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Effect of Bombyx mori chitinase against Japanese pine sawyer (Monochamus alternatus) adults as a biopesticide.

Bombyx mori chitinase (Bm-CHI), with a molecular mass of 75 kDa, was investigated on the possibility that it can serve as a biocontrol agent against the adult Japanese pine sawyer (JPS), Monochamus alternatus (Coleoptera: Cerambycidae). Oral ingestion of purified chitinase at concentrations of 3 microM (11.25 microg/50 microl) and 0.3 micoM (1.125 microg/50 microl) caused high mortality in JPS, a significant decrease in bark consumption, and, only in high concentration, a slight reduction of body weight. Fluorescence assays indicated that peritrophic membrane (PM) chitin is degraded by the action of orally ingested Bm-CHI at 3 microM concentration only. Scanning electron micrographs clearly indicated that the beetles that ingested Bm-CHI of the same high concentration had their PM perforated and disrupted, but ultrastructural studies showed that the ingested chitinase did not affect the midgut epithelium. These findings open up the possibility of using insect chitinase as a biopesticidal enzyme. It should have agronomic potential for insect control.

Aging↗

Farming from a new perspective: remote sensing comes down to earth.

Farmers strive to increase the yield of their fields by adding nutrients and water to the land, and using pesticides to control insects and disease. In addition to bountiful harvests, the results of their endeavors may include elevated amounts of fertilizers in surface waters and aquifers and potential risk to themselves and their neighbors from exposure to pesticides. Precision agriculture is the use of modern information technologies such as geographic information systems, the global positioning system, and remote sensing from the air to reduce the environmental effects of these chemicals while enhancing the productivity of farming. By combining crop yield maps with soil survey maps and remote sensing output, farmers can identify areas that need more or less fertilizer, water, or pesticide.

Agriculture↗

Biomarkers of human exposure to pesticides.

For centuries, several hundred pesticides have been used to control insects. These pesticides differ greatly in their mode of action, uptake by the body, metabolism, elimination from the body, and toxicity to humans. Potential exposure from the environment can be estimated by environmental monitoring. Actual exposure (uptake) is measured by the biological monitoring of human tissues and body fluids. Biomarkers are used to detect the effects of pesticides before adverse clinical health effects occur. Pesticides and their metabolites are measured in biological samples, serum, fat, urine, blood, or breast milk by the usual analytical techniques. Biochemical responses to environmental chemicals provide a measure of toxic effect. A widely used biochemical biomarker, cholinesterase depression, measures exposure to organophosphorus insecticides. Techniques that measure DNA damage (e.g., detection of DNA adducts) provide a powerful tool in measuring environmental effects. Adducts to hemoglobin have been detected with several pesticides. Determination of chromosomal aberration rates in cultured lymphocytes is an established method of monitoring populations occupationally or environmentally exposed to known or suspected mutagenic-carcinogenic agents. There are several studies on the cytogenetic effects of work with pesticide formulations. The majority of these studies report increases in the frequency of chromosomal aberrations and/or sister chromatid exchanges among the exposed workers. Biomarkers will have a major impact on the study of environmental risk factors. The basic aim of scientists exploring these issues is to determine the nature and consequences of genetic change or variation, with the ultimate purpose of predicting or preventing disease.

Biomarkers↗

The structure of the juvenile hormone binding protein gene from Galleria mellonella.

Juvenile hormone (JH) and ecdysone are the key hormones controlling insect growth and development. The juvenile hormone binding protein (JHBP) is the first member in the array of proteins participating in JH signal transmission. In the present report a whole jhbp gene sequence (9790 bp) is described. The jhbp gene contains four introns (A-D). All the introns have common flanking sequences: GT at the 5' and AG at the 3' end. The first intron is in phase 1, the second in phase 2, and the third and fourth in phase 1. An analysis of these sequences suggests that U2-class spliceosomes are involved in intron excision from pre-mRNA. Several horizontally transmitted elements from other genes were found in the introns. All jhbp exons are positioned in local AT-reach regions of the gene. A search for core promoter regulatory elements revealed that the TATA box starts 29 bp preceding the start of transcription; the sequence TCAGTA representing a putative initiator sequence (Inr) starts at position +14. Eight characteristic sequences for binding Broad-Complex gene products, which coordinate the ecdysone temporal response, are present in the non-coding sequence of the jhbp gene. An analysis of exon locations and intron phases indicates that jhbp gene organization is related to the retinol binding protein gene, a member of the lipocalin family.

Animals↗

[Pachycrepoideus vindemiae (Hymenoptera: Pteromalidae) as parasite of Ophyra aenescens (Diptera: Muscidae) in Brazil].

The first occurrence of the parasitoid Pachycrepoideus vindemiae on pupae of Ophyra aenescens, a fly of medical-sanitary importance, is reported. A swine carcass was used as bait to collect the insects. In the study, 302 pupae of Ophyra aenescens (Wiedemann) (Diptera: Muscidae) were obtained, 6 (1.98%) of them yielded the parasitoid Pachycrepoideus vindemiae (Hymenoptera: Pteromalidae

Animals↗

Larvicidal activity of Bacillus sphaericus 2362 against Anopheles nuneztovari, Anopheles darlingi and Anopheles braziliensis (Diptera, Culicidae).

In this present study, preliminary data was obtained regarding the mortality rate of the Amazonian anophelines, Anopheles nuneztovari, Anopheles darlingi and Anopheles braziliensis when subjected to treatment with Bacillus sphaericus strain 2362, the WHO standard strain. Initially, experiments were conducted to test the mortality rate of the three species of anopheline larvae. The third larval instar of An. nuneztovari and the second and third larval instars of An. darlingi proved to be the least susceptible. In other experiments, the same three mosquito species were tested with the standard strain 2362, An. nuneztovari was the least susceptible to this insect pathogen, while An. braziliensis was the most susceptible. This latter species showed a difference in the level of LC50 concentration, when compared to the former, of 2.4, 2.5 and 1.8 in readings taken 24, 48 and 72 hours after exposure to the bacillus.

Animals↗

Interrupting Chagas disease transmission in Venezuela.

The interruption of vectorial transmission of Chagas disease in Venezuela is attributed to the combined effects of ongoing entomoepidemiological surveillance, ongoing house spraying with residual insecticides and the concurrent building and modification of rural houses in endemic areas during almost five decades. The original endemic areas which totaled 750,000 km(2), have been reduced to 365,000 km(2). During 1958-1968, initial entomological evaluations carried out showed that the house infestation index ranged between 60-80%, the house infection index at 8-11% and a house density index of 30-50 triatomine bugs per house. By 1990-98, these indexes were further reduced to 1.6-4.0%, 0.01-0.6% and 3-4 bugs per house respectively. The overall rural population seroprevalence has declined from 44.5% (95% C.I.: 43.4-45.3%) to 9.2% (95% C.I.: 9.0-9.4%) for successive grouped periods from 1958 to 1998. The annual blood donor prevalence is firmly established below 1%. The population at risk of infection has been estimated to be less than four million. Given that prevalence rates are stable and appropriate for public health programmes, consideration has been given to potential biases that may distort results such as: a) geographical differences in illness or longevity of patients; b) variations in levels of ascertainment; c) variations in diagnostic criteria; and d) variations in population structure, mainly due to appreciable population migration. The endemic areas with continuous transmission are now mainly confined to piedmonts, as well as patchy foci in higher mountainous ranges, where the exclusive vector is Rhodnius prolixus. There is also an unstable area, of which landscapes are made up of grasslands with scattered broad-leaved evergreen trees and costal plains, where transmission is very low and occasional outbreaks are reported.

Adolescent↗

Domestic Rhodnius ecuadoriensis (Hemiptera, Reduviidae) infestation in Northern Peru: a comparative trial of detection methods during a six-month follow-up.

Two passive methods in the assessment of intradomiciliary infestation by Rhodnius ecuadoriensis were tested: (i) the Gomes Nu ez sensor box (GN), (ii) sheets of white typing paper and (iii) one active timed manual method. The study was carried out in the Alto Chicama River Valley, Province of Gran Chim , Department of La Libertad. The study design consisted of an initial searching of triatomines inside of the domestic environment by the manual capture active procedure (man/hour) covering all the studied houses. Then, matched pairs of GN boxes and paper sheets were simultaneously installed in the bedrooms of 207 households distributed in 19 localities. A comparative prospective trial of these passive detection devices were monitored at 2, 4 and, finally 6 months follow-up. Parasitological Trypanosoma rangeli and/or T. cruzi infections were investigated in two houses with high level of infestation by R. ecuadoriensis. 16.9% of the 207 households investigated by an initial active manual method were infested with R. ecuadoriensis. The proportion of infested houses fluctuated from 6.2 to 55.5% amongst the 19 localities investigated. T. rangeli natural infection was detected in R. ecuadoriensis specimens collected in two households. Parasite rates in the bugs ranged from 16.6 to 21.7% respectively. The most striking fact was an average rate of salivary gland infection ranging from 7.4 to 8.3%. At the end of the sixth month period, a cumulative incidence of 31.4% of positive GN boxes against 15.9% for paper sheets was recorded. All three methods combined detected domestic infestation in 129 (62.3%) of the 207 houses studied in the 19 localities. The range of houses infested varies from 6.7% to 92.9%. In areas with low bug density infestation rates, the methodology experienced in our studies, seems to be the best choice for investigations on domestic R. ecuadoriensis populations.

Animals↗

[Modification of the perihabitational biotype in the prevention of Chagas disease].

In zones endemic for the American trypanosomiasis the modification of the biotopes surrounding human, rural, sylvatic or suburban housing, involves the arrangement of a clean perimetral area completely free of shrubs and chaparral, devoid of dens of wild animals and dwellings of domestic animals, to hinder the persistence of peridomestic foci where the proliferation of Triatomine bugs encourage the reinfestation of the human lodgings. The success of insecticide spraying campaigns, even with simultaneous amelioration of housing, are enhanced by the modification of the biotopes. A pilot field experience is presented; a 2 year active campaign in a suburban area of Villa Carlos Paz, province Cordoba, Argentina, confirming the methods to eliminate reinfestation of houses from peridomestic sites, in an area of low vector density.

Animals↗

[Broadening the scope of triatomine research in the attendance of notifications of Triatoma sordida (Stål, 1859) in the State of São Paulo].

The objective of this study was to broaden the inspection of home units to a radius of 200 meters from the residence of each notified case. The notifications received by the regional Services of SUCEN of São José do Rio Preto, Araçatuba and Presidente Prudente were evaluated in August, September and October of 2002. There was a total of 263 notifications of triatomines, of which 79 were positive. Broadening the scope meant another 610 domestic units were included in the investigation and in 14.5% of these triatomines were found. It was observed that 24.7% of the domestic units neighboring the house of the notified case presented positive results in the triatomines investigation. When a notified domestic unit presented a positive result, broadening the scope showed positivity in 42.5% of neighboring domestic units (Odds ratio 2.252 (1.25<OR<4.06, with a 95% confidence limit). This study demonstrated that it is necessary to broaden the scope of investigation when attending notifications by the local population.

Animals↗

[Integral insecticide spraying followed by immediate triatomine research, as an additional strategy for the epidemiological surveillance of Chagas' disease, in areas of residual persisting foci].

The locality of Altolândia (Tapiraí Municipality, Minas Gerais, Brazil), frequently presents Panstrongylus megistus infestation in the domiciliary environment. In order to improve epidemiological surveillance in this area, a strategy of domiciliary pyrethroid spraying with high flushing-out effect followed by immediate triatomine research, was implemented in all the existing dwellings. The main objectives were the detection and elimination of cryptic foci, thus reducing the opportunities for new infestations.

Animals↗

An attempt to control Phlebotomine sand flies (Diptera: Psychodidae) by residual spraying with deltamethrin in a Colombian village.

An attempt was made to control phlebotomine sand flies biting indoors in a rural community near Cali, Colombia, using the residual insecticide "K-Othrine" (deltamethrin) sprayed on the inside walls of houses. Twelve houses were divided into matched pairs based on physical characteristics, one house in each pair being left untreated while the inside walls of the other were sprayed with 1% deltamethrin at a concentration of 500 mg a.i./m2. Sand flies were sampled each week using protected human bait and sticky trap collections for four months after spraying. The number of sand flies (Lutzomyia youngi) collected on sticky traps was significantly lower (P = 0.004) in the untreated houses than in the treated ones with which they were matched. This difference was not significant for L. columbiana; the other anthropophilic species were not present in large numbers. The numbers collected on human bait in treated and untreated houses were not significantly different for either species. Activity of the insecticide as determined by contact bioassays remained high throughout the study and failure to control the insects was attributed to two factors: the tendency of sand flies to bite before making contact with the insecticide and the fact that the number of sand flies that entered houses represented a relatively small proportion of the population in the wooded areas surrounding the settlement in the study.

Animals↗