The potential for insecticide resistance in Glossina (Diptera: Glossinidae)— an investigation by computer simulation and chemical analysis

1981 ◽  
Vol 71 (4) ◽  
pp. 691-702 ◽  
Author(s):  
I. Maudlin ◽  
C. H. Green ◽  
F. Barlow
Keyword(s):  
Insecticide Resistance ◽  
Control Strategies ◽  
Glossina Morsitans Morsitans ◽  
Wild Type ◽  
Tsetse Control ◽  
Population Extinction ◽  
Tsetse Population ◽  
Control Programmes ◽  
Evolution Of Resistance ◽  
Relationship Of

AbstractA computer model of a tsetse population was developed to determine whether insecticide resistance could evolve as a result of current tsetse control programmes. Chemical analyses were also carried out which showed that Glossina morsitans morsitans Westw. can metabolise DDT to DDE, indicating a potential for insecticide resistance in this species. The model showed that a completely isolated tsetse population stands little chance of surviving attacks with insecticides repeated at short intervals. However, when sufficient time is allowed between applications, such a population may survive and evolution of resistance take place. Given a small amount of immigration, the evolution of resistance is retarded, but population extinction is prevented. The degree of resistance developed by a population also depends on the dominance relationship of a resistant gene with its wild-type allele and on the reproductive fitness of the mutant. It is suggested that control strategies are adopted which would minimise the risk of insecticide resistance becoming a problem in tsetse and that susceptibility studies are carried out both before spraying operations and on any residual population post-spraying.

Cyclical transmission of pathogenic Trypanosoma species by gamma-irradiated sterile male Glossina morsitans morsitans

Parasitology ◽  
1982 ◽  
Vol 84 (2) ◽  
pp. 289-296 ◽  
Author(s):  
S. K. Moloo
Keyword(s):  
Glossina Morsitans Morsitans ◽  
Sterile Male ◽  
Infection Rates ◽  
Ambient Conditions ◽  
Glossina Morsitans ◽  
Tsetse Control ◽  
Significant Difference ◽  
Control Programmes ◽  
Domestic Livestock ◽  
Gamma Irradiated

SUMMARYInvestigations were conducted on the infection rates and transmission charecteristics of sterile male Glossina morsitans morsitans for Trypanosoma vivax, T. congolense and T. brucei. Pupae were irradiated after the first flush of female emergences with 7, 10 or 13 krad. in a 137caesium radiation source under ambient conditions. The emergent males were fed on a T. viuax-infected goat at peak parasitaemia. They were subsequently mated at 8 days old with 3-day-old normal, virgin females. A batch of sexually fertile males which had been infected as tenerals on the goat at the same time were similarly mated to serve as controls. All the tsetse were maintained on rabbits' ears; the survival and reproductive performance were monitored for seven age-group periods of 9 days each. The sterility rates of the males were 73, 91 and 98% for the 7, 10 and 13 krad. doses of radiation; the percentage of T. vivax infection rates were 78·3, 82·3 and 74·4, respectively. For the control males, the fecundity of the mated females was 90% and the infection rate was 75·7%. In all other experiments, the 10 krad. dose was selected since both the survival and the sterility of the irradiated males were good. The T. vivax-challenged cows and goats died with symptoms of anaemia. There was no difference in the transmission characteristics between sterile and fertile vectors. There was also no significant difference between the sterile and normal males in the infection rates and the transmission frequency of T. congolense and T. brucei to cattle, goats and mice. These results indicate that release of sterile male tsetse in tsetse control programmes will potentially increase the trypanosomiasis risk in the affected area. Consideration must therefore be given to integrating adequate surveillance and chemotherapeutic measures for protection of man and his domestic livestock in the region during the period of such tsetse control campaigns.

A field trial of pyriproxyfen-treated targets as an alternative method for controlling tsetse (Diptera: Glossinidae)

1993 ◽  
Vol 83 (3) ◽  
pp. 361-368 ◽  
Author(s):  
J. W. Hargrove ◽  
P. A. Langley
Keyword(s):  
Chemical Analysis ◽  
Technical Problem ◽  
Glossina Morsitans Morsitans ◽  
Tsetse Flies ◽  
Research Station ◽  
Glossina Morsitans ◽  
Tsetse Control ◽  
Tsetse Population ◽  
Hot Dry Season ◽  
Juvenile Hormone Mimic

AbstractA juvenile hormone mimic (pyriproxyfen) was used with odour-baited targets to assess its suitability for controlling tsetse flies (Glossina spp.). In August 1991, 41 odour-baited targets identical to those used with insecticide in tsetse control operations, were each treated with 4 g of pyriproxyfen and deployed near Rekomitjie Research Station, Zambezi Valley, Zimbabwe, in a 12.3 km2 block of woodland habitat of Glossina morsitans morsitans Westwood and G. pallidipes Austen. After three months, emergence rates from puparia of the two species collected in the block fell to 34% and 20% of control levels; 50 and 70%, respectively, of puparia of the two species collected were found, on dissection, to show arrested development. Changes in mean ovarian age and wing-fray category in the tsetse population during the trial were due partially to the pyriproxyfen and partially to high mortality, in the larval/pupal stages and in young adult flies, which occurs each year in the hot/dry season. Chemical analysis of cloth samples indicated that after four months 68–85% of the pyriproxyfen had been lost, a large proportion apparently dripping off the bottom of the target. If the technical problem of persistence can be solved pyriproxyfen could substitute for pesticides in target-based tsetse control operations.

scholarly journals Evaluation of resistance to pyrethroid and organophosphate adulticides, and kdr genotyping in Ades aegypti populations from Roraima, the Northernmost Brazilian State

2020 ◽  
Author(s):  
Ramão Luciano Nogueira Hayd ◽  
Luana Carrara ◽  
Joel de Melo Lima ◽  
Nathalia Coelho Vargas de Almeida ◽  
José Bento Pereira Lima ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Control Strategies ◽  
Wild Type ◽  
Urban Centers ◽  
Channel Gene ◽  
S Haplotype ◽  
International Borders ◽  
Two Cities ◽  
Amazonas State ◽  
Taqman Qpcr

Abstract Background Roraima is the northernmost State in Brazil and makes international borders with Venezuela and Guyana. Although mostly covered by the tropical forests, the urban centers are highly infested with Ae. aegypti and endemic for dengue, Zika and chikungunya. Here we presented the levels of Ae. aegypti infestation and number of arboviruses cases between 2015 and 2018 in the studied localities. We evaluated the insecticide resistance status of Ae. aegypti populations from the capital Boa Vista, two cities in international borders: Pacaraima and Bonfim, and Rorainópolis in the limit with Amazonas State, collected in 2016 and 2018. Methods WHO like tube tests with the pyrethroid deltamethrin (0.05 and 0.12%) and the organophosphate malathion (0.7%) were conducted. Genotyping of kdr mutations, related to resistance to pyrethroids, were performed for the SNP variations in the sites 1016 and 1534 of the voltage gated sodium channel gene (Na V ) with a TaqMan qPCR approach. Results Only Ae. aegypti was present in our collection, meaning that there is still a barrier that Ae. albopictus was still not able to transpose from Amazonas toward Roraima. All Ae. aegypti populations were susceptible to 0.7% malathion in 2016, however mortality dropped to under 90% in Bonfim and Pacaraima in 2018. All populations were resistant to 0.5% deltamethrin in both years. The time that 50% of females suffered knockdown ( Kd T 50 ) under exposition to 0.5% deltamethrin was 3.3-5.9 fold longer in mosquitoes from the populations compared to Rockefeller. Only Pacaraima (2018) remained resistant to 0.12% deltamethrin. The kdr genotyping revealed the absence of the wild-type Na V S haplotype (1016Val + 1534Phe) in populations from Roraima, meaning that all tested individuals had a genetic background for resistance to pyrethroid. The double kdr Na V R2 haplotype (1016Ile + 15434Cys) was under higher frequencies in all populations except Rorainópolis, where this haplotype seems to have arrived recently. Conclusions These results are important to the knowledge about insecticide resistance status of Ae. aegypti populations from Roraima and will help to improve vector control strategies that may be applied to diverse localities with similar conditions.

Chemical control of ticks on cattle and the resistance of these parasites to acaricides

Parasitology ◽  
2004 ◽  
Vol 129 (S1) ◽  
pp. S353-S366 ◽  
Author(s):  
J. E. GEORGE ◽  
J. M. POUND ◽  
R. B. DAVEY
Keyword(s):  
World War Ii ◽  
Control Strategies ◽  
Simulation Models ◽  
Tick Control ◽  
Mitigation Strategies ◽  
Control Programmes ◽  
Concomitant Reduction ◽  
Evolution Of Resistance ◽  
Tick Borne Disease ◽  
Organic Pesticides

Toward the end of the nineteenth century a complex of problems related to ticks and tick-borne diseases of cattle created a demand for methods to control ticks and reduce losses of cattle. The discovery and use of arsenical solutions in dipping vats for treating cattle to protect them against ticks revolutionized tick and tick-borne disease control programmes. Arsenic dips for cattle were used for about 40 years before the evolution of resistance of ticks to the chemical, and the development and marketing of synthetic organic acaricides after World War II provided superior alternative products. Most of the major groups of organic pesticides are represented on the list of chemicals used to control ticks on cattle. Unfortunately, the successive evolution of resistance of ticks to acaricides in each chemical group with the concomitant reduction in the usefulness of a group of acaricides is a major reason for the diversity of acaricides. Whether a producer chooses a traditional method for treating cattle with an acaricide or uses a new method, he must recognize the benefits, limitations and potential problems with each application method and product. Simulation models and research were the basis of recommendations for tick control strategies advocating approaches that reduced reliance on acaricides. These recommendations for controlling ticks on cattle are in harmony with recommendations for reducing the rate of selection for acaricide resistance. There is a need to transfer knowledge about tick control and resistance mitigation strategies to cattle producers.

scholarly journals High insecticide resistance mediated by different mechanisms in Culex quinquefasciatus populations from the city of Yaoundé, Cameroon

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abdou Talipouo ◽  
Konstantinos Mavridis ◽  
Elysée Nchoutpouen ◽  
Borel Djiappi-Tchamen ◽  
Emmanouil Alexandros Fotakis ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Vector Control ◽  
High Resistance ◽  
Culex Quinquefasciatus ◽  
Control Strategies ◽  
Cuticular Hydrocarbon ◽  
Control Measures ◽  
High Frequencies ◽  
The City ◽  
Integrated Vector Control

AbstractCulex mosquitoes particularly Culex quinquefasciatus are important arboviral and filariasis vectors, however despite this important epidemiological role, there is still a paucity of data on their bionomics. The present study was undertaken to assess the insecticide resistance status of Cx. quinquefasciatus populations from four districts of Yaoundé (Cameroon). All Culex quinquefasciatus populations except one displayed high resistance to bendiocarb and malathion with mortalities ranging from 0 to 89% while high resistance intensity against both permethrin and deltamethrin was recorded. Molecular analyses revealed high frequencies of the ACE-1 G119S mutation (ranging from 0 to 33%) and kdr L1014F allele (ranging from 55 to 74%) in all Cx. quinquefasciatus populations. Significant overexpression was detected for cytochrome P450s genes CYP6AA7 and CYP6Z10, as well as for Esterase A and Esterase B genes. The total cuticular hydrocarbon content, a proxy of cuticular resistance, was significantly increased (compared to the S-lab strain) in one population. The study confirms strong insecticide resistance mediated by different mechanisms in Cx. quinquefasciatus populations from the city of Yaoundé. The expansion of insecticide resistance in Culex populations could affect the effectiveness of current vector control measures and stress the need for the implementation of integrated vector control strategies in urban settings.

scholarly journals The development and validation of an age-structured model for the evaluation of disease control strategies for intestinal helminths

Parasitology ◽  
1994 ◽  
Vol 109 (3) ◽  
pp. 389-396 ◽  
Author(s):  
M. S. Chan ◽  
H. L. Guyatt ◽  
D. A. P. Bundy ◽  
G. F. Medley
Keyword(s):  
Helminth Infection ◽  
Control Strategies ◽  
Intestinal Helminth ◽  
Intestinal Helminths ◽  
Parasite Control ◽  
Age Related ◽  
Control Programmes ◽  
Age Structured ◽  
Development And Validation ◽  
Age Structured Model

SummaryEpidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted treatment programmes. The model was verified using field data from control programmes for Ascaris lumbricoides and Trichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes.

scholarly journals Molecular detection and phylogenetic relationship of wild-type strains of canine distemper virus in symptomatic dogs from Uberlândia, Minas Gerais

2015 ◽  
Vol 67 (6) ◽  
pp. 1510-1518
Author(s):  
S.A. Headley ◽  
T.R. Santos ◽  
L. Bodnar ◽  
J.P.E. Saut ◽  
A.P. Silva ◽  
...  
Keyword(s):  
Canine Distemper Virus ◽  
Phylogenetic Analyses ◽  
Clinical Manifestations ◽  
N Gene ◽  
Clinical Samples ◽  
Canine Distemper ◽  
Wild Type ◽  
Age Related ◽  
Relationship Of ◽  
Type Strains

This study investigated the occurrence of canine distemper virus (CDV) by evaluating the presence of viral RNA within urine samples of dogs from Uberlândia, MG, with clinical manifestations suggestive of infection by CDV by targeting the CDV N gene. Of the clinical samples collected ( n =33), CDV viruria was detected in 45.5%. Five dogs died spontaneously; all had characteristic CDV-associated histopathological alterations and demonstrated CDV viruria. Statistical analyses revealed that the age, gender, breed, or the organ system of the dog affected had no influence on the occurrence of canine distemper. Myoclonus and motor incoordination were the most significant neurological manifestations observed. A direct association was observed between keratoconjunctivitis and dogs with CDV viruria. These findings suggest that CDV viruria in symptomatic dogs might not be age related, and that symptomatic dogs can demonstrate clinical manifestations attributed to CDV without viruria identified by RT-PCR. Additionally, the results of the sequence identities analysed have suggested that all Brazilian wild-type strains of CDV currently identified are closely related and probably originated from the same lineage of CDV. Nevertheless, phylogenetic analyses suggest that there are different clusters of wild-type strains of CDV circulating within urban canine populations in Brazil.

scholarly journals NIM1 Overexpression in Arabidopsis Potentiates Plant Disease Resistance and Results in Enhanced Effectiveness of Fungicides

2001 ◽  
Vol 14 (9) ◽  
pp. 1114-1124 ◽  
Author(s):  
Leslie Friedrich ◽  
Kay Lawton ◽  
Robert Dietrich ◽  
Michael Willits ◽  
Rebecca Cade ◽  
...  
Keyword(s):  
Disease Resistance ◽  
Plant Disease Resistance ◽  
Systemic Acquired Resistance ◽  
Control Strategies ◽  
Chemical Activation ◽  
Acquired Resistance ◽  
Wild Type ◽  
Protein Levels ◽  
Rapid Induction ◽  
Dependent Signal

The NIM1 (for noninducible immunity, also known as NPR1) gene is required for the biological and chemical activation of systemic acquired resistance (SAR) in Arabidopsis. Overexpression of NIM1 in wild-type plants (hereafter referred to as NIM1 plants or lines) results in varying degrees of resistance to different pathogens. Experiments were performed to address the basis of the enhanced disease resistance responses seen in the NIM1 plants. The increased resistance observed in the NIM1 lines correlated with increased NIM1 protein levels and rapid induction of PR1 gene expression, a marker for SAR induction in Arabidopsis, following pathogen inoculation. Levels of salicylic acid (SA), an endogenous signaling molecule required for SAR induction, were not significantly increased compared with wild-type plants. SA was required for the enhanced resistance in NIM1 plants, however, suggesting that the effect of NIM1 overexpression is that plants are more responsive to SA or a SA-dependent signal. This hypothesis is supported by the heightened responsiveness that NIM1 lines exhibited to the SAR-inducing compound benzo(1,2,3)-thiadiazole-7-car-bothioic acid S-methyl ester. Furthermore, the increased efficacy of three fungicides was observed in the NIM1 plants, suggesting that a combination of transgenic and chemical approaches may lead to effective and durable disease-control strategies.

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