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PubMed2000

Effects of pyriproxyfen spray, powder, and oral bait treatments on the relative abundance of fleas (Siphonaptera: Ceratophyllidae) in black-tailed prairie dog (Rodentia: Sciuridae) towns.

Separate black-tailed prairie dog, Cynomys ludovicianus (Ord), towns on the Rocky Mountain Arsenal National Wildlife Refuge, Colorado, were treated with technical pyriproxyfen (Nylar) using spray, powder, and oral bait carriers. Direct combing methods (1997 and 1998) and burrow flagging (1998) were used to estimate relative abundance of the plague vector Oropsylla hirsuta (Baker). Pyriproxyfen spray (0.05%) and powder (0.05%) did not significantly reduce (P > 0.05) O. hirsuta abundance. Pyriproxyfen bait, when applied every 4 wk at a concentration of 286 mg/50 g bait, significantly reduced (P < or = 0.05) O. hirsuta infesting prairie dogs, 4 mo after initial treatment. However, flea populations had recovered to pretreatment levels by the following summer (July 1999).

Animals↗
PubMed2001

Seasonal occurrence of Ctenocephalides felis felis and Ctenocephalides canis (Siphonaptera: Pulicidae) infesting dogs and cats in an urban area in Cuernavaca, Mexico.

The seasonal occurrence of Ctenocephalides felis felis (Bouché and Ctenocephalides canis (Curtis) infestation on dogs and cats in Cuernavaca City in Mexico, was determined by examining 1,803 dogs and 517 cats at two veterinary clinics during 1995-1997. The overall flea infestation was 30.3 and 30.1% for dogs and cats, respectively. There were no significant differences (P > 0.05) in percentage of infestation among years for both hosts. The infestation was somewhat higher in spring, summer, and autumn than in winter, but no statistical differences was found among seasons (P > 0.05) for both pets. No relationship existed between percentage of flea infestation and temperature or rainfall among seasons. On dogs, 81.1% were infested with only C. felis felis, 16.8% with C. canis, and 2% had both flea species; whereas 92.3% of the cats were infested with C. felis felis and 7.7% with C. felis felis and C. canis. The cat flea was the most prevalent flea species found other than C. canis; no other species were found on the dogs and cats. It appeared that flea life cycle development continued throughout the year.

Animals↗
PubMed2001

Field trial of systemically delivered arthropod development-inhibitor (fluazuron) used to control woodrat fleas (Siphonaptera: Ceratophyllidae) and ticks (Acari: Ixodidae).

An orally delivered arthropod development-inhibitory (fluazuron) was evaluated for its potential to reduce the number of flea and tick vectors found on the dusky-footed woodrat Neotoma fuscipes Baird, a reservoir host important in disease enzootiology in northern California. Pigmented bait cubes containing fluazuron were distributed monthly to woodrat nests in a chaparral habitat for 1 yr. When compared with control woodrats, the numbers of fleas [primarily Orchopeas sexdentatus (Baker)] on treated woodrats were significantly reduced 3-4 mo after initial application, and remained so for the duration of the application period. By contrast, tick numbers were not significantly reduced on treated woodrats. After the cessation of treatments, flea indices remained lower on treated animals for up to 2 mo after application. Approximately 93% of woodrats captured in the treatment area excreted pigmented feces and 93% of distributed bait cubes were removed by woodrats, which indicates that the bait cube formulation and delivery system were highly effective. Bait cubes also were attractive to small rodents and ground-frequenting birds. The results of this study suggest that a monthly application program of fluazuron delivered by bait cube is effective in reducing woodrat flea-burdens, but is not effective, at least in the short-term, in controlling ticks.

Animals↗
PubMed2001

Effects of juvenile hormone on eggs and adults of the cat flea (Siphonaptera: Pulicidae).

Juvenile hormone III plays a major role in regulating feeding and reproduction in the adult cat flea, Ctenocephalides felis (Bouché). Both blood consumption and egg production increased in a dose-dependent manner up to a maximum at 1,250 ppm when fleas were continuously exposed to concentrations up to 12,500 ppm juvenile hormone. Histological studies demonstrated that juvenile hormone III also stimulated cellular differentiation of salivary gland epithelia, midgut epithelia, and fat body cells, enhancing the ability of the adult flea to digest blood and synthesize vitellogenins for the maturing oocytes. In unfed fleas, exposure of adults to concentrations of > or = 1,000 ppm juvenile hormone III applied to filter paper resulted in membrane lysis and destruction of salivary gland and midgut epithelial cells, fat body cells, and ovarian tissue. Unlike juvenile hormone mimics, which have potent ovicidal effects in fleas, juvenile hormone had little effect in preventing egg hatch; 58% of the eggs laid by fleas treated with 12,500 ppm juvenile hormone III hatched, and a concentration of 30,000 ppm was required to reduce hatch to 2% in untreated eggs exposed to treated filter paper for 2 h. Compared with the juvenile hormone mimic pyriproxyfen, juvenile hormone III was less toxic to fed adult fleas. However, at a concentration of 12,500 ppm, juvenile hormone killed approximately 45% of the adults and caused autolysis and yolk resorption in the developing oocytes. Thus, at high concentrations, juvenile hormone appears to have a pharmacological effect on fleas, which is highly unusual in insects.

Animals↗
PubMed2001

Topical application as a method for comparing the effectiveness of insecticides against cat flea (Siphonaptera: Pulicidae).

A topical (micro-droplet) bioassay is described for the cat flea, Ctenocephalides felis (Bouche). Key parameters are the short carbon dioxide anesthetization and the use of 0.1 ml of acetone per flea. The method was used to compare the effectiveness of 13 insecticides. LD95 values in nanograms per flea were nitenpyram 0.68, fipronil 0.69, deltamethrin 0.70, imidacloprid 0.81, cypermethrin 5.4, fenthion 8.0, diazinon 12, permethrin 19, malathion 29, bendiocarb 170, DDT 710, propoxur 1,300, carbaryl >10,000. Experiments repeated 2-5 yr later, with five of the chemicals, in a different facility, showed only small shifts in potency (0.38- to twofold of the original LD50 values).

Animals↗
PubMed2001

Fleas (siphonaptera) collected from small mammals in Southern Viet Nam in 1997-1998.

We report on fleas collected from small mammals in two forests, a lowland semideciduous dipterocarp forest and a highland evergreen forest, in southern Viet Nam. In the lowland forest, only one species of flea (Xenopsylla vexabilis Jordan) infested a single species of rodent [Berylmys berdmorei (Blyth)]. In the highland forest, seven species of fleas were collected from eight species of small mammals. Three species of fleas, Lentistivalius insolli (Traub), Lentistivalius occidentayunnanus Li, Xie & Gong, and Gryphopsylla jacobsoni (Jordan & Rothschild), collected from mammals in the highland forest represent new records for Viet Nam.

Animals↗
PubMed2001

Off-host observations of mating and postmating behaviors in the cat flea (Siphonaptera: Pulicidae).

A blood meal was necessary for a male cat flea, Ctenocephalides felis (Bouché), to display the mating attempts to an unfed or fed female. More mating pairs resulted when both sexes were fed. Copulation occurred when fed fleas were placed on surfaces with temperatures from 34 to 42 degrees C. This article not only describes the mating and postmating behaviors of cat fleas, but also compares them with those of other fleas. The sequence of mating behavior began when a male approached a female ventrally, and the male's antennae and claspers became erect to attach to the abdomen of the female. Clasper attachment lasted until copulation ended, whereas the male retrieved his antennae immediately after genitalia linkage. The male generally grasped the female's tarsi with his claws during mating. The length of the mating interval terminated by the male ranged from 25 to 110 min and was significantly longer than that terminated by the female (averaging 12.11 min). After the mating pair separated, the male displayed a series of postmating behaviors discussed herein. This article documents grasping and postmating behaviors of the male cat flea.

Animals↗
PubMed2001

Seasonal abundance of fleas (Siphonaptera: Pulicidae, Ceratophyllidae) on wild rabbits in a semiarid area of northeastern Spain.

This paper reports the annual dynamics of wild rabbit fleas in a study site located in the Middle Ebro Valley, northeastern Spain. Fleas collected directly from wild rabbits included the species Spilopsyllus cuniculi (Dale), Xenopsylla cunicularis (Smit), Echidnophaga iberica (Ribeiro, Lucientes, Osácar, and Calvete), Caenopsylla laptevi (Beaucournu, Gil-Collado and Gilot), and Pulex irritans (L.). Monthly collections of adult and larval fleas made from within the first meter of selected burrow entrances also yielded fleas belonging to the same five species. Larval specimens of X. cunicularis, E. iberica, and C. laptevi were also found. Spilopsyllus cuniculi, a winter species that can only breed during the rabbit breeding season, was common on hosts from November to April. Xenopsylla cunicularis and E. iberica were summer species, whereas C. laptevi was abundant during the autumn and winter. Xenopsylla cunicularis and E. iberica larvae were found in burrows only during April and May, whereas those of C. laptevi were collected from October to January. The data suggested that X. cunicularis and E. iberica might diapause during the egg stage whereas C. laptevi diapauses during the pupal stage.

Animals↗
PubMed2001

Laboratory techniques for rearing the fleas (Siphonaptera: Ceratophyllidae and Pulicidae) of California ground squirrels (Rodentia: Sciuridae) using a novel nest box.

Three species of fleas, Oropsylla montana (Baker), Hoplopsyllus anomalus (Baker), and Echidnophaga gallinacea (Westwood), occur seasonally on the California ground squirrel, Spermophilus beecheyi (Richardson). Few studies have focused on the biology and ecology of these fleas despite their importance in the epidemiology of sylvatic plague. To best duplicate a natural parasite-host relationship in the laboratory, a novel nest box was developed that facilitated housing wild-caught S. beecheyi, was conducive to rearing fleas, and met modern standards for laboratory animal hygiene. This flexible system allowed adult fleas with different feeding strategies to be colonized successfully while providing sufficient flea eggs for both colony maintenance and biological research. The techniques described could be adapted to work with other species of rodents and their fleas.

Animals↗
PubMed2001

Systemic activity of the avermectins against the cat flea (Siphonaptera: Pulicidae).

Ivermectin has potent systemic activity against numerous species of nematodes and arthropods, but there are some important species in these two groups, such as the cat flea, Ctenocephalides felis (Bouché), that appear to be refractory to it. In an effort to determine if the lack of systemic activity against C. felis is specific to ivermectin, or if it is a class-wide phenomenon, 20 avermectin derivatives were tested in an artificial membrane flea feeding system at concentrations of 20, 10, and 1 microg/ml. Results showed that ivermectin had LC90 and LC50 values against fleas of 19.1 and 9.9 microg/ml, respectively. Only four of the other 19 compounds evaluated possessed both LC90 and LC50 values more potent than ivermectin and even then the advantage was modest. Among those four compounds was a two-fold increase in potency relative to ivermectin when the LC90 values were considered (range, 9.2-10.3 microg/ml) and a two- to eight-fold increase when the LC50 values were examined (range, 1.23-5.26 microg/ml). Neither the possession nor the number of oleandrosyl sugars on the macrocyclic backbone were relevant for additional flea activity because among these four compounds were two disaccharides, a monosaccharide and an aglycone. Also, bond disposition between C-22 and 23 did not contribute to increase in activity because these molecules comprise members with either single or double bonds. One of these avermectin analogs was scaled-up and tested subcutaneously in a dog at >100 times the commercial ivermectin dosage and zero efficacy was observed against the flea. We conclude that even the best in vitro avermectin does not have the in vivo potential to become a commercial oral or subcutaneous flea treatment for companion animals.

Animals↗
PubMed2001

Effect of air temperature and humidity on the survival of pre-imaginal stages of two flea species (Siphonaptera: Pulicidae).

The survival of immatture fleas at 25 and 28 degrees C and 40, 55, 75, and 92% RH was studied to test the hypothesis that the difference in microclimatic preferences determines habitat distribution of Xenopsylla conformis Wagner, 1903 and Xenopsylla ramesis Rothschild, 1904. Survival of X. conformis eggs did not depend on either temperature or humidity or both, whereas eggs of X. ramesis survived significantly less at 40% RH than at higher humidities. No larva of either species survived at 40% RH at either temperature. Larval survival of both species at both temperature regimes was significantly lower at 55% humidity than at higher humidities. Maximal survival time of larvae that died before pupation depended on both temperature and humidity in both species. Change of humidity during early stages of the life cycle (from egg to larva) increased the maximal survival time in X. conformis larvae but decreased that in X. ramesis larvae. Pupal survival was higher at higher humidities independent of temperature. Survival of X. conformis pupae was lower than that of X. ramesis pupae when the relative humidity was low. Humidity change on later stages (from larva to cocoon) decreased X. conformis pupal survival and had no effect on X. ramesis pupal survival. The sex ratio of emerged adults was not affected by either temperature or humidity in both species. Changes in humidity between egg and larval emvironments significantly decreased the percentage of females in X. conformis emergence at 28 degrees C.

Air↗
PubMed2001

Respiratory gas exchange in the flea Xenopsylla conformis (Siphonaptera: Pulicidae).

Respiratory gas exchange was measured in various developmental stages of the flea Xenopsylla conformis mycerini (Rothschild, 1904) originating from the central Negev in Israel. Gas exchange in fleas was measured using a flow-through respirometry system that monitored CO2 emission. Lowest metabolic rates were found in the cocooned stage, which included prepupae, early stage pupae, late stage pupae, and preemerged adults. Newly emerged adults and feeding larvae had metabolic rates 2.5-3.0 times greater than those for the cocooned stages. Highest rates of gas exchange were found in feeding fleas. The low metabolic rates of the cocooned stages is thought to contribute to their ability to survive for longer periods than free-living larvae and adults.

Animals↗
PubMed2002

Laboratory evaluation of fipronil and imidacloprid topical insecticides for control of the plague vector Oropsylla montana (Siphonaptera: Ceratophyllidae) on california ground squirrels (Rodentia: Sciuridae).

Two insecticides, fipronil and imidacloprid, were evaluated for efficacy and longevity against Oropsylla montana (Baker), the most important vector of plague in California. Wild-caught California ground squirrels, Spermophilus beecheyi (Richardson), were individually housed in the laboratory to serve as natural hosts to O. montana and for on-animal insecticide trials. Several concentrations oftechnical grade fipronil and imidacloprid in acetone were applied to samples of clean rodent bedding to determine residual activity and longevity against fleas. Immature and adult cat fleas, Ctenocephalides felis (Bouche), were used as representative fleas for periodic assays in place of less fecund O. montana. Toxicity of treated bedding did not decrease significantly for 1 yr at all applied concentrations. Fipronil provided 100% kill for at least 1 yr at > or = 100 ppm, whereas imidacloprid required 10,000 ppm for similar performance. Laboratory squirrels were treated with topical formulations of fipronil (Frontline Top Spot) and imidacloprid (Advantage Flea Adulticide) at a dosage rate of 15 mg/kg and evaluated for residual activity every 2 wk against adult O. montana. Residual activity was determined by percent recovery of O. montana adults released on treated and untreated animals after 48 h. Frontline provided 100% kill of adult fleas for at least 10 wk, and up to 26 wk on one animal. Advantage failed to provide 100% kill of adult fleas at 2 wk, with complete loss of efficacy by week 6. Concurrent assays with bedding samples from squirrel nest boxes showed negligible toxicity transfer from treated animals to nest bedding.

Animals↗
PubMed2002

Effect of diet composition on weight gain, sperm transfer, and insemination in the cat flea (Siphonaptera: Pulicidae).

Weight gain by adult cat fleas, Ctenocephalidesfelis (Bouché), was influenced primarily by the concentrations of protein and sodium chloride in the feeding solution. After 48 h of feeding, fleas fed whole blood weighed almost twice as much as fleas fed plasma or hemolyzed blood and 1.25 times as much as fleas fed 0.15 M sodium chloride. When fleas were fed sodium chloride solutions ranging from 0 to 0.5 M, weight gain was greatest on the 0.15- or 0.2-M solutions. Weight gain decreased significantly when fleas were fed plasma, hemolyzed blood or 0.3 or 0.5 M sodium chloride in place of whole blood, but improved when plasma was diluted 100% and when hemolyzed blood was diluted 10% with distilled water. Adenosine-5'-triphosphate did not appear to stimulate weight gain in cat fleas; weight gain was unchanged in fleas fed hemolyzed blood or 0.15 M sodium chloride to which 0.005 M ATP was added. Insemination did not occur in starved fleas or those fed protein-free diets. When fleas were starved or fed distilled water, sodium chloride, or other salt solutions, sperm was transferred from the testes to the vas deferens in 91-94% of males, but no females were inseminated. In contrast, when fleas were fed whole blood, hemolyzed blood, plasma, or bovine serum albumin (3.5 or 7.0 g/deciliter) dissolved in 0.15 M saline, 80, 80, 10, and 10% of the females were inseminated, respectively.

Animals↗
PubMed2002

Factors influencing sperm transfer and insemination in cat fleas (Siphonaptera: Pulicidae) fed on an artificial membrane system.

Sperm transfer through the epididymis, a prerequisite for insemination of cat fleas, Ctenocephalides felis (Bouché) was stimulated by exposure of unfed male fleas to juvenile hormone III residues for 3 d at 25 degrees C or exposure of unfed fleas to 37 degrees C for 6 d. Sperm transfer was completed at least three times faster in unfed males held at 37 degrees C than in those held at 25 degrees C. Although percentage sperm transfer in fleas fed water or 0.15 M saline at 37 degrees C was not significantly increased over that of unfed fleas, a significantly greater percentage of blood-fed males completed sperm transfer at 2, 3, and 6 d. At least two factors influenced insemination: exposure of fleas to host body temperature and amount of food consumption. When blood-fed males and females were paired and fed 0.15 M saline, 0% were inseminated at 25 degrees C versus 35% at 37 degrees C. Because percentage insemination did not increase in blood-fed males and females that were paired and fed 0.15 M saline at 37 degrees C for an additional 48 h, continuous bloodfeeding appeared to be required for maximal rates of mating and insemination. Furthermore, no females were inseminated when blood-fed males and females were paired at 37 degrees C and starved. Treatment of unfed fleas with juvenile hormone III did not substitute for bloodfeeding in stimulating mating and insemination; when blood-fed males were paired with JH III-treated females and vice versa and fed 0.15 M saline at 37 degrees C, 0% were inseminated. However, when fleas were fed 0.15 M saline and exposed to 1,250 ppm juvenile hormone III or fed whole blood and exposed to 12.5, 125, or 1,250 ppm juvenile hormone III, percent insemination was significantly increased in comparison to the controls. Therefore, juvenile hormone secretion in blood-fed fleas may regulate mating success indirectly by stimulating sperm transfer.

Animals↗
PubMed2002

Development of a larval bioassay for susceptibility of cat fleas (Siphonaptera: Pulicidae) to imidacloprid.

Strategies for controlling cat fleas, Ctenocephalidesfelisfelis (Bouché), have undergone dramatic changes in the past 5 yr. With the advent of on-animal treatments with residual activity the potential for the development of insecticide resistance increases. A larval bioassay was developed to determine the baseline susceptibility of field-collected strains of cat fleas to imidacloprid. All four laboratory strains tested showed a similar level of susceptibility to imidacloprid. Advantages of this bioassay are that smaller numbers of fleas are required because flea eggs are collected for the test. Insect growth regulators and other novel insecticides can also be evaluated. Using a discriminating dose, the detection of reduced susceptibility in field strains can be determined with as few as 40 eggs.

Acetone↗
PubMed2002

Distribution of cat fleas (Siphonaptera: Pulicidae) on the cat.

A total of 3,382 cat fleas, Ctenocephalidesfelis (Bouche), was taken from 164 of the 200 stray cats examined. It was observed that cat fleas preferred specific areas on the cat. A significantly higher mean number of fleas was found on the area of head plus neck than on the ventral part of the body. More specifically, the mean number of fleas was highest on both of the neck and dorsal areas. However, in terms of the density of fleas, the neck had more fleas than the dorsal area did. The fewest fleas were found infesting the legs and tail. Distribution of fleas on the cat may well be explained by the various grooming patterns of the cat, and the knowledge of flea distribution may be valuable for application of on-animal flea control procedures.

Animals↗
PubMed2002

Insecticide susceptibilities of cat fleas (Siphonaptera: Pulicidae) from several regions of the United States.

Eleven cat flea, Ctenocephalides felis (Bouchè), strains, seven field-collected and four laboratory-colonized, were assayed for susceptibilities to five insecticides (carbaryl, chlorpyrifos, malathion, permethrin, and pyrethrin) with an insecticide-treated, horizontally-oriented, Nylon 6,6 disk in a test tube. The pyrethrin was synergized using piperonyl butoxide (PBO). Flea mortality at two doses was recorded after 4 and 24 h exposures. The field strains from Texas and Florida tolerated carbaryl, chlorpyrifos, and malathion; and carbaryl and PBO-synergized pyrethrin, respectively. Tolerance was observed in a field strain from Kansas against malathion. Colonies from California and North Carolina were susceptible to malathion and PBO-synergized pyrethrin, and chlorpyrifos and permethrin, respectively, but three colonies showed tolerance. The insecticidal response of the California colony varied; when exposed to a chlorpyrifos dose of 10 mg (AI)/m2 for 24 h, at various times had mortality of 3-100%. With a PBO-synergized pyrethrin dose of 396 mg (AI)/ m2 for 4 h, the mortality ranged between 4.2 and 97%. Colonized strains were more susceptible than field strains at 4 h exposure to all insecticides except PBO-synergized pyrethrin. Colonized strains survived better in control tubes. The colony strains' susceptibility and variability are of considerable importance because these strains are used for flea product efficacy evaluations and bioassays. The differences in susceptibility between laboratory colonies and the field strains suggested development of both adaptation to colonization, and extensive, multiple cross-resistance to insecticides in field strains. Varying susceptibility of cat fleas may affect control success.

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