Multiple insecticide resistance in the major malaria vector Anopheles funestus in southern Ghana: implications for malaria control

Background Understanding the dynamics of insecticide resistance in African malaria vectors is crucial for successful implementation of resistance management strategies in the continent. This study reports a high and multiple insecticide resistance in Anopheles funestus from southern Ghana which could compromise the Malaria Operational Plan in this country, if not tackled. Adult Anopheles mosquitoes were collected in Obuasi and Adawukwa, in southern Ghana. Plasmodium infection rates, susceptibility to the main insecticides used in public health and the molecular basis of insecticide resistance were established. Results An. funestus (sensu stricto) (s.s.) was the predominant mosquito species found resting inside the houses in Obuasi, while at Adawukwa it was found together with An. coluzzii. Parasite rates were high in An. funestus (s.s.) populations from both localities, with Plasmodium infection rates greater than 12.5 %. Both, An. funestus (s.s.) and An. coluzzii, from the two sites exhibited high resistance to the insecticide from various classes including the pyrethroids, carbamates and DDT, but remained fully susceptible to the organophosphates. A preliminary characterization of the underlying molecular mechanisms of resistance in An. funestus (s.s.) populations from both sites revealed that CYP6P9a, CYP6P9b, CYP6M7 and GSTe2 genes are upregulated, markedly higher in Obuasi (between 3.35 and 1.83 times) than in Adawukwa population. The frequency of L119F-GSTe2 and A296S-RDL resistance markers were also higher in Obuasi (42.5 and 68.95 % higher), compared with An. funestus (s.s.) populations from Adawukwa. These findings suggest that the similar resistance pattern observed in both An. funestus (s.s.) populations are driven by different mechanisms. Conclusions Resistance to multiple insecticides in public health use is present in malaria vectors from Ghana with major resistance genes already operating in the field. This should be taken into consideration in the design of resistance management strategies to avoid operational failure

Incidence, prevalence and severity of fall armyworm infestation in Ghana: a case of two maize enclaves in the Ashanti Region of Ghana

Maize production is an important enterprise in Ghana, providing livelihood for thousands of people. It is challenged by fall armyworm infestation causing destruction to many cultivated lands in production enclaves and threatening food security. Effective control, however, requires information on the actual pest infestation as well as the effect of climate factors on infestation in these enclaves. The study assessed the incidence, prevalence and severity of fall armyworm infestation on maize farms in two major maize enclaves (Ejura and Ejisu) in Ghana. Data was taken on the presence, infestation levels and damage of fall armyworms as well as the climatic conditions in each district. Data collection was done by sampling 50 maize plants each on 40 maize farms in both districts and assessing them for the incidence, larval prevalence, leaf damage and severity. Results showed varying infestation in both districts (p < 0.0001) with Ejisu having a higher prevalence (0.10 ± 0.04 larvae per plant) than Ejura (0.05 ± 0.03 larvae per plant) in the minor season at seedling stage. At the vegetative stage, Ejisu recorded a higher prevalence in both seasons. A low severity was recorded at the seedling stage in both districts for all seasons which, however, varied among seasons at vegetative stage. Climatic variables including rainfall, temperature, relative humidity and wind were found to significantly impact infestation in both districts. The study thus, showed fall armyworm infestation to be a major challenge to maize production in both districts confirming it as a major constraint to maize production in the region

Co-Development of AICCRA Ghana Cluster Partnerships on NFCS, One-Health, Ag-data hub and EWRR Cluster

This paper highlights the draft partnership agreements developed by stakeholders in the agriculture sector of Ghana to became necessary to promote partnerships for the National Framework for Climate Services (NFCS), One-Health, Ag-data hub, and Early Warning & Rapid Response for pests and diseases (EWRR)

Detection of a reduced susceptibility to chlorfenapyr in the malaria vector Anopheles gambiae contrasts with full susceptibility in Anopheles funestus across Africa

New insecticides have recently been produced to help control pyrethroid-resistant malaria vectors including the pyrrole, chlorfenapyr. Monitoring the susceptibility of mosquito populations against this new product and potential cross-resistance with current insecticides is vital for better resistance management. In this study, we assessed the resistance status of the major malaria vectors Anopheles gambiae and Anopheles funestus to chlorfenapyr across Africa and explored potential cross-resistance with known pyrethroid resistance markers. Efficacy of chlorfenapyr 100 µg/ml against An. gambiae and An. funestus from five Cameroonian locations, the Democratic Republic of Congo, Ghana, Uganda, and Malawi was assessed using CDC bottle assays. Synergist assays were performed with PBO (4%), DEM (8%) and DEF (0.25%) and several pyrethroid-resistant markers were genotyped in both species to assess potential cross-resistance between pyrethroids and chlorfenapyr. Resistance to chlorfenapyr was detected in An. gambiae populations from DRC (Kinshasa) (mortality rate: 64.3 ± 7.1%) Ghana (Obuasi) (65.9 ± 7.4%), Cameroon (Mangoum; 75.2 ± 7.7% and Nkolondom; 86.1 ± 7.4). In contrast, all An. funestus populations were fully susceptible. A negative association was observed between the L1014F-kdr mutation and chlorfenapyr resistance with a greater frequency of homozygote resistant mosquitoes among the dead mosquitoes after exposure compared to alive (OR 0.5; P = 0.02) whereas no association was found between GSTe2 (I114T in An. gambiae; L119F in An. funestus) and resistance to chlorfenapyr. A significant increase of mortality to chlorfenapyr 10 µg/ml was observed in An. funestus after to PBO, DEM and DEF whereas a trend for a decreased mortality was observed in An. gambiae after PBO pre-exposure. This study reveals a greater risk of chlorfenapyr resistance in An. gambiae populations than in An. funestus. However, the higher susceptibility in kdr-resistant mosquitoes points to higher efficacy of chlorfenapyr against the widespread kdr-based pyrethroid resistance

Making Climate Smart Agriculture Innovations One Health Sensitive

That is, the CSA practices ensure a healthy ecosystem (humans, animals and plants, and their shared environment). This policy brief highlights CSA and One Health concepts and outlines how CSA innovations and for that matter, any innovation can be made One Health sensitive. Ensuring CSAs are One Health sensitive brings great benefit to our agri-food systems, livelihoods as well as to the ecosystem

Media and mass campaign on CSA/CIS and One-health concept and innovations

AICCRA Ghana is leverage the wide network of media and mass dissemination tools to scale Climate Smart Innovations and Climate Information Services to farmer

Comparative study of the effect of solvents on the efficacy of neonicotinoid insecticides against malaria vector populations across Africa

Background: New insecticides with a novel mode of action such as neonicotinoids have recently been recommended for public health by WHO. Resistance monitoring of such novel insecticides requires a robust protocol to monitor the development of resistance in natural populations. In this study, we comparatively used three different solvents to assess the susceptibility of malaria vectors to neonicotinoids across Africa. Methods: Mosquitoes were collected from May to July 2021 from three agricultural settings in Cameroon (Njombe-Penja, Nkolondom, and Mangoum), the Democratic Republic of Congo (Ndjili-Brasserie), Ghana (Obuasi), and Uganda (Mayuge). Using the CDC bottle test, we compared the effect of three different solvents (ethanol, acetone, MERO) on the efficacy of neonicotinoids against Anopheles gambiae s.l. In addition, TaqMan assays were used to genotype key pyrethroid-resistant markers in An. gambiae and odds ratio based on Fisher exact test were used to evaluate potential cross-resistance between pyrethroids and clothianidin. Results: Lower mortality was observed when using absolute ethanol or acetone alone as solvent for clothianidin (11.4‒51.9% mortality in Nkolondom, 31.7‒48.2% in Mangoum, 34.6‒56.1% in Mayuge, 39.4‒45.6% in Obuasi, 83.7‒89.3% in Congo and 71.1‒95.9% in Njombe pendja) compared to acetone + MERO for which 100% mortality were observed for all the populations. Similar observations were done for imidacloprid and acetamiprid. Synergist assays (PBO, DEM and DEF) with clothianidin revealed a significant increase of mortality suggesting that metabolic resistance mechanisms are contributing to the reduced susceptibility. A negative association was observed between the L1014F-kdr mutation and clothianidin resistance with a greater frequency of homozygote resistant mosquitoes among the dead than among survivors (OR = 0.5; P = 0.02). However, the I114T-GSTe2 was in contrast significantly associated with a greater ability to survive clothianidin with a higher frequency of homozygote resistant among survivors than other genotypes (OR = 2.10; P = 0.013). Conclusions: This study revealed a contrasted susceptibility pattern depending on the solvents with ethanol/acetone resulting to lower mortality, thus possibly overestimating resistance, whereas the MERO consistently showed a greater efficacy of neonicotinoids but it could prevent to detect early resistance development. Therefore, we recommend monitoring the susceptibility using both acetone alone and acetone + MERO (4 µg/ml for clothianidin) to capture the accurate resistance profile of the mosquito populations. Graphical Abstract

Escalating pyrethroid resistance in two major malaria vectors Anopheles funestus and Anopheles gambiae (s.l.) in Atatam, Southern Ghana

Background: Aggravation of insecticide resistance in malaria vectors is threatening the efforts to control malaria by reducing the efficacy of insecticide-based interventions hence needs to be closely monitored. This study investigated the intensity of insecticide resistance of two major malaria vectors An. funestus sensu stricto (s.s.) and An. gambiae sensu lato (s.l.) collected in southern Ghana and assessed the bio-efficacy of several long-lasting insecticidal nets (LLINs) against these mosquito populations. Methods: The insecticide susceptibility profiles of Anopheles funestus s.s. and Anopheles gambiae s.l. populations from Obuasi region (Atatam), southern Ghana were characterized and the bio-efficacy of some LLINs was assessed to determine the impact of insecticide resistance on the effectiveness of these tools. Furthermore, molecular markers associated with insecticide resistance in both species were characterized in the F0 and F1 populations using PCR and qPCR methods. Results: Anopheles funestus s.s. was the predominant species and was resistant to pyrethroids, organochlorine and carbamate insecticides, but fully susceptible to organophosphates. An. gambiae s.l. was resistant to all four insecticide classes. High intensity of resistance to 5 × and 10 × the discriminating concentration (DC) of pyrethroids was observed in both species inducing a considerable loss of efficacy of long-lasting insecticidal nets (LLINs). Temporal expression analysis revealed a massive 12-fold increase in expression of the CYP6P4a cytochrome P450 gene in An. funestus s.s., initially from a fold change of 41 (2014) to 500 (2021). For both species, the expression of candidate genes did not vary according to discriminating doses. An. gambiae s.l. exhibited high frequencies of target-site resistance including Vgsc-1014F (90%) and Ace-1 (50%) while these mutations were absent in An. funestus s.s. Conclusions: The multiple and high intensity of resistance observed in both malaria vectors highlights the need to implement resistance management strategies and the introduction of new insecticide chemistries

Basic Developmental Characteristics of the Fall Armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), Reared under Laboratory Conditions

The life cycle of the invasive alien insect pest, fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), was studied using a colony established from field-collected larvae. Eggs, neonate larvae, and newly emerged adult moths were used in experiments to investigate the basic biology of the FAW. Adult females laid up to 1184 eggs with a mean of 469 ± 22 eggs per female. The incubation period of eggs and percentage hatchability were 2-3 days and 80–87%, respectively. The mean larval lengths from the first to the sixth instar were 4.63, 6.60, 9.76, 15.86, 25.13, and 27.81 mm, respectively. The mean larval weights were 0.003, 0.019, 0.045, 0.050, 0.060, and 0.067 g, respectively, for the six instars. The mean width of the head capsule of the sixth instar larva was 2.76 mm. The total larval duration throughout the six instar stages was 16–18 days, while the mean pupal weight was 0.25 ± 0.001 g and 0.35 ± 0.011 g for males and females, respectively. The mean pupal length was 14.3 ± 0.16 mm for males and 17.2 ± 0.14 mm for females. Pupal duration ranged from 8 to 14 days, with a mean of 10.35 ± 0.26 days, while the pupal emergence rate ranged from 60 to 94%, with a mean of 80.25 ± 1.28%. The life cycle of males lasted 33–44 days and that of females lasted 36–49 days under laboratory conditions. Adult copulation occurred between 8 and 11 pm, with the peak occurring at 9 pm. This study provides baseline information about the biology of the FAW. Apart from being an important reference point for future research on the FAW, the data provided would aid FAW management decision-making

Farmers’ knowledge, experience and management of fall armyworm in a major maize producing municipality in Ghana

AbstractSince its discovery in Ghana, the fall armyworm (FAW) has damaged maize farms resulting in yield losses. This study investigated farmers’ knowledge, practices and impact of the pest in a major maize growing municipality in Ghana. A structured questionnaire was used to obtain information from 200 randomly sampled farmers on their knowledge, practices, perceived effect and management of the FAW. FAW susceptibility to insecticides was also assessed. Although insecticide application was dominant (98%) and farmers experienced adverse health effects, application frequency and the resulting effects were not significantly related (p > 0.05). Usage of personal protective equipment (PPE) was low (45.7%) and only 2% of the farmers used complete PPE. Gender correlated positively with PPE usage with more females wearing PPE compared to males. Age, farming experience, education and farm size did not significantly impact on PPE usage. The FAW outbreak negatively affected farmers’ relationships (36.5%) and caused economic loss to many farmers (80%). FAW was susceptible to emamectin benzoate (1.9% w/v) and emamectin benzoate (48 g/L) + acetamiprid (64 g/L) but not Bacillus thuringiensis (55%) + monosultap (45%) under laboratory conditions. The findings and implications of the study on farmer safety and sustainable pest management are discussed