Dataset Information

Optimization of odour-baited resting boxes for sampling malaria vector, Anopheles arabiensis Patton, in arid and highland areas of Africa.

ABSTRACT:

Background

Odour baited resting boxes are simple, reliable and important tools for sampling malaria vector mosquitoes in surveillance and control programmes in different parts of Africa. To optimize the use of cow urine baited resting boxes for sampling An. arabiensis, a community-based study was conducted in Mabogini hamlet in the Lower Moshi irrigation scheme area.

Method

Experimental designs using 3 by 3 Latin square were conducted for twenty days to evaluate the following: i) the effect of different parameters in the sampling of mosquitoes using odour baited resting boxes; ii) the performance of odour baited traps under indoor and outdoor conditions and the effect of people sleeping indoors on mosquito density; iii) the effect of position in the placement of traps on collection of mosquitoes; and, iv) the efficiency of the trap outdoors at three different distances from the house wall. One extra house served as the sentinel house to monitor species abundance using a CDC-miniature light trap.

Results

8581 mosquitoes were sampled by odour baited resting boxes of which, 8051 (93.82%) were An. arabiensis and 530 (6.18%) Cx. quinquefasciatus. The light trap collected 12,420 mosquitoes, of which 9442 (76.02%) were An. arabiensis, 126 (1.01%) An. funestus group, 230 (1.85%) An. rufipes and 2622 (21.11%) Cx. quinquefasciatus. The best height for outdoor mosquitoes sampling was 15 cm and 220 cm while indoors was 105 cm. The difference in mosquito collection between different outdoor and indoor heights was statistically significant (p < 0.0001). The optimal outdoor location of odour baited resting boxes from the wall of the house was 3 m.

Conclusions

The results of these studies demonstrate an optimal method for sampling during surveillance and control programmes in rural villages of highlands and arid areas of Africa using inexpensive baits and boxes.

SUBMITTER: Kweka EJ

PROVIDER: S-EPMC2933686 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Optimization of odour-baited resting boxes for sampling malaria vector, Anopheles arabiensis Patton, in arid and highland areas of Africa.

Kweka Eliningaya J EJ Mwang'onde Beda J BJ Mahande Aneth M AM

Parasites & vectors 20100819

<h4>Background</h4>Odour baited resting boxes are simple, reliable and important tools for sampling malaria vector mosquitoes in surveillance and control programmes in different parts of Africa. To optimize the use of cow urine baited resting boxes for sampling An. arabiensis, a community-based study was conducted in Mabogini hamlet in the Lower Moshi irrigation scheme area.<h4>Method</h4>Experimental designs using 3 by 3 Latin square were conducted for twenty days to evaluate the following: i) ...[more]

PMID: 20723243

Similar Datasets

Project description:BACKGROUND: Anopheles arabiensis, an important malaria vector in Sudan and other countries in sub-Saharan Africa, exhibits considerable ecological and behavioural plasticity allowing it to survive in the harsh conditions of arid regions. It has been shown that adult populations of An. arabiensis in the semi-desert habitat of western Khartoum State survive through the long dry season in a state of partial aestivation, characterized by limited feeding activity and a degree of arrested ovarian development. Anopheles arabiensis in these sites occurs in two phenotypic forms. One is large and heavily melanized, the other has the typical characteristics of An. arabiensis as found elsewhere in Africa. The extent of genetic variation in these forms was examined in widely separated locations in Sudan, including Kassala, Gedaref and the Northern States between 1998 and 1999 and 2004 and 2006. METHODS: Each mosquito specimen was identified using standard morphological keys and a species-specific PCR test. Sequence variation in a 660 bp fragment of the mtDNA ND5 coding region was examined and the extent of genetic divergence between the forms was estimated from FST values using DNASP version 4.9. TCS 1.13 software was used to determine the genealogical relationships and to reflect clustering among mtDNA haplotypes. RESULTS: The melanic and normal forms were found in sympatry in Kassala, Gedaref and Khartoum states, with the melanic form commonest in the hottest and most arid areas. Both forms were encountered in the periods of study: 1998-1999, and 2004-2006. Only ten specimens of An. arabiensis were collected from the Northern State in February 2006, all of which were of the normal form.Based on the ND5 analysis, there was a marked subdivision between the normal and melanic forms (FST?=?0.59). Furthermore, the melanic form showed more genetic variability, as measured by haplotype diversity (0.95) compared with the normal form (0.57), suggesting larger effective population. CONCLUSIONS: This is the first demonstration of correspondent phenotypic and genetic structuring in An. arabiensis. The high level of genetic differentiation shown by the mtDNA ND5 locus suggests that the two forms may represent separate species. It is hypothesized that the melanic form is better adapted to hot and arid environments.

Project description:BackgroundMalaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya.MethodsThe study was carried out in 2018-2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area.ResultsAnopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8-84% to 83.3-78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1-16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection.ConclusionAnopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.

Project description:Malaria transmission is dependent on the propensity of Anopheles mosquitoes to bite humans (anthropophily) instead of other dead end hosts. Recent increases in the usage of Long Lasting Insecticide Treated Nets (LLINs) in Africa have been associated with reductions in highly anthropophilic and endophilic vectors such as Anopheles gambiae s.s., leaving species with a broader host range, such as Anopheles arabiensis, as the most prominent remaining source of transmission in many settings. An. arabiensis appears to be more of a generalist in terms of its host choice and resting behavior, which may be due to phenotypic plasticity and/or segregating allelic variation. To investigate the genetic basis of host choice and resting behavior in An. arabiensis we sequenced the genomes of 23 human-fed and 25 cattle-fed mosquitoes collected both in-doors and out-doors in the Kilombero Valley, Tanzania. We identified a total of 4,820,851 SNPs, which were used to conduct the first genome-wide estimates of "SNP heritability" for host choice and resting behavior in this species. A genetic component was detected for host choice (human vs cow fed; permuted P = 0.002), but there was no evidence of a genetic component for resting behavior (indoors versus outside; permuted P = 0.465). A principal component analysis (PCA) segregated individuals based on genomic variation into three groups which were characterized by differences at the 2Rb and/or 3Ra paracentromeric chromosome inversions. There was a non-random distribution of cattle-fed mosquitoes between the PCA clusters, suggesting that alleles linked to the 2Rb and/or 3Ra inversions may influence host choice. Using a novel inversion genotyping assay, we detected a significant enrichment of the standard arrangement (non-inverted) of 3Ra among cattle-fed mosquitoes (N = 129) versus all non-cattle-fed individuals (N = 234; χ2, p = 0.007). Thus, tracking the frequency of the 3Ra in An. arabiensis populations may be of use to infer selection on host choice behavior within these vector populations; possibly in response to vector control. Controlled host-choice assays are needed to discern whether the observed genetic component has a direct relationship with innate host preference. A better understanding of the genetic basis for host feeding behavior in An. arabiensis may also open avenues for novel vector control strategies based on driving genes for zoophily into wild mosquito populations.

Dataset Information

Optimization of odour-baited resting boxes for sampling malaria vector, Anopheles arabiensis Patton, in arid and highland areas of Africa.

Background

Method

Results

Conclusions

Publications

Optimization of odour-baited resting boxes for sampling malaria vector, Anopheles arabiensis Patton, in arid and highland areas of Africa.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets