Category Archives: Publications

With the increasing world population, identifying additional food sources is crucial. Mushrooms have long been considered a nutraceutical and are consumed globally, including in Sri Lanka. Due to its abundant biodiversity, there is a significant potential for diverse wild edible mushrooms in Sri Lanka. However, the identification of these mushrooms based on morphological characteristics can often be misleading. Molecular characterization ensures more accurate and reliable identification of mushrooms, yet it has not been conducted extensively in Sri Lanka. This study collected several wild edible mushroom samples from Colombo and Rathnapura Districts of Sri Lanka. The edibility of these wild edible mushrooms was confirmed based on traditional knowledge and later verified by published literature. Phylogenetic analyses based on maximum likelihood (ML) analyses of ITS rDNA sequence data and morphological characteristics were used to determine the identity of the collected mushrooms. In this study, six edible mushrooms, Calvatia candida, Pleurotus giganteus, Schizophyllum radiatum, Termitomyces heimii, T. microcarpus, and Volvariella volvacea were identified based on morphology and phylogeny. Calvatia candida and S. radiatum are reported as new records for Sri Lanka, while this is the first study conducted on molecular characterization of V. volvacea in Sri Lanka. Finally, this study aims to increase the research interest, cultivation, commercialization, and conservation of these identified edible mushrooms in Sri Lanka.

Metarhizium, a globally distributed genus, showcases adaptability to various habitats, predominantly in soil or intricate relationships as insect pathogens. Metarhizium spp. have become focal points in recent entomopathogenic fungal research due to their limited host range, safety profile, environmental friendliness, and scalability in mass production. Remarkably, certain Metarhizium species exhibit dual efficacy against both insect pests and plant pathogens, indicating their potential in biocontrol strategies for crop protection. This review underscores the practicality of Metarhizium species, particularly in their role as insect pathogens. Their crucial role in controlling harmful insect populations and addressing agricultural and health concerns through innovative biocontrol strategies was also emphasised. We identified that 11 Metarhizium species are currently employed worldwide as bioinsecticides. These species include Metarhizium acridum, M. anisopliae, M. brunneum, M. flavoviride, M. majus, M. humberi, M. guizhouense, M. novozealandicum, M. pemphigi, M. pingshaense, and M. rileyi. Among them, the most utilised species is M. anisopliae. Commercialisation of Metarhizium species as biological control agents was explored, showcasing their mass production methods and application in managing various insect pests. An updated multi-locus phylogenetic analysis based on a concatenated SSU, LSU, tef1, rpb1, and rpb2 sequences of Metarhizium species was performed to show their phylogenetic relationships. The review concludes with insights into modern biotechnological approaches, including genetic transformations, and integrated applications combining chemical products and entomopathogens to enhance effectiveness.

https://www.tandfonline.com/doi/full/10.1080/0028825X.2024.2325006

The use of household insecticides in the formulation of mosquito coils and vaporizers is common among the public to protect against mosquito-borne diseases. However, information regarding the use of these commonly practiced household insecticides is scarce in Sri Lanka. A questionnaire-based survey was directed to 600 households in Colombo, Gampaha, Kandy, Kalutara, Jaffna, and Galle districts in Sri Lanka. Household insecticides were used by the majority of the respondents (57.0%), and electric liquid vaporizers (46.7%) and mosquito coils (45.7%) were the commonly used forms. The active ingredients in mosquito coils were d-trans-allethrin (w/w 0.12%), metofluthrin (w/w 0.005%), and dimefluthrin (w/w 0.01%); in liquid vaporizers, they were prallethrin (w/v 1.24% and w/v 1.26%) and transfluthrin (w/v 0.9%). The majority of the household insecticide consumers were moderately satisfied with the effectiveness of the products (68.6%), and most of the participants used household insecticides daily (35.5%), especially during the evening (41.6%). Most of the consumers were unaware of the chemicals included in household insecticides (62.8%). Mosquito coils were abundantly used by rural area participants (75.8%), whereas liquid vaporizers were the most common among the urban participants (56.4%). The findings indicate that demographic and socioeconomic factors influence household insecticide practices. To our knowledge, this study reveals the use of household insecticides to control mosquitoes for the first time in Sri Lanka and highlights the importance of awareness programs and the proper utilization of these products.

Background

The unplanned and intensified use of insecticides to control mosquito-borne diseases has led to an upsurge of resistance to commonly used insecticides. Aedes aegypti, the main vector of dengue, chikungunya, and Zika virus, is primarily controlled through the application of adulticides (pyrethroid insecticides) and larvicides (temephos). Fine spatial-scale analysis of resistance may reveal important resistance-related patterns, and the application of mathematical models to determine the phenotypic resistance status lessens the cost and usage of resources, thus resulting in an enhanced and successful control program.

Methods

The phenotypic resistance for permethrin, deltamethrin, and malathion was monitored in the Ae. aegypti populations using the World Health Organization (WHO) adult bioassay method. Mosquitoes’ resistance to permethrin and deltamethrin was evaluated for the commonly occurring base substitutions in the voltage-gated sodium channel (vgsc) gene. Rational functions were used to determine the relationship between the kdr alleles and the phenotypic resistant percentage of Ae. aegypti in Sri Lanka.

Results

The results of the bioassays revealed highly resistant Ae. aegypti populations for the two pyrethroid insecticides (permethrin and deltamethrin) tested. All populations were susceptible to 5% malathion insecticide. The study also revealed high frequencies of C1534 and G1016 in all the populations studied. The highest haplotype frequency was detected for the haplotype CC/VV, followed by FC/VV and CC/VG. Of the seven models obtained, this study suggests the prediction models using rational approximation considering the C allele frequencies and the total of C, G, and P allele frequencies and phenotypic resistance as the best fits for the area concerned.

Conclusions

This is the first study to our knowledge to provide a model to predict phenotypic resistance using rational functions considering kdr alleles. The flexible nature of the rational functions has revealed the most suitable association among them. Thus, a general evaluation of kdr alleles prior to insecticide applications would unveil the phenotypic resistance percentage of the wild mosquito population. A site-specific strategy is recommended for monitoring resistance with a mathematical approach and management of insecticide applications for the vector population.

https://link.springer.com/article/10.1186/s13071-023-06100-9