cat fleas, Ctenocephalides felis (Bouché), from domestic house cats. Felis catus, were recorded at 1-h intervals over a 24-h period, in a photoperiod of 12:12 (L:D) (photophase, 0600-1800 hours [EST]). Egg production averaged 23.96 +/- 0.83 eggs per female per day and was greatest from 2400 to 0300 hours and lowest from 0700 to 0900 hours and from 1700 to 1900 hours. Daily fecal deposition was 0.77 +/- 0.03 mg feces per flea and did not vary significantly among hours. Flea eggs and adult feces were dropped continuously from infested cats, but significantly more eggs were shed at times of day when cats normally rest. More feces are concentrated in the small areas where cats rest than over the large areas they roam. Consequently, eggs and feces would not be deposited uniformly throughout the hosts home range, resulting in a clumped distribution of larval development sites at host resting areas.

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PubMed1992

Spectrophotometric method of quantifying adult cat flea (Siphonaptera: Pulicidae) feces.

Cat flea, Ctenocephalides felis felis (Bouché), feces are an essential part of larval nutrition under natural conditions. The mass values of adult flea feces can be measured by dissolving samples of flea feces in Drabkin's reagent, filtering, centrifuging, and measuring absorbance spectrophotometrically at 540 nm. Either flea feces or air-dried host blood can be used to generate the standard curve used to convert absorbance (optical density) values into mass values. Debris collected from flea-infested house cats averaged 23.02 mg debris per cat per h with an average of 10.41 mg flea feces per cat per h. Flea feces deposited in the environment serve as potential larval food. Adult flea feces comprised an average of 44.28% of the debris deposited from infested domestic house cats in this study.

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PubMed1992

Influence of photoperiod on egg production of cat fleas (Siphonaptera: Pulicidae) infesting cats.

Photoperiod affected the production of cat flea eggs by cats infested with cat flea, Ctenocephalides felis (Bouché). Cat flea eggs have a smooth chorion and do not adhere to the host. About 60% of fluorescing eggs placed in the pelage were recovered in collecting trays underneath the host in 2 h. An average of 87.7 eggs per cat was laid during the last 8 h of the scotophase compared with 49.9 and 59.1 eggs during the other 8-h periods. Significant variation in the number of eggs collected daily existed among the six cats. The activity budgets were similar for all the cats with the maximum sleep period during the photophase. The possible adaptive advantages of synchronizing egg production with photoperiod are discussed.

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PubMed1992

Laboratory and field trials of permethrin-treated cotton used as nesting material to control fleas (Insecta: Siphonaptera) on cricetid rodents.

Upholstery cotton treated with four different concentrations (0.25-2.0%) (2,500-20,000 ppm) of an aqueous permethrin solution, used as nesting material by white mice, was laboratory-tested against the potential plague vectors Oropsylla montana (Baker), Thrassis bacchi (Rothschild), and Orchopeas howardi (Baker) and found highly effective (P less than 0.001) for 1 yr. Similarly treated cotton gauze was tested under ambient and 75% RH and was found to be highly effective (P less than 0.001) in both environments for 1 yr. A separate test determined that the LD50 of permethrin-treated cotton was less than 10 ppm. Cotton tested with 0.5% permethrin and distributed under field conditions to cricetid rodents for use as nesting material was found to be highly effective (P less than 0.001 as a pulicide for greater than 4 mo when tested during winter in Larimer County, Colo. Permethrin-treated cotton was less successful in controlling fleas on cricetid rodents during the summer months in a New Mexico hyperendemic plague area.

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PubMed1992

Reproductive activity of Synosternus cleopatrae (Siphonaptera: Pulicidae) in relation to host factors.

Reproductive activity of Synosternus cleopatrae (Rothschild) infesting Gerbillus andersoni allenbyi Thomas was studied in a natural setting in Israel. Rodents were trapped and measured (weight and length), their sex was identified, and their reproductive status estimated. Their ectoparasites were removed, and fleas were dissected and their oocytes measured. Two indices of flea reproductive activity were analyzed: "reproductive status," which distinguished between gravid and nongravid females, and "reproductive intensity," which was estimated as the sum over the two largest oocytes of the products of oocyte length multiplied by oocyte width. Both indices showed that no reproduction took place between November and January, but reproduction was relatively stable during the rest of the year. Although flea reproductive activity differed significantly among individual hosts, only a small fraction of gerbils (10-15%) carried a significantly different proportion of reproductive fleas than their monthly sample proportion (based on all fleas regardless of hosts). All these hosts carried a lower proportion of reproductive fleas than their monthly sample proportion. The host's sex, but not reproductive status or age, had a significant effect on flea reproduction, expressed as a higher reproductive activity on male gerbils. Infestation burden expressed as ectoparasite counts was included in the statistical analysis. Only lice, Polyplax gerbilli Ferris, but not S. cleopatrae, Stenoponia tripectinata (Tiraboschi), and a total of five mesostigmatid Acari had a significantly negative association with S. cleopatrae reproductive activity. These relationships between S. cleopatrae reproductive activity and the host infestation burden do not support the hypothesis of modulation of S. cleopatrae reproduction by the infestation burden. However, differences in the reproductive activity of ectoparasites between their hosts may play a major role to generate the parasite clumped distribution. Thus, gerbil males probably carry more fleas than gerbil females because of the higher reproductive activity of S. cleopatrae on gerbil males.

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PubMed1992

Preparation and examination of flea larvae (Siphonaptera) by light and electron microscopy.

Techniques are described for making permanent slide-mounted specimens. Larvae were thoroughly macerated in KOH to remove soft internal tissue, yielding specimens with enhanced transparency and allowing examination of most of the exoskeleton in a single larva. Fatty material was removed in acetone to eliminate confusion of fat globules with sensilla in the cuticle. The more sclerotized exoskeletal elements, such as integumentary scales and the body sclerites together with their setae and sensilla, were highlighted by staining with carbol fuchsin. Resolution of numbers and arrangement of setae, especially those on the dorsum of the head capsule, in the anal comb, and on the anal mounds, was greatly facilitated by mounting larvae in dorsal orientation. Clearer views of the antennae and mouthparts were obtained, in orientations seldom achieved in whole mounts, by dissecting the head capsule. Discrimination of many taxonomically valuable features was enhanced by the use of phase-contrast microscopy. Interpretation of structures noted in light microscopy was complemented using scanning electron microscopy. The latter allowed differentiation between surface and internal cuticular structures.

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