Lethality of triatomines (Hemiptera: Reduviiae), vectors of Chagas' disease, feeding on blood baits containing synthetic insecticides, under laboratory conditions

A laboratory study was conducted to test the toxicity of synthetic insecticides added to defibrinated sheep blood kept at room temperature and offered as food to the following triatomine species: Triatoma infestans, Panstrongylus megistus, Triatoma vitticeps, Triatoma pseudomaculata, Triatoma brasiliensis and Rhodnius prolixus. The insecticides used, at a concentration of 1g/l, were: HCH, DDT, Malathion and Trichlorfon, and the lethalithy observed at the end of a 7-day period varied according to the active principle of each. HCH was the most effective by the oral route, killing 100% of the insects, except P. megistus (95.7%) and T. pseudomaculata (94.1%). Trichlorfon killed the insects at rates ranging from 71.8% (T. vitticeps) to 98% (R. prolixus). Malathion was slightly less efficient, killing the insects at rates from 56.8% (T. vitticeps) to 97% (T.brasiliensis). DDT was the least effective, with a killing rate of 10% (T. vitticeps) to 75% (T.brasiliensis). Since the tests were performed at room temperature, we suggest that baits of this type should be tried for the control of triatomines in the field.

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First Report ofAprostocetus asthenogmus(Hymenoptera: Eulophidae) in South America and Parasitizing Eggs of Triatominae Vectors of Chagas Disease

Journal of Parasitology Research ◽

10.1155/2014/547439 ◽

2014 ◽

Vol 2014 ◽

pp. 1-4 ◽

Cited By ~ 1

Author(s):

Claudiney Biral dos Santos ◽

Marcelo Teixeira Tavares ◽

Gustavo Rocha Leite ◽

Adelson Luiz Ferreira ◽

Leonardo de Souza Rocha ◽

...

Keyword(s):

South America ◽

Chagas Disease ◽

Biological Control Agent ◽

Control Agent ◽

Triatoma Infestans ◽

Disease Vectors ◽

Parasitoid Species ◽

Triatomine Species ◽

Chagas Disease Vectors ◽

First Time

We report for the first time the parasitism of eggs of two triatomine Chagas disease vectors,Triatoma infestansandT. vitticeps, by the microhymenopterous parasitoidAprostocetus asthenogmus. We also describe the first identification of this parasitoid in South America.A. asthenogmuswere captured near unparasitized triatomine colonies in the municipality of Vitória, state of Espírito Santo, Brazil, and placed into pots with recently laid triatomine eggs. After 24 days, we observed wasps emerging fromT. infestansandT. vitticepseggs. Several characteristics of this parasitoid species suggest that it could be a potential biological control agent of triatomine species.

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The occurrence of synanthropic triatomines in Bahia, Brazil: what changed after 40 years of the vector-control program?

10.21203/rs.3.rs-50744/v1 ◽

2020 ◽

Author(s):

Gilmar Ribeiro ◽

Cristiane Medeiros Moraes de Carvalho ◽

Renato Freitas de Araújo ◽

Fernanda Cardoso Lanza ◽

Diego Lopes Paim Miranda ◽

...

Keyword(s):

Vector Control ◽

Chagas Disease ◽

Relative Abundance ◽

Disease Transmission ◽

Control Program ◽

The State ◽

Triatoma Infestans ◽

Entomological Surveillance ◽

Triatomine Species ◽

Vector Control Program

Abstract Background: This study presents a descriptive analysis of the occurrence of synanthropic triatomine species in the state of Bahia, before and after the implementation of the vector control program. Methods: Occurrence and number of collected specimens in the municipalities were analyzed in two periods: (A) 1957 to 1971, before systematic vector control actions; and (B) 2006 to 2019, after the certification of interruption of Chagas disease transmission by Triatoma infestans. Results: In total, 17 species were recorded during period A and 21 during period B. Panstrongylus megistus was the most frequent species in period A (42%), while Triatoma pseudomaculata (42%) and T. sordida (38%) were more frequent in period B. In period A, T. infestans was found in 26 (9%) municipalities, and in period B it was found in 7 (2%). During period B, most triatomines (88%) were captured at the peridomestic habitats, with a predominance of T. sordida (85%). Species with greatest relative abundance within the household were T. sordida (49%), T. brasiliensis (27%), and T. pseudomaculata (15%). Conclusions: We have observed a clear reduction in the occurrence of P. megistus and T. infestans and an increase in the relative abundance and geographical distribution of T. sordida and T. pseudomaculata after 40 years of the vector-control program. High frequency of other triatomine species in the municipalities of the state of Bahia and a great abundance of T. sordida in recent years, highlight the need to reinforce permanent entomological surveillance actions for Chagas disease.

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Lethal effect of a bait for Rhodnius prolixus (Hemiptera: Reduviidae), the vector of Chagas' disease, containing hexachlorocyclohexane (HCH), under laboratory conditions

Revista do Instituto de Medicina Tropical de São Paulo ◽

10.1590/s0036-46651992000400005 ◽

1992 ◽

Vol 34 (4) ◽

pp. 295-301 ◽

Cited By ~ 3

Author(s):

Marli Maria Lima ◽

Luis Rey ◽

Rubens Pinto de Mello

Keyword(s):

Mortality Rate ◽

Chagas Disease ◽

Room Temperature ◽

Lethal Effect ◽

Rhodnius Prolixus ◽

Active Principle ◽

Laboratory Conditions

The lethal effect of a bait containing an aqueous hexachlorocyclohexane (HCH) suspension at the concentration of 1g/l and maintained at room temperature was studied in the laboratory over a period of 12 weeks. The suspension was placed in a latex bag hanging inside a 1000-ml beaker tightly covered with nylon netting, and left there with no changes for 85 days. Sixteen groups of R. prolixas bugs, consisting on average of 30 specimens each, were successively exposed to the bait and observed at different intervals for one week each. The mortality rate was 100% for all groups, except for the 16th, whose mortality rate was 96.7%. As the groups succeeded one another, mortality started to occur more rapidly and was more marked at the 6- and 24-h intervals. Later tests respectively started at 6:00 a.m. and 6:00 p.m. showed that diurnal and nocturnal periodicity in the offer of food had no effect on mortality. First- and 2nd- instar nymphs and adults male were more sensitive and 5th- instar nymphs were more resistant to the active principle of the bait.

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Phenetic analysis of Panstrongylus megistus Burmeister, 1835 (Hemiptera: Reduviidae: Triatominae) in the State of Paraná-Brazil

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132009000200012 ◽

2009 ◽

Vol 52 (2) ◽

pp. 349-357 ◽

Cited By ~ 3

Author(s):

Rogério Luiz Kopp ◽

Vanete Thomaz-Soccol ◽

Débora do Rocio Klisiowicz ◽

Norberto Membrive ◽

José Maria Soares Barata ◽

...

Keyword(s):

Genetic Variability ◽

Chagas Disease ◽

The State ◽

Triatoma Infestans ◽

Phenetic Analysis ◽

Genetic Studies ◽

Panstrongylus Megistus ◽

Disease Vector ◽

Different Populations ◽

South Of Brazil

Panstrongylus megistus is an important Chagas Disease vector and is said to be one of the species that might replace Triatoma infestans as the main vector of that disease in Brazil. The different degrees of P. megistus domiciliation in Brazil and its epidemiological relevance draw forth the need for the development of genetic studies that make it possible to analyze and understand the interchange of individual and gene fluxes among different populations. Thus, the present work aimed at studying the genetic variability of P. megistus in the State of Paraná - south of Brazil- and at comparing it with populations of the same species from five other states in Brazil (SP, MG, SC, RS, SE). In order to attain the proposed objective, 25 populations were studied using fifteen isoenzymatic systems (6PGD, G6PD, ME¹, ME², ICD, PGM, GPI, GOT¹, GOT², NP¹, NP², DIA, MPI, F, and MDH). The phenetic analysis allowed the individuation of 22 electromorphs and five zymodemes. The G6PD enzyme was the only polymorphic one presenting four electromorphs for the studied populations, all of them described for the State of Paraná-BR. The P. megistus populations from other states grouped with those from Paraná-BR, evidencing a low genetic variability in that species. Despite the existing geographic barriers, sub-samples - away from one another by at most 570km - were grouped in one and the same zymodeme. The epidemiological implications of such results are discussed in the present work.

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Studies in search of a suitable experimental insect model for xenodiagnosis of hosts with Chagas' disease: 3 - On the interaction of vector species and parasite strain in the reaction of bugs to infection by Trypanosoma cruzi

Revista de Saúde Pública ◽

10.1590/s0034-89101988000500004 ◽

1988 ◽

Vol 22 (5) ◽

pp. 390-400 ◽

Cited By ~ 20

Author(s):

Alina Perlowagora-Szumlewicz ◽

Carlos Alberto Muller ◽

Carlos José de Carvalho Moreira

Keyword(s):

Trypanosoma Cruzi ◽

Chagas Disease ◽

Acute Infection ◽

Rhodnius Prolixus ◽

Triatoma Infestans ◽

Parasite Strain ◽

Vector Species ◽

Panstrongylus Megistus ◽

Acute Infections ◽

Triatoma Sordida

The reaction of nine vector species of Chagas' disease to infection by seven different Trypanosoma cruzi strains; Berenice, Y, FL, CL, S. Felipe, Colombiana and Gávea, are examined and compared. On the basis of the insects' ability to establish and maintain the infection, vector species could be divided into two distinct groups which differ in their reaction to an acute infection by T. cruzi. While the proportion of positive bugs was found to be low in Triatoma infestans and Triatoma dimidiata it was high, ranging from 96.9% to 100% in the group of wild (Rhodnius neglectus, Triatoma rubrovaria)and essentially sylvatic vectors in process of adaptation to human dwellings, maintained under control following successful insecticidal elimination of Triatoma infestans (Panstrongylus megistus, Triatoma sordida and Triatoma pseudomaculata). An intermediate position is held by Triatoma brasiliensis and Rhodnius prolixus. This latter has been found to interchange between domestic and sylvatic environments. The most important finding is the strikingly good reaction between each species of the sylvatic bugs and practically all T. cruzi strains herein studied, thus indicating that the factors responsible for the excellent reaction of P.megistus to infection by Y strain, as previously reported also come into operation in the reaction of the same vector species to acute infections by five of the remaining T.cruzi strains. Comparison or data reported by other investigators with those herein described form the basis of the discussion of Dipetalogaster maximus as regards its superiority as a xenodiagnostic agent.

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Excito-repellency effect of deltamethrin on triatomines under laboratory conditions

Revista da Sociedade Brasileira de Medicina Tropical ◽

10.1590/s0037-86822000000300002 ◽

2000 ◽

Vol 33 (3) ◽

pp. 247-252 ◽

Cited By ~ 10

Author(s):

Liléia Diotaiuti ◽

Claysson Marques Penido ◽

Holbiano Saraiva de Araújo ◽

Christopher John Schofield ◽

Cláudio Teixeira Pinto

Keyword(s):

Triatoma Infestans ◽

Low Doses ◽

Additional Advantage ◽

Panstrongylus Megistus ◽

Laboratory Conditions ◽

Triatoma Sordida ◽

Triatomine Species ◽

Insect Mortality ◽

The Moment

This work demonstrates that deltamethrin in low doses produces an excito-repellency effect on triatomines, as already observed for mosquitoes. A wooden box covered with a cloth impregnated with deltamethrin at doses of 2.5 and 5mg ai/m² was utilized for the experiment. The triatomine species studied were Triatoma infestans, Panstrongylus megistus, Rhodnius neglectus and Triatoma sordida. Adults were released in one of the sides of the box and their position was noted in subsequent periods. The observations were realized on the day the cloth was impregnated and subsequently repeated at 30 and 60 days for T. sordida; on day 120, the remaining species were included. Insect mortality and attempts at flight from the box were also observed. Excito-repellency was evident for all species and doses up to day 120. The only species that attempted to fly was P. megistus. The excito-repellency effect may be considered as an additional advantage to the insecticide power, as it should be able to prevent the installation of new colonies by females that fly into the homes, and at the moment of the spraying, it should promote the flushing out of triatomines from the wall crevices and from other shelters.

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Geographic Distribution of Chagas Disease Vectors in Brazil Based on Ecological Niche Modeling

Journal of Tropical Medicine ◽

10.1155/2012/705326 ◽

2012 ◽

Vol 2012 ◽

pp. 1-15 ◽

Cited By ~ 102

Author(s):

Rodrigo Gurgel-Gonçalves ◽

Cléber Galvão ◽

Jane Costa ◽

A. Townsend Peterson

Keyword(s):

Chagas Disease ◽

Geographic Distribution ◽

Disease Transmission ◽

Ecological Niche Modeling ◽

Transmission Risk ◽

Triatoma Infestans ◽

Ecological Niches ◽

Triatoma Sordida ◽

Triatomine Species ◽

Chagas Disease Vectors

Although Brazil was declared free from Chagas disease transmission by the domestic vectorTriatoma infestans, human acute cases are still being registered based on transmission by native triatomine species. For a better understanding of transmission risk, the geographic distribution of Brazilian triatomines was analyzed. Sixteen out of 62 Brazilian species that both occur in>20 municipalities and present synanthropic tendencies were modeled based on their ecological niches.Panstrongylus geniculatusandP. megistusshowed broad ecological ranges, but most of the species sort out by the biome in which they are distributed:Rhodnius pictipesandR. robustusin the Amazon;R. neglectus,Triatoma sordida, andT. costalimaiin the Cerrado;R. nasutus,P. lutzi,T. brasiliensis,T. pseudomaculata,T. melanocephala, andT. petrocchiaein the Caatinga;T. rubrovariain the southern pampas;T. tibiamaculataandT. vitticepsin the Atlantic Forest. Although most occurrences were recorded in open areas (Cerrado and Caatinga), our results show that all environmental conditions in the country are favorable to one or more of the species analyzed, such that almost nowhere is Chagas transmission risk negligible.

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