The earliest documented specimen of an exotic east Asian mosquito Ochlerotatus (Finlaya) japonicus japonicus (Theobald) in the Western Hemisphere is reported along with the results of a state wide survey to determine the distribution and abundance of this mosquito in Connecticut. Ochlerotatus japonicus was collected from 87 locations in eight counties. It is established throughout the state and occurs in a variety of natural and artificial container habitats including discarded tire casings, bird baths, wooden barrels, porcelain bath tubs (used for watering animals), plastic milk cartons, toys, vinyl tarpaulins (covering wood piles and swimming pools), exposed rock holes in stream beds, tree holes, subterranean catch basins, surface water rain pools, and spring-fed depressions. Larvae were particularly common in containers with water, decaying leaves, and algae, in shaded and sunlit areas and, in rock-pool habitats along streambeds, in association with Ochlerotatus atropalpus (Coquillett). Adult females were collected in sod grass-infused gravid and CO₂-baited light traps, from early June through October, with peak collections in September. Biting females were collected by human bait method augmented with CO₂, verifying its capacity to feed on humans. The ovitraps used in this study were not effective for recovering this species. Our results suggest that Oc. japonicus was introduced into Connecticut between 1992 and 1998. Because of the ability of Oc. japonicus to transmit West Nile virus, and because of the recent detection of this virus in field-collected specimens, the introduction of Oc. japonicus is considered a significant public health development.

The cattle tick Boophilus microplus (Canestrini) is one of the most important ectoparasites affecting tropical cattle with worldwide distribution. Application of organophosphate compounds (OP) is extensively used as a tick control method. However, the appearance of ticks resistant to the OP decreases the therapeutic efficacy of such compounds. Esterases have been implicated as potential biochemical mechanisms for detoxification in B. microplus larvae. We found increased esterase activity in the inner layers of the integument of OP resistant adult female B. microplus ticks as compared with the OP susceptible ticks. We discuss the potential role of these enzymes during acaricide metabolism and propose future research.

Lutzomyia pseudolongipalpis, the first new sand fly species within the longipalpis complex, is described based on females and males from La Rinconada, Curarigua, Lara State, Venezuela. Similar to Lutzomyia longipalpis sensu lato, females of the new species show spermathecae with 8–10 annulations and cibarial armature with 8–12 horizontal teeth. However, L. pseudolongipalpis females show conspicuous vertical cibarial teeth, large stipites and wing vein sections, round cerci, and short and broad valvifers that separate them from L. longipalpiss. l. females. L. pseudolongipalpis and L. longipalpis s. l. males are isomorphic, both having parameres with two curved setae on a simple tubercle. The analysis of morphometric characters and their diagnostic value is in progress.

We have investigated the tissue distribution of overproduced esterases A (A1 and A2) and B (B1 and B2) in strains of Culex pipiens L. by immunocytochemistry. S-LAB mosquitoes, lacking overproduced esterases, were used as reference. Tissues showing a strong specific reaction (fluorescence) were observed with anti-esterase A1 antiserum in S54 (with A1) and BOUAKE (with A2) strains, and with anti-esterase B1 antiserum in TEM-R and EDIT (with B1) and BOUAKE (with B2) strains. Overproduction of esterases A and B was tissue-specific. The most constant pattern for the two types of esterases was their overproduction in the alimentary canal and Malpighian tubes, although fluorescence varied in intensity depending on strains and developmental stages. There was no difference in the tissue distribution of esterases A1 and A2. In contrast, esterases B pattern was highly variable among strains. Differences between TEM-R and EDIT were explained by the different overall overproduction and number of copies of the amplified gene (10-fold higher in TEM-R). The most striking difference in esterase B1 and B2 tissue localization concerned the nervous system where neurons were intensely fluorescent in TEM-R and EDIT (B1), but not in BOUAKE (B2). All esterase B positive tissues in TEM-R contained large quantities of esterase B1 mRNA (in situ hybridization), indicating that at least part of the protein revealed by immunochemistry was produced in the tissues where it was observed. Our results are discussed in terms of the protection that the different esterases can confer during exposition to organophosphorous insecticides.

A comparative study was made of the structures of the preantennal region of nine species of Damalinia Mjöberg, 1910 (Phthiraptera: Trichodectidae). Variability in the form of the head, ventral carina, pulvinus, mandibles, and labrum was observed by light and scanning electron microscopy. According to previous studies, the form of the head is possibly influenced by the density and texture of the hair of the host. The ventral carina, which may be sharp or blunt, and the pulvinus, a membranous lobe, of these parasite species of different hosts, were studied. Photographs of the mandibles and labrum show a high variability according to species.

Racemic 1-[3-cyclohexen-1-ylcarbonyl]-2-methylpiperidine repels blood-feeding arthropods such as mosquitoes, chiggers, and ticks. The compound contains two asymmetric carbon atoms and the racemate consists of four stereoisomers. Quantitative mosquito bioassays using Aedes aegypti (L.) showed that (1S,2′S) and (1R,2′S) configurations were 2.8–3.1 and 1.6–1.8 times more effective, respectively, than the other two stereoisomers in reducing mosquito bites. (1S,2′S) was 2.5 more repellent than the racemate. Biological data show that an interaction of the (2′S)-2-methylpiperidine configuration with a repellent receptor system in A. aegypti is apparently important to repellent activity. Nuclear magnetic resonance spectra and molecular mechanics calculations for the stereoisomers provided insight into the conformation of the (2′S)-group. Results indicate that enhanced repellent effects can be realized through formulation of the most active stereoisomers of the compound.

We studied the spatial localization of mosquitoes in a sylvatic focus of Venezuelan equine encephalitis virus in western Venezuela to identify mosquito species potentially involved in the hypothesized transport of viruses out of enzootic foci. The following criteria were used to identify species with potential for virus export: (1) common in the forest and surrounding area, (2) feeding on a wide range of vertebrates; (3) long dispersal capabilities, and (4) established vectorial competence for enzootic or epizootic VEE viruses. CDC traps baited with light/CO₂ were operated for four and 12-h intervals to collect mosquitoes at four stations along two forest/open area transects from September to November 1997. We collected 60,444 mosquitoes belonging to 11 genera and 34 species. The most common species were Aedes serratus (Theobald), Ae. scapularis (Rondani), Ae. fulvus (Wiedmann), Culex nigripalpus Theobald, Cx. (Culex) “sp”, Cx. mollis Dyar & Knab, Cx. spissipes (Theobald), Cx. pedroi Sirivanakarn and Belkin, Psorophora ferox (Humboldt), Ps. albipes (Theobald), and Ps. cingulata (F.). Very few mosquitoes were captured during the day in the open area outside the forest, suggesting that any virus export from the forest may occur at night. The following mosquitoes seemed to be mostly restricted to the forest habitat: Ae. serratus, Ps. ferox, Ps. albipes, sabethines, Cx. spissipes, Cx. pedroi, Cx. dunni Dyar, and Ae. fulvus. The main species implicated in potential virus export were Cx. nigripalpus, Ae. scapularis, and Mansonia titillans (Walker).

The effect of zooprophylaxis on malaria transmission has not been studied on the African continent despite that the World Health Organization has recommended this intervention method since 1982. The effect of passive zooprophylaxis on malaria vector abundance, mosquito feeding preferences, and infectivity was studied in an area of moderate seasonal transmission in The Gambia. A paired cohort of 204 children <7 yr of age was selected and matched in groups for presence or absence of cattle (Bos taurus) within 20 m of their bedroom. Comparisons were made between mosquitoes collected from the bedrooms of the two groups of children. Other ruminants and equines were present in both groups of compounds. Most of the anopheline mosquitoes (98.5%) collected were Anopheles gambiae sensu lato. There was no difference in the geometric mean number of An. gambiae s.l. mosquitoes caught in houses near or far from cattle. The species composition of the An. gambiae complex was similar in both groups. Blood meal analysis of specimens collected in houses without cattle showed a human blood index (HBI) of 82% for An. Arabiensis (Patton), 56% for An. gambiae sensu stricto (Giles), and 36% for Anopheles Melas (Theobald), indicating that each of these sibling species fed readily on animals. The presence of cattle reduced the HBI of An. arabiensis but did not significantly alter the HBI of An. gambiae s.s. or An. melas. There was no significant difference between the groups in the sporozoite rates of An. gambiae s.l. nor in the estimated malaria transmission risk. These findings suggest that passive zooprophylaxis using cattle does not alter the individual exposure to malaria parasites in The Gambia.

We observed the movement, attraction, and resting behavior of laboratory Rhodnius prolixus Stål within a house environment, simulated by a Styrofoam box. Movement of R. prolixus into various refuge types (fiberpots or white-, cream-, or black-colored modified Gomez-Nunez boxes) at different strata was assessed. Greater numbers of fifth instars sought a refuge than third instars. Fasted nymphs sought a refuge more than fed nymphs. Our simulated house environment showed potential as a laboratory arena to observe the resting preferences, dispersal, and response of kissing bugs to potential attractants. Our data indicated that fiberpot refuges may serve as an effective and inexpensive monitoring device to detect low density kissing bug infestations.

The wound-healing processes in the mosquito Armigeres subalbatus (Coquillett) were observed with electron microscopy. The initial reaction involved wound contraction and aggregation of injured surface tissues, cell debris and movement of granulocytes toward the wound. Granulocytes first aggregated around the surface of the wound and many filamentous filopodia protruded to connect with cytoplasmic strands. These strands were then interconnected to form a network coagulum resulting in wound closure to prevent body fluid loss. Granulocytes lysed on the wound-site and released granular materials around the wound, inducing localized clot formation. These results suggested that wound-healing in this mosquito species involved both humoral and cellular reactions. The latter reaction involved the movement of plasmatocytes to the basement membrane of the epidermis beneath the wound-site and epithelial cells regeneration. Our observations revealed that wound-healing in A. subalbatus involves the wound contraction, formation of a temporary cellular clump, scar formation, basement membrane formation, and reepithelialization. The larvae neither discarded the wound scar nor secreted a new cuticle until the next molting. Based on the ultrastructural observations, it is suggested that the wound-healing reaction in A. subalbatus was probably a typical response employed by other members of the family Culicidae.

Intracellular bacteria of the genus Wolbachia often behave as reproductive parasites by manipulating host reproduction to enhance the vertical transmission of infections. Wolbachia infections in Aedes albopictus (Skuse) cause a reproductive manipulation known as cytoplasmic incompatibility, which can reduce brood hatch. Because field populations of Ae. albopictus are naturally infected, studies of Wolbachia-induced effects on Ae. albopictus reproduction and fitness require that Wolbachia be artificially removed. Although simple techniques for clearing Wolbachia infections from other host insects have been developed, removal of Wolbachia bacteria from Ae. albopictus is difficult. Here we describe an improved method for removing Wolbachia infections Ae. albopictus. This method differs from earlier techniques in that it relies upon the tetracycline treatment of adults instead of larvae. We demonstrate that tetracycline treatment of adult Ae. albopictus can predictably generate uninfected individuals, simplify the procedure required for Wolbachia removal, and reduce the level of inbreeding required to produce uninfected lines.

A review of the literature and unpublished records from the U.S. National Tick Collection on the importation of ticks from foreign lands reveals that at least 99 exotic tick species assignable to 11 genera have been either detected and destroyed at ports of entry or inadvertently imported into the United States in the past half century. This number includes four argasid and 95 ixodid species, some of which are important vectors of agents that cause disease to both man and animals. If one includes Aponomma sp. and Hyalomma sp. and the subspecies of Rhipicephalus, the total exceeds 100 taxa. It is notable that the number of imported tick species recorded herein exceeds the total number of tick species native to the United States. It appears that the soft tick genera Argas, Antricola and Nothoaspis have not been imported, although at some point in time Argas persicus (Oken) was introduced because it is resident although not often collected. The hard tick genera Anomalohimalaya, Cosmiomma, Margaropus, Nosomma and Rhipicentor, and the nuttalliellid genus Nuttalliella have also not been imported.

Of the 17 genera in Triatominae, only one, Linshcosteus, occurs exclusively outside the New World (India). Its relationship to the rest of the subfamily has been questioned, a question made urgent by the fact that many triatomines are vectors of the protozoan which causes Chagas’ disease. Using a simple measure of similarity, we show that Linshcosteus is less similar to the other triatomine genera than each of them is to the others.

In field studies, Anopheles gambiae Giles sensu stricto obtains most blood meals from humans, whereas Anopheles quadriannulatus Theobald bites predominantly bovids. We investigated whether host odors modulate the host preference of these mosquito species. In a dual-choice olfactometer, mosquitoes were given a choice between clean air and putative host-specific odor blends. An. gambiae chose ‘human odor’ over clean air and clean air over ‘cow odor.’ Although Anopheles quadriannulatus did not choose cow odor over clean air, it chose clean air over human odor. Cheese odor, which attracted An. gambiae, did not result in higher trap catch of An. quadriannulatus. We conclude that the degree of anthropophagy of An. gambiae s.l. has an innate olfactory basis.