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PubMed2003

Transmission of malaria and its control in the northeastern region of India.

Let alone the eradication, malaria control itself has amounted to be a challenge, and is detrimental to the all round development of the northeastern region of India. Focal outbreaks are frequent taking heavy tool on human lives. Plasmodium falciparum is the predominant parasite species and is solely responsible for increased morbidity and mortality. The region contributes bulk of P. falciparum cases for the rest of India, and its proportions are increasing. Efficient vectors like Anopheles minimus, Anopheles fluviatilis and Anopheles dirus persistently support transmission of malaria. The present review gives a comprehensive account of the factors responsible for transmission of the disease with focus on vector bionomics, its prevention and control.

Animals↗
PubMedDate not supplied

Metalloproteases in Trypanosoma rangeli-infected Rhodnius prolixus.

Protease activities in the haemolymph and fat body in a bloodsucking insect, Rhodnius prolixus, infected with Trypanosoma rangeli, were investigated. After SDS-polyacrylamide gel electrophoresis containing gelatin as substrate, analysis of zymograms performed on samples of different tissues of controls and insects inoculated or orally infected with short or long epimastigotes of T. rangeli, demonstrated distinct patterns of protease activities: (i) proteases were detected in the haemolymph of insects which were fed on, or inoculated with, short epimastigotes of T. rangeli (39 kDa and 33 kDa, respectively), but they were not observed in the fat body taken from these insects; (ii) protease was also presented in the fat bodies derived from naive insects or controls inoculated with sterile phosphate-saline buffer (49 kDa), but it was not detected in the haemolymph of these insects; (iii) no protease activity was observed in both haemolymph and fat bodies taken from insects inoculated with, or fed on, long epimastigotes of T. rangeli. Furthermore, in short epimastigotes of T. rangeli extracts, three bands of the protease activities with apparent molecular weights of 297, 198 and 95 kDa were detected while long epimastigotes preparation presented only two bands of protease activities with molecular weights of 297 and 198 kDa. The proteases from the insect infected with T. rangeli and controls belong to the class of either metalloproteases or metal-activated enzymes since they are inhibited by 1,10-phenanthroline. The significance of these proteases in the insects infected with short epimastigotes of T. rangeli is discussed in relation to the success of the establishment of infection of these parasites in its vector, R. prolixus.

Adipose Tissue↗
PubMed2003

Effect of aromatic cedar mulch on Argentine ant (Hymenoptera: Formicidae) foraging activity and nest establishment.

In the laboratory, Argentine ant, Linepithema humile (Mayr), mortality was positively correlated to the length of an aromatic cedar mulch section that had to be crossed before food could be reached. When ants could access food without crossing the mulch, mortality was not correlated to mulch section length. In the field, Argentine ants showed a tendency to avoid aromatic cedar mulch as a nesting substrate. In plant beds alongside buildings the number of ant nests (pockets containing brood) found was not significantly different between aromatic cedar and cypress mulch. However, when pine straw mulch around oak trees was replaced with aromatic cedar or cypress mulch, a similar number of ant nests was found in the cypress mulch as in the original pine straw, whereas numbers in aromatic cedar mulch were significantly lower. Also, fewer ants were trailing on the trees surrounded by aromatic cedar mulch compared with cypress mulch or the original pine straw. The number of ants attracted to apple jelly baits placed alongside the buildings did not differ between mulch types; neither did the number of ant trails crossing the mulch beds around the buildings. We suggest that aromatic cedar mulch may help control Argentine ants and reduce insecticide input when applied in combination with conventional control methods.

Animals↗
PubMed2004

[Techniques of diseases, insect pests and weeds control and their efficacy in bio-rational rice production].

Studies on the efficacy of bio-rational pesticides and agricultural methods against the chief diseases, insect pests and weeds of rice showed that the efficacy of the mixtures of jingangmycin and bacillus-cereus, and jingangmycin and polyoxin against rice sheath blight were 75.16%-94.27% after sprayed once at the tiller and boot end stages of rice, respectively, and better than that of chemical fungicide triadimefon. The efficacy of kasugamycin and blasticidin was 50.54%-72.67% on rice leaf blast and 76.66%-87.42% on rice head blast, and equal to the chemical fungicide tricyclazole after sprayed once at the initial stage of rice leaf blast occurrence and the initial and end stages of earing, respectively. The efficacy of bacillus thuringiensis on Chilo suppressalis and Cnaphalocrocis medinalis was better than that of chemical insecticide bisultap, and the efficacy of saponin-nicotine and matrine was equal to that of chemical insecticide bisultap when the three biorational insecticides were sprayed at 1-2 instar larvae of pests. The efficacy of saponin-nicotine and matrine was above 70%, and lower than that of chemical insecticide imidacloprid 3-30 d after sprayed at 1-2 instar larvae of Nilaparvata lugens. The occurrence of weeds could be controlled, and the rice yield could be raised when the suitable non-thorough decomposed organism was applied or weeding was carried after the field had been ploughed twice before rice transplant. The rice yield could be raised by using biorational pesticides and agricultural methods against the chief diseases, insect pests and weeds of rice. The residue of pesticides in rice was lower in the bio-control area than in the chemical control area, according with the demands of health target of green food.

Crops, Agricultural↗
PubMed2006

Structure and putative function of dark- and light-adapted as well as UV-exposed eyes of the food store pest Psyllipsocus ramburi Sélys-longchamps (Insecta: Psocoptera: Psyllipsocidae).

The psocopteran Psyllipsocus ramburi Sélys-Longchamps can render food stuffs unpalatable and may serve as an intermediate host for cestodes. Its two circular compound eyes consist of about 26 facets, capped by strongly convexly curved corneae of 10-18 microm in diameter. Corneal nipples or interommatidial hairs are not developed. Beneath each corneal lens a cluster of four cone cells, enveloped by two primary pigment cells, separates an ommatidial group of eight retinula cells from the inner corneal surface. Membrane specializations of the retinula cells, known as the microvilli, measure 60 nm in diameter, and collectively make up the rhabdom, which is columnar in shape and has a distal diameter of 4 or 5 microm, depending on whether it is day- or night-adapted. Cone cell lengths measure 4.5 microm during the day and 8.5 microm at night and retinula cell screening pigments closely approach the edge of the rhabdom during the day. A 1-h exposure to UV-A (lambda(max)=351 nm) of ca. 1200 lx causes an almost total destruction of the photoreceptive membranes of the rhabdom and bleached all retinula cell screening pigments, but not the pigment grains of the primary pigment cells. Calculations, based on the anatomical data, suggest that the eyes are adapted to function under dim light levels, but cannot produce sharp images since their best possible acceptance angles are 22 degrees and 28 degrees in light- and dark-adapted states, respectively. Destruction of vision, likely affecting biorhythm and reproduction, by exposing the insects to UV-A may offer an alternative to the use of chemicals in controlling these insects.

Adaptation, Physiological↗
PubMed2003

Chagas disease: current epidemiological trends after the interruption of vectorial and transfusional transmission in the Southern Cone countries.

Chagas disease, named after Carlos Chagas who first described it in 1909, exists only on the American Continent. It is caused by a parasite, Trypanosoma cruzi, transmitted to humans by blood-sucking triatomine bugs and by blood transfusion. Chagas disease has two successive phases, acute and chronic. The acute phase lasts 6 to 8 weeks. After several years of starting the chronic phase, 20% to 35% of the infected individuals, depending on the geographical area will develop irreversible lesions of the autonomous nervous system in the heart, esophagus, colon and the peripheral nervous system. Data on the prevalence and distribution of Chagas disease improved in quality during the 1980's as a result of the demographically representative cross-sectional studies carried out in countries where accurate information was not available. A group of experts met in Bras lia in 1979 and devised standard protocols to carry out countrywide prevalence studies on human T. cruzi infection and triatomine house infestation. Thanks to a coordinated multi-country program in the Southern Cone countries the transmission of Chagas disease by vectors and by blood transfusion has been interrupted in Uruguay in1997, in Chile in 1999, and in 8 of the 12 endemic states of Brazil in 2000 and so the incidence of new infections by T. cruzi in the whole continent has decreased by 70%. Similar control multi-country initiatives have been launched in the Andean countries and in Central America and rapid progress has been recorded to ensure the interruption of the transmission of Chagas disease by 2005 as requested by a Resolution of the World Health Assembly approved in 1998. The cost-benefit analysis of the investments of the vector control program in Brazil indicate that there are savings of US$17 in medical care and disabilities for each dollar spent on prevention, showing that the program is a health investment with good return. Since the inception in 1979 of the Steering Committee on Chagas Disease of the Special Program for Research and Training in Tropical Diseases of the World Health Organization (TDR), the objective was set to promote and finance research aimed at the development of new methods and tools to control this disease. The well known research institutions in Latin America were the key elements of a world wide network of laboratories that received - on a competitive basis - financial support for projects in line with the priorities established. It is presented the time line of the different milestones that were answering successively and logically the outstanding scientific questions identified by the Scientific Working Group in 1978 and that influenced the development and industrial production of practical solutions for diagnosis of the infection and disease control.

Animals↗