An Internet offer was made to identify any spider in the United States perceived to be a brown recluse spider, Loxosceles reclusa Gertsch & Mulaik (Sicariidae). In total, 1,773 arachnids from 49 states represented three orders (Araneae, Solifugae, and Opiliones) and the identifiable spiders (Araneae) consisted of 38 families, 88 genera, and 158 recognizable species. Participants from states at least half within the known brown recluse distribution submitted Loxosceles spiders 32–89% of the time, except Louisiana and Mississippi with no submissions. From 25 of 29 states completely or almost completely outside of the range of Loxosceles spiders, no recluse spiders were submitted. Only two discoveries of brown recluses and two of the worldwide tramp species Loxosceles rufescens (Dufour) were submitted from nonendemic Loxosceles areas. States on distribution margins of brown recluse or other native Loxosceles spiders were intermediate in their Loxosceles submissions. This study showed that 1) the general public perceives brown recluses to occur over wide-ranging areas of the United States; and 2) brown recluses are frequently submitted from endemic states and almost never from nonendemic states, and therefore are virtually limited to their known distributions. This study corroborates opinions that diagnosis of brown recluse spider bites is best restricted to areas historically supporting proven, widespread populations of Loxosceles spiders.

A morphological comparison and molecular study of the Afrotropical Funestus and Afro-Oriental Minimus groups within the Myzomyia series of Anopheles (Cellia) was conducted to determine their phylogenetic affinities. Relationships were investigated using morphological characters and ribosomal (D3) and mitochondrial (COII) nucleotide sequences. Cross-identification of specimens from one group by using keys for the other group confirmed their morphological similarity, i.e., members of one group shared the key characters with members of the other group. Molecular analyses recognized five clades, not strictly related to geographical distribution: the Aconitus, Culicifacies, Funestus, Minimus, and Rivulorum subgroups. Morphological observations were congruent with the results of molecular analyses. Anopheles leesoni, an Afrotropical species, is closely related to the Oriental Minimus complex, and these taxa share a close relationship with the Fluviatilis complex that occurs from the Arabian Peninsula through India. The immature and adult stages of An. rivulorum in Africa bear morphological characters that distinguish this species from members of the Afrotropical Funestus subgroup. A composite scheme of classification based on the results and previously published information is proposed for the two groups. It is noted that An. fluviatilis species S is conspecific with An. minimus species C.

Euschoengastia suzukii Takahashi, Fukaya & Takahashi is described and illustrated. The type material was collected from soil samples in the nest burrows of the sea bird streaked shearwater, Calonectris leucomelas (Temminck), living on Mikurajima Island in Tokyo; Oomorijima Island, Oki, Shimane Prefecture; and Awashima Island, Niigata Prefecture, in Japan, indicating that C. leucomelas is the main parasitic host of E. suzukii new species.

We studied the embryos of Ixodes ricinus (L.) in the second and third trimester of embryonic development, by using light and transmission electron microscopy. At the beginning of the second trimester, the formation of the foregut and rectal sac, by a process of invagination, was observed. The invagination, which develops into the primordium of the hindgut, forms only in the third trimester. The rectum forms in the last phase of embryogenesis. The development of the midgut is incomplete during embryogenesis. The yolk is surrounded by a wall, formed of an amorphous basal lamina and flattened cells, that gradually accumulate deutoplasmic material. These cells do not acquire the typical features of the gut epithelium until after larval hatching. These features are, however, found in the cells forming the rectal sac.

We compared the development of the molecular forms of Anopheles gambiae s.s. in different larval habitats. First stage larvae (L1s) of wild-caught females were placed into cages in natural habitats of the M form (rice fields) or the S form (puddles/quarries). Each cage was covered with cloth, allowing exchange of water, solutes, and small particles, including microorganisms, and was seeded with 100 L1s of a single form (M or S) or by a mixture of 50:50 of M and S forms. Emergence success of both forms in puddles and quarries was three-fold higher than in the rice fields. The emergence rate of the S form was higher than that of the M form in both habitats, but the form × habitat interaction was not significant. In temporary larval sites such as puddles, emergence success of the M form was lower in mixed cages than in single form cages, whereas the reverse was true for the S form, suggesting competition between the forms. The median developmental time was not significantly different between forms. Although these findings demonstrate differences between forms, they do not suggest that their spatial segregation is determined by differences in their exploitation of the physical and chemical conditions in these environments. These results should be regarded with caution because small numbers of first stage larvae could pass through the cloth of the cages.

Species compositions of Culicoides paraensis (Goeldi) (Diptera: Ceratopogonidae), the major vector of Oropouche virus to humans in Central and South American urban cycles, and Culicoides insinuatus Ortiz & Leon differed along a northeast-to-southwest transect across Iquitos, Department of Loreto, Peru. The relative distributions of the species were consistent with patterns of human outbreaks along the Amazon River. We resumed collection of biting midges between May 2000 and January 2004 at three sites previously sampled (1996–1997) to determine whether the known vector was expanding its range relative to the earlier survey. C. paraensis did not replace C. insinuatus across the region surveyed. Instead, C. insinuatus dominated the more southern sites and significantly increased its relative proportion at all three sites. Apparently, microhabitat differences and not range expansion by C. paraensis were responsible for differences in species compositions across the sample sites.

We tested for competitive advantage among larvae of Aedes albopictus (Skuse) and Culex pipiens L. in a laboratory experiment and determined the frequency and spatial and temporal patterns of co-occurrence in the field in East St. Louis, IL. In a laboratory competition experiment at multiple combined densities of Ae. albopictus and Cx. pipiens larvae, Ae. albopictus survivorship and developmental times were significantly affected by conspecific densities but not by Cx. pipiens densities. In contrast, Cx. pipiens survivorship and developmental times were significantly affected by both conspecific and Ae. albopictus densities. Per capita rate of increase (r′) for Ae. albopictus cohorts declined significantly due to density of conspecifics, but not density of Cx. pipiens. Interspecific competition between Ae. albopictus and Cx. pipiens under these laboratory conditions was strong and asymmetrical, with the effect of Ae. albopictus on Cx. pipiens much stronger than the reverse. In monthly samples from tire sites in East St. Louis, Ae. albopictus was highly seasonal, occurring in relatively low abundance from early May to July and increasing in abundance in August and September. Co-occurrence corresponded to the seasonality of Ae. albopictus, with Cx. pipiens encountering Ae. albopictus in more tires and at higher numbers within a tire, in August and September. Abundance of both species was high in residential areas and was unrelated to overstory cover, total nitrogen, and total phosphorus. Abundance of Ae. albopictus, but not of Cx. pipiens, was positively associated with conductivity. We expect Cx. pipiens to suffer from the effects of interspecific competition in tires in which it encounters Ae. albopictus. Interspecific competition between these species may be of both ecological and medical importance.

Triatoma guasayana (Wygodzinsky & Abalos) is a secondary vector of Trypanosoma cruzi (Chagas), the etiologic agent of Chagas disease, in the Chaco region of Argentina, Bolivia, and Paraguay. The spatial distribution of T. guasayana in a rural community in northwestern Argentina is described and analyzed using very high spatial resolution satellite imagery, geographic information systems, and spatial statistics. Since a 1992 residual spraying with insecticides of all houses, site-specific domestic and peridomestic reinfestations by triatomine bugs were monitored using various methods semiannually from 1993 to 2002. The reinfestation by T. guasayana started with finding of only adult bugs in a few sites. Bug abundance was significantly clustered and predominantly peridomestic in the southern and northern extremes of the community. The identified source of reinfestation in the northern cluster was a colonized wood pile, whereas no potential peridomestic source was found for the southern cluster. The spatial distribution of T. guasayana was positively associated with the abundance and spatial distribution of goats. Active dispersal from the hypothesized source and the surrounding sylvatic environment, and passive transport of bugs in wood piles seems to be the most likely mechanisms underlying the observed spatial pattern of T. guasayana. The absence of domestic colonization indicates that, to date, there is no trend toward increased local domiciliation of T. guasayana. The clustering zones can be considered “hot spots” where bug invasion from other sources is expected to be higher and where eventually, introduction of sylvatic T. cruzi to suitable hosts may occur.

We continuously recorded the activity of adult and nymphal blacklegged ticks, Ixodes scapularis Say, exposed to diurnal light and temperature cycles in a laboratory test chamber by using a digital camera controlled by an intervalometer. Adult ticks collected and tested in the fall exhibited a bimodal pattern of activity, with peaks shortly after lights on and shortly after lights off, and substantial daytime activity. However, adult ticks collected in the winter and early spring exhibited a unimodal pattern of activity, peaking shortly after lights off, and minimal daytime activity. Nymphs, collected and tested in the summer, exhibited only a unimodal pattern of activity, peaking after lights off. Limited data also are presented for adult ticks exposed to only a temperature cycle or to only a light cycle in the spring. Ticks exposed to a temperature cycle exhibited a unimodal pattern of activity, similar to that exhibited by ticks exposed to both light and temperature cycles at the same time of year, whereas those exposed to a light cycle exhibited a bimodal pattern of activity. Although the difference did not quite reach statistical significance, there is a possibility that temperature is a stronger entraining agent for tick diurnal activity than is light, an unusual situation. The change in diurnal activity pattern from fall to spring suggests that ticks are adjusting their strategy for host finding, possibly in relation to remaining stored food supplies or host activity, and may have practical implications for sampling carried out to track tick populations.

The New Word screwworm, Cochliomyia hominivorax (Coquerel 1858) (Diptera: Calliphoridae), is one of the most important insect pests of livestock in the Neotropical region. In this work, polymerase chain reaction-restriction fragment length polymorphism of mitochondrial DNA (mtDNA) was used to study the diversity and population structure of seven geographically distinct populations of C. hominivorax from most of the important livestock areas in Uruguay. The control region (A T/12S) and subunits 1 and 2 of cytochrome oxidase (cox1/cox2) were amplified and digested with restriction endonucleases. Nine haplotypes were observed among the populations sampled. The mean nucleotide diversity and the haplotype diversity indicated high mtDNA variability in this species. The similarity index, average nucleotide divergence, and analysis of molecular variance results showed no evidence of subpopulation differentiation, indicating that the C. hominivorax populations of Uruguay form a single panmitic population. The distribution pattern of the genetic variation in natural populations of C. hominivorax and the implications of these results for establishing control program are discussed.

Previous studies have shown that sympatric populations of M and S molecular forms of Anopheles gambiae sensu stricto exhibit strong assortative mating. In the few documented cases of cross-mating between M and S forms, females that mated with a male of the alternative form were often also mated with a male of their own form. A potential explanation for the association between cross-mating and double mating could be that male accessory gland or sperm proteins that are responsible for inducing refractoriness to further mating by females have diverged between the M and S forms. This mechanism of postmating reproductive isolation would have important implications for our understanding of the speciation processes in the An. gambiae complex. We tested for this mechanism, by comparing the likelihood of mating, feeding, and laying eggs, as well as the fertility of females presented with males of their own form or the alternate form in the laboratory. We also compared the likelihood of remating in cross-mated and assortatively-mated females, and we analyzed their progeny to unravel patterns of sperm precedence. We found that cross-mated females differed from assortatively-mated females only in terms of egg-hatching rate and larval survival but that these effects could be attributed to hybrid vigor rather than differential response to seminal products. Cross-mating between forms was not associated with remating behavior. These results indicate that the sex proteins responsible for inhibiting further insemination and triggering the gonotrophic cycle in females have not diverged between these M and S populations. We discuss alternative explanations for the patterns of cross-mating and multiple mating observed in the field.

Isozymes from five wild-caught populations of Aedes aegypti (L.) were compared using starch gel electrophoresis to estimate rates of gene flow between and among geographically close mosquito populations. Ae. aegypti were collected from five different locations in Bangkok, Thailand. One collection was obtained from central Bangkok (Huai-Khwang); the other four samples were obtained from surrounding areas (Districts Latkrabang, Ratburana, Laksi, and Bangkok Noi). Based on 24 loci (17 enzyme systems), only minor genetic differentiation was observed between all five populations. The highest percentage of polymorphic loci (34.3) was observed from the central Bangkok population; the least percentage of polymorphism (20.0) was seen from Laksi (north Bangkok). This study indicates that a large effective migration rate exists among all five populations. No fixed genetic differences were detected.

The Hyrcanus group comprises many closely related species with wide distributions in the Oriental and Palaearctic regions. The sequences of the second internal transcribed spacer (ITS2) of ribosomal DNA were determined for 12 species in China—An. crawfordi, An. hyrcanus, An. junlianensis, An. kunmingensis, An. kweiyangensis, An. lesteri, An. liangshanensis, An. peditaeniatus, An. pullus, An. sinensis, and two unknown species within the group. The length of the ITS2 ranged from 436 bp in An. hyrcanus to 469 bp in An. crawfordi, with GC contents of 44.9–46.8%. Intraspecific variation was found in three species (An. junlianensis, An. liangshanensis, and An. pullus) at the level of 0.0–0.4%, whereas interspecific differences ranged from 1.6% between An. liangshanensis and An. kunmingensis to 50.8% between An. peditaeniatus and sp. 1. The ITS2 comparisons revealed two unknown species, verified the valid species status for An. kunmingensis, and found An. pullus in China. We agree that An. anthropophagus is a junior synonym of An. lesteri. The validation of An. junlianensis awaits recognition of the molecular identity of the entity identified as An. yatsushiroensis. The ITS2 divergences were used for inferring phylogenetic relationships among 12 species in China. The estimation revealed close relationships among An. liangshanesis, An. kunmingensis, An. kweiyangensis, An. lesteri, and An. sinensis. Our study emphasizes the need for the molecular identity of the species members in integrated studies in systematics, bionomics, and population genetics for the Hyrcanus group.

The effects of pyriproxyfen were tested against a local population of Aedes aegypti (L.) in Iquitos, Perú. Bioassays showed that, when applied to late instars, pyriproxyfen prevented adult emergence at extremely low concentrations (LC₅₀ = 0.012 ppb). There was no adult emergence from water sampled from storage tanks that had been seeded with the equivalent of 50–83 ppb (AI) pyriproxyfen. Five months after treatment, despite constant dilution of these tanks, water sampled from these sources continued to be lethal to larvae and pupae. Additional studies, carried out in the laboratory, showed that groups of five or 20 female blood-fed mosquitoes, exposed to residues of ≈0.003 g (AI) pyriproxyfen/m², could transfer enough chemical to new oviposition sites to prevent ≈80% of adult emergence from larvae developing in that previously uncontaminated water. Moreover, although the fecundity of the adult females used as the transfer vehicles in these tests was unaffected, the subsequent eclosion of the eggs that these mosquitoes laid was decreased by 70–90%. It also was shown that, at very high concentrations (>30,000 ppb), pyriproxyfen-treated water sources were as likely to be used as oviposition sites as untreated sources. These data suggest that treated sites might act as sinks for mosquito reproduction and moreover that such sites might act as dissemination sources for the horizontal transfer of larvicides to new environments by mature females. We review the literature on the environmental and human health effects of this compound and discuss its potential for use as a mosquito control agent in the field.

The susceptibility of four laboratory strains of cat fleas, Ctenocephalides felis (Bouché), to imidacloprid was determined by three different laboratories, by using a standardized bioassay protocol. The probit lines generated by the different laboratories were very similar, with LC₅₀ values ranging from 0.32 to 0.81 ppm. Based on these data, a diagnostic dose (DD) of 3 ppm imidacloprid in larval rearing media was provisionally identified for detecting shifts in tolerance, possibly as a consequence of incipient imidacloprid resistance. None of the larvae from the susceptible laboratory strains survived the DD. Eighteen field-collected isolates were evaluated for their susceptibility to imidacloprid and to validate a DD of 3 ppm. Probit lines from 18 field-collected isolates were very similar, with LC₅₀ values ranging from 0.14 to 1.52 ppm. When exposed to the DD, between 3 and 10% of the exposed larvae emerged as adults from only three of the 18 isolates. All other field isolates gave 100% mortality at the DD. Under the criteria established (>5% survivorship at 3 ppm), two isolates would be established on mammalian hosts and more extensive tests conducted to exclude or confirm the presence of resistance. The DD of 3 ppm is robust enough to eliminate most of the susceptible isolates collected until today, yet low enough to identify possible isolates for further testing.

Field populations of Triatoma infestans Klug were collected during 2002 from four villages in northern Argentina (El Chorro, La Toma, El Sauzal, and Salvador Mazza), after application of deltamethrin and other pyrethroids was ineffective. High levels of resistance to the pyrethroid insecticides deltamethrin, β-cypermethrin, β-cyfluthrin, and lambda-cyhalothrin were detected in all of the evaluated populations. The resistance ratio to pyrethroids determined by topical application ranged from 50.5 (deltamethrin, El Sauzal) to 667.6 (β-cyfluthrin, Salvador Mazza). None of the pyrethroid-resistant insects was resistant to the organophosphorus insecticide fenitrothion. Topical application of piperonyl butoxide to the most deltamethrin-resistant population (Salvador Mazza) led to slight reduction in levels of resistance. Activity of P450 monooxygenase, measured in individual insects through ethoxycoumarine-O-deethylase, showed a slight but noticeable difference in the distribution of activities between susceptible and resistant populations. The total percentage of insects below 0.48 pmol of 7-OH coumarine/min/insect was 36.4 for Salvador Mazza population and 64.3 pmol of 7-OH coumarine/min/insect for CIPEIN strain. Whereas a low level of resistance to deltamethrin was previously related to monooxygenase activity in T. infestans, the high levels of resistance shown by these populations seem to involve monooxygenase in combination with other resistance mechanisms, for example, insensitivity of nervous membrane. Research on T. infestans resistance is in progress to improve Chagas vector control programs in Latin America and to implement resistance management strategies.

Recently, catnip, Nepeta cataria L. (Lamiaceae), essential oil has been formulated and marketed as an alternative repellent for protection against biting arthropods by several vendors. We isolated the major active components of catnip oil, E,Z- and Z,E-nepetalactone, and quantitatively measured their antibiting efficacy compared with the repellents N,N-diethyl-3-methylbenzamide (deet) and chiral (1S,2′S)-2-methylpiperidinyl-3-cyclohexene-1-carboxamide (SS220) against the yellowfever mosquito, Aedes aegypti (L.), by using an in vitro assay and human volunteers at 24 nmol compound/cm² (cloth or skin). Of all compounds tested in an in vitro assay, SS220 ranked as the most effective, whereas catnip oil and the nepetalactone compounds did not differ significantly from each other or from deet. However, in human volunteer bioassays, neither E,Z and Z,E-nepetalactone nor racemic nepetalactone deterred mosquito biting as effectively as SS220 or deet. All compounds differed significantly from the control. We conclude that catnip oil and nepetalactone isomers are significantly less effective than deet or SS220 in deterring the biting of Ae. aegypti.

The crested auklet, Aethia cristatella, emits a class of aldehydes shown to be potent invertebrate repellents when used by heteropterans against their predators. Our aim was to determine the efficacy of these aldehydes against mosquitoes in the laboratory. Synthetic analogues of the auklet odorant were strongly repellent to mosquitoes in controlled laboratory trials. Furthermore, the efficacy was similar to previous reports for commercial mosquito repellents. These results, in combination with a previously published study, show that constituents of the aldehyde odorant are broad spectrum in efficacy against ectoparasitic arthropods of birds. Our report is the first empirical evidence for an endogenous mosquito repellent in birds.

The effectiveness of light-induced killing of mosquito larvae in the presence of photosensitizers was studied with larvae of Aedes aegypti (L.), Anopheles stephensi (Liston), and Culex quinquefasciatus Say grown in the laboratory and of Cx. quinquefasciatus grown under field conditions. Tested photosensitizers included xanthene, chlorin, and porphyrin derivatives. All the larvae were treated at the fourth instar. Preliminary laboratory experiments showed a light-induced lethal effect of Rose Bengal (RB) on three species of mosquito larvae. Compared with other photosensitizers, RB seemed to be more efficient at even lower concentration than chlorin (e6) and chlorophyllin on Ae. aegypti larvae. Among the four porphyrin derivatives, i.e., chloroquinoline tetraphenyl propioamidoporphine, tetraphenyl porphine tetrasulfonate, hematoporphyrin (HP), and tetraphenylporphine-propionic acid porphine, HP was the only effective photosensitizer on Ae. aegypti larvae. The best conditions for field tests using RB were conducted on Cx. quinquefasciatus in Bobo-Dioulasso, Burkina Faso. The mortality induced by RB varied from 80 to 96% obtained with unfiltered cesspit water to 0.4 to 6.7% in cesspits with a heavy load of organic materials, thus providing the basis for further developments of this technique under field conditions.

Previous studies have shown that polymerase chain reaction (PCR) heteroduplex analysis (HDA) of the cytochrome B (cytb) gene is useful in identifying mosquito bloodmeals derived from avian hosts. However, interpretation of PCR-HDA gels is performed visually, which can make it difficult to analyze large numbers of specimens and to compare results between laboratories. We investigated the utility of a terminal restriction fragment length polymorphism (T-RFLP) assay to analyze cytb PCR products. PCR was performed on 123 blood or tissue samples from 55 avian, 13 mammalian, and one amphibian species by using end-labeled primers to amplify a 358-bp segment of cytb. Each PCR product was sequenced to determine predicted terminal restriction fragment (TRF) profiles. Additionally, experimental TRFs were determined by sizing fragments from restriction endonuclease digests with capillary electrophoresis. A Web-based searchable database was created to compare unknown mosquito bloodmeal TRF profiles against sequence-predicted and experimentally derived terminal fragment lengths of known vertebrates. The predictive value of experimental profiles was found to be accurate to the species level for 67 of 69 species (97%). Fifty-nine field-collected mosquitoes were tested to determine the bloodmeal source using the T-RFLP method. The bloodmeal source from 50 of these mosquitoes was identified by comparing the TRF profile of the unknown source against the cytochrome B database. The bloodmeal source from the remaining nine mosquitoes was not identified as no known profile matched the experimentally derived profile. T-RFLP analysis is a highly reproducible technique and the searchable TRF database is continually being expanded to include additional species from diverse geographic areas.

Anaplasma marginale Theiler is a tick-borne intraerythrocytic rickettsial pathogen of cattle that also can be mechanically transmitted by biting flies. Rickettsemia during the acute phase of infection may reach as high as 10⁹ infected erythrocytes (IEs) per milliliter of blood. Animals that survive acute infection develop a life-long persistent infection that cycles between 10^2.5 and 10⁷ IE/ml of blood. We compared stable fly Stomoxys calcitrans (L.)-borne mechanical transmission during acute infection with Rocky Mountain wood tick, Dermacentor andersoni Stiles-borne biological transmission in the persistent phase of infection to demonstrate quantitatively that biological transmission by ticks is considerably more efficient than mechanical transmission by biting flies. Stable flies that partially fed on an acutely infected calf and were immediately transferred to susceptible calves to complete their bloodmeals failed to transmit A. marginale. Ticks that fed on the original acquisition host after it reached the persistent phase of infection (>300-fold lower rickettsemia) successfully transmitted A. marginale after transfer to the same calves that failed to acquire infection after fly feeding. Failure of fly-borne mechanical transmission at a rickettsemia >300-fold higher than that from which ticks transmit with 100% efficiency demonstrates that tick-borne biological transmission is at least 2 orders of magnitude more efficient than direct stable fly-borne mechanical transmission.

Maintenance in nature of Borrelia burgdorferi, the pathogenic bacterium that causes Lyme disease, requires transmission through an infectious cycle that includes a tick vector and a mammalian host. The genetic requirements for persistence in these disparate environments have not been well defined. B. burgdorferi has a complex genome composed of a chromosome and >20 plasmids. Previous work has demonstrated that B. burgdorferi requires two plasmids, lp25 and lp28-1, in the mammalian host. To investigate the requirement for these same two plasmids during tick infection, we experimentally infected larval ticks with B. burgdorferi lacking either lp25 or lp28-1 and then assessed the spirochete load in ticks at different points of the infection. Whereas plasmid lp28-1 was dispensable in ticks, plasmid lp25 was essential for tick infection. Furthermore, we investigated the requirement in ticks for the lp25 gene bbe22, which encodes a nicotinamidase that is necessary and sufficient for mammalian infection by B. burgdorferi clones lacking lp25. This gene was also sufficient in ticks to restore survival of spirochetes lacking lp25. This is the first study to investigate the requirement for specific plasmids by B. burgdorferi within the tick vector, and it begins to establish the genomic components required for persistence of this pathogen throughout its natural infectious cycle.

Although they provide a number of valuable ecological services, wetlands also may harbor mosquitoes that are vectors of human pathogens. During 2002 and 2003, we measured biological (i.e., abundances of mosquitoes, other insects, and total heterotrophic bacteria, vegetational cover, and dead organic material), chemical (i.e., pH, dissolved nitrate, dissolved nitrite, dissolved phosphate, total alkalinity, and electrical conductivity), and physical (i.e., water temperature, dissolved oxygen, depth, and turbidity) attributes at fixed survey sites in Beaver Valley Wetlands, a small reconstructed palustrine wetland in Black Hawk County, Iowa. The number of immature mosquitoes was significantly correlated with dissolved nitrate and dissolved phosphate concentrations in both years. During the second year of the study, the number of immature mosquitoes was significantly correlated with nonpredators and water turbidity, but not with other measured variables. Independent variables explained 87 and 70% of the variability in mosquito numbers per survey site for the 2 yr of the study, respectively. The most common species of mosquitoes developing in Beaver Valley Wetlands were Aedes vexans (Meigen) Culex territans Walker, Uranotaenia sapphirina (Osten Sacken), and Culex tarsalis Coquillet. We compared relative risks of disease transmission by the mosquitoes developing in wetland microhabitats based upon published species-specific infection rates and propensities to bite humans. The majority of mosquitoes and the greatest potential disease risks were associated with temporary pools, which represented a small proportion of the wetlands. Although relatively few mosquitoes developed in Beaver Valley Wetlands, targeted control efforts could dramatically reduce the numbers of mosquitoes produced with minimal impacts upon nontarget species.

A rapid and sensitive protocol using Chelex 100 resin for DNA extraction and the polymerase chain reaction for detection of Babesia microti Franca within its vector Ixodes scapularis Say is described. The level of detection of this protocol was determined to be the approximate equivalent of one parasite.

Cutaneous leishmaniasis due to Leishmania tropica Wright seems to be an emerging disease in Chichaoua, a province located in southwestern Morocco. In this study, sand flies (Diptera: Psychodidae) were collected from 12 stations. Sticky traps were placed in domestic, peridomestic, and sylvatic sites. In total, 3,787 specimens consisting of 10 species (seven Phlebotomus and three Sergentomiya) were identified. Phlebotomus perniciosus Newstead, the predominant species, was abundant, especially in mountainous areas. Phlebotomus sergenti Parrot (12%) was found in all studied villages where it was associated with domestic and peridomestic habitats. On the basis of its abundance, distribution, and notable anthropophily, P. sergenti, a proven vector of L. tropica elsewhere, is considered the cutaneous leishmaniasis vector in this emerging focus.

We report a forensic entomology case associated with human myiasis in Chiang Mai Province, northern Thailand. The remains of a 53-yr-old-male were concurrently infested with third instars of the two blow fly species, Chrysomya megacephala (F.) and Chrysomya rufifacies (Macquart), near a severe tumor lesion presented on the lower right leg. The presence of third instars, ≈5 d old, on the day following postmortem indicated that myiasis occurred before death. This is the first report of both fly species acting as a myiasis-producing agent in Thailand. Unsynchronized data between the age of fly larvae due to myiasis premortem and verified age/condition of the corpse suggest a potential complication and error in the estimation of postmortem interval if other predisposition fly infestations are not considered.

Populations of adult stable flies, Stomoxys calcitrans (L.), were visually estimated by counting flies on the front legs of cattle on southern and central California confined dairy feedlots between late April and mid-June (encompassing the peak stable fly activity period). Fly counts on 45–90 animals (three to six dairies) per weekly sample date were conducted in 1985, 1986, 1993, 2002, and 2003. Average biting intensity (flies per front leg) for the peak fly season was not significantly related to early winter (December–January), late winter (February–March), or total period (December–March) rainfall, but it was strongly related (r² = 0.726) to March rainfall. March rains probably moistened outside decaying manure habitats and similar substrates that are particularly suitable at that time for stable fly oviposition and larval development. Degree-day accumulations link the timing of significant (≥1.3 cm) late winter or early spring rains to peak adult stable fly activity two generations later in May and early June.

Proper DNA storage is critical for studies involving genetic analysis of insects and for molecular diagnostics of pathogens carried by them. Molecular surveillance of pathogens carried by insects can involve screening of thousands of insect DNA samples. Problems with storage and degradation of these samples can arise. In this study, a simple filter paper-based method for storage and preservation of insect DNA was evaluated using polymerase chain reaction (PCR). DNA was isolated from individual house fly, Musca domestica L., adults by using a cell lysis technique. From 50 house flies known to carry Campylobacter spp., a portion of the DNA sample was stored frozen and another portion was pipetted onto filter paper. At monthly intervals for 7 mo, PCR was conducted using 1 μl of the frozen DNA sample and a 2.0-mm disk from the filter paper samples as the PCR template. Two markers were used, a 450-bp region of the insect mitochondrial DNA (mtDNA) ND5 gene and a 857-bp region of the Campylobacter spp. mtDNA 16S rDNA gene. PCR amplification was successful for all of the samples regardless of the storage method. The filter paper method is a simple and economical way to store, preserve, and distribute DNA samples for PCR analysis.

The L35 strain of Anopheles gambiae Giles was genetically selected for its ability to melanize and kill malaria parasites. A wide range of Plasmodium species are subject to this response when orally ingested, including the rodent malaria, P. berghei. However, when we directly injected P. berghei into the hemocoel, we found that parasites developed normally to the oocyst stage. This work suggests that the parasite melanization response depends on the interaction of the ookinetes and the midgut. This result is surprising because it contrasts with a genetically validated model system, where injection of CM-Sephadex beads directly into the hemocoel results in bead melanization.

The cinnabar gene of Drosophila melanogaster (Meigen) encodes for kynurenine hydroxylase, an enzyme involved in ommochrome biosynthesis. This gene is commonly included as a visible genetic marker in gene vectors used to create transgenic Aedes aegypti (L.) that are homozygous for the kh^w allele, the mosquito homolog of cinnabar. Unexpectedly, the phenotype of cells expressing kynurenine hydroxylase in transgenic Ae. aegypti is cell autonomous as demonstrated by the recovery of insects heterozygous for the kynurenine hydroxylase transgene with mosaic eye color patterns. In addition, a transgenic gynandromorph was recovered in which one-half of the insect was expressing the kynurenine hydroxylase transgene, including one eye with red pigmentation, whereas the other half of the insect was homozygous kh^w and included a white eye. The cell autonomous behavior of cinnabar in transgenic Ae. aegypti is unexpected and increases the utility of this genetic marker.