Hypopi (deutonymphs) of the family Hypoderatidae were found in a barn owl, Tyto alba (Scopoli), and a burrowing owl, Speotyto cunicularia (Molina), from Texas. A redescription is provided for mature specimens of the hypopus of Tytodectes (Tytodectes) tyto Fain from the subcutaneous adipose tissues of the pelvic region in the barn owl. The hypopus of Tytodectes (Tytodectes) speotyto n. sp. is described from specimens in the subcutaneous adipose tissues of the pelvic region and in the adipose tissues of the intermuscular fasciae of the ankle in the burrowing owl. T (T) speotyto appears most similar in size and chaetotaxy to T (T) glaucidii Cerny described from the Cuban pygmy owl, Glaucidium siju (d'Orbigny), in Cuba, but differs in the presence of a spine on tibia IV, which also occurs in T (T) tyto. Both of the former species have the anterior apodemes of coxae I fused in a simple V and lack a sternum. They differ from T (T) tyto which has the anterior apodemes of coxae I fused in a Y and there is a well developed sternum. Based on the above 3 described hypopi, the hypoderatids of owls represent an assemblage of small closely related, but easily differentiated, species. The occurrence of a few specimens of Neottialges evansi Fain in the barn owl and Hypodectes (Hypodectoides) propus (Nitzsch) in the burrowing owl probably represent examples of host capture by hypopi that normally occur in cormorants and pigeons, herons or egrets, respectively.

The development of Anaplasma marginale Theiler was studied in ticks using a nonradioactive in situ hybridization method developed in our laboratory. Male Rocky Mountain wood ticks Dermacentor andersoni Stiles, were infected intrastadially by allowing them to feed for 7 d on an infected calf (acquisition feeding). The ticks were then removed and held in a humidity chamber for 5 d before being fed on a 2nd susceptible calf for 10 d (transmission feeding). Two groups of 10 ticks were collected daily during the 22-d experiment. In one group one-half of each tick was processed and embedded in paraffin and in the other group one-half of each tick was embedded in LR White for in situ hybridization. The companion tick halves from each group were fixed and embedded in Dow Epoxy Resin resin for routine light and electron microscopy. As detected by in situ hybridization on LR White-and paraffin-embedded sections and by microscopy, initial infection of A. marginale in ticks occurred in gut tissues either on the 7th d of acquisition feeding or the 1st d of the held period and infection persisted throughout transmission feeding. The highest number of ticks with gut infection was observed on the 5th d of transmission feeding. Salivary glands became infected with A. marginale on the 1st day of transmission feeding and remained infected throughout the transmission feeding period. Peak infection was observed on day 4 of transmission feeding. After the beginning of transmission feeding, A. marginale infection was also observed in interstitial, reproductive, skeletal muscle, fat body, and Malpighian tubule tissues. Although A. marginale infection of ticks clearly originates in midgut epithelial cells, many tissues eventually become infected during transmission feeding, resulting in a generalized infection. The infection of multiple tissues may contribute to the ability of A. marginale infection to persist in intrastadially infected male ticks.

Although the recent distribution of yellowfever mosquito, Aedes aegypti (L.), in Pakistan has been restricted to the port city of Karachi, adult and immature mosquitoes breeding in imported tires in warehouses at Landi Kotal (North-West Frontier Province) were identified as Ae. aegypti. The patterns of tire trade and the current disjunct distribution of Ae. aegypti indicated that the introduction into Landi Kotal may have been either from Karachi or India. Thermal fog application of pirimiphos-methyl and residual spray of malathion during 1993 reduced abundance in October-November. Living larvae or adults were not found during January 1994, apparently because of cold weather. However, Ae. aegypti reappeared during May-June 1994, most probably from eggs that overwintered. Population increased during late August when another round of spray using the same insecticides and fenthion as an additional larvicide again reduced abundance. Although this mosquito apparently has not spread into neighboring areas, its survival at Landi Kotal through all seasons despite control measures indicates its potential of becoming established in other areas of Pakistan.

Seasonal variations in the density of questing Ixodes ricinus (L.) nymphs and their prevalence of infection with Borrelia burgdorferi s.l. Johnson, Schmid, Hyde, Steigerwalt and Brenner were studied during 1991-1993 at a locality in southcentral Sweden. The seasonal pattern of the density of questing I. ricinus nymphs was variable, there was a bimodal pattern with peaks of similar magnitude in 1991, a bimodal pattern with a small spring peak and a greater autumn peak in 1992, and a unimodal pattern with a spring peak and lower values during summer and autumn in 1993. The seasonal pattern of prevalence of Borrelia infection in questing nymphs was similar during all 3 yr, with a peak infection prevalence in late spring or early summer, followed by lower infection prevalences in late summer and autumn. There was a significant correlation between the monthly density of Borrelia-infected nymphs and the monthly density of nymphs. This suggests that, within a certain range of nymphal densities, it may be possible to assess the density of Borrelia-infected I. ricinus nymphs without examining nymphs for B. burgdorferi s.l.

The feeding behavior, seasonality, and natural infection rate of Lutzomyia evansi (Nunez-Tovar) with Leishmania chagasi (Cuna and Chagas) was studied during a 12-mo period at 2 hamlets, El Contento and Vidales. Sand fly abundance in extra-, peri-, and intradomestic habitats was evaluated with sticky traps and CDC light traps, whereas human bait and Shannon trap collections were made only in peridomestic habitats. All trapping methods showed a clear predominance of L. evansi throughout the year. Sand flies were present during most of the year, with the exception of the driest months (February and March). Although the total number of sand flies was higher in El Contento than in Vidales, a larger proportion of L. evansi was found in intradomestic habitat than in the peri- and extradomestic habitats at Vidales. Also, sand flies from Vidales had a higher infection rate with L. chagasi than did those from El Contento. Although 2 of 9 promastigote infections detected in L. evansi were identified as L. chagasi, the difficulty of isolating and propagating Leishmania strains from this visceral leishmaniasis focus precluded characterization of most parasite samples. Parous and infected sand flies were most abundant toward the end of the rainy season (October-December). For this reason, control strategies based on reducing sand fly populations or avoiding human-vector contact should be concentrated during the October-December period.

An improvement in colonizing the biting midge Forcipomyia taiwana (Shiraki) was achieved by a new technique that facilitated the rearing of the midges and induced them to mate in the laboratory. At temperatures of 15, 20, 25, and 30 degrees C, the developmental duration of the egg, 4 larval instars, and pupa decreased as temperature increased. Among 7 different diets, the blue green algae, Anabaena sp.Ch3, was the best food for rearing the midges. When the larvae were fed on the blue green algae at 25 degrees C, they needed 12 d to pupate, the pupation rate was 71.4%, the emergence rate was 80.2%, and the average longevity of the male and the female 38.3 and 22.6 d, respectively. When 120 pairs were kept in a plastic cage (60 by 60 by 60 cm), swarming and copulation occurred during 0700-0900 and 1700-1800 hours. Swarm occurred throughout the cage and consisted of 10 males. The copulation was performed on the wall and the bottom of the cage, and the average duration was 290 s.

Overall, 37 of 79 water wells in 3 diverse geographic areas of Greece were found to harbor sand flies. The predominant species were Phlebotomus tobbi Adler, Theodor and Lourie and P. neglectus Tonnoir, species implicated in the transmission of Leishmania infantum Nicolle. Three additional species of Phlebotomus and 2 Sergentomyia spp. also were encountered. Wells appear to be resting and possibly breeding habitat for sand flies in Greece.

Anticoagulant activity was detected in fractions of a reversed phase-high-performance liquid chromatography (RP-HPLC) of salivary gland lysate from Simulium vittatum Zetterstedt. Using a plasma recalcification time assay, these fractions did not inhibit factor Xa or thrombin. HPLC-purified fractions showing the anticoagulant property were pooled and examined using the activated partial thromboplastin time test conducted on normal plasma and plasmas deficient in factors V, VIII, IX, XI, and XII. The anticoagulant prolonged the clotting time of all the plasmas, except plasma deficient in factor V. The detection of antifactor V activity, together with other anticoagulants reported from Simulium spp. indicates a feeding strategy that targets enzymes in the terminal portion of the coagulation cascade.

Off-host survival, water balance, and cold tolerance of unfed adult, Cayenne ticks, Amblyomma cajennense (F.), were examined to evaluate species characteristics important to zoogeography and off-host ecology. Survivorship decreased when males and females were subjected to progressively drier constant environmental conditions. Average maximum survival was 641.2 and 682.5 d at 85% RH and 23 degrees C (2.98 mm Hg) for males and females, respectively. Mean survival in both sexes was progressively less variable in drier conditions. Slopes of loglinear models of survival days based on saturation deficit (mm Hg) were significantly different between males and females at 50%, but not at 25 or 0%. Whole-body water loss rates for 4wk-old adults were measured at 0% RH and 23 degrees C until ticks became nonambulatory. The mean whole-body water loss rate of females, 0.06128% h-1, was 11.3% less than for males, 0.06914% h-1. Although nonambulatory ticks appeared dead, > 1/2 of the individuals from each sex regained ambulatory status after they were removed from 0% RH and exposed to 96% RH for 24 h. Among these, male kicks averaged 0.44 more recuperative (ambulatory) cycles than females, although, the duration encompassing all recuperative cycles was generally longer for females and on average, females gained 8.16% more weight than males upon each rehydration. Estimates of the mean critical equilibrium activity for males and females were 0.74 av and 0.79 av, respectively. A. cajennense adults were found to be less tolerant to -12.5 degrees C than adult lone star ticks, Amblyomma americanum (L.), whose distribution encompasses more temperate regions. Although A. cajennense exhibit little host preference and are capable of extended off-host survival, the establishment of populations beyond this species zoogeographic distribution may be constrained by an intolerance to cold.