Studies were conducted to determine development rates of of Dermestes maculatus DeGeer at temperatures of 15, 20, 25, 30, and 35°C. No individuals completed development to the adult stage at 15°C. For the other temperatures, survivorship ranged from 9.3% at 20°C to 36% at 35°C. Time required for development varied inversely with temperature from a mean of 89.7 d at 20°C to 36.4 d at 35°C. For specimens held individually, survivorship was higher at 25 and 30°C, i.e., 83.2 and 60.2%, respectively. No specimens held individually at 35°C survived past the first larval instar. Mortality during the egg stage at 25 and 30°C was 4.52–5.23%, whereas mortality during the first instar was significantly higher for the individuals held at 30°C and 100% for those at 35°C. There was an inverse relation observed between larval density and both survivorship and mean adult weights.

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°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.

Ixodes ricinus (L.) was collected by standard dragging in 2,082 different sites in 18 broad vegetation categories in northern Spain to explore the influence of vegetation on its abundance. Of these, 785 sites were surveyed in 1995, 636 in 1996, and 661 in 1997. The impact of habitat features on differences in tick numbers is addressed. The tick was present in low numbers in areas of old, heterogeneous coniferous forests. Ticks appeared to prefer sites that had substantial secondary plant growth such as river canopies, heterogeneous Pinus uncinata forests, mixed forests, and deciduous heterogeneous woods. Highest tick abundance was recorded for sites that contained Quercus spp., as well as for mixed old forests that had many ecotones. I. ricinus was absent in open habitats, homogeneous young coniferous forests, and open hillsides. These differences were attributed to greater shrub cover and litter depth, which created more favorable microclimatic conditions for tick survival. The abundance of I. ricinus nymphs was not homogeneous in sites within the same habitat category and vegetation physiognomy at these sites did not appear to cause differences in tick abundance. Analysis of variance (ANOVA) indicated that variation in tick abundance could be explained by the exposure of the sampled site, at least for some zones within deciduous forest categories. However, this factor did not explain the variation observed in other habitats. Temperature and vegetation (normalized derived vegetation index) features were recorded daily by remotely sensed imagery throughout the study period and the data were used to obtain long-term mean and maximum values of the physical parameters considered. Multiple regression analysis performed between these long-term abiotic factors and nymphal abundance in positive sites showed high relationship (R² coefficients) for every habitat category and explained >50% of the variation in tick abundance.

Random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) polymorphism was analyzed in five Aedes aegypti (L.) populations from Argentina and one from Puerto Rico to estimate levels of intraspecific polymorphism and genetic relatedness. Allele frequencies were estimated assuming that RAPD products segregate as dominants and that genotype frequencies at those loci are in Hardy–Weinberg equilibrium. Mean expected heterozygosity (H_e) was 0.350; F_ST values were significant at all loci except one, supporting the usefulness of the fragments used here to discriminate among populations. Rogers’ genetic similarity between samples ranged from 0.806 to 0.621. The population from Puerto Rico was the most different from the Argentina populations. Considering that Ae. aegypti eggs, larvae, and pupae can be transported easily, relationships among the Argentinian populations may reflect the routes and intensity of commercial transit.

In sub-Saharan Africa, tsetse flies are the vectors of trypanosomes, the causative agents of sleeping sickness in humans and nagana in animals. Certain wild populations of the palpalis group exhibit intraspecific variation and are suspect of manifest differences in vectorial capacity. The current study reports the identification of 13 polymorphic microsatellite loci from Glossina palpalis palpalis Robinean-Desvoidy. The majority of these markers amplify corresponding loci from the related species G. p. gambiensis Vanderplank, G. f. fuscipes Newstead, and G. tachinoides Westwood. Only seven of 13 loci were amplified from G. austeni Newstead. Genetic variability was estimated in one field population of G. p. gambiensis. These results confirmed that microsatellite markers may be used to examine the subpopulation structure of tsetse flies.

Maternally inherited bacteria of the genus Wolbachia can cause cytoplasmic incompatibility resulting in the developmental arrest of early embryos. Previous studies have shown that both single- and superinfections of Wolbachia naturally occur in populations of Aedes albopictus (Skuse). Here, we report crossing experiments using three infection types occurring in Ae. albopictus: uninfected, single-infected, and superinfected individuals. Crosses were monitored over the lifetime of adults to detect possible effects of host age on cytoplasmic incompatibility levels and infection virulence. Both single- and superinfections induced high levels of cytoplasmic incompatibility throughout the lifetime of Ae. albopictus, demonstrating that both the single- and superinfections are well adapted for invasion of Ae. albopictus populations. Superinfected females were the longest lived and had the highest oviposition rates, whereas in males, uninfected individuals were the longest lived. These latter results demonstrate the need for additional experiments to better elucidate Wolbachia effects on host fitness in addition to cytoplasmic incompatibility.

The dry season survival mechanism of Anopheles gambiae Giles is one of the most vexing deficiencies in our understanding of the biology of the major malaria vectors. In this study, we examined the dynamics of anopheline adult mosquitoes, their larval habitats, and egg survival potential during the dry season in the basin region of Lake Victoria, western Kenya. Through field surveys, we demonstrated two survival strategies of An. gambiae sensu stricto during the dry season: continuous reproduction throughout the year and embryo dormancy in moist soil for at least several days. We further demonstrated that An. gambiae shows a strong preference for moist soil as an oviposition substrate rather than dry soil substrate under the insectary conditions. The observation that anopheline eggs remain a dormant stage to resist desiccation clearly contrasts the conventional wisdom that anopheline eggs hatch shortly after they are laid. Our results from western Kenya are consistent with the suggestion that anopheline mosquitoes do not necessarily suffer a severe population bottleneck during the dry season and thus maintain a large effective population size.

Field-collected house finches of mixed sex and age were infected experimentally with either western equine encephalomyelitis (WEE) or St. Louis encephalitis (SLE) viruses during the summer or fall of 1998 and maintained over the winter under ambient conditions. To detect natural relapse during the spring, 32 birds were bled weekly from February through June 1999, and then necropsied 1 yr after infection to detect chronic infections using a reverse transcription polymerase chain reaction (RT-PCR). After 10 mo, 13/14 surviving birds previously infected with WEE were antibody positive by enzyme immunoassay (EIA), and 11/14 had plaque reduction neutralization test (PRNT) antibody titers >1:20, whereas only of 8/13 birds previously infected with SLE were positive by EIA and all had PRNT titers <1:20. When necropsied, 1/14 and 1/13 birds had WEE and SLE RT-PCR positive lung or spleen tissue, respectively; blood, brain, and liver tissues were negative as were all previous blood samples. All tissues from these birds including weekly blood samples tested negative for infectious virus by plaque assay on Vero cell culture. To determine if persistent antibody was protective, birds infected initially with WEE or SLE in November 1998 were challenged 6 mo later with homologous virus. WEE antibody persisted well (5/6 birds remained PRNT positive before challenge) and remained protective, because 0/6 birds were viremic after challenge. In contrast, SLE antibody decayed rapidly (0/6 birds remained PRNT positive before challenge) and was not protective, because 3/6 birds developed an ephemeral viremia on day 1 after infection (mean titer, 10^2.73 plaque forming units/0.1 ml). When necropsied 7 wk after challenge, 1/10 birds infected with WEE and 1/10 birds infected with SLE exhibited an RT-PCR positive spleen, despite the fact that both birds had PRNT antibody titers >1:40 at this time. To determine if immunosuppression would cause a chronic infection to relapse, eight birds initially infected with either WEE or SLE were treated with cyclophosphamide and then tested repeatedly for viremia; all samples were negative for virus by plaque assay. Collectively, our results indicated that a low percentage of birds experimentally infected with WEE or SLE developed chronic infections in the spleen or lung that could be detected by RT-PCR, but not by plaque assay. Birds did not appear to relapse naturally or after immunosuppression. The rapid decay of SLE, but not WEE, antibody may allow the relapse of chronic infections of SLE, but not WEE, to produce viremias sufficiently elevated to infect mosquitoes.

Ectoparasites of 13 species of molossid, mormoopid, and vespertilionid bats from the Trans-Pecos region of Texas were studied, as follows: Antrozous pallidus (LeConte), Corynorhinus townsendii (Cooper), Eptesicus fuscus (Palisot de Beauvois), Lasiurus cinereus (Palisot de Beauvois), Mormoops megalophylla (Peters), Myotis thysanodes G. S. Miller, Myotis velifer (J. A. Allen), Myotis volans(H. Allen), Myotis yumanensis (H. Allen), Nyctinomops femorosaccus (Merriam), Nyctinomops macrotis (Gray), Pipistrellus hesperus (H. Allen), and Tadarida brasiliensis (I. Geof. St.-Hilaire). The bats were netted, examined for ectoparasites and released. Ectoparasites recovered included three species of flea, three species of streblid, three species of nycteribiid, two species of cimicid, two species of tick, and 17 species of mite. New ectoparasite records are given for hosts in seven instances and for the Trans-Pecos region of Texas in three instances.

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.

Adult female Aedes aegypti (L.), the vector of dengue and yellow fever viruses, have an affinity for feeding on human blood and a tendency to forego feeding on sugar. This observation challenges two tenets of mosquito biology: (1) mosquitoes imbibe plant carbohydrates for synthesis of energy reserves and blood for reproduction and (2) egg production is reduced when mosquitoes feed on human blood compared with blood from other species. Sub-optimal amounts of the amino acid isoleucine in human blood (particularly free isoleucine in plasma) are thought to be responsible for lowered egg production when human blood is ingested. We tested the hypothesis that feeding on human blood is associated with a selective advantage for Ae. aegypti and is an underlying reason for this mosquito’s intimate and epidemiologically important relationship with human beings. Our five experiments examined the effects of different isoleucine concentrations on accumulated energy reserves, frequency of host contact, survival, and egg production. When mosquitoes imbibed blood meals over a 7- to 10-d period and were not fed sugar, increased isoleucine concentration decreased energy reserves and did not increase egg production. Aedes aegypti took smaller but more frequent blood meals when feeding on a low-isoleucine human host daily compared with a high-isoleucine mouse host. Previous reports that isoleucine enhances egg production were confirmed only when females were fed sugar, an unusual behavior for most domestic Ae. aegypti populations. Females fed human blood and water had greater age-specific survival (l_x), reproductive output (m_x), and cumulative net replacement (R₀) than cohorts fed human blood plus sugar or isoleucine-rich mouse blood with or without access to sugar. The unique isoleucine concentration of human blood is associated with Ae. aegypti’s unusual propensity to feed preferentially and frequently on humans—a behavior that increases this mosquito’s fitness, synthesis of energy reserves, and contact with human hosts, making it an especially effective disseminator of human pathogens.

Antennal sensilla patterns were used to explore intraspecific variability among Triatoma infestans (Klug) from domestic habitats in Argentina and Bolivia, and from sylvatic habitats in Bolivia. The sensilla pattern was effective in distinguishing individuals at sexual, ecotopic, and geographic levels, and supported the idea of a lack of gene flow between sylvatic and domestic habitats.

A new artificial shelter unit was compared with segments of bamboo cane lined with pleated filter paper for detecting peridomestic Triatoma infestans Klug at Amamá and nearby rural villages in northwestern Argentina. The new shelter unit consisted of a black plastic, wide-mouthed jar with a screw cap on the top, and a removable central structure made of pleated corrugated paper. In devices exposed from February to December 1999 at 24 sites positive for T. infestans by timed manual collections with an irritant in April 1999, the cumulative percentage of sites with any sign of infestation detected by the shelter unit increased from 71% after 2 mo to 96% after 10 mo, whereas bamboo cane units concurrently detected only 12–42% of the sites. Sensitivity increased with time of exposure and the abundance of T. infestans per site. In 19 sites negative for T. infestans by inspection, shelters increasingly detected infestation at 16–63% of sites after 10 mo, whereas the bamboo canes only detected one infestation. Shelter units inspected three times over an 11-mo period were significantly more sensitive than a single manual search with an irritant performed in March 2000. Our study provided conclusive field evidence that the shelter unit was more sensitive for detecting peridomestic T. infestans than were timed manual searches, the standard reference method, or bamboo cane units. Rapid timed searches by skilled bug collectors during the early surveillance phase overlooked many peridomestic populations that, in the absence of control, inevitably would increase in abundance and repopulate treated areas.

The ectoparasitic mite Knemidokoptes jamaicensis Turk burrows into the cornified epithelium of the legs and feet of Passeriform birds and has been reported from 12 species of North American birds. Here we establish new host and distribution records for K. jamaicensis from eight species of birds from three habitats in the Dominican Republic. These species include Hispaniolan pewee (Contopus hispaniolensis Bryant), northern mockingbird (Mimus polyglottos L.), Cape May warbler (Dendoica tigrina Gmelin), prairie warbler (Dendroica discolor Vieillot), palm warbler (Dendroica palmarum Gmelin), green-tailed warbler (Microligea palustris Cory), black-crowned palm tanager (Phaenicophilus palmarum L.), and Greater Antillean bullfinch (Loxigilla violacea L.). Rates of infestation were as great as 18.2% but varied between species and habitats. Mites were far more common in the dry desert thorn scrub than they were in higher elevation and more moist habitats, despite the fact that many of the affected species had distributions that spanned multiple habitat types. Results suggest that the abundance of scaley-leg mites is controlled by the abundance of suitable host species and by specific ecological conditions that promote transmission.

The effect of a protracted dry season on the viability of Ae. aegypti (L.) eggs was examined in Townsville, northern Queensland, Australia. Eggs were placed in several different surface and subterranean larval habitats; and after four dry season months, only 1–10% of eggs remained viable in the surface and subterranean sites, respectively. Low humidity and predation by Periplaneta americana (L.) were the major causes of egg mortality in eggs in surface sites. P. americana was the most significant cause of egg predation in subterranean breeding sites but fungi, especially Penicillium citrinum Thom, covered egg batches within 15 d. Mycotoxins produced by the spores of P. citrinum are believed to have killed embryonating eggs. The high mortality rate of Ae. aegypti eggs during the dry season suggests that this survival strategy is unlikely to contribute to rapid and successful recolonization of surface sites at the end of the wet season.

The surface features of the eggs of Aedes aegypti (L.) and the effect of garlic extracts on their hatching were studied by scanning electron microscopy. The exochorion and endochorion layers of the eggshells display an essentially pentagonal reticulation. The exochorion meshwork exhibits large and small papillae interconnected by horizontal struts. At higher magnification, the large papillae show aeropyles on their rough surface. Eggs hatched in deionized water undergo complete fracture near the anterior poles producing free shell caps. In contrast, eggs placed in 6% reconstituted Kyolic garlic extract are only partially fractured, display attached shell caps, and the larvae remain trapped within the shells. In the natural garlic bulb extract, the eggs show no fracture lines in their shells. No larvae were observed either alive or dead in the garlic extracts, suggesting the embryos were disabled before they could escape from their eggshells as viable larvae. It is concluded that aqueous extracts of garlic inhibit hatching of Aedes eggs. Thus, compounds in garlic may be beneficial in the control of mosquitoes.

A survey in Cameroon compared the usefulness of the circumsporozoite protein enzyme-linked immunosorbent assay (CSP ELISA) to dissection and microscopic examination of anopheline salivary glands for measuring infectivity rates in anopheline mosquitoes. The salivary glands of 375 females, belonging to four species were examined for sporozoites. After microscopic examination, the glands as well as all the remaining heads and thoraces were tested by ELISA. The sensitivity of ELISA was 100% (18/18), confidence interval (CI) (78.1–100) and the specificity was 99.7% (357/358), CI (98.2–100). The Kappa value, agreement between examination of the glands and salivary gland ELISA, was 0.97. The head–thorax CSP ELISA overestimated the true salivary gland infection rate by 12.0%. The results obtained in Central Africa in a village with perennial transmission highly justified the use of the ELISA for measuring the entomological inoculation rate.

Antimite activity of essential oils and their components obtained from Taiwania cryptomerioides Hayata heartwood against Dermatophagoides pteronyssinus (Trouessart) and Dermatophagoides farinae Hughes was investigated in this study. Results from antimite tests demonstrated that the essential oil extracted from T. cryptomerioides heartwood had miticidal activity against D. pteronyssinus and D. farinae with a mortality of 67.0 and 36.7% at the dosage of 12.6 μg/cm² after 48 h. Alpha-cadinol possessed the strongest antimite activity compared with other components of the T. cryptomerioides heartwood essential oil. The rectified mortalities of D. pteronyssinus and D. farinae were 100% for α-cadinol at the dosage of 6.3 μg/cm². The order of antimite activity of four dominant constituents was α-cadinol > T-muurolol > ferruginol > T-cadinol. Paired Student’s t-tests showed that there were significant differences between the rectified mortality of α-cadinol, T-muurolol, ferruginol and that of T-cadinol at the dosage of 6.3 μg/cm² after 48 h.

A survey of the vectors of spotted fever group Rickettsiae and of murine typhus was carried out in Rahat, a Bedouin town in the Negev Desert, where the diseases are endemic. Houses with known cases of spotted fever group Rickettsiae or murine typhus were compared with those without reported clinical cases. A neighboring Jewish community, Lehavim, where no cases of spotted fever group Rickettsiae and murine typhus were reported in recent years, was used as a control. In the houses of patients with spotted fever group Rickettsiae in Rahat, an average of 7.4 times more ticks were found than in control houses. Out of 190 ticks isolated from sheep and goats or caught by flagging in Rahat, 90% were Rhipicephalus sanguineus (Latreille), 7.9% Rhipicephalus turanicus Pomerantzev, and 2.1% were Hyalomma sp. In the houses of patients with murine typhus, three times more rats were caught and, on the average, each rat was infested with 2.2 times more fleas than rats in the control houses. Out of 323 fleas collected from 35 Norwegian rats (Rattus norvegicus Berkenhout), 191 were Xenopsylla cheopis Rothschild and 132 Echidnophaga murina Tiraboschi. Thus, there was a six to seven times higher probability of encountering a tick or flea vector where infections had occurred than in control houses in Rahat. The percentage of rats seropositive to Rickettsia typhi was similar in study and control households (78.3 and 76.2, respectively). In the control settlement, Lehavim, only three Mus musculus L. were caught, which were not infested with ectoparasites and their sera were negative for murine typhus. Out of 10 dogs examined in this settlement, 15 R. sanguineus and eight specimens of the cat flea (Ctenocephalides felis felis Bouché) were isolated. No rats were caught in this settlement. These data indicate that there is a correlation among the density of domestic animals, their ectoparasites, and the incidence of spotted fever group Rickettsiae and murine typhus in Rahat.

We examined the effect of simulated overwintering temperatures on West Nile (WN) virus replication in Culex pipiens L. derived from mosquitoes collected during the autumn 1999 WN epizootic in New York. The WN virus was a strain isolated from a dead crow also collected during this outbreak. Virus was recovered from most mosquitoes held exclusively at 26°C. In contrast, none of the mosquitoes held exclusively at the lower temperatures had detectable infections. When mosquitoes were transferred to 26°C after being held at 10°C for 21–42 d, infection and dissemination rates increased with increased incubation at 26°C. Future studies involving the attempted isolation of WN virus from overwintering mosquitoes may benefit from holding the mosquitoes at 26°C before testing for infectious virus.

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.