Three species of scorpions have been reported from Tunisia: Androctonus amoreuxi Audoin, A. aeneas Koch, and A. australis L. The latest has been divided in two subspecies: A. australis garzonii Goyffon & Lamy and A. australis hector Koch. Despite the public health importance of these animals, which cause several cases of poisoning each year, nothing is know about the genetic diversity of the group. To gain a better understanding of the group, we studied the variation of rDNA sequences of the ITS1, 5.8S, and ITS2 region of 14 representatives of the four taxa in Tunisia. The main result is the high polymorphism of the ITS regions. In some instances in both intra- and interspecific comparisons, it was difficult to unambiguously align the sequences. However, some representatives of different species were relatively similar, so that it appeared difficult to recognize the species on the basis of these sequences. A phylogenetic analysis was conducted that inquires the validity of the subspecies status of A. australis garzonii and A. australis hector. Moreover, the taxonomic status of A. aeneas is also questioned. Our studies highlighted the need of a revision of the taxonomy of the scorpions in Tunisia; however, the use of other genetic markers will be necessary to solve this question.

We used molecular phylogenetic techniques to study the systematic relationships and host specificity of Psoroptes mange mites, which are pests of numerous domestic and wild ungulates. Phylogenetic analysis of DNA sequence data from the internal transcribed spacer region 1 (ITS1) of nuclear ribosomal DNA indicated that populations of Psoroptes are not host specific. Furthermore, the currently used taxonomy of Psoroptes is not concordant with the phylogeny derived from ITS1. During the course of the study, we discovered apparent paralogous ITS sequences within individual mites as a result of varying polymerase chain reaction reaction conditions. This finding concords with other studies of ITS and suggests a cautious approach when interpreting data from ITS sequences. Host DNA contamination was also found to be a significant problem in data collection, and we report on the development of methods to overcome the problems of contamination in parasitic mites.

One hypothesis to explain the southern extension of Japanese encephalitis (JE) virus from Papua New Guinea into the Torres Strait islands in 1995 and to mainland Australia in 1998 is the dispersal of infected mosquitoes, particularly Culex annulirostris Skuse from which JE virus has been isolated repeatedly. To investigate whether this species disperses in this manner, mosquitoes were identified from 368 aerial kite trap collections operated at 50–310 m (altitude) at inland New South Wales between November 1979 to December 1984. Forty samples (9 during daylight and 31 at night) contained mosquitoes, of which 221 could be identified as Culex australicus Dobrotworsky & Drummond (58.8%), Culex annulirostris (21.3%), Anopheles annulipes Walker s.l. (10.4%), Aedes theobaldi (Taylor) (7.2%), Aedes rubrithorax (Macquart) (1.4%), and Aedes sagax (Skuse) (<0.9%). During the night, mosquitoes were found in 22.6% of the collections at a mean density (±SD) of 91.3 ± 151.7/10⁶ m³ of air sampled. During the day, only 3.8% were positive at a mean density 125.3 ± 152.1. When examined in relation to possible flying time and wind speed, mean ± SD dispersal distances by day and night were 23.9 ± 15.3 km and 152.4 ± 116.3 km, respectively. These data provide circumstantial evidence that aerial carriage southward ≈200 km from Papua New Guinea to Cape York peninsula is feasible, but that southern dispersal of Murray Valley encephalitis virus infected mosquitoes from tropical to temperate Australia is unlikely.

To establish a transient expression system for genes introduced into sand fly cell lines, we tested the expression of the luciferase reporter gene under control of different promoters. Towards this end, we lipofected cell lines obtained from New and Old World sand flies, LL-5 from Lutzomyia longipalpis Lutz & Neiva and PP-9 from Phlebotomus papatasi Scopoli, respectively. The relative levels of luciferase expression were studied under control of Drosophila melanogaster Meigen heat shock protein 70 (hsp70), human cytomegalovirus, simian virus 40 or Junonia coenia (Hübner) densovirus (P9) promoters. The Drosophila heat shock protein 70 promoter, originating from insect genes, functioned as a strong promoter in both cell lines. Promoters from the different virus genes also were capable of driving transgene expression in both cell lines.

The effect of 90% RH on the embryonic development of Hyalomma marginatum marginatum Koch was investigated at 25°C. Under the influence of this factor, 2.1% dead eggs, 13.0% dead embryos, 6.9% abnormally hatched larvae, 0.2% larvae with malformations, and 77.8% normal larvae appeared. The embryos died during the cleavage of nuclei, the formation of the blastoderm, the formation of the germ band and its metamerization, and the differentiation of the leg anlagen. Egg hatch was also inhibited in various phases. Various kinds of anomalies were observed in larvae of Hyalomma m. marginatum. Most teratological changes (70.8%) occurred within the idiosoma. They were hetromorphose (32.6%), oligomely (15.4%), heterosymely (12.3%), symely (1.5%), atrophy (6.1%), and ectomely (3.1%). Anomalies within the gnathosoma occurred rarely (3.1%). As many as 26.2% larvae had composite anomalies (oligomely, heterosymely, atrophy) together. They contained various structures of the gnathosoma or idiosoma. These anomalies decreased the survival rate of the larvae. The investigations showed that during the formation of the blastoderm, the formation of the germ band and its metamerization the embryos have the largest susceptibility of being affected by high humidity. Some anomalies in specimens collected from nature may develop under influence of unfavorable humidity levels.

Viral growth characteristics that favor rapid and prodigious virion production may increase virus transmission but be detrimental to infected hosts. Several arboviruses, including eastern equine encephalomyelitis (EEE) virus, negatively affect the survival of their infected mosquito vectors. To test the hypothesis that the mosquito virulent properties of EEE virus are caused by the presence of intrinsic viral growth properties, we investigated the effects of infecting dose on the survival of intrathoracically inoculated Culiseta melanura (Coquillett). Daily survival of age-matched females inoculated with either a low initial dose of 10^1.5 plaque-forming units (PFUs) per mosquito or a high initial dose of 10^5.5 PFUs per mosquito was monitored for 8 wk. Compared with diluent inoculated controls, mosquitoes from both dosage groups displayed highly significant decreases in survival. No significant differences in daily survival were detected between the two infected groups. Virus production within inoculated mosquitoes was assessed by sampling mosquitoes every 12 h for 96 h after inoculation. Rapid virus amplification occurred in both dosage groups, and by 24 h after exposure the mean viral loads in mosquitoes inoculated with the low dose were comparable to those inoculated with the high dose. Likewise, although detectable virions appeared sooner in the saliva of high dosage mosquitoes, by 72 h after inoculation no significant differences in virus transmission were detected between the two exposure groups. These results indicate that the virulence of EEE virus for its enzootic North American mosquito vector is not dosage dependent and likely reflects the inherent growth properties of this virus within infected mosquitoes.

From January 1995 to June 1996, ticks were studied in a fragment of Atlantic Forest in a residential area in the city of Itapevi, State of Sao Paulo, Brazil. Cases of human Lyme disease-like illness were registered in this area during the spring of 1992. The monthly relative density of ticks was determined and the influence of seasonal climatic conditions was evaluated as well as the relationship between ticks and hosts. Ticks (n = 88) were collected from small mammals captured (n = 134) in monthly trappings where the traps were operated for five consecutive days. Immature ticks (n = 42, 47.7%) were identified as Ixodes spp. The adult ticks (n = 46, 52.3%) were identified as Ixodes didelphidis Fonseca and Aragão (n = 19, 21.6%), I. loricatus Neumann (n = 26, 29.5%) and Amblyomma cajennense (F.) (n = 1, 1.1%). The monthly correlations between tick numbers and meteorological data were not significant. The correlation between the different stages of ticks and the two seasons (cold-dry and warm-rainy) indicated that both immature and adult ticks showed a seasonal pattern of abundance. The highest numbers of immature ticks were observed on rodents, during the cold-dry season (from April to September) with a peak in August 1995. Adults ticks were predominant during the warm-rainy season (from October to March) with a peak in January 1995. Adult ticks were only collected on marsupials.

Multiple mating behavior of female cat fleas, Ctenocephalides felis (Bouché), was confirmed in this study, and its effects on fecundity and fertility were investigated as well. The number of fertile eggs produced by mated females was close to nil within 7 d after removal of males, but it was resumed when females were exposed to males again on day 7. Multiple-mated females displayed significantly higher fecundity (400.3 eggs per female) and fertility (182.8 viable eggs per female) than single-mated females (61.7 and 19.0, respectively) in the 24-d period, suggesting that multiple mating by females is an advantageous strategy for cat fleas. The duration of first mating averaged 63.1 min. The high ratio (55.56%) and short duration (34.0 min) of impotent mating suggested that cryptic female choice may be involved during copulation.

Mosquitoes collected in the Amazon Basin, near Iquitos, Peru, were evaluated for their susceptibility to epizootic (IAB and IC) and enzootic (ID and IE) strains of Venezuelan equine encephalomyelitis (VEE) virus. After feeding on hamsters with a viremia of ≈10⁸ plaque-forming units of virus per milliliter, Culex (Melanoconion) gnomatus Sallum, Huchings, & Ferreira, Culex (Melanoconion) vomerifer Komp, and Aedes fulvus (Wiedemann) were highly susceptible to infection with all four subtypes of VEE virus (infection rates ≥87%). Likewise, Psorophora albigenu (Peryassu) and a combination of Mansonia indubitans Dyar & Shannon and Mansonia titillans (Walker) were moderately susceptible to all four strains of VEE virus (infection rates ≥50%). Although Psorophora cingulata (Fabricius) and Coquillettidia venezuelensis (Theobald) were susceptible to infection with each of the VEE strains, these two species were not efficient transmitters of any of the VEE strains, even after intrathoracic inoculation, indicating the presence of a salivary gland barrier in these species. In contrast to the other species tested, both Culex (Melanoconion) pedroi Sirivanakarn & Belkin and Culex (Culex) coronator Dyar & Knab were nearly refractory to each of the strains of VEE virus tested. Although many of the mosquito species found in this region were competent laboratory vectors of VEE virus, additional studies on biting behavior, mosquito population densities, and vertebrate reservoir hosts of VEE virus are needed to incriminate the principal vector species.

Anopheline specimens collected in Papua New Guinea were morphologically identified as the rarely recorded Anopheles clowi Rozeboom & Knight. Amplification of the rDNA ITS2 region of this material revealed a fragment of 750 bp confirming its placement in the Anopheles punctulatus group. This group contains 12 species and includes the major malaria vectors in the islands of the southwest Pacific. Digestion of the ITS2 with the restriction enzyme MspI produced restriction fragment-length polymorphism with bands at 380, 300, and 150bp, a pattern shared by no other members of this group. Phylogenetic analysis involving the sequencing of a 2 kb region of the rDNA 18S gene indicated that An. clowi was monophyletic and basal to the rest of the group and showed considerable independent evolution from the other members. This is the first record of An. clowi in Papua New Guinea and only the third collection of this species since its discovery in 1945.

In north Queensland, 14 localities were surveyed for mosquito larvae (third and fourth instar) during summer/autumn and winter from 1996 to 1999. Absolute population numbers in subterranean habitats, mainly service manholes and pits (97%) but also some wells, septic tanks, storm drains, and sumps, were expressed as a proportion of total numbers in these sites plus surface sites within a 100-m radius. When correction factors were applied to subterranean samples, the 472,477 larvae mainly of Aedes tremulus (Theobald) group, Aedes notoscriptus (Skuse), and Aedes aegypti (L.) comprised 78% of the total population. In relation to the proportion of the overall immature mosquito population from subterranean habitats (propsub), linear regression coefficients for minimum temperature, relative humidity, and Mesocyclops copepod prevalence were significant for winter data; but for summer, only relative humidity was significant. Linear regression coefficients for Mesocyclops prevalence approached significance (P = 0.061) in summer. When multiple linear regression was used to model propsub, 68% of the variation was accounted for by relative humidity and the prevalence of Mesocyclops. In the drier and cooler towns, increased use of subterranean sites during winter was caused by reduced availability of surface oviposition sites because of the dry season. In the wetter coastal towns, no such restrictions applied and ambient conditions remained more equitable all year round. Mesocyclops were surprisingly common, particularly in these coastal towns. Release of known numbers of Mesocyclops indicated that 3-sweep netting in service manholes was sensitive down to densities of one Mesocyclops per 10 liters, and overall recovery varied from 1 to 4%. In relation to control, service manholes represent a stable habitat for mosquito (7% positive overall) and Mesocyclops populations. If they remained wet, service manholes positive for mosquito immatures or Mesocyclops during summer/autumn had 96% and 85% chance, respectively, of being positive the following winter. Even allowing for the effect of drying, a mosquito-positive manhole had a 79% chance of remaining positive the following winter. In view of the importance of these sites as refuges from adverse ambient conditions, it is proposed that a winter control strategy using Mesocyclops presents a cost-effective control option to reduce the recolonization of surface sites when conditions become more suitable.

Scanning electron microscope observations were made on second instars of unindentified sarcophagid maggots recovered from the foot of a 2-mo-old child. The child had a 3-d history of irritation and swelling of the left foot, and larvae were present in the skin on the plantar surfaces. The lesions were not furuncular, but erythema and a serous exudate were evident and swelling of the infested toes was noted. Larvae were removed manually from the lesions and fixed in formalin. External features, examined by scanning electron microscopy (SEM), were typical for muscomorph larvae and shared features common to other sarcophagids. Details of the cephalic, thoracic, and terminal abdominal sensory structures and variation in the structure of spines from various body regions are described. Comparisons of SEM observations on the cephalic, thoracic, and posterior abdominal regions with other published information did not yield information that allowed the accurate identification of the larvae from this infestation.

Sensilla on the male terminalia of four different species of sand flies (Diptera: Psychodidae) are described. Two species belonged to the same species complex: Lutzomyia longipalpis (Lutz & Neiva) and L. cruzi (Mangabeira). Other Brazilian species complex was represented by L. lenti (Mangabeira) and L. carmelinoi (Ryan, Fraiha, Lainson & Shaw). Approximately 5–15 sensilla were found on the initial part of the styles of all species. Structurally, the sensory organs were similar to small coeloconica sensilla. Their number varied both individually and interspecifically. These sensilla may play an important role in the copulation behavior of these species of sand flies.

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 ≤ 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).

Isoenzymes, random amplified polymorphic DNA (RAPD), and morphometry were used to compare genetic variability within and between three populations of Triatoma brasiliensis Neiva, 1911 from northeast Brazil. The isoenzyme profiles were identical for the three populations, whereas the complex RAPD patterns allowed clear discrimination between the three. Morphometric analysis, using characters of the head capsule, also showed discrimination between the three populations but only in comparisons of males, not females. The results show considerable genetic heterogeneity in T. brasiliensis, with an indication of geographic structuring possibly resulting from a recent series of domestication events.

White-tailed deer treated themselves with a commercial pour-on acaricide formulation containing 2% amitraz as they fed from an ARS-patented ‘4-poster’ topical treatment device. Whole kernel corn attracted deer to a single device placed in each of two deer-fenced pastures. In the treatment pasture, the rollers of the treatment device were charged with the acaricide, whereas the rollers of the device in the other pasture remained untreated. Deer were allowed to use the ‘4-posters’ during periods of tick activity beginning in early to midspring and lasting through late summer to early fall for three consecutive years. Pretreatment sampling of adults and nymphs with dry-ice traps and larval masses with flip cloths showed no significant differences in population indices between the two pastures; however, after the third year of treatment, control of nymphal and adult ticks in the treated pasture was 91.9 and 93.7%, respectively, when compared with the untreated pasture. Control of larval masses increased from 68.4% in year 1 to 96.4% in year 2, but declined to 88.0% in year 3, probably because of the presence of feral hogs. This study demonstrated that application of amitraz to white-tailed deer through free-choice interaction with a ‘4-poster’ device significantly reduced the abundance of free-living lone star ticks in a deer-fenced experimental pasture. Moreover, the yearly pattern of incremental increases in control and the final percentage control values for all three parasitic life stages in this topical application study were similar in magnitude to that observed in a previously conducted study in which the systemic acaricide ivermectin was used to reduce populations of free-living ticks by controlling ticks on deer.

In the United States, Ixodes scapularis Say has been implicated as the vector of at least three human pathogens. Tick induced modulation of host immunity is increasingly recognized as an important factor in successful transmission or establishment of tick-borne pathogens. This study was conducted to determine the effects of repeated infestations with pathogen-free I. scapularis nymphs on in vitro proliferative responses of splenic lymphocytes from C3H/HeN mice. Lymphocytes from repeatedly infested and uninfested mice were exposed to concanavalin A (Con A), Escherichia coli Castellini & Chalmers lipopolysaccharide (LPS), or I. scapularis salivary gland soluble proteins (SGSP), to determine if lymphocyte responses differed between tick-exposed and nonexposed mice. Female C3H/HeN mice were infested one to four times with pathogen-free I. scapularis nymphs, with a 14-d tick-free period between each exposure. After each infestation, tick biology parameters were measured and lymphocyte proliferative responses assessed. Acquired resistance to I. scapularis was not evident in mice subjected to tick feeding. Significant differences in the responses of lymphocytes exposed to I. scapularis SGSP were observed between infested and noninfested mice. In contrast, few differences between infested and noninfested mice were evident for lymphocytes exposed to Con A or LPS. Our results suggest that repeated exposure to I. scapularis nymphs does not affect Con A or LPS-induced proliferation of splenic lymphocytes, but significantly effects lymphocyte responses to tick salivary gland antigens.

In mosquitoes, in addition to larval and adult peritrophic membranes (PMs), a PM (meconial peritrophic membrane or MPM1) forms in the pupa around the meconium, the sloughed, degenerating larval midgut epithelium. Often, a second membrane (MPM2) forms in temporal proximity to adult emergence. Differences in the occurrence, persistence, and timing of disappearance of the meconium/MPMs and gas were studied by dissecting the midgut contents from pupae of known ages postpupation and from adults of known ages postemergence. MPM1 was found in all Anopheles and Culex studied and nearly all Culiseta. The occurrence of MPM1 varied in the Aedes species. In one series of Aedes aegypti (L.) dissections, no fully formed MPM2 was found in any specimens. The occurrence of MPM2 appeared to be associated with adult emergence and varied among and within the seven species studied. It typically was seen in recently emerged adults but was observed occasionally in old pupae. Much of our data supports the idea that MPM2 formation is stimulated by midgut epithelium distention.

Among the morsitans-group of tsetse there are several pairs of taxa in which there is a marked hybridization asymmetry (HA), i.e., one cross produces significantly more offspring than does the reciprocal cross. To investigate the relative contribution of maternally inherited factors (MIF) and chromosomal factors to HA, three hybrid lines were established in which flies have MIF from one taxon and chromosomes from another. HA was then compared among crosses of the parental taxa and crosses of each parental taxon with the appropriate hybrid line. The results indicate that HA in reciprocal crosses of Glossina morsitans morsitans Westwood and Glossina swynnertoni Austin and in reciprocal crosses of G. m. morsitans and Glossina morsitans centralis Machado are caused by chromosomal factors, not MIF. Reciprocal crosses of G. m. centralis and G. swynnertoni do not display HA, and none developed as a result of a novel combination of MIF and tsetse chromosomes.

Thirteen Aedes hexodontus Dyar populations from throughout the western United States were examined for genetic and morphological variation. Analysis of allozyme frequencies at 16 loci revealed a pattern of genetic variation that formed a north-south cline across Washington, Oregon, and California in the number of alleles per locus, the percent of polymorphic loci, and the frequency of one allele of aconitase-1. Comparison of the genetic profile of Ae. hexodontus populations to two other widely distributed members of the punctor subgroup, Aedes punctor (Kirby) and Aedes abserratus (Felt & Young), revealed only one diagnostic locus for all three species. Seven loci exhibited frequency differences among species but were not diagnostic. Morphological characters also exhibited little variation within and among the three species. The adult females differed only in the scaling of the probasisternum. This area was extensively scaled in 91% of Ae. hexodontus specimens but bare or only lightly scaled in Ae. puntor and Ae. abserratus. No other differences were observed in the adult females or the male genitalia in any of the three species. The larvae of Ae. abserratus could be separated by the single-branched seta 2-X. Six larval characters differed between Ae. hexodontus and Ae. punctor but the ranges of each character overlapped and none were diagnostic. These comparisons indicated that Ae. hexodontus is a single species, at least in the southern part of its range. Also, genetic and morphological comparison of the three species within the punctor subgroup attested to the close relationship hypothesized for these mosquitoes.

This study examined the prevalence of Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Brenner in host-seeking adult and nymphal Ixodes pacificus Cooley & Kohls and estimated the I. pacificus infestation and B. burgdorferi infection of rodent and avian hosts in the western Sierra Nevada foothills of northern California. Additionally, we identified species likely to participate in an enzootic cycle for B. burgdorferi in this yellow pine transition habitat. Evidence of infection with B. burgdorferi was identified in 7.3 and 5.4% of host-seeking I. pacificus adults and nymphs, respectively. Mean numbers of I. pacificus observed on rodents were 1.15 for Neotoma fuscipes Baird and 0.18 for Peromyscus spp. One of 104 ear punch tissues obtained from woodrats and none from 49 Peromyscus spp. yielded B. burgdorferi. A total of 291 collected birds representing 34 species had a mean of 0.27 I. pacificus per bird. The mean I. pacificus infestation of ground-dwelling birds was 2.5 ticks per bird. Forty-nine of 92 (53%) blood smears collected from birds were reactive to a B. burgdorferi specific antibody. This study presents the identification of a B. burgdorferi-like spirochete in birds in western North America. The tick burden and spirochete infection of birds suggests that birds may be involved in a local B. burgdorferi enzootic cycle and likely participate in the transport of ticks and spirochetes to other locations while rodents from this site do not appear to be major contributors.

Repellent efficacy of N,N-diethyl-3-methyl-benzamide (deet), the piperidine, 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine (AI3-37220), and a 1:1 ratio of deet AI3-37220 were evaluated topically (0.25 mg/cm² applied in ethanol solution) on human volunteers against the mosquito Aedes communis (DeGeer) and the black fly Simulium venustum Say. The average repellency of all three formulations was >95% at 4 h. For both mosquitoes and black flies, deet alone provided <90% protection at 6 h, whereas AI3-37220 provided >95% protection. Although repellent treatments were not significantly different overall, the contrasts between AI3-3720 versus deet were significant at 6 and 8 h. The 95% confidence interval on percent repellency at 6 h ranged from 90.1 to 98.9% for AI3-37220 versus 64.3 to 82.2% for deet, and at 8 h ranged 76.1 to 88.5% for AI3-37220 versus 47.8 to 64.0% for deet. Similarly, the confidence interval for protection against black flies at 6 h by (AI3-37220 ranged from 86.3 to 99.5% and did not overlap with the confidence interval provided by deet alone (51.2 to 78.8%). There was no evidence of synergistic repellency from a combination of the two compounds; i.e., protection from combined compounds was no better than either repellent used alone.

The bacterial diversity in the intestinal tract of Musca domestica L. was examined in larvae collected from turkey bedding and corn silage. Aerobic culturing yielded 25 bacterial species, including 11 from larvae collected from turkey bedding and 14 from larvae collected from corn silage. Providencia rettgeri (Hadley, Elkins & Caldwell) was the only species common to both environments. Two mammalian pathogens, Yersinia pseudotuberculosis (Pfeiffer) and Ochrobactrum anthropi (Holmes), were isolated from the larval intestinal tracts. The majority of isolates represented facultatively anaerobic heterotrophs capable of fermentation. The significance of these bacteria for development of house fly larvae was evaluated by bioassays on trypticase soy egg yolk agar. Pure cultures of individual bacterial species isolated from the intestinal tract of larvae from turkey bedding supported development of flies to a much greater extent than those isolated from larvae from corn silage. House fly development was best supported by a Streptococcus sanguis (White) isolate. The significance of bacteria for development of house flies is discussed.

Carcinops pumilio (Erichson) were collected using two trapping methods: a black light pitfall trap and a mesh-bottomed trap placed on poultry manure. C. pumilio collected with black lights and subsequently starved had a significantly higher dispersal rate during days 1-3 than fully fed groups. When densities of <500 Caloglyphus berlesei (Michael) (Acarina: Acaridae) per 50 C. pumilio were provided, mite availability had a significant effect on dispersal of beetles captured with both black light traps and the mesh-bottomed trap during the day 1-3 period. Our results indicate that the availability of acceptable food sources can delay and possibly prevent dispersal by C. pumilio. Black light-captured beetles appeared to be in a state of dispersal when captured. A subset of dispersing beetles was present in groups captured with the mesh-bottomed trap.

The Anopheles maculatus Theobald complex includes important vectors of malaria. Based on chromosomal and morphological evidence, two species in this complex occur in the Philippines. Because separation of these species, An. dispar Rattanarithikul & Harbach and An. greeni Rattanarithikul & Harbach, is problematic due to the difficulty or unreliability of the identification methods currently available, we sought a molecular technique for identifying these two species. We sequenced two regions of nuclear ribosomal DNA; the second internal transcribed spacer (ITS2) and the third domain (D3) of the 28S gene, from An. maculatus sensu lato (s.l.) collected throughout the Philippines. Two sequence groups were identified that corresponded morphologically to An. dispar and An. greeni. Four percent of the 318–320 bp ITS2 and 2.5% of the 367 bp D3 differed between the two species. No evidence of intraspecific variation in sequences was found. From the sequence data, we developed a more reliable and easier method for identifying An. dispar and An. greeni, based on a HaeII restriction fragment-length polymorphism in a polymerase chain reaction amplified fragment of ITS2. This method will facilitate future vector studies, which will be necessary, as previous data collected on An. maculatus s.l. in the Philippines is unreliable given the multispecies nature of this taxon.

A fatty acid-binding protein (FABP) from the cytosolic fraction of the triatomine Dipetalogaster maximus (Uhler) flight muscles was purified by a procedure based on gel filtration, reverse-phase high performance liquid chromatography, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The protein has an apparent molecular mass of 14 kDa, and its N-terminus is unblocked. Its N-terminal sequence was obtained by submitting an SDS-PAGE band blotted onto a polyvinylidene difluoride membrane to Edman degradation. The sequence obtained indicates that this FABP belongs to the heart type. This is the first time that a fatty acid-binding protein has been reported for a triatomine. The presence of said FABP, abundant mitochondria, and lipid stores in the flight muscles of D. maximus suggests that beta oxidation of fatty acids is used by the triatomine thoracic muscle as an energy source, and could be related to its dispersal capacity.

We previously reported that enterohemorrhagic Escherichia coli O157: H7 (EHEC) proliferates in the mouthparts of the house fly Musca domestica vicina Macquart and are excreted for at least 3 d after ingestion. However, the role of the crop and excretory behavior of the house fly in contamination of human food with EHEC is not known. In the current experiments, EHEC persisted in the crop of house flies for at least 4 d. The number of EHEC in an excreted droplet was ≈10⁴ 1 h after bacterial feeding, >1.8 × 10⁵ 3 h after feeding, and then drastically decreased after 24 h. Excretion is one of the major mechanisms for decreasing number of EHEC in the crop and gut of the house fly. The frequency of excretion by females with developing eggs in their ovary was clearly higher (6.5 min per drop) than for males or females with mature eggs. Minute eosin-sign around a container filled with eosin-supplemented trypticase soy broth might be derived from frequent contact by house fly contaminated mouthparts. These results show that frequent excretion potentially enhances the dissemination of EHEC to foods, particularly during the first 24 h after ingestion of the bacteria.

The intensity and prevalence of parasitism by Ascogregarina barretti (Vavra) in Aedes triseriatus (Say) did not differ between tires and tree holes in field samples taken in September 1996. There was significant variation in the intensity of parasitism among containers that was not significantly correlated with the pH, conductivity, or temperature of the container water. In an experiment manipulating habitat drying, treatments had a significant effect on A. barretti infection of Ae. triseriatus, only during midsummer in one of two years. Containers maintained at maximal volume had the lowest prevalence of parasitism, and containers that dried out had the greatest prevalence. In this experiment, there was also a season-dependent difference in the intensity and prevalence of infection between tree holes and tires. The first larvae to reach the fourth instar in tires in the early summer had lower intensity and prevalence of infection than did larvae in tree holes during the same period. The seasonal difference in intensity of parasitism between tires and tree holes was not related to differences in pH, conductivity, and temperature.

The attraction response of Stomoxys calcitrans (L.) to its own feces was evaluated in a triple cage olfactometer. Both time- and concentration-response relationships were obtained for female S. calcitrans exposed to cellulose sponges impregnated with fresh fly feces or filter papers treated with chloroform:methanol extracts of fresh fly feces in 6-min tests. Attraction to feces collected on cellulose sponges decreased as the air flow increased. Feces collected on cellulose sponges and held for 28–31 d retained attractive activity. More female flies were attracted than males to feces on sponges or to polar solvent extracts of feces-contaminated cages. The activity of feces extract on filter paper decreased rapidly. Chemical identification of the active compounds present could lead to useful baits for traps.

Coelomomyces numularius sp. nov., a fungus parasitizing the larvae of Anopheles squamosus Theobald in southern Angola, Africa, is described and illustrated, with comments on its diagnosis and host specificity. Because of the general surface ornamentation of the resting sporangia, this new species is placed in group V of Bland and Couch. Resting sporangia can be distinguished from other species in group V by their dimensions, unique wall structure, placement of the dehiscence slit, and symmetrical shape.

Neutralizing antibodies for dengue virus serotypes 1 and 2 and serotypes 2 and 3 were detected in 1998 in 12 of 53 (22.6%) and 3 of 10 (30.0%) bats sampled in Costa Rica and Ecuador, respectively. Dengue is a consistent health problem in the two Costa Rican communities in which bats were sampled. The high percentage of bats with neutralizing antibodies to dengue virus in these two Costa Rican communities suggests that bats may become infected with dengue virus. This appears to be the case in Costa Rica and Ecuador.

Embryos of the primary screwworm, Cochliomyia hominivorax (Coquerel), were successfully permeabilized for use in subsequent cryopreservation studies. Mortality was greater for eggs incubated for <5 h before treatment. The mean survival of embryos to first instars was 55.7, 61.1, and 62.6% when the embryos were incubated for 5, 5.5, and 6 h before treatment, respectively. The survival to the pupal and adult stages was low. An improved media for culturing the embryos during and immediately after treatment needs to be devised and the procedure for rearing the larval stages also needs to be altered to improve survival for emerging adults.

Ticks were collected from pastures and domestic and wild vertebrates during the rainy seasons of 1994 and 1996 in Guinea-Bissau. We collected the following species: from pastures Rhipicephalus lunulatus Neumann, R. muhsamae Morel & Vassiliades, R. senegalensis Koch, and R. sulcatus Neumann; from reptiles Amblyomma nuttalli Dönitz and Aponomma flavomaculatum (Lucas); and from mammals Amblyomma paulopunctatum Neumann, Amblyomma splendidum Giebel, Amblyomma variegatum (F.), Hyalomma truncatum Koch, R. muhsamae, R. sanguineus (Latreille), R. senegalensis, and R. sulcatus. New host records are as follows: Amblyomma nuttalli on Senegal flap shelled turtle (Cyclanorbis senegalensis Dumeril & Bibron), Aponomma flavomaculatum on West African dwarf crocodile (Osteolaemus tetraspis Cope), and R. sulcatus on bushbuck (Tragelaphus scriptus Pallas). We reviewed the literature for earlier records of ticks from Guinea-Bissau. The regional distributions of the 21 tick species hitherto recorded in Guinea-Bissau are listed.

Amblyomma auricularium (Conil) was collected from an armadillo in Glades County, FL. Two females and 11 males were collected. This is the first record of this species in the United States.

This paper describes the identification of ticks from wild animals of the Pantanal region in Brazil as part of a comprehensive study about established and emerging tick-host relationships and related pathological aspects. Eighty-one animals were captured (representing 13 species, six orders), and ticks were found on 63 (78%). Tick species identified included Boophilus microplus (Canestrini), Amblyomma cajennense (F.), Amblyomma parvum Aragão, Amblyomma pseudoconcolor Aragão, Amblyomma scalpturatum Neumann, Amblyomma nodosum Neumann, Amblyomma ovale Koch, and Amblyomma tigrinum Koch. Dragging from grasslands yielded negative results compared with the high concentration of ticks that were collected from leaves in the forests.

1-Octen-3-ol with and without ammonia were evaluated as attractants in canopy traps for Haematopota pluvialis L., Hybomitra expollicata Pand., and Morellia spp. Baited traps collected significantly more Tabanidae and female Morellia spp. than unbaited traps. 1-Octen-3-ol or 1-octen-3-ol with ammonia, increased catch by 4.2- and 4.3-fold for H. pluvialis, 5.9- and 8.6-fold for H. expollicata, and 1.2- and 1.6-fold for female Morellia spp., respectively.