Simulation studies of African horse sickness and Culicoides imicola (Diptera:Ceratopogonidae)

A simulation model of African horse sickness in Spain was developed to investigate what factors affect the likelihood of an epidemic after the introduction of the virus. The model included 2 host species (horses and donkeys) and 1 vector species (Culicoides imicola Kieffer). Latin hypercube sampling was used for sensitivity analysis of the model, to include uncertainty in parameter estimates. In general, if an epidemic occurred most hosts were infected. The peak prevalence in midges was low, and never exceeded 3%. Midge population size, the recovery rate in horses, and the time of year when the virus was introduced were the most significant factors in determining whether or not an epidemic occurred. The uncertainty in interbloodmeal interval, removal rate (mortality and recovery) of infectious horses, midge population size, and transmission rates were significant factors in the size of the epidemic. These factors should be priorities for empirical research, and should be considered in the design of control strategies in areas at risk of virus introduction.     

Methods for enhancing the blood feeding response of field-collected Culicoides impunctatus (Diptera:Ceratopogonidae)

Handling methods were found to be lengthen the time after capture that Culicoides impunctatus Goetghebuer could be blood fed successfully in the laboratory using an artificial membrane technique. By maintaining high levels of humidity in holding cages kept in a cool, dark environment, > 30% feeding success was achieved 72 h after capture, when feeding was carried out at low light conditions.     

Association between risk of seroconversion of sentinel cattle to bluetongue viruses and Culicoides species (Diptera: Ceratopogonidae) in Queensland, Australia

The association between risk of seroconversion of sentinel cattle to bluetongue viruses and the number of Culicoides brevitarsis Kieffer and C. wadai Kitaoka caught by light traps was investigated using survival analysis. Eight sentinel herds that seroconverted to bluetongue viruses between 1990 and 1994, and for which insect-trapping data were available, were selected for inclusion in the study. These herds were located at six sites along the eastern coast of Queensland, Australia, from approximately latitude 10 degrees South to 25 degrees South. C. brevitarsis was detected at all locations where sentinel herds were maintained, whereas C. wadai was detected at only two locations in northern Queensland where four sentinel herds were maintained during the study period. The mean number of C. brevitarsis and C. wadai caught per month was 230 and 21, respectively. A significant (P = 0.05) positive association was found between the risk of seroconversion of sentinel cattle to bluetongue viruses and the number of C. wadai caught in the same month.     

Seasonal abundance and parity of stock-associated Culicoides species (Diptera: Ceratopogonidae) in different climatic regions in southern Africa in relation to their viral vector potential

We identified a Xenopus gene closely related to mammalian bone morphogenetic protein (BMP)-7 (also termed osteogenic protein-1 or OP-1). It resembles the mammalian gene in primary structure and expression pattern much more closely than does a previously described Xenopus homologue, originally termed XBMP-7 [Nishimatsu, Suzuki, Shoda, Murakami and Ueno (1992) Biochem. Biophys. Res. Commun. 186, 1487-1495]. The novel gene has therefore been designated XBMP-7 and the gene described earlier has been renamed XBMP-7R (M. Moos and N. Ueno, unpublished work). It has a broad distribution, primarily in the anterior and posterior ventral regions during gastrulation, subsequently becoming prominent at different stages in a wide variety of structures (eyes, neural structures, heart, pronephros, posterior ventral region and other structures), paralleling the distribution of XBMP-4 closely. However, its expression begins later than that of XBMP-4 during gastrulation. Lithium treatment of embryos concentrates the XBMP-7 expression in the expanded eye and heart structures. Ventral overexpression of XBMP-7 produces large protrusions that ultimately develop colouration characteristic of haemoglobin, which is confirmed by markedly expanded expression of alpha-globin. Dorsal overexpression suppresses dorsal anterior structures. Molecular analysis of animal caps overexpressing XBMP-7 reveals induction of markers associated with ventral and haematopoietic tissue, which is consistent with whole-embryo overexpression results. Globin induction by XBMP-7 can be blocked by a truncated BMP receptor previously shown to interrupt BMP-4 signalling, indicating XBMP-7 also interacts with this receptor. Our data support the concept that XBMP-7 may play a variety of roles during embryogenesis, and suggest a possible role in haematogenesis.     

Lizard feeding by Leptoconops (Brachyconops) californiensis (Diptera: Ceratopogonidae) on desert sand dunes

Adult females of Leptoconops (Brachyconops) californiensis Wirth & Atchley and 1 female of Leptoconops (Holoconops) sp. near knowltoni were collected from 5 species of lizards in desert sand dune habitats in San Bernardino and Riverside counties, California, and northern Sonora, Mexico. Feeding by L. californiensis was observed on the dorsum (usually the heads) of the lizards, with up to 6 L. californiensis on a host at 1 time. The L. sp. near knowltoni appeared to be trying to feed but did not contain blood. Midges fed during calm, warm daylight periods from March through October. Reptile feeding by Ceratopogonidae is reviewed.     

Larval rearing water and preexisting eggs influence oviposition by Aedes aegypti and Ae. albopictus (Diptera: Culicidae)

Two-choice laboratory bioassays were used to evaluate oviposition responses of gravid Aedes aegypti (L.) and Ae. albopictus (Skuse) to larval rearing water and eggs from prior egg deposition. Oviposition responses by female Ae. aegypti were similar between larval water from Ae. aegypti and water controls but significantly greater to larval water from Ae. albopictus (12.2%) compared with water controls. Oviposition by Ae. albopictus females increased significantly in response to larval water from either species compared with water controls with increases of 15.1% to Ae. aegypti larval water and 17.6% to Ae. albopictus larval water. Oviposition responses of gravid Ae. aegypti and Ae. albopictus were evaluated in the presence of preexisting conspecific and heterospecific eggs on strips of oviposition paper. Significantly more eggs were laid by gravid Ae. aegypti females on oviposition paper containing either Ae. aegypti or Ae. albopictus eggs than on oviposition paper without eggs. In contrast, oviposition responses of gravid Ae. albopictus females were unaffected by the presence of eggs of either species.     

小足倒毛摇蚊的再描述(双翅目:摇蚊科)

对摇蚊科(Chironomidea)倒毛摇蚊属(Microtendipes Kieffer),1915小足倒毛摇蚊[M.pedellus(De Geer,1776)]进行再描述,并附主要特征图.     

Ultrastructure of eggs of Anopheles rondoni, Anopheles lutzii, and Anopheles parvus, three species of the subgenus Nyssorhynchus

We have studied the influence of aging on the kinetics of autoimmune response in Experimental Autoimmune Prostatis (EAP). EAP was induced in 3- and 12-month-old Wistar rats by i.d. immunization with a saline extract of rat male sex accessory glands (RAG), chemically modified, and emulsioned in CFA. After immunization, 12-month-old rats developed a faster and stronger specific DTH response against RAG and mononuclear infiltration in the prostate. The levels of total IgM and IgG against RAG were lower in 12-month-old rats than in 3-month-old rats, with a prevalence of IgG2a, IgG2b, and IgG2c subclasses in both ages. Immunization stimulated slightly the appearance of specific IgG1 to RAG only in 3-month-old rats but in 12-month-old rats there was no specific IgG1 to RAG. On the other hand, normal 12-month-old rats showed higher levels of some natural antibodies and their thymocytes and peripheral lymphocytes had a diminished proliferative capacity compared to 3-month-old rats. These data demonstrated that 12-month-old rats show parameters of an aged immune system and present an exacerbated autoimmune prostatitis compared with 3-month-old rats.     

Morphological, molecular, and chromosomal discrimination of cryptic Anopheles (Nyssorhynchus) (Diptera: Culicidae) from South America

Based on similarity of male genitalia, the malaria vector Anopheles trinkae Faran from the eastern Andean piedmont of Colombia, Ecuador, Peru, and Bolivia was determined by Peyton (1993) to be a junior synonym of An. dunhami Causey, then known from a single locality in Amazonian Brazil. Following an appraisal of molecular, chromosomal, and morphological characters, we conclude herein that the 2 taxa are specifically distinct and remove An. trinkae from synonymy with An. dunhami. Eggs of the 2 species are distinguished easily by the anterior crown, long floats, and closed deck that occur only in An. trinkae. The X chromosome of larval polytenes is divisible into R and L arms in An. dunhami, but not in An. trinkae. A phenogram based on banding pattern scores from 18 random amplified polymorphic DNA primers separated with 100% resolution An. dunhami, An. trinkae, Anopheles nuneztovari Gabaldón and Anopheles darlingi Root. In the ITS2 region of rDNA, 25% of base sites distinguished An. trinkae from An. dunhami and 21% from the related An. nuneztovari; males of these 3 species had accessory glands of significantly different sizes. Preliminary isoenzyme screening indicated that 3 of 11 loci were diagnostic for separating An. trinkae from An. dunhami. The results indicate that An. dunhami is related more closely to An. nuneztovari than to An. trinkae and illustrate the merits of a multidisciplinary approach to mosquito systematics.     

Aedes albopictus (Skuse) (Diptera, Culicidae) in eastern Veneto

A survey was carried out in autumn 1992 and spring-autumn 1993 to study the seasonal distribution and the dispersal of Aedes albopictus (Skuse) in Portogruaro (province of Venice; North-Eastern Italy). Larvae and pupae were found from May through September; the larvae hatching from eggs after the end of September seemed unable to complete development. The adults bit until October. The mosquito spread in new areas of Portogruaro town, even after insecticidal treatments. Private areas seemed to play an important role in the preservation of the infestation, as they were not treated by the public pest control service.     

Ultrastructure of the spermatozoa and eggs of the ocean pout (Macrozoarces americanus L.), an internally fertilizing marine fish

Ultrastructure of sperm and eggs of the ocean pout (Macrozoarces americanus L.), an internally fertilizing marine teleost, was examined by scanning and transmission electron microscopy. The results showed that the sperm do not have an acrosome but have a very long mid-piece (one to two times the sperm head length) containing numerous well-developed elongated mitochondria. The sperm also have two tails (is biflagellate) each consisting of nine peripheral and one central pair (9 +/- 2) of microtubules. This long mid-piece and the biflagellate nature of the sperm appear to be associated with the long life-span of the sperm and with sperm dispersal in the ovary to fertilize the eggs internally. The ocean pout eggs are enveloped by a porous chorionic membrane similar to that found in other teleosts but have two micropyles, a condition likely related to a mechanism of egg fertilization which increases the egg fertility in the presence of low sperm numbers. Following insemination, some biochemically undefined excretions appeared on the surface of fertilized eggs and led to the acquisition of adherent capability of the eggs which formed a tightly associated egg mass in sea water.     

Survival, developmental and morphogenic deficiencies of Parasarcophaga argyrostoma (Diptera: Sarcophagidae) induced by the biosynthesis inhibitor, chlorfluazuron (IKI-7899)

To evaluate the activity of benzoylphenyl urea chitin biosynthesis inhibitor chlorfluazuron (IKI-7899) against Parasarcophaga argyrostoma, seven doses were topically applied (once) onto early third (last) instar larvae, puparia, or newly formed pupa: 150, 100, 50, 10, 1.0, 0.5, and 0.25 microgram/insect. After topical treatment of last instar larvae, the highest mortality was caused by both higher doses and the lowest mortality was caused by the lowest dose. The lethal activity of IKI-7899 as pronouncedly decreased as the treatment was lately carried out (at the puparial time). IKI-7899 failed to cause cumulative mortality because no pupal or adult mortalities were observed, irrespective of the time of treatment. Treated larvae suffered the action of IKI-7899 because they had decreased weight gain. Except the lowest dose, the weight gain of larvae inversely correlated with the dose-levels. IKI-7899 prolonged not only the larval duration but also the pupal duration after topical treatment of last instar larvae with doses 50-0.25 micrograms/larva. With no exception, all doses topically applied onto puparia or newly formed pupae enhanced pupae to live longer. Topical application onto last instar larvae resulted in different degrees of reduction of pupation rate, but IKI-7899 could not affect the pupal morphogenesis after larval treatment except by its highest dose which led to 8.33% pupal deformities and 7.69% larval-pupal intermediates. The dose 100 micrograms/larva topically applied onto last instar larvae detained 7.69% of what known as "permanent larvae" which suffered the action of the compound along 16 days and eventually perished without any external feature of puparium formation. A metamorphic effect of IKI-7899 pronouncedly appeared in the adult stage. Three higher doses completely arrested the adult flies. Topical application of the compound onto prepupae did not greatly reduce the pupation rate especially at the doses 50, 10 and 1.0 micrograms/puparium. The dose 50 micrograms/puparium was only the dose halting the pupal moulting program because 7.14% of permanent prepupae remained about 12 days and then died. In respect to adult emergence, the highest dose led to zero rate and the lowest dose allowed to all pupae to emerge without malformation.     

Bioecology in Haiti of Anopheles albimanus Wiedemann, 1820 (Diptera:Culicidae)

The association of prostate cancer mortality and testicular cancer mortality with environmental exposure to the anti-androgen dichlorodiphenyltrichloroethane (DDT) derivative p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) in the USA was explored in the period 1971-1994 using multiple linear regression analysis. Environmental p,p'-DDE contamination by state was estimated by p,p'-DDE concentrations in the subcutaneous fat of population samples and by measurements of p,p'-DDE in tree bark. On average, African Americans had adipose p,p'-DDE levels 74% higher than Whites (8.49 vs. 4.88 microg/g; p < 0.001). Neither prostate cancer mortality nor testicular cancer mortality showed a positive association with either indicator of p,p'-DDE environmental contamination. On the contrary, the regression coefficient for prostate cancer was constantly inverse for adipose p,p'-DDE along the period of study, although it approached statistical significance only for African Americans in 1981-1985 (P=-0.755; 0.10 > p > 0.05). This ecologic study does not provide support to the hypothesis of a link between environmental exposure to DDT derivatives and cancer of the male reproductive tract.     

Mediation of deet repellency in mosquitoes (Diptera: Culicidae) by species, age, and parity

Diabetes insipidus (DI) is an uncommon but important complication in the neurosurgical population. This retrospective study aimed to determine the incidence, profile and outcome of patients admitted to an 18-bedded neurosurgical intensive care unit who developed DI. The overall incidence was 3.7% (29/792 admissions). Aetiologies included subarachnoid haemorrhage (12/29), severe head injury (11/29), post-surgical excision of craniopharyngioma or pituitary adenoma (5/29) and acute haemorrhagic stroke (1/29). All patients were treated with a regime of fluid replacement, electrolyte correction, parenteral or intranasal desmopressin (DDAVP), or parenteral pitressin. Overall mortality was 72.4%. There were no deaths in the patients who underwent excision of tumours. Complications included acute pulmonary oedema, hypernatremia and hypokalaemia. The development of DI was found to be associated with impending brain death and mortality in the majority of patients with subarachnoid haemorrhage and severe head injury. However, careful diagnosis and management of DI after hypothalamo-neurohypophyseal surgery did not result in any permanent neurological sequelae.     

Ultrastructure of the gravid uterus of Hymenolepis diminuta (Platyhelminthes: Cestoda)

The fine structure of the uterus in gravid proglottids of Hymenolepis diminuta was examined by standard techniques for scanning and transmission electron microscopy. The uterus consisted of a syncytial uterine epithelium attached to the medullary parenchyma through a thin extracellular basal matrix. The epithelium contained prominent nuclei in the juxtalumenal cytoplasm. The cytoplasm was dominated by extensive granular endoplasmic reticulum, with dilated cisternae containing an electron-lucent material and widely scattered electron-dense spherical bodies. No Golgi body or other agranular endomembrane component was observed, but the epithelium contained numerous free ribosomes and a few mitochondria. The apical plasma membrane was folded into long microlamellae. Epithelial and epitheliomesenchymal folds and villi resulted in a compartmentalized uterine lumen, with each chamber containing 1 to several eggs. These data suggest a high level of synthetic activity within the uterine epithelium, but the chemical products and functional significance of this activity are not yet known.     

1st isolation of Aedes (Ochlerotatus) sticticus (Diptera, Culicidae) in the Po-Venetian valley

Aedes sticticus is recorded for the first time in northern Italy. The species was collected in some relict woods mainly at sea level in the Po-Venetian valley (Northern-Italy). Larval growth took place in residual puddles originated by rain or river floods. The most abundant adult emergence was observed in April or May. Minor earlier or later adult emergencies were observed depending from egg submersion and temperature. Data on larval chetotaxy are presented.     

Mitotic and polytene chromosome analyses in the Queensland fruit fly, Bactrocera tryoni (Diptera: Tephritidae)

The Queensland fruit fly, Bactrocera tryoni, like the Mediterranean fruit fly, Ceratitis capitata, has a diploid complement of 12 chromosomes, including five pairs of autosomes and a XX/XY sex chromosome pair. Characteristic features of each chromosome are described. Chromosomal homology between B. tryoni and C. capitata has been determined by comparing chromosome banding pattern and in situ hybridisation of cloned genes to polytene chromosomes. Although the evidence indicates that a number of chromosomal inversions have occurred since the separation of the two species, synteny of the chromosomes appears to have been maintained.     

Temperature requirements of Chrysomya albiceps (Wiedemann, 1819) (Diptera, Calliphoridae) under laboratory conditions

Chrysomya albiceps specimens were obtained from colonies established with larvae and adults collected at the Federal Rural University in Rio de Janeiro, Seropédica, State of Rio de Janeiro. The larval stage of C. albiceps was allowed to develop in climatic chambers at temperatures of 18, 22, 27 and 32 degrees C, and the pupal stage was allowed to develop at 22, 27 and 32 degrees C (60 +/- 10% RH and 14 hr photoperiod). The duration and viability of the larval stage of C. albiceps at 18, 22, 27 and 32 degrees C were 21.30, 10.61, 5.0 and 4.0 days and 76.5, 88.5, 98.5 and 99.5%, respectively, with mean mature larval weights of 45.16, 81.86, 84.35 and 70.53 mg, respectively. Mean duration and viability of the pupal stage at 22, 27 and 32 degrees C were 9.36, 4.7 and 3.0 days and 93.8, 100 and 100%, respectively. The basal temperature for the larval and pupal stage and for the larval and adult phase were 15.04, 17.39 and 15.38 degrees C, corresponding to 65.67, 44.15 and 114.23 DD.     

Breeding structure of screwworm fly populations (Diptera: Calliphoridae) in Colima, Mexico

Starch gel electrophoresis was used to resolve gene frequencies among populations of screwworm, Cochliomyia hominivorax (Coquerel). The loci examined coded for alpha-glycerophosphate dehydrogenase, octanol dehydrogenase, and phosphoglucomutase. Flies were sampled by traps widely distributed in Colima Province, southwestern Mexico. Gene frequencies at Odh differed significantly among the 11 populations. Alleles segregating at Pgm and alpha-Gpdh were homogeneous among populations. There were significant departures from random mating within populations, but no genetic differentiation among populations was detected. The data suggest unrestricted gene flow among populations. Departures from random mating within populations were explained by the pooling of samples from separate breeding units.