scholarly journals Quantifying flight aptitude variation in wild A. gambiae s.l. in order to identify long-distance migrants

2020 ◽  
Author(s):  
Roy Faiman ◽  
Alpha Seydou YARO ◽  
Moussa Diallo ◽  
Adama Dao ◽  
Djibril Samake ◽  
...  
Keyword(s):  
Sensu Stricto ◽  
Flight Activity ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Wing Size ◽  
Wet Season ◽  
Long Distance ◽  
Flight Duration ◽  
Tethered Flight ◽  
Gravid Females

Abstract Background In the West African Sahel, mosquito reproduction is halted during the 5-7 month-long dry season, due to the absence of surface waters required for larval development. However, recent studies have suggested that both Anopheles gambiae sensu stricto (s.s.) and Anopheles arabiensis repopulate this region via migration from distant locations where larval sites are perennial. Anopheles coluzzii engages in more regional migration, presumably within the Sahel, following shifting resources correlating with the ever-changing patterns of Sahelian rainfall. Understanding mosquito migration is key to controlling malaria—a disease that continues to claim more than 400,000 lives annually, especially those of African children. Using tethered flight data of wild mosquitoes, the distribution of flight parameters were evaluated as indicators of long-range migrants versus appetitive flyers, and the species specific seasonal differences and gonotrophic states compared between two flight activity modalities. Morphometrical differences were evaluated in the wings of mosquitoes exhibiting high flight activity (HFA) vs. low flight activity (LFA).Methods A novel tethered-flight assay was used to characterize flight in the three primary malaria vectors- An. arabiensis, An. coluzzii and An. gambiae s.s. The flights of tethered wild mosquitoes were audio-recorded from 21:00h to 05:00h in the following morning and three flight aptitude indices were examined: total flight duration, longest flight bout, and the number of flight bouts during the assay.Results The distributions of all flight indices were strongly skewed to the right, indicating that the population consisted of a majority of low-flight activity (LFA) mosquitoes and a minority of high-flight activity (HFA) mosquitoes. The median total flight was 586 seconds and the maximum value was 16,110 seconds (~4.5 h). In accordance with recent results, flight aptitude peaked in the wet season, and was higher in gravid females than in non-blood-fed females. Flight aptitude was also found to be higher in An. coluzzii compared to An. arabiensis, with intermediate values in An. gambiae s.s., but displaying no statistical difference. Evaluating differences in wing size and shape between LFA individuals and HFA ones, the wing size of HFA An. coluzzii was larger than that of LFAs during the wet season—its length was wider than predicted by allometry alone, indicating a change in wing shape. No statistically significant differences were found in the wing size/shape of An. gambiae s.s. or An. arabiensis.Conclusions The partial agreement between the tethered flight results and recent results based on aerial sampling of these species suggest a degree of discrimination between appetitive flyers and long-distance migrants although identifying HFAs as long-distance migrants is not recommended without further investigation.

scholarly journals Quantifying flight aptitude variation in wild An. gambiae s.l. in order to identify long-distance migrants

2020 ◽  
Author(s):  
Roy Faiman ◽  
Alpha Seydou YARO ◽  
Moussa Diallo ◽  
Adama Dao ◽  
Djibril Samake ◽  
...  
Keyword(s):  
Flight Activity ◽  
Malaria Vectors ◽  
Wing Size ◽  
Wet Season ◽  
Long Distance ◽  
Flight Duration ◽  
Tethered Flight ◽  
Gravid Females ◽  
Species Specific ◽  
The Right

Abstract Background In the West African Sahel, mosquito reproduction is halted during the 5-7 month-long dry season, due to the absence of surface waters required for larval development. However, recent studies have suggested that both Anopheles gambiae s.s and An. arabiensis repopulate this region via migration from distant locations where larval sites are perennial. An. coluzzii engages in more regional migration, presumably within the Sahel, following shifting resources correlating with the ever-changing patterns of Sahelian rainfall. Understanding mosquito migration is key to controlling malaria—a disease that continues to claim more than 400,000 lives annually, especially those of African children. Using tethered flight data of wild mosquitoes, we evaluated the distribution of flight parameters as indicators of long-range migrants vs. appetitive flyers, compared species specific seasonal differences and gonotrophic states on flight activity. We also evaluated morphometrical differences in the wings of mosquitoes exhibiting high flight activity (HFA) vs. low flight activity (LFA). Methods We used a novel tethered-flight assay to characterize flight in the three primary malaria vectors- An. arabiensis, An. coluzzii and An. gambiae s.s. The flights of tethered wild mosquitoes were audio-recorded from 21:00h to 05:00h in the following morning and three flight aptitude indices were examined: total flight duration, longest flight bout, and the number of flight bouts during the assay. Results The distributions of all flight indices were strongly skewed to the right, indicating that the population consisted of a majority of low-flight activity (LFA) mosquitoes and a minority of high-flight activity (HFA) mosquitoes. The median total flight was 586 seconds and the maximum value was 16,110 seconds (~4.5 h). In accordance with recent results, flight aptitude peaked in the wet season, and was higher in gravid females than in non-bloodfed females. Flight aptitude was also found to be higher in An. coluzzii compared to An. arabiensis, with intermediate values in An. gambiae s.s., but displaying no statistical difference. Evaluating differences in wing size and shape between LFA individuals and HFA ones, the wing size of HFA An. coluzzii was larger than that of LFAs during the wet season—its length was wider than predicted by allometry alone, indicating a change in wing shape. No statistically significant differences were found in the wing size/shape of An. gambiae s.s. or An. arabiensis. Conclusions The partial agreement between the tethered flight results and recent results based on aerial sampling of these species suggest a degree of discrimination between appetitive flyers and long-distance migrants although identifying HFAs as long-distance migrants is not recommended without further investigation.

scholarly journals Quantifying flight aptitude variation in wild A. gambiae s.l. in order to identify long-distance migrants

2020 ◽  
Author(s):  
Roy Faiman ◽  
Alpha Seydou YARO ◽  
Moussa Diallo ◽  
Adama Dao ◽  
Djibril Samake ◽  
...  
Keyword(s):  
Shape Change ◽  
Flight Activity ◽  
Malaria Vectors ◽  
Wing Size ◽  
Wet Season ◽  
Anopheles Gambiae S.S ◽  
Long Distance ◽  
Flight Duration ◽  
Size And Shape ◽  
Gravid Females

Abstract Background In the West African Sahel, during the 5-7 month-long dry season mosquito reproduction is halted due to the absence of surface waters required for larval development. Recent studies have suggested that both Anopheles gambiae s.s and A. arabiensis persist in this region by migration from distant locations where larval sites are perennial, and A. coluzzii engages in long-distance migration, presumably within the Sahel, following shifting resources due to the ever-changing patterns of Sahelian rainfall. Understanding mosquito migration is key to malaria control, a disease that still kills >400,000 people, mostly children in Africa. Methods We used a new tethered-flight assay to characterize flight in the three primary malaria vectors mentioned above and evaluated seasonal differences in their flight activity. The flight of tethered wild mosquitoes was audio-recorded from 21:00h to 05:00h in the following morning and three flight aptitude indices were examined: total flight duration, longest flight bout, and the number of flight bouts during the assay. Based on recent studies, we predicted that (i) the distribution of the flight aptitude indices would exhibit bi-modality and/or marked skewness, indicating a subpopulation of high flight activity (HFA) associated with long-distance migrants, in contrast to low flight activity (LFA) in appetitive flyers. Additionally, flight aptitude would (ii) increase in the wet season, (iii) increase in gravid females, and (iv) vary among the vector species. ResultsThe distributions of all flight indices departed sharply from a normal curve, and were strongly skewed to the right, consistent with the division of the population into a majority of LFAs and a minority of HFAs, e.g., the median total flight was 586 seconds, and its maximum value was 16,110 seconds (~4.5 h). As predicted, flight aptitude peaked in the wet season and was higher in gravid females than in non-bloodfed females. Flight aptitude was higher in A. coluzzii than in A. arabiensis, but A. gambiae s.s. was not statistically different from either. We evaluated differences in wing size and shape between LFAs and HFAs. During the wet season, wing size of HFA A. coluzzii was larger than that of LFAs; it was wider than predicted by its length, indicating a shape change. However, no statistically significant differences were found in wings of A. gambiae s.s. or A. arabiensis. ConclusionsThe partial agreement between the assay results and predictions suggest a degree of discrimination between appetitive flyers and long-distance migrants. Wing size and shape seems to indicate higher flight activity in A. coluzzii during the wet season.

scholarly journals Quantifying flight aptitude variation in wild A. gambiae s.l. in order to identify long-distance migrants

2020 ◽  
Author(s):  
Roy Faiman ◽  
Alpha S. Yaro ◽  
Moussa Diallo ◽  
Adama Dao ◽  
Samake Djibril ◽  
...  
Keyword(s):  
Shape Change ◽  
Flight Activity ◽  
Malaria Vectors ◽  
Wing Size ◽  
Wet Season ◽  
Long Distance ◽  
Flight Duration ◽  
Size And Shape ◽  
Gravid Females ◽  
The Right

AbstractBackgroundIn the West African Sahel, during the 5-7 month-long dry season mosquito reproduction is halted due to the absence of surface waters required for larval development. Recent studies have suggested that both Anopheles gambiae s.s and A. arabiensis persist in this region by migration from distant locations where larval sites are perennial, and A. coluzzii engages in long-distance migration, presumably within the Sahel, following shifting resources due to the ever-changing patterns of Sahelian rainfall. Understanding mosquito migration is key to malaria control, a disease that still kills >400,000 people, mostly children in Africa.MethodsWe used a new tethered-flight assay to characterize flight in the three primary malaria vectors mentioned above and evaluated seasonal differences in their flight activity. The flight of tethered wild mosquitoes was audio-recorded from 21:00h to 05:00h in the following morning and three flight aptitude indices were examined: total flight duration, longest flight bout, and the number of flight bouts during the assay. Based on recent studies, we predicted that (i) the distribution of the flight aptitude indices would exhibit bi-modality and/or marked skewness, indicating a subpopulation of high flight activity (HFA) associated with long-distance migrants, in contrast to low flight activity (LFA) in appetitive flyers. Additionally, flight aptitude would (ii) increase in the wet season, (iii) increase in gravid females, and (iv) vary among the vector species.ResultsThe distributions of all flight indices departed sharply from a normal curve, and were strongly skewed to the right, consistent with the division of the population into a majority of LFAs and a minority of HFAs, e.g., the median total flight was 586 seconds, and its maximum value was 16,110 seconds (~4.5 h). As predicted, flight aptitude peaked in the wet season and was higher in gravid females than in non-bloodfed females. Flight aptitude was higher in A. coluzzii than in A. arabiensis, but A. gambiae s.s. was not statistically different from either. We evaluated differences in wing size and shape between LFAs and HFAs. During the wet season, wing size of HFA A. coluzzii was larger than that of LFAs; it was wider than predicted by its length, indicating a shape change. However, no statistically significant differences were found in wings of A. gambiae s.s. or A. arabiensis.ConclusionsThe partial agreement between the assay results and predictions suggest a degree of discrimination between appetitive flyers and long-distance migrants. Wing size and shape seems to indicate higher flight activity in A. coluzzii during the wet season.

Influence of geographical location on abundance assortment of Anopheles mosquito species (Diptera: Culicidae) on malaria parasite rate in Enugu State, Nigeria

2021 ◽  
Vol 42 (1) ◽  
pp. 31-40
Author(s):  
G.I. Ngwu ◽  
F.C. Okafor ◽  
J.E. Eyo ◽  
M.I. Ngwu
Keyword(s):  
Malaria Parasite ◽  
Mosquito Species ◽  
Geographical Location ◽  
Sensu Stricto ◽  
Anopheles Mosquito ◽  
Malaria Vectors ◽  
Malaria Control Programme ◽  
Anopheles Coluzzii ◽  
Anopheles Gambiae S.S ◽  
Enugu State

Assessment of geographical distribution of malaria vectors is essential to effective malaria parasite control. This study evaluated the influence of geographical locations on distribution of Anopheles mosquito species and malaria parasite vectorial efficacy in Enugu State, Nigeria. Mosquitoes were collected, using indoor resting pyrethrum spray collection (IRPSC) method. They were morphologically identified and molecularly (PCR) characterised. The M form (now called Anopheles coluzzii) and S form (now called nominotypical Anopheles gambiae s.s.), were identified using Restriction Fragment Length Polymorphism (RFLP). Plasmodium falciparum sporozoite rates of sampled mosquitoes and malaria status of households were evaluated microscopically and by using rapid diagnostic kits. An. gambiae Giles (sensu stricto), and bands resembling An. melas and An. arabiensisspecies complexes were observed. Out of 300 An. gambiae s.l. identified using PCR, 243 were An. gambiae Giles (sensu stricto), 6 were An. melas and 5 were An. arabiensis. Out of the 243 An. gambiae Giles (sensu stricto), 184 were M form (now An. coluzzii) and 59 were S form (now nominotypical An. gambiae s.s).The M form (now An. coluzzii) constituted 99% of Anopheles mosquitoes from southernmost part of the study area while northernmost part showed 100% S form (An. gambiae s.s.). The median location had the M form (An. coluzzii) and S form (An. gambiae s.s.) in  sympatric. Sporozoite rate in northernmost area was highest when compared with median and southernmost parts. The S form (An. gambiae s.s.) was observed as more important malaria parasite vector, and the results revealed that geographical location affected species diversities which is an important consideration for malaria control  programme. Keywords: Anopheles, distribution, sporozoite, malaria parasite

Some Factors Affecting Flight Activity in Individual Milkweed Bugs (Oncopeltus)

1966 ◽  
Vol 44 (2) ◽  
pp. 335-343
Author(s):  
HUGH DINGLE
Keyword(s):  
Total Duration ◽  
Flight Activity ◽  
Peak Activity ◽  
Growth Rings ◽  
Peak Period ◽  
Flight Duration ◽  
Factors Affecting ◽  
Continuous Contact ◽  
Tethered Flight ◽  
Opposite Sex

1. Individual adults of Oncopeltus were tested repeatedly at 2- or 3-day intervals, using tethered flight, to determine the amount of flight activity as measured by flight duration. 2. The peak period of activity occurred 8 days after the final moult with later flights scattered and showing no concentration at a particular age. Deposition of cuticular growth rings ceased at about 7 days; the peak activity was thus post-teneral and probably represents migration. 3. Only 23.8% of bugs tested showed flights of over 30 min. Those bugs which flew for long periods at 8 days were more likely to show long flights at a later age than were bugs which did not fly at day 8. There thus seems to be a behavioural polymorphism with distinct ‘flyers’ and ‘non-flyers’. 4. More females, 30.7%, than males, 18.1%, exhibited flights of over 30 minutes. Males which did have such long flights were, however, more likely than females to have them repeatedly. 5. In both sexes virgins seemed to be more active in respect of long flights than bugs allowed continuous contact with the opposite sex. 6. Calculations based on estimates of flight speed and total duration of flight indicate that an individual migrant Oncopeltus is capable of covering a considerable distance, 100 kilometres or more, during its lifetime.

scholarly journals Evidence for Divergent Selection on Immune Genes between the African Malaria Vectors, Anopheles coluzzii and A. gambiae

Insects ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 893
Author(s):  
Yoosook Lee ◽  
Lattha Souvannaseng ◽  
Travis C. Collier ◽  
Bradley J. Main ◽  
Laura C. Norris ◽  
...  
Keyword(s):  
Permutation Test ◽  
Wide Distribution ◽  
Sensu Stricto ◽  
Life Cycles ◽  
Malaria Vectors ◽  
Immune Gene ◽  
Anopheles Coluzzii ◽  
Potential Force ◽  
Larval Habitats ◽  
Immune Genes

During their life cycles, microbes infecting mosquitoes encounter components of the mosquito anti-microbial innate immune defenses. Many of these immune responses also mediate susceptibility to malaria parasite infection. In West Africa, the primary malaria vectors are Anopheles coluzzii and A. gambiae sensu stricto, which is subdivided into the Bamako and Savanna sub-taxa. Here, we performed whole genome comparisons of the three taxa as well as genotyping of 333 putatively functional SNPs located in 58 immune signaling genes. Genome data support significantly higher differentiation in immune genes compared with a randomly selected set of non-immune genes among the three taxa (permutation test p < 0.001). Among the 58 genes studied, the majority had one or more segregating mutations (72.9%) that were significantly diverged among the three taxa. Genes detected to be under selection include MAP2K4 and Raf. Despite the genome-wide distribution of immune genes, a high level of linkage disequilibrium (r2 > 0.8) was detected in over 27% of SNP pairs. We discuss the potential role of immune gene divergence as adaptations to the different larval habitats associated with A. gambiae taxa and as a potential force driving ecological speciation in this group of mosquitoes.

Flight performance of Macdunnoughia crassisigna (Lepidoptera: Noctuidae)

2017 ◽  
Vol 107 (6) ◽  
pp. 715-723 ◽  
Author(s):  
X.-W. Fu ◽  
H. Chang ◽  
L.-M. He ◽  
S.-Y. Zhao ◽  
K.-M. Wu
Keyword(s):  
Abiotic Factors ◽  
Flight Activity ◽  
Pest Species ◽  
Flight Performance ◽  
Long Distance ◽  
Flight Duration ◽  
Flight Mills ◽  
Different Temperatures ◽  
Flight Parameters ◽  
Lepidoptera Noctuidae

AbstractMacdunnoughia crassisigna Warren (Lepidoptera: Noctuidae) is a highly destructive herbivore that poses a serious risk to cotton, maize, soybean, and cruciferous vegetables in East Asia. Examining the effects of various biotic and abiotic factors on the flight performance of M. crassisigna is crucial for a better understanding of its trans-regional migration. In this study, the flight activity of M. crassisignai moths of different ages, under different temperatures and relative humidity (RH) levels, was evaluated by tethering individuals to computerized flight mills for a 24-h trial period. The results showed that M. crassisignai had the capacity for sustained flight and the flight ability was strongest in 3-day-old individuals, and then their flight performance decreased significantly in older moths. For both sexes, temperature had a significant effect on their flight performance, and the flight activity was relatively higher at 24–28°C than other temperatures. There was a significant effect of RH on all flight parameters of the tested moths, and the flight activity was relatively higher at RH of 60–75% than other RH levels. For 3-day-old moths under the optimum conditions (24°C and 75% RH) throughout the 24 h scotophase, their mean flight distance reached 66 km, and the mean flight duration reached 13.5 h, suggesting M. crassisigna possess strong potential to undertake long-distance migration. These findings will be helpful for developing sound forecasting systems of this pest species.

scholarly journals Juvenile hormone regulation on the flight capability of Bactrocera dorsalis (Diptera: Tephritidae)

2019 ◽  
Author(s):  
Peng Chen ◽  
Min Chen ◽  
Hui Ye ◽  
Ruiling Yuan ◽  
Chunhua Du ◽  
...  
Keyword(s):  
Juvenile Hormone ◽  
Fruit Fly ◽  
Flight Activity ◽  
Bactrocera Dorsalis ◽  
Hormone Regulation ◽  
Long Distance ◽  
Physiological Basis ◽  
Flight Duration ◽  
Flight Mills ◽  
Old Adult

AbstractThe oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is considered a major economic threat in many regions worldwide. In order to better understand the flight capacity of B. dorsalis and its physiological basis, the functions and regulatory roles of juvenile hormone (JH) in the flight muscle of B. dorsalis were studied under a controlled environment. JH titer of B. dorsalis varied with age and sex. Females, irrespective of age, have higher JH than males for ovarian development and maturation in addition to better flight capabilities. The flight duration and distance of both males and females increased with the gradual increase of JH titer after adult emergences. JH titer peaked in 15-d-old adult and declined subsequently with age. Flight activity stimulated the production of JH as adults flown for 24 hours on the flight mills have the highest JH titers compare to adults tethered on shorter flight durations. Furthermore, JH III-treated adults were able to perform long-duration and long-distance flights. The mutual reinforcement of JH and flight activity provides fundamental understanding on the physiological aspects of the flight capability and dispersal, which facilitates strategies for the long-term control of this destructive pest.

scholarly journals Laboratory and microcosm experiments reveal contrasted adaptive responses to ammonia and water mineralisation in aquatic stages of the sibling species Anopheles gambiae (sensu stricto) and Anopheles coluzzii

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Nwamaka Oluchukwu Akpodiete ◽  
Frédéric Tripet
Keyword(s):  
West Africa ◽  
Anopheles Gambiae ◽  
Emerging Adults ◽  
Sibling Species ◽  
Adult Emergence ◽  
Ecological Speciation ◽  
Sensu Stricto ◽  
Rice Fields ◽  
Anopheles Coluzzii ◽  
Phenotypic Quality

Abstract Background The sibling species of the malaria mosquito, Anopheles gambiae (sensu stricto) and Anopheles coluzzii co-exist in many parts of West Africa and are thought to have recently diverged through a process of ecological speciation with gene flow. Divergent larval ecological adaptations, resulting in Genotype-by-Environment (G × E) interactions, have been proposed as important drivers of speciation in these species. In West Africa, An. coluzzii tends to be associated with permanent man-made larval habitats such as irrigated rice fields, which are typically more eutrophic and mineral and ammonia-rich than the temporary rain pools exploited by An. gambiae (s.s.) Methods To highlight G × E interactions at the larval stage and their possible role in ecological speciation of these species, we first investigated the effect of exposure to ammonium hydroxide and water mineralisation on larval developmental success. Mosquito larvae were exposed to two water sources and increasing ammonia concentrations in small containers until adult emergence. In a second experiment, larval developmental success was compared across two contrasted microcosms to highlight G × E interactions under conditions such as those found in the natural environment. Results The first experiment revealed significant G × E interactions in developmental success and phenotypic quality for both species in response to increasing ammonia concentrations and water mineralisation. The An. coluzzii strain outperformed the An. gambiae (s.s.) strain under limited conditions that were closer to more eutrophic habitats. The second experiment revealed divergent crisscrossing reaction norms in the developmental success of the sibling species in the two contrasted larval environments. As expected, An. coluzzii had higher emergence rates in the rice paddy environment with emerging adults of superior phenotypic quality compared to An. gambiae (s.s.), and vice versa, in the rain puddle environment. Conclusions Evidence for such G × E interactions lends support to the hypothesis that divergent larval adaptations to the environmental conditions found in man-made habitats such as rice fields in An. coluzzii may have been an important driver of its ecological speciation.

scholarly journals Anopheles gambiae Genome Conservation as a Resource for Rational Gene Drive Target Site Selection

Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 97
Author(s):  
Nace Kranjc ◽  
Andrea Crisanti ◽  
Tony Nolan ◽  
Federica Bernardini
Keyword(s):  
Anopheles Gambiae ◽  
Data Storage ◽  
Genomic Variation ◽  
Malaria Vectors ◽  
Anopheles Coluzzii ◽  
Structural Constraints ◽  
Gene Drive ◽  
Genetic Traits ◽  
A Genome ◽  
Insight Into

The increase in molecular tools for the genetic engineering of insect pests and disease vectors, such as Anopheles mosquitoes that transmit malaria, has led to an unprecedented investigation of the genomic landscape of these organisms. The understanding of genome variability in wild mosquito populations is of primary importance for vector control strategies. This is particularly the case for gene drive systems, which look to introduce genetic traits into a population by targeting specific genomic regions. Gene drive targets with functional or structural constraints are highly desirable as they are less likely to tolerate mutations that prevent targeting by the gene drive and consequent failure of the technology. In this study we describe a bioinformatic pipeline that allows the analysis of whole genome data for the identification of highly conserved regions that can point at potential functional or structural constraints. The analysis was conducted across the genomes of 22 insect species separated by more than hundred million years of evolution and includes the observed genomic variation within field caught samples of Anopheles gambiae and Anopheles coluzzii, the two most dominant malaria vectors. This study offers insight into the level of conservation at a genome-wide scale as well as at per base-pair resolution. The results of this analysis are gathered in a data storage system that allows for flexible extraction and bioinformatic manipulation. Furthermore, it represents a valuable resource that could provide insight into population structure and dynamics of the species in the complex and benefit the development and implementation of genetic strategies to tackle malaria.

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