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Governments budget cuts to free agricultural extension services in developing countries have led to advocacy for development and implementation of cost-effective extension services to be partly paid for by beneficiary farmers. Accordingly, understanding farmers’ preferences and willingness to pay is essential for successful implementation of any such cost-sharing extension service schemes; but empirical studies to support cost-sharing extension service schemes in the Ghanaian cocoa sector is hard to find. The study contributes to the knowledge gap by examining key drivers of cocoa farmers’ preferences and willingness to pay for a climate-smart extension service using discrete choice experiment data which was analysed with a mixed logit model. Data was collected from 720 cocoa farmers who were sampled using multistage sampling process. The study finds that farmers have significant preference for the climate-smart extension service, with a marginal willingness to pay of approximately GH¢ 15.15 for improvements in product attributes. Farmers’ preferred product attributes include in-person accessibility, advanced climate-smart content, flexible demand-based delivery and high service reliability, taking into consideration price affordability. Additionally, willingness to pay is significantly influenced by perceived service quality, rainfall and temperature variability, climate change impact, age, education, access to credit, and farm income. The study recommends that extension service providers and policymakers should focus on the identified climate-smart cocoa extension service attributes preferred by farmers and the significant determinants of the farmers’ willingness to pay when developing and implementing climate-smart extension services to enhance cocoa farmers’ resilience to climate risks. Plain Language Summary Determinants of cocoa farmers’ preference and willingness to pay for climate smart extension service There has been declining government budgetary allocation to the free-to-use agricultural extension service scheme in most developing countries; thus, advocacy for a complementary cost-sharing service scheme. The successful implementation of any such cost-sharing service scheme requires understanding of farmers’ preference and willingness to pay. Choice experiment approach was used to collect data from 720 cocoa farmers about their preference and willingness to pay for a climate smart cocoa extension service. Farmers prefer climate smart cocoa extension service attributes that comprise of: an in-person face-to-face accessibility mode, advance climate-smart cocoa extension service content, a flexible demand-based extension service delivery and above-average service reliability, taking into consideration price affordability. Farmers willingness to pay for the climate smart cocoa extension service is significantly influenced by perceived extension service quality, perceived rainfall variability, perceived temperature variability, perceived impact of climate change, age, education, access to credit and farm income. It is recommended that extension providers and policymakers to focus on the preferred attributes of the climate smart cocoa extension service and to give attention to the observed determinants of willingness to pay in the development and implementation of a climate smart cocoa extension service to farmers to improve cocoa farmers resilience to climate risks.

Background Theoretically, social climate and social networking which may affect attitudes, motivations, and readiness towards quality improvement and rewards, influence the adoption decision process by possibly modifying the risk behaviour/attitudes of individuals. Thus for effective promotion of agricultural technologies among farmers in Africa, it is necessary to understand the social context within which risk attitudes are formed and social participation decisions are made. The study, therefore, employed the recursive bivariate endogenous switching probit model to examine how risk attitudes of farmers are shaped through social interactions in the information and communication networks of farmers to influence their technology adoption decisions. Here, the empirical application was done with the contextual case of agriculture intensification technologies in the Root and Tuber Improvement and Marketing Programme (RTIMP) introduced to smallholder cassava farmers in Ghana. This paper makes a contribution to recent advances in the empirical analysis of impact where anticipated problems posed by unobserved confounders are accounted for. This was possible since the approach used allows for the estimation of the treatment effect of endogenous risk attitude variable of interest on farmers’ adoption decisions. Results The study found that the effectiveness and usefulness of social interactions as well as a high degree of trust by cassava farmers in their social networks have higher tendencies to lower the degree of risk aversion behaviour of the farmers to significantly influence RTIMP Technologies adoption decisions positively. The ATE estimate confirms that there has been a significant increase of 38% probability in the likelihood of adopting agricultural intensification technologies in the RTIMP attributable to the non-risk aversion attitudes of cassava farmers. The cassava farmers’ risk attitudes were found to be significantly influenced by the effectiveness and usefulness of social interactions, and a high degree of trust as well as age, frequency of extension services, access to credit, and revenue. Conclusion By implication, attempts to introduce innovations to improve agricultural commodities value chains that target farmers must pay particular attention to the information and communication network to ensure the effectiveness and usefulness of information dissemination to farmers in an honest manner, so as to build trust; which will go a long way to reduce doubts and uncertainties (function of risk aversion). This will help achieve higher innovation adoption impacts thereby resulting in attaining the overall deliverable objectives of agricultural innovations.

The Anopheles gambiae sensu lato species complex consists of a number of cryptic species with different habitats and behaviours. These morphologically indistinct species are identified by chromosome banding. Several molecular diagnostic techniques for distinguishing between An. coluzzii and An. gambiae are still under improvement. Although, the current SINE method for identification between An. coluzzii and An. gambiae works reliably, this study describes a refinement of the SINE method to increase sensitivity for identification of An. coluzzii, An. gambiae and An. arabiensis based on amplicon dissociation curve characteristics. Field-collected samples, laboratory-reared colonies and crossed specimens of the two species were used for the design of the protocol. An. gambiae, An. coluzzii, and hybrids of the two species were sampled from Ghana and An. arabiensis from Kenya. Samples were first characterised using conventional SINE PCR method, and further assayed using SYBR green, an intercalating fluorescent dye. The three species and hybrids were clearly differentiated using the melting temperature of the dissociation curves, with derivative peaks at 72°C for An. arabiensis, 75°C for An. gambiae and 86°C for An. coluzzii. The hybrids (An. gambiae / An. coluzzii) showed both peaks. This work is the first to describe a SYBR green real time PCR method for the characterization of An. arabiensis, An. gambiae and An. coluzzii and was purposely designed for basic melt-curve analysis (rather than high-resolution melt-curve) to allow it to be used on a wide range of real-time PCR machines.

Dengue, Zika and chikungunya are Aedes -borne viral diseases that have become great global health concerns in the past years. Several countries in Africa have reported outbreaks of these diseases and despite Ghana sharing borders with some of these countries, such outbreaks are yet to be detected. Viral RNA and antibodies against dengue serotype-2 have recently been reported among individuals in some localities in the regional capital of Ghana. This is an indication of a possible silent transmission ongoing in the population. This study, therefore, investigated the entomological transmission risk of dengue, Zika and chikungunya viruses in a forest and domestic population in the Greater Accra Region, Ghana. All stages of the Aedes mosquito (egg, larvae, pupae and adults) were collected around homes and in the forest area for estimation of risk indices. All eggs were hatched and reared to larvae or adults for morphological identification together with larvae and adults collected from the field. The forest population had higher species richness with 7 Aedes species. The predominant species of Aedes mosquitoes identified from both sites was Aedes aegypti (98%). Aedes albopictus , an important arbovirus vector, was identified only in the peri-domestic population at a prevalence of 1.5%, significantly higher than previously reported. All risk indices were above the WHO threshold except the House Index for the domestic site which was moderate (19.8). The forest population recorded higher Positive Ovitrap (34.2% vs 26.6%) and Container (67.9% vs 36.8%) Indices than the peri-domestic population. Although none of the mosquito pools showed the presence of dengue, chikungunya or Zika viruses, all entomological risk indicators showed that both sites had a high potential arboviral disease transmission risk should any of these viruses be introduced. Continuous surveillance is recommended in these and other sites in the Metropolis to properly map transmission risk areas to inform outbreak preparedness strategies.

Background Malaria vector control methods involving the use of pyrethroids remain the strategies being used against malaria vectors in Ghana. These methods include the use of long-lasting insecticidal nets and indoor residual spraying in many areas in Ghana. However, there is evidence that pyrethroid resistance is widespread in many areas in Ghana. Synergists have been shown to be useful in inhibiting the enzymes that are responsible for the development of resistance and hence enhance the insecticide susceptibility of Anopheles gambiae sensu lato ( s.l. ) in many areas. The present study investigated the effect of piperonyl butoxide (PBO) on the susceptibility status of An. gambiae s.l. across some sentinel sites in Ghana. Methods Three to five day old An. gambiae s.l. reared from larvae were used in WHO susceptibility tube assays. Batches of 20–25 female adult An. gambiae s.l. were exposed simultaneously to the insecticide alone and to the PBO + insecticide. The knock down rate after 60 min and mortality at 24 h were recorded. Results Deltamethrin and permethrin resistance of An. gambiae s.l. was observed in all the sites in 2015 and 2016. The mortality after 24 h post exposure for deltamethrin ranged from 16.3% in Weija to 82.3% in Kade, whereas that for permethrin ranged from 3.8% in Gomoa Obuasi to 91.3% in Prestea. A significant increase in susceptibility to deltamethrin and less to permethrin was observed during both 2015 and 2016 years in most of the sites when An. gambiae s.l. mosquitoes were pre-exposed to PBO. Conclusion Findings from this study showed that the use of PBO significantly enhanced the susceptibility of An. gambiae s.l. mosquitoes in most of the sentinel sites. It is recommended that vector control strategies incorporating PBO as a synergist can be effective in killing mosquitoes in the presence of deltamethrin and permethrin resistance.

Background Insecticide resistance of Anopheles gambiae ( s.l. ) against public health insecticides is increasingly reported in Ghana and need to be closely monitored. This study investigated the intensity of insecticide resistance of An. gambiae ( s.l. ) found in a vegetable growing area in Accra, Ghana, where insecticides, herbicides and fertilizers are massively used for plant protection. The bioefficacy of long-lasting insecticidal nets (LLINs) currently distributed in the country was also assessed to delimitate the impact of the insecticide resistance intensity on the effectiveness of those nets. Methods Three- to five-day-old adult mosquitoes that emerged from collected larvae from Opeibea, Accra (Ghana), were assayed using CDC bottle and WHO tube intensity assays against different insecticides. The Vgsc-L1014F and ace-1 mutations within the population were also characterized using PCR methods. Furthermore, cone bioassays against different types of LLINs were conducted to evaluate the extent and impact of the resistance of An. gambiae ( s.l. ) from Opeibea. Results Anopheles gambiae ( s.l. ) from Opeibea were resistant to all the insecticides tested with very low mortality observed against organochlorine, carbamates and pyrethroid insecticides using WHO susceptibility tests at diagnostic doses during three consecutive years of monitoring. The average frequencies of Vgsc-1014F and ace-1 in the An. gambiae ( s.l. ) population tested were 0.99 and 0.76, respectively. The intensity assays using both CDC bottle and WHO tubes showed high resistance intensity to pyrethroids and carbamates with survivals at 10× the diagnostic doses of the insecticides tested. Only pirimiphos methyl recorded a low resistance intensity with 100% mortality at 5× the diagnostic dose. The bioefficacy of pyrethroid LLINs ranged from 2.2 to 16.2% mortality while the PBO LLIN, PermaNet ® 3.0, was 73%. Conclusions WHO susceptibility tests using the diagnostic doses described the susceptibility status of the mosquito colony while CDC bottle and WHO tube intensity assays showed varying degrees of resistance intensity. Although both methods are not directly comparable, the indication of the resistance intensity showed the alarming insecticide resistance intensity in Opeibea and its surroundings, which could have an operational impact on the efficacy of vector control tools and particularly on pyrethroid LLINs.

Background Aedes -borne arboviral diseases, especially dengue, are on the rise. The global expansion of Aedes mosquitoes, driven by changing climatic conditions, has led to the emergence of these diseases in previously non-endemic regions. Effective entomological surveillance, which considers changes in weather conditions, is crucial for the timely detection, emergency preparedness and control of Aedes- borne diseases. Methods In this study, we collected Aedes eggs using ovitraps and estimated peri-domestic larval indices from urban locations over 6 months. Regression models were applied to determine the influence of meteorological factors on Aedes breeding and temporal trends in entomological indices pertinent to disease risk prediction. Results Ovitraps and larval sampling identified different months as most conducive for Ae. aegypti breeding activities, highlighting the impact of sampling method on surveillance and data interpretation for outbreak preparedness. Temperature and wind speed were identified as strong predictors of the entomological indices investigated. Rainfall was not a consistent predictor of Ae. aegypti breeding, except when in combination with temperature or wind speed. The presence of unused tyres within the peri-domestic environment was identified as a primary breeding site, but other open receptacles such as discarded cans and broken clay pots, especially in the absence of tyres, also contributed to Aedes presence. Conclusions Our models demonstrated predictive potential for estimating vector populations and risk of disease outbreaks, which could help in emergency preparedness and the deployment of control measures. Additionally, these models offer a tool for anticipating shifts in vector distribution under changing climate conditions, providing valuable insights for improving disease prevention strategies.

Higher temperatures expected in a future warmer climate could adversely affect the growth and development of mosquitoes. This study investigated the effects of elevated temperatures on longevity, gonotrophic cycle length, biting rate, fecundity, and body size of Anopheles gambiae (s.l.) (Diptera: Culicidae) mosquitoes. Anopheles gambiae (s.l.) eggs obtained from laboratory established colonies were reared under eight temperature regimes (25, 28, 30, 32, 34, 36, 38, and 40°C), and 80 ± 10% RH. All adults were allowed to feed on a 10% sugar solution soaked in cotton wool; however, some mosquitoes were provided blood meal using guinea pig. Longevity was estimated for both blood-fed and non-blood-fed mosquitoes and analyzed using the Kaplan–Meier survival analysis. One-way ANOVA was used to test the effect of temperature on gonotrophic cycle length, biting rate, and fecundity. Adult measurement data were log-transformed and analyzed using ordinary least square regression with robust standard errors. Increasing temperature significantly decreased the longevity of both blood-fed (Log-rank test; X2(4) = 904.15, P < 0.001) and non-blood-fed (Log-rank test; X2(4) = 1163.60, P < 0.001) mosquitoes. In addition, the fecundity of mosquitoes decreased significantly (ANOVA; F(2,57) = 3.46, P = 0.038) with an increase in temperature. Body size (β = 0.14, 95% CI, 0.16, 0.12, P < 0.001) and proboscis length (β = 0.13, 95% CI, 0.17, 0.09, P < 0.001) significantly decreased with increasing temperature from 25 to 34°C. Increased temperatures expected in a future warmer climate could cause some unexpected effects on mosquitoes by directly influencing population dynamics and malaria transmission.

The most widespread arboviral diseases such as Dengue, Chikungunya, and Zika are transmitted mainly by Aedes mosquitoes. Due to the lack of effective therapeutics for most of these diseases, vector control remains the most effective preventative and control measure. This study investigated and compared the species composition, insecticide susceptibility, and resistance mechanisms in Aedes mosquito populations from a forest reserve converted to an eco-park and a peri-domestic sites in urban Accra, Ghana. Immature Aedes were sampled from the study sites, raised to adults, and exposed to deltamethrin, permethrin, DDT, fenitrothion, bendiocarb, permethrin + PBO, and deltamethrin + PBO using WHO tube assays. Melting curve analyses were performed for F1536C, V1016I, and V410L genetic mutations in surviving and dead mosquitoes following exposure to deltamethrin and permethrin. Microplate assay was used to access enzyme activity levels in adult mosquitoes from both populations. Aedes aegypti was found to be the dominant species from both study populations. The susceptibility test results revealed a high frequency of resistance to all the insecticides except fenitrothion. F1534C mutations were observed in 100% and 97% of mosquitoes from the peri-domestic and forest population, respectively but were associated with pyrethroid resistance only in the forest population (P < 0.0001). For the first time in Aedes mosquitoes in Ghana, we report the existence V410L mutations, mostly under selection only in the forest population (HWE P < 0.0001) and conclude that Aedes vectors in urban Accra have developed resistance to many commonly used insecticides. This information is important for the formulation of vector control strategies for Aedes control in Ghana.

Resistance to insecticides in Anopheles mosquitoes threatens the effectiveness of malaria control, but the genetics of resistance are only partially understood. We performed a large scale multi-country genome-wide association study of resistance to two widely used insecticides: deltamethrin and pirimiphos-methyl, using sequencing data from An. gambiae and An. coluzzii from ten locations in West Africa. Resistance was highly multi-genic, multi-allelic and variable between populations. While the strongest and most consistent association with deltamethrin resistance came from Cyp6aa1 , this was based on several independent copy number variants (CNVs) in An. coluzzii , and on a non-CNV haplotype in An. gambiae . For pirimiphos-methyl, signals included Ace1 , cytochrome P450s, glutathione S-transferases and the nAChR target site of neonicotinoid insecticides. The regions around Cyp9k1 and the Tep family of immune genes showed evidence of cross-resistance to both insecticides. These locally-varying, multi-allelic patterns highlight the challenges involved in genomic monitoring of resistance, and may form the basis for improved surveillance methods. Insecticide resistance in mosquitoes threatens the success of malaria control programmes. This study found that in different populations of a malaria mosquito species in West Africa, resistance is associated with different genes or different mutations in the same set of genes.