Silas Wintuma Avicor

Although information on insecticide toxicity on pests abounds, this is limited on non-target organisms like ants in cocoa production systems. This study determined the toxicity of insecticides (containing acetamiprid 40 g L⁻¹ EW, acetamiprid 64 g L⁻¹ + emamectin benzoate 48 g L⁻¹ EC, acetamiprid 20 g L⁻¹ + lambda-cyhalothrin 15 g L⁻¹ SC, emamectin benzoate 5% WDG and pyrethrins 50 g L⁻¹ EW) used against cocoa pests on non-target predatory ants (Crematogaster africana, Oecophylla longinoda and Pheidole megacephala) under laboratory (using filter-paper method) and field conditions to identify less harmful products for use in the cropping system. Ant knockdown and mortality varied significantly among insecticides at their recommended rates, with emamectin benzoate being the least toxic and acetamiprid + lambda-cyhalothrin the most toxic. LC₉₅s varied significantly, with emamectin benzoate having the highest predator safety index, while pyrethrins had the lowest. Generally, selectivity towards O. longinoda was higher than that towards the other ants. In the field, emamectin benzoate had the least acute adverse effect on ant abundance. Ant population generally rebounded to pre-treatment levels at 1 month after the last insecticide application. The study indicates differential toxicity and identifies ant-compatible insecticide options contingent on the autochthonous ant composition.

Modern sustainable agriculture often relies on pesticide application, which may unintentionally affect non-target soil microorganisms. This study assessed the effects of commonly used pesticides in cabbage cultivation on bacteria diversity, composition, and abundance in soils from some farming communities in Bosome Freho District, Ghana. The pesticides included a neonicotinoid (acetamiprid), microbial agents (Pieris rapae granulosis virus+ Bacillus thuringiensis), avermectin (emamectin benzoate), and pyrrole (chlorfenapyr). Soil samples were collected from non-contaminated (NCS), abandoned pesticide-contaminated (AB-PCS) and actively pesticide-contaminated (AC-PCS) soils. Bacteria communities were analysed in the soil at phylum, class, order, family, genus, and species levels using 16S rRNA gene sequencing. The soils were also analyzed for physicochemical properties. Our results showed a decrease in bacteria diversity and abundance in pesticide-contaminated soils in the following order: NCS > AB-PCS > AC-PCS. Sorensen’s coefficient of similarity indicated major shifts in bacteria taxa composition due to pesticide contamination. In NCS, Pseudomonas veronii, Bacillus sp., and Prevotella albensis were the most abundant species, while Rhodoplanes elegans and Nostocoida limicola dominated AB-PCS. In AC-PCS, R. elegans, Gemmata obscuriglobus, Nitrospira calida, and N. limicola were the most abundant species. The abundance of Bacillus sp., P. veronii, and P. albensis decreased in the contaminated soils, while the abundance of N. calida, Cystobacter sp., Pedomicrobium australicum and Byssovorax cruenta was higher in the contaminated soils. Key genera involved in nutrient cycling such as Clostridium, Bacillus, Prevotella, Pseudomonas, and Arthrobacter, declined in abundance in pesticide exposed soils. In contrast, an increase in abundance of various taxa such as Pedomicrobium, Hyphomicrobiaceae, Pirellulaceae, Comamonadaceae, Nitrospirales, Nitrospira, Anaerolineae, Planctomycetes, Acidobacteriaí and Nitrospirae was observed in the contaminated soils. These bacteria may possess bioremediation potential that could be exploited for environmental remediation. Soil physicochemical properties and nutrient levels varied across the three soil treatments, with potential implications for bacteria community structure.

With the search for alternative pest management strategies due to the concerns associated with synthetic pesticides, botanicals have been of increasing interest. However, the potential of plants such as soybean (Glycine max) as biopesticides is less known. Hence, this study assessed the activity of soybean extract (SBE) on insects and Phytophthora pod rot pathogens of cocoa using the filter paper contact toxicity and amended-agar plate techniques, respectively. Concentrations of 0.001–100% w/v SBE induced a mortality of 17.02–100% on the cocoa mirid Sahlbergella singularis and 2.5–90% and 5.26–100% on the ants Crematogaster africana and Pheidole megacephala, respectively. Also, 0.001–20% w/v SBE inhibited mycelial growth by 0–72% (Phytophthora palmivora isolates) and 1.17–81.03% (Phytophthora megakarya isolates). The minimum inhibitory concentration for P. palmivora and P. megakarya isolates was 1% and 0.001% w/v SBE, respectively. The median lethal concentration was 3.50% (S. singularis) and 193.73% w/v (C. africana), while the median inhibitory concentrations were 4.70 and 7.87% (P. palmivora isolates) and 1.13 and 1.48% (P. megakarya isolates). The activity of SBE on the pests was differential but non-toxic to the ant C. africana. The findings indicate the potential of SBE as a biopesticide against S. singularis and Phytophthora pod rot pathogens of cocoa.

Plants are known to possess antimicrobial properties, as such, their extracts remain potential sources of eco‐friendly antimicrobial products. Extracts from sweet orange have been evaluated as potential antimicrobial sources. However, their activity against pathogens of major agricultural crops such as cocoa is unknown. In this study, the essential oil (EO) of the peel of sweet orange was evaluated against Marasmiellus scandens and Erythricium salmonicolor , the pathogens, respectively, responsible for causing white thread blight and pink disease on cocoa. Minimum Inhibitory Concentration (MIC), IC ₅₀ , IC ₉₀ , and IC ₉₅ against mycelial growth of the pathogens were determined by agar plate tests following 7 days of incubation. Mycelial growths of the two pathogens were completely (100%) inhibited at 10% (w/v) of the EO. The MIC, IC ₅₀ , IC ₉₀ , and IC ₉₅ against M. scandens were 0.1%, 0.25%, 1.23%, and 2.11% while those against E. salmonicolor were 0.01%, 0.13%, 0.75%, and 1.35%, respectively. This study shows that EO of sweet orange peel has antifungal activity against the pathogens. Determining the bioactivity of the individual compounds in the EO and field application of effective formulations in future research has potential for the biological control of these fungal diseases of cocoa.

Pseudotheraptus devastans (Dist.), a coreid bug, feeds on pods causing extensive deformation of the pods and clumping of beans, resulting in reduced yields. This pest was considered important in the 1960s and was more prevalent on hybrid cocoa in the Eastern region of Ghana. With the increase in the use of hybrid planting materials across the entire cocoa landscape in Ghana, information on distribution and population dynamics of the pest is needed to aid effective management. The distribution survey involving 1,740 farms indicated that the pest is present in all the cocoa‐growing regions. P. devastans numbers and associated damage pods were assessed monthly on 35 farms (100 trees per farm) using the visual hand‐height sampling method from 2018 to 2021. The P. devastans population peaked in April, followed by a decline from June with a minor peak in August. Pest numbers and damaged pods were significantly different for the different months but not for the regions. No significant relationship was observed between P. devastans numbers sampled to hand‐height and their associated damage pods. This suggests that damage can occur regardless of the quantity of pests. Regular pest monitoring in cocoa farms is needed to ensure that pest damage is spotted early enough to avoid crop loss since P. devastans numbers do not necessarily correlate with damage.

Modified landscapes could create breeding habitats for mosquitoes and affect their community structure and susceptibility with implications for their management. Hence, in this study, household mosquito control methods in two urbanized landscapes; industrial and residential human settlements, in Ghana and insecticide susceptibility of the inhabiting Anopheles populations were assessed. Household knowledge and usage pattern of mosquito control methods in the modified landscapes were obtained using a questionnaire. Female adult Anopheles mosquitoes were also subjected to susceptibility tests using mosquito coils (0.08% meperfluthrin, 0.03% dimefluthrin, and 0.3% transfluthrin) and World Health Organization (WHO) insecticide test papers (0.05% deltamethrin, 4% DDT, 0.1% bendiocarb, 0.25% pirimiphos‐methyl, and 5% malathion). Although insecticide‐treated nets and aerosols were used for mosquito control, mosquito coils were the most common and widely preferred household method. The Anopheles mosquitoes were resistant to all the insecticides (mosquito coils and WHO test papers) except pirimiphos‐methyl. Land use type did not affect insecticide resistance, but the insecticide type did. The findings indicate the effect of household insecticide usage practices on local mosquito populations and their implications for effective vector management and disease control in modified landscapes.

Shea is an agroforestry tree species known primarily for its rich butter, which contains stearin and tocopherol, and has ultraviolet ray absorption property; it is used in cooking, body care and traditional medicines. This tree is, however, uncultivated and collection of its nuts by rural dwellers is threatened by increased urbanization with its accompanying land use pressure and the need for fuel wood for rural households. There is also increased demand for shea products worldwide necessitating the need for shea improvement strategies. At the apex of this improvement program lies the need for germplasm collection, characterization, conservation and utilization. In order to conserve elite shea materials amidst dwindling shea populations threatened by climate change, there is a need to develop shea germplasm banks based on the representation of genetic and phenotypic variation focusing on known traits. The objective of the study was to evaluate 282 shea accessions for germplasm conservation and to determine the genetic diversity of the collected materials to inform future collections and drive crop improvement strategies. Leaf traits were used to differentiate and group the selected materials. Leaf length ranged between 16.83 cm and 30.85 cm, and leaf blade length ranged between 12.28 cm and 20.68 cm. Petiole length varied between 5.53 cm and 10.2 cm and the blade to petiole ratio was from 1.41 to 2.69. Correlation studies revealed significant negative correlation between the latitude of collection and all leaf traits measured. There was significant positive correlation between blade length and petiole length (0.57), blade length and total leaf length (0.87) and petiole length and breadth (0.49). The collected materials were grouped at 90% into two, based on the morphological descriptors studied. Three different approaches were employed to genetically analyze the materials based on single nucleotide polymorphic markers (SNP). A phylogenetic tree was constructed based on the SNPs generated; this grouped the materials into three, with various subgroups. Principal coordinate analysis also produced three distinct groups with groupings not based on geographical area of collection. Discriminant analysis of principal components (DAPC) also confirmed three groupings. The genetic diversity of the collection was very low (Hs) = 0.0406, which is an indication of potential inbreeding within the shea populations. To conclude, there was higher variation within locations than between locations.

Cola nitida (Kola) is an important cash crop cultivated in the forest areas of West Africa. The crop is attacked by a lot of insect pests, chief among them are the kola seed weevil, Balanogastris kolae, and some Sophrorhinus pest species. Not much is known about the pest status of fruit fly species on the crop, especially Bactrocera invadens and Ceratitis colae which is known to feed exclusively on the crop. This study seeks to assess the incidence, population dynamics and damage caused by insect pests on kola in the middle belt of Ghana to inform pest management decisions. The major insect pests identified on kola in the study include the kola seed weevils Balanogastris kolae, Sophrorhinus spp and fruit fly species Bactrocera invadens, Ceratitis colae and other Ceratitis spp. There was a significant locational effect on the number of fruit fly species trapped. The kola nut weevils (Balanogastris kolae and the Sophrorhinus species) remain the most important kola pests accounting for 81.4% of the sampled damaged pods. Information obtained from the population dynamics of these kola insect pests could aid in the development of an integrated strategy for managing these pests on the crop.