scholarly journals Bulk-up Synchronisation of Successive Larval Cohorts of Anopheles Gambiae Sensu Stricto and Anopheles Coluzzii Through Temperature Reduction at Early Larval Stages: Effect on Emergence Rates, Body Size and Mating Success

2020 ◽  
Author(s):  
Qaswa Zubair ◽  
Holly Matthews ◽  
Seynabou Sougoufara ◽  
Fatima Mujeeb ◽  
Simon Ashall ◽  
...  
Keyword(s):  
Body Size ◽  
Mating Success ◽  
Mass Rearing ◽  
Sensu Stricto ◽  
Alternative Methods ◽  
Mosquito Vector ◽  
Anopheles Coluzzii ◽  
Simple Method ◽  
Cooling Period ◽  
Larval Stages

Abstract Background: Malaria persists as a huge medical and economic burden. Although the number of cases and death rates have reduced in recent years, novel interventions are a necessity if such gains are to be maintained. Alternative methods to target mosquito vector populations that involve the release of large numbers genetically modified mosquitoes are in development. However, their successful introduction will require innovative strategies to bulk-up mosquito numbers and improve mass rearing protocols for Anopheles mosquitoes.Methods: Here we aimed to exploit the relationship between mosquito aquatic stage development and temperature so that multiple cohorts of mosquitoes, from separate egg batches, could be synchronised for a ‘bulk-up’ of the number of mosquitoes released. First instar larvae were separated into two cohorts: the first, maintained under standard insectary conditions at 27oC, the second subjected to an initial 5-day cooling period at 19oC. Results: Cooling of 1st instars slowed the mean emergence times of An. coluzzii and An. gambiae by 2.4 and 3.5 days, respectively, compared to their 27oC counterparts. Pupation and emergence rates were good (> 85%) in all conditions. Temperature adjustment had no effect on mosquito sex ratio and adult fitness parameters such as body size and mating success were also comparable with the control cohort. Conclusions: Bulk-up larval synchronization is a simple method allowing more operational flexibility in mosquito production towards mark-release-recapture studies and mass release interventions.

scholarly journals Bulk-up synchronisation of successive larval cohorts of Anopheles gambiae sensu stricto and Anopheles coluzzii through temperature reduction at early larval stages: effect on emergence rates, body size and mating success

2021 ◽  
Author(s):  
Qaswa Zubair ◽  
Holly Matthews ◽  
Seynabou Sougoufara ◽  
Fatima Mujeeb ◽  
Simon Ashall ◽  
...  
Keyword(s):  
Body Size ◽  
Mating Success ◽  
Mass Rearing ◽  
Sensu Stricto ◽  
Alternative Methods ◽  
Mosquito Vector ◽  
Anopheles Coluzzii ◽  
Simple Method ◽  
Cooling Period ◽  
Larval Stages

Abstract Background: Malaria persists as a huge medical and economic burden. Although the number of cases and death rates have reduced in recent years, novel interventions are a necessity if such gains are to be maintained. Alternative methods to target mosquito vector populations that involve the release of large numbers genetically modified mosquitoes are in development. However, their successful introduction will require innovative strategies to bulk-up mosquito numbers and improve mass rearing protocols for Anopheles mosquitoes. Methods: Here we aimed to exploit the relationship between mosquito aquatic stage development and temperature so that multiple cohorts of mosquitoes, from separate egg batches, could be synchronised for a ‘bulk-up’ of the number of mosquitoes released. First instar larvae were separated into two cohorts: the first, maintained under standard insectary conditions at 27 o C, the second subjected to an initial 5-day cooling period at 19 o C. Results: Cooling of 1 st instars slowed the mean emergence times of An. coluzzii and An. gambiae by 2.4 and 3.5 days, respectively, compared to their 27 o C counterparts. Pupation and emergence rates were good (> 85%) in all conditions. Temperature adjustment had no effect on mosquito sex ratio and adult fitness parameters such as body size and mating success were also comparable with the control cohort. Conclusions: Bulk-up larval synchronization is a simple method allowing more operational flexibility in mosquito production towards mark-release-recapture studies and mass release interventions.

scholarly journals Bulk‐up synchronization of successive larval cohorts of Anopheles gambiae and Anopheles coluzzii through temperature reduction at early larval stages: effect on emergence rate, body size and mating success

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Qaswa Zubair ◽  
Holly Matthews ◽  
Seynabou Sougoufara ◽  
Fatima Mujeeb ◽  
Simon Ashall ◽  
...  
Keyword(s):  
Body Size ◽  
Anopheles Gambiae ◽  
Mating Success ◽  
Mass Rearing ◽  
Alternative Methods ◽  
Mosquito Vector ◽  
Anopheles Coluzzii ◽  
Simple Method ◽  
Cooling Period ◽  
Larval Stages

Abstract Background Malaria persists as a huge medical and economic burden. Although the number of cases and death rates have reduced in recent years, novel interventions are a necessity if such gains are to be maintained. Alternative methods to target mosquito vector populations that involve the release of large numbers genetically modified mosquitoes are in development. However, their successful introduction will require innovative strategies to bulk-up mosquito numbers and improve mass rearing protocols for Anopheles mosquitoes. Methods The relationship between mosquito aquatic stage development and temperature was exploited so that multiple cohorts of mosquitoes, from separate egg batches, could be synchronized to ‘bulk-up’ the number of mosquitoes released. First instar larvae were separated into two cohorts: the first, maintained under standard insectary conditions at 27oC, the second subjected to an initial 5-day cooling period at 19oC. Results Cooling of 1st instars slowed the mean emergence times of Anopheles coluzzii and Anopheles gambiae by 2.4 and 3.5 days, respectively, compared to their 27oC counterparts. Pupation and emergence rates were good (> 85 %) in all conditions. Temperature adjustment had no effect on mosquito sex ratio and adult fitness parameters such as body size and mating success. Conclusions Bulk-up larval synchronization is a simple method allowing more operational flexibility in mosquito production towards mark-release-recapture studies and mass release interventions.

scholarly journals Bulk-up synchronization of successive larval cohorts of Anopheles gambiae and Anopheles coluzzii through temperature reduction at early larval stages: effect on emergence rates, body size and mating successss

2021 ◽  
Author(s):  
Qaswa Zubair ◽  
Holly Matthews ◽  
Seynabou Sougoufara ◽  
Fatima Mujeeb ◽  
Simon Ashall ◽  
...  
Keyword(s):  
Body Size ◽  
Anopheles Gambiae ◽  
Mass Rearing ◽  
Alternative Methods ◽  
Mosquito Vector ◽  
Anopheles Coluzzii ◽  
Simple Method ◽  
Cooling Period ◽  
Larval Stages ◽  
Fitness Parameters

Abstract Background Malaria persists as a huge medical and economic burden. Although the number of cases and death rates have reduced in recent years, novel interventions are a necessity if such gains are to be maintained. Alternative methods to target mosquito vector populations that involve the release of large numbers genetically modified mosquitoes are in development. However, their successful introduction will require innovative strategies to bulk-up mosquito numbers and improve mass rearing protocols for Anopheles mosquitoes.Methods The relationship between mosquito aquatic stage development and temperature was exploited so that multiple cohorts of mosquitoes, from separate egg batches, could be synchronized to ‘bulk-up’ the number of mosquitoes released. First instar larvae were separated into two cohorts: the first, maintained under standard insectary conditions at 27oC, the second subjected to an initial 5-day cooling period at 19oC. Results Cooling of 1st instars slowed the mean emergence times of Anopheles coluzzii and Anopheles gambiae by 2.4 and 3.5 days, respectively, compared to their 27oC counterparts. Pupation and emergence rates were good (> 85%) in all conditions. Temperature adjustment had no effect on mosquito sex ratio and adult fitness parameters such as body size and mating success were also comparable with the control cohort. Conclusions Bulk-up larval synchronization is a simple method allowing more operational flexibility in mosquito production towards mark-release-recapture studies and mass release interventions.

scholarly journals Local adaptation and colonization are potential factors affecting sexual competitiveness and mating choice in Anopheles coluzzii populations

2022 ◽  
Vol 12 (1) ◽  
Author(s):  
Charles Nignan ◽  
Bèwadéyir Serge Poda ◽  
Simon Péguédwindé Sawadogo ◽  
Hamidou Maïga ◽  
Kounbobr Roch Dabiré ◽  
...  
Keyword(s):  
Local Adaptation ◽  
Mating Success ◽  
Mating Behaviour ◽  
Mass Rearing ◽  
Anopheles Coluzzii ◽  
Extrinsic Factors ◽  
Factors Affecting ◽  
Reproduction Biology ◽  
Potential Factors ◽  
Mating Choice

AbstractThe mating behaviour of the malaria vector Anopheles gambiae complex is an important aspect of its reproduction biology. The success of mosquito release programmes based on genetic control of malaria crucially depends on competitive mating between both laboratory-reared and wild individuals, and populations from different localities. It is known that intrinsic and extrinsic factors can influence the mating success. This study addressed some of the knowledge gaps about factors influcencing mosquito mating success. In semi-field conditions, the study compared the mating success of three laboratory-reared and wild allopatric An. coluzzii populations originating from ecologically different locations in Burkina Faso. Overall, it was found that colonization reduced the mating competitiveness of both males and females compared to that of wild type individuals. More importly, females were more likely to mate with males of their own population of origin, be it wild or colonised, suggesting that local adaptation affected mate choice. The observations of mating behaviour of colonized and local wild populations revealed that subtle differences in behaviour lead to significant levels of population-specific mating. This is the first study to highlight the importance of local adaptation in the mating success, thereby highlighting the importance of using local strains for mass-rearing and release of An. coluzzii in vector control programmes.

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 Immunohistopathological response against anisakid nematode larvae and a coccidian in Micromesistius poutassou from NE Atlantic waters

2021 ◽  
Vol 95 ◽  
Author(s):  
B. Sayyaf Dezfuli ◽  
E. Simoni ◽  
G. Bosi ◽  
M. Palomba ◽  
S. Mattiucci ◽  
...  
Keyword(s):  
Sensu Stricto ◽  
Cell Swelling ◽  
Epithelioid Cells ◽  
Larval Stages ◽  
The North ◽  
Eastern Atlantic Ocean ◽  
Larval Infection ◽  
High Infection ◽  
North Eastern ◽  
Multilocus Approach

Abstract A survey on Anisakis simplex (sensu stricto (s.s.)) from blue whiting, Micromesistius poutassou, in the north-eastern Atlantic Ocean revealed the occurrence of high infection levels of third larval stages in visceral organs and flesh. Larvae were genetically identified with a multilocus approach as A. simplex (s.s.). Histochemical, immunohistochemical and ultrastructural observations were conducted on 30 M. poutassou specimens. Gonads, pyloric caeca and flesh harboured encapsulated larvae of A. simplex (s.s.) but no intense host reaction was encountered around the parasite in the above organs. In the liver, the most infected organ, the larvae co-occurred with the coccidian Goussia sp. Within the granuloma around the A. simplex (s.s.) larvae, two concentric layers were recognized, an inner mostly comprising electron-dense epithelioid cells and an outer layer made of less electron-dense epithelioid cells. Macrophages and macrophage aggregates (MAs) were abundant out of the granulomas, scattered in parenchyma, and inside the MAs, the presence of engulfed Goussia sp. was frequent. In liver tissue co-infected with Goussia sp. and A. simplex (s.s.), hepatocytes showed cytoplasmic rarefaction and acute cell swelling. Results suggest that the host-induced encapsulation of A. simplex (s.s.) larvae is a strategic compromise to minimize collateral tissue damage around the larval infection sites, to facilitate the survival of both parasite and host.

Body size and lifetime mating success of male midges (Diptera: Chironomidae)

1990 ◽  
Vol 40 (4) ◽  
pp. 648-652 ◽  
Author(s):  
R.M. Neems ◽  
A.J. McLachlan ◽  
R. Chambers
Keyword(s):  
Body Size ◽  
Mating Success
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