Stability of the effect of silencing genes involved in the midgut homeostasis on Anopheles arabiensis mosquito reared under different breeding site conditions

Abstract Background: Malaria vector mosquitoes acquire midgut microbiota primarily from their habitat. The homeostasis of these microbial communities plays an essential role in the mosquito longevity, the most essential factor in the mosquito vectorial capacity. Our recent study revealed that silencing genes involved in regulation of the midgut homeostasis including FN3D1, FN3D3, and GPRGr9 reduced the survival of female adult Anopheles arabiensis mosquito. In the present study, we investigate the stability of the gene silencing efficiency of mosquitoes reared in three different breeding conditions representing distinct larval habitat types: town brick pits in Jimma, flood pools in the rural land of Asendabo and roadside pools in Wolkite. Methods: First instar larvae of An. arabiensis mosquitoes were reared separately using water collected from the three breeding sites. The resulting adult females were micro-injected with dsRNA targeting the FN3D1 gene (AARA003032) and their survival was monitored. Control mosquitoes were injected with dsRNA Lacz. In addition, the load of midgut microbiota of these mosquitoes was determined using flow cytometry.Result: Survival of naïve adult female mosquitoes differed between the three sites. Mosquitoes reared using water collected from brick pits and flood pools survived longer than mosquitoes reared using water collected from roadside. However, the FN3D1 gene silencing effect on survival did not differ between the three sites. Conclusion: The present study revealed that the efficacy of FN3D1 gene silencing is not affected by variation in the larval habitat. Thus, silencing this gene using genetic engineering approaches can have a large potential for application throughout sub-Saharan Africa.

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Is High Whitefly Abundance on Cassava in Sub-Saharan Africa Driven by Biological Traits of a Specific, Cryptic Bemisia tabaci Species?

Insects ◽

10.3390/insects12030260 ◽

2021 ◽

Vol 12 (3) ◽

pp. 260

Author(s):

Habibu Mugerwa ◽

Peter Sseruwagi ◽

John Colvin ◽

Susan Seal

Keyword(s):

Food Security ◽

Bemisia Tabaci ◽

Development Time ◽

Adult Emergence ◽

Sub Saharan Africa ◽

Biological Traits ◽

Population Development ◽

Species Classification ◽

First Instar ◽

Sub Saharan

In East Africa, the prevalent Bemisia tabaci whiteflies on the food security crop cassava are classified as sub-Saharan Africa (SSA) species. Economically damaging cassava whitefly populations were associated with the SSA2 species in the 1990s, but more recently, it has been to SSA1 species. To investigate whether biological traits (number of first instar nymphs, emerged adults, proportion of females in progeny and development time) of the cassava whitefly species are significant drivers of the observed field abundance, our study determined the development of SSA1 sub-group (SG) 1 (5 populations), SG2 (5 populations), SG3 (1 population) and SSA2 (1 population) on cassava and eggplant under laboratory conditions. SSA1-(SG1-SG2) and SSA2 populations’ development traits were similar. Regardless of the host plant, SSA1-SG2 populations had the highest number of first instar nymphs (60.6 ± 3.4) and emerged adults (50.9 ± 3.6), followed by SSA1-SG1 (55.5 ± 3.2 and 44.6 ± 3.3), SSA2 (45.8 ± 5.7 and 32.6 ± 5.1) and the lowest were SSA1-SG3 (34.2 ± 6.1 and 32.0 ± 7.1) populations. SSA1-SG3 population had the shortest egg–adult emergence development time (26.7 days), followed by SSA1-SG1 (29.1 days), SSA1-SG2 (29.6 days) and SSA2 (32.2 days). Regardless of the whitefly population, development time was significantly shorter on eggplant (25.1 ± 0.9 days) than cassava (34.6 ± 1.0 days). These results support that SSA1-(SG1-SG2) and SSA2 B. tabaci can become highly abundant on cassava, with their species classification alone not correlating with observed abundance and prevalence.

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Assortments of Digestive Enzymes Induced in First Instar Larvae of Busseola fusca Feeding on Different Plants

International Journal of Insect Science ◽

10.1177/1179543319843521 ◽

2019 ◽

Vol 11 ◽

pp. 117954331984352 ◽

Cited By ~ 1

Author(s):

Gérald Juma ◽

Bruno Le Ru ◽

Paul-André Calatayud

Keyword(s):

Plant Species ◽

Digestive Enzymes ◽

Host Plants ◽

Feeding Habits ◽

Busseola Fusca ◽

Stem Borer ◽

Sub Saharan Africa ◽

Host Acceptance ◽

First Instar ◽

Sub Saharan

The stem borer Busseola fusca (Fuller) (Lepidoptera: Noctuidae) is an important pest of maize and sorghum in sub-Saharan Africa. This insect has oligophagous feeding habits, feeding mostly on maize and sorghum with a narrow range of wild Poaceous plant species. We hypothesised that first instar B. fusca larvae, the critical stage for successful establishment on a host plant, can establish and then grow on a particular plant as a result of induction of a complement of digestive enzymes that mediates host acceptance at first instars. A fast semi-quantitative analysis of potentially digestive enzymatic activities present in the first larvae previously fed for 4 days on leaves of host and non-host plants was performed using the API-ZYM kit system able to detect a multiplex of enzyme activities. Regardless of the plant species, the larvae exhibited higher activities of the carbohydrate metabolising enzymes than of aminopeptidases and proteases. In addition, highest activities of carbohydrates degrading enzymes were exhibited by larvae that consumed leaves of the most preferred plant species of B. fusca. Conversely, esterases were only detected in neonate larvae that consumed leaves of the less preferred and non-host plants. No alkaline phosphatase and lipase activities were detected. The significance of these results was discussed in terms of food requirements of first instar larvae when settling on a plant.

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Molecular typing of bacteria of the genus Asaia in malaria vector Anopheles arabiensis Patton, 1905

Journal of Entomological and Acarological Research ◽

10.4081/jear.2012.e7 ◽

2012 ◽

Vol 44 (2) ◽

pp. 7 ◽

Cited By ~ 1

Author(s):

S. Epis ◽

M. Montagna ◽

F. Comandatore ◽

C. Damiani ◽

A. Diabaté ◽

...

Keyword(s):

Molecular Typing ◽

Internal Transcribed Spacer ◽

Anopheles Arabiensis ◽

Acetic Acid Bacterium ◽

Sub Saharan Africa ◽

Randomly Amplified Polymorphic Dna ◽

Chain Reaction ◽

Polymerase Chain ◽

Sub Saharan ◽

Dna Pcr

The acetic acid bacterium Asaia spp. was successfully detected in Anopheles arabiensis Patton, 1905, one of the major vector of human malaria in Sub-Saharan Africa. A collection of 45 Asaia isolates in cellfree media was established from 20 individuals collected from the field in Burkina Faso. 16S rRNA universal polymerase chain reaction (PCR) and specific qPCR, for the detection of Asaia spp. were performed in order to reveal the presence of different bacterial taxa associated with this insect. The isolates were typed by internal transcribed spacer-PCR, BOX-PCR, and randomly amplified polymorphic DNA-PCR, proved the presence of different Asaia in A. arabiensis.

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Economic freedom, competition and bank stability in Sub-Saharan Africa

International Journal of Productivity and Performance Management ◽

10.1108/ijppm-06-2019-0310 ◽

2020 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Emmanuel Sarpong-Kumankoma ◽

Joshua Yindenaba Abor ◽

Anthony Q. Q. Aboagye ◽

Mohammed Amidu

Keyword(s):

Economic Freedom ◽

Banking Sector ◽

Generalized Method Of Moments ◽

Sub Saharan Africa ◽

Bank Stability ◽

Content Type ◽

Show Evidence ◽

Negative Effect ◽

Sub Saharan ◽

The Stability

PurposeThis study aims to analyze the potential implications of economic freedom and competition for bank stability.Design/methodology/approachUsing system generalized method of moments and data from 139 banks across 11 Sub-Saharan African (SSA) countries during the period 2006–2012, this study considers whether the degree of economic freedom affects the relationship between competition and bank stability.FindingsThe results show evidence of the competition-fragility hypothesis in SSA banking, but suggests that beyond a setting threshold, increases in market power may also be damaging to bank stability. Financial freedom has a negative effect on bank stability, suggesting that banks operating in environments with greater financial freedom generally tend to be less stable or more risky. The authors also find evidence of a conditional effect of economic freedom on the competition–stability relationship, implying that bank failure is more likely to occur in countries with greater economic freedom, but with low competition in the banking sector.Practical implicationsThe results suggests to policy makers that a moderate level of competition and economic freedom may be the appropriate policy to ensure the stability of banks.Originality/valueThe study provides insight on the competition–bank stability relationship, by providing new empirical evidence on the effect of economic freedom, which has not been previously considered.

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Negotiating an ecological barrier: crossing the Sahara in relation to winds by common swifts

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2015.0393 ◽

2016 ◽

Vol 371 (1704) ◽

pp. 20150393 ◽

Cited By ~ 25

Author(s):

Susanne Åkesson ◽

Giuseppe Bianco ◽

Anders Hedenström

Keyword(s):

Arabian Peninsula ◽

Sub Saharan Africa ◽

Breeding Sites ◽

Western Sahara ◽

The Earth ◽

Ultimate Explanation ◽

Wintering Areas ◽

Central Route ◽

Sub Saharan ◽

Alternative Routes

The Sahara Desert is one of the largest land-based barriers on the Earth, crossed twice each year by billions of birds on migration. Here we investigate how common swifts migrating between breeding sites in Sweden and wintering areas in sub-Saharan Africa perform the desert crossing with respect to route choice, winds, timing and speed of migration by analysing 72 geolocator tracks recording migration. The swifts cross western Sahara on a broad front in autumn, while in spring they seem to use three alternative routes across the Sahara, a western, a central and an eastern route across the Arabian Peninsula, with most birds using the western route. The swifts show slower migration and travel speeds, and make longer detours with more stops in autumn compared with spring. In spring, the stopover period in West Africa coincided with mostly favourable winds, but birds remained in the area, suggesting fuelling. The western route provided more tailwind assistance compared with the central route for our tracked swifts in spring, but not in autumn. The ultimate explanation for the evolution of a preferred western route is presumably a combination of matching rich foraging conditions (swarming insects) and favourable winds enabling fast spring migration. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’.

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The interplay of competition, regulation and stability: the case of Sub-Saharan African commercial banks

Banks and Bank Systems ◽

10.21511/bbs.14(1).2019.07 ◽

2019 ◽

Vol 14 (1) ◽

pp. 65-80

Author(s):

Joseph Olorunfemi Akande ◽

Farai Kwenda ◽

Dev Tewari

Keyword(s):

Regional Integration ◽

Commercial Banks ◽

Structural Equation ◽

Empirical Studies ◽

Sustainable Growth ◽

Sub Saharan Africa ◽

Equation Modelling ◽

Sub Saharan ◽

The Stability ◽

Bank System

Stimulating competition in the bank system without compromising the stability constitutes a major puzzle that bank regulators and practitioners face. Hitherto, empirical studies focusing on Sub-Saharan Africa in addressing these issues for the anticipated regional integration and sustainable growth are rare. This study applied structural equation modelling to simultaneously analyze competition, regulation and stability in a panel of 440 Sub-Saharan African commercial banks over the period from 2006 to 2015. The results provided evidence that competition affects stability via efficiency and that regulation affects stability via competition and efficiency. This study produced critical theoretical and methodological insights with substantial implications for the conduct of bank regulatory policy.

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The determinants of Party System Change in Sub-Saharan Africa

Otoritas Jurnal Ilmu Pemerintahan ◽

10.26618/ojip.v8i2.1161 ◽

2018 ◽

Vol 8 (2) ◽

pp. 124-129

Author(s):

Riccardo Pelizzo

Keyword(s):

Social Transformation ◽

Party System ◽

System Change ◽

Party Systems ◽

Party Competition ◽

Sub Saharan Africa ◽

Democratic Regimes ◽

Primary Driver ◽

Sub Saharan ◽

The Stability

This article examines what socio-economic factors are conducive to changes in the patterns of inter-party competition in Sub-Saharan Africa (SSA). The literature has in recent years paid considerable attention to measuring party system change, to identifying the consequences of party system instability for the proper functioning of democratic regimes, and to understanding what factors are responsible for the instability of party systems. In contrast to previous studies that view political change in general and party system change more specifically as the result of social transformation, development, modernization and change in the cleavage structure, this paper shows instead that poverty is the primary driver of party system change in the SSA region. In countries with high levels of poverty, political elites do enjoy little to no performance-based legitimacy. The lack of performance-based legitimacy is the reason why voters in such countries are willing to alter their voting habits and parties are unable to preserve their electoral fortunes over time—which is precisely why party systems do change. The literature showed that stable party systems are good for democracy. This paper shows that to enhance the stability of party system in SSA, poverty has to be reduced and possibly eradicated.

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A Qualitative Evidence of the Breeding Sites of Anopheles arabiensis Patton (Diptera: Culicidae) in and Around Kassala Town, Eastern Sudan

International Journal of Insect Science ◽

10.4137/ijis.s40071 ◽

2016 ◽

Vol 8 ◽

pp. IJIS.S40071 ◽

Cited By ~ 2

Author(s):

Asma Mahmoud Hamza ◽

El Amin El Rayah

Keyword(s):

Anopheles Arabiensis ◽

Habitat Type ◽

Larval Habitat ◽

Mosquito Larvae ◽

Habitat Types ◽

Breeding Sites ◽

Water Pipes ◽

Control Programs ◽

Qualitative Evidence ◽

Eastern Sudan

Anopheles arabiensis Patton (Diptera: Culicidae) is considered the most efficient malaria vector in eastern Sudan. This study aims to characterize the breeding sites of An. arabiensis throughout the year in and around Kassala town, eastern Sudan. Diverse larval habitat types were visited and characterized based on the habitat type and chemical composition. Mosquito larvae were found in many diverse habitats. During the rainy season, rain pools and water bodies created by the seasonal Gash River serve as the main breeding sites. In the dry season, irrigation canals, seepage from water pipes, neglected wells, artificial containers, and man-made ditches serve as the main breeding sites. Breeding water showed a pH of 7.9 and a low concentration of the total dissolved salts. The results of this study may be considered in planning and implementing larval control programs in the area.

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Nest success and conservation status of the Blue Swallow Hirundo atrocaerulea in Swaziland

Bird Conservation International ◽

10.1017/s0959270906000232 ◽

2006 ◽

Vol 16 (3) ◽

pp. 187-196 ◽

Cited By ~ 3

Author(s):

ARA MONADJEM ◽

RICHARD C. BOYCOTT ◽

KIM ROQUES ◽

RAY GAMA ◽

DAVID GARCELON

Keyword(s):

Total Population ◽

Conservation Status ◽

Significant Proportion ◽

Egg Laying ◽

Breeding Habitat ◽

Sub Saharan Africa ◽

Breeding Sites ◽

Double Brooding ◽

Sub Saharan ◽

Timber Plantations

The Blue Swallow Hirundo atrocaerulea is a globally threatened species endemic to sub-Saharan Africa. The total population breeding south of the Limpopo River (i.e. in South Africa and Swaziland) probably numbers around 100 pairs. A significant proportion of these birds breed in Swaziland, but to date little has been published on this population. Suitable breeding habitat has been reduced significantly in the country in recent decades, due mostly to afforestation with exotic timber plantations, with urbanization playing a lesser role. In Swaziland, breeding sites are restricted to grasslands above 1,200 m, but mostly above 1,300 m. Timing of egg laying is bimodal indicating double brooding. The number of nests initiated in a season is weakly correlated with rainfall in preceding months. Nests were built predominantly in disused antbear Orycteropus afer burrows, with smaller numbers in natural sinkholes. Mean clutch size was 2.80, and 61% of eggs laid resulted in fledged offspring. Mean productivity was 1.30 fledglings per pair per nest attempt. These figures suggest that breeding success is not currently being reduced in Swaziland. The minimum total population currently thought to be breeding in Swaziland is 10 pairs, but this is based on intensive studies of only part of the suitable range. It is recommended that a complete survey be conducted covering the entire range of the species in Swaziland.

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