Studies on the sandfly fauna of Samuel Ecological Station, Porto Velho Municipality, Rondônia State, Brazil

In a study of sandfly species in the Samuel Ecological Station, in Porto Velho, Rondônia State, the following species were identified: Lutzomyia brasiliensis, L. evangelistai, L. gomezi, L. anduzei, L. flaviscutellata, L. richardwardi, L. shawi, L. umbratilis, L. yuilli yuilli, L. dendrophyla, L. puctigeniculata, L. shannoni, L. amazonensis, L. ayrozai, L. carrerai carrerai, L. claustrei, L. davisi and L. lainsoni. L. richardwardi, L. umbratilis and L. c. carrerai were the predominant species captured of man forming 60.30% of the total catch. L. richarwardi was the most frequent at ground level (29.9%), while L. umbratilis predominated in the canopy (48.5%).

Field Monitoring of Cypermethrin Residual Effect on the Mortality Rates of the Phlebotomine Sand Fly Lutzomyia longipalpis in the State of Paraíba, Brazil

In a visceral leishmaniasis endemic locality of northeast of Brasil where all settlements were treated with cypermethrin, a follow-up of Lutzomyia longipalpis populations was carried out by regular collections. The residual effect of the insecticide was studied using biological assays on three different types of walls. The results showed that the insecticides had an effect on intradomiciliar Lu. longipalpis populations limited to two months, and had no significant effect on peridomiciliar vector populations. The mortality rates of the tested sandflies were variable according to the type of wall. The decreasing of the insecticide effect was marked since the 3rd month, and mortality rates were identical whatever the type of wall since the 4th month. Unsufficient residual effect was detected after the 4th month.

On a New Species of Hysterothylacium (Nematoda: Anisakidae) from Cauque mauleanum (Pisces: Atherinidae) by Brightfield and Scanning Electron Microscopy

Hysterothylacium geschei n. sp. (Nematoda, Anisakidae) is described from the intestine of Cauque mauleanum (Steindachner) (Pisces: Atherinidae) from Lake Panguipulli (39º43'S; 72º13'W), Chile. Eleven (78.6%) out of 14 fish were infected, with a mean intensity (range) of 14.4 (1-55) worms. The new species can be differentiated from the two previously described species of freshwater fishes from South America by the presence of lateral alae, the number of caudal papillae, and the length of the spicules, oesophagus, intestinal caecum, distance vulva-anterior extremity and the length ratio intestinal caecum: ventricular appendix. From the fishes examined in Lake Panguipulli, including the introduced salmonid species Oncorhynchus mykiss (Walbaum) and the authochthonous species Basilichthys australis Eigenmann (Atherinidae) and Percichthys trucha (Valenciennes) (Percichthyidae), only one specimen of P. trucha was found parasitized by a third-stage larva of this species.

The Effects of a DNA Virus Infection on the Reproductive Potential of Female Tsetse Flies, Glossina morsitans centralis and Glossina morsitans morsitans (Diptera: Glossinidae)

Reproductive anomalies associated with the tsetse DNA virus infection in the female tsetse hosts, Glossina morsitans centralis Machado and Glossina morsitans morsitans Westwood, inoculated with the virus during the 3rd instar larval stage were studied and the data compared to those obtained from the control females injected with sterile physiological saline. Virus infected flies had significantly longer first and second pregnancy cycles (P<0.0001) and produced pupae that were of significantly less weight in milligrams (P<0.0001) compared to controls. Transmission of the virus to progeny was not absolute and only 21% of G. m. centralis and 48% of G. m. morsitans first progeny flies from infected females developed salivary gland hypertrophy as a result of transmission from mother to progeny. The virus infected females produced significantly fewere pupae compared to the controls during the experimental period (P<0.00001).

A Preliminary Investigation on the Chemical Composition of the Cell Surface of Five Enteropathogenic Escherichia coli Serotypes

The cell surfaces of five enteropathogenic Escherichia coli serotypes (O111:H2; O111:H12; O125:H9; O119:H6; O26:H11) were assayed by chemical methods, lectin agglutination tests and spectroscopy associated to transmission electron microscopy. Results of lectin agglutination assays showed that all strains reacted with mannosebinding lectins. Strains belonging to serotype O125:H9 also agglutinated with lectins which recognize galactose and Nacetylgalactosamine residues. The bacterial cells were treated with 0.01M phosphate buffered saline (pH 7.0) at 100oC for 2 hr and the extracts were submitted to precipitation and fractionated by Cetavlon. Phosphate, total sugar and protein contents were determined. Gas liquid chomatography-mass spectrometry analysis of alditol acetates showed the presence of galactose, mannose, fucose, glucose and traces of ribose. Spectroscopic analysis of intact cells showed the presence of a capsule-like structure which was not totally preserved after extraction. Some cells were still surrounded by an amorphous capsular-like material after polysaccharide extraction.

Mitochondrial DNA variation of Triatoma infestans populations and its implication on the specific status of T. melanosoma

DNA sequence comparison of 412 base-pairs fragments of the mitochondrial cytochrome B gene was used to infer the genetic structure of nine geographical Triatoma infestans populations and their phylogenetic relationship with T. melanosoma and T. brasiliensis. T. infestans and T. melanosoma were compared by morphometry, allozyme and cytogenetic analyses, as well as subjected to reciprocal crosses, in order to clarify the taxonomic status of the latter. No differences were found to distinguish the two species and the crosses between them yielded progeny. T. infestans populations presented four haplotypes that could be separated in two clusters: one formed by the samples from Bolivia (Andes and Chaco) and the other formed by samples from Argentina and Brazil. Silvatic and domestic T. infestans populations from Bolivia (Andes) were genetically identical.