Nanoparticle-mediated dsRNA delivery for precision insect pest control: a comprehensive review.

Nanoparticle-based delivery systems have emerged as powerful tools in the field of pest management, offering precise and effective means of delivering double-stranded RNA (dsRNA), a potent agent for pest control through RNA interference (RNAi). This comprehensive review aims to evaluate and compare various types of nanoparticles for their suitability in dsRNA delivery for pest management applications. The review begins by examining the unique properties and advantages of different nanoparticle materials, including clay, chitosan, liposomes, carbon, gold and silica. Each material's ability to protect dsRNA from degradation and its potential for targeted delivery to pests are assessed. Furthermore, this review delves into the surface modification strategies employed to enhance dsRNA delivery efficiency. Functionalization with oligonucleotides, lipids, polymers, proteins and peptides is discussed in detail, highlighting their role in improving stability, cellular uptake, and specificity of dsRNA delivery.This review also provides valuable guidance on choosing the most suitable nanoparticle-based system for delivering dsRNA effectively and sustainably in pest management. Moreover, it identifies existing knowledge gaps and proposes potential research directions aimed at enhancing pest control strategies through the utilization of nanoparticles and dsRNA.

Mosquitocidal and water purification properties of Cynodon dactylon, Aloe vera, Hemidesmus indicus and Coleus amboinicus leaf extracts against the mosquito vectors.

Ethanolic extracts of Cynodon dactylon, Aloe vera, Hemidesmus indicus and Coleus amboinicus were tested for their toxicity effect on the third-instar larvae of Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti. The leaves of C. dactylon, A. vera, H. indicus and C. amboinicus were collected from natural habitats (forests) in Western Ghats, Tamil Nadu, India. A total of 250 g of fresh, mature leaves were rinsed with distilled water and dried in shade. The dried leaves were put in Soxhlet apparatus and extract prepared using 100% ethanol for 72 h at 30-40°C. Dried residues were obtained from 100 g of extract evaporated to dryness in rotary vacuum evaporator. Larvicidal properties of ethanolic leaf extracts showed that the extracts are effective as mosquito control agents. The larval mortality was observed after 24 h exposure. No mortality was observed in the control. The median lethal concentration (LC(50)) values observed for the larvicidal activities are 0.44%, 0.51%, 0.59% and 0.68% for extracts of C. dactylon, A. vera, H. indicus and C. amboinicus, respectively. The observed mortality were statistically significant at P < 0.05 level. C. dactylon showed the highest mortality rate against the three species of mosquito larvae in laboratory and field. The selected plants were shown to exhibit water purification properties. Water quality parameters such as turbidity, pH and water clarity were analyzed in the water samples (pre-treatment and post-treatment of plant extracts) taken from the different breeding sites of mosquitoes. Water colour, turbidity and pH were reduced significantly after treatment with C. dactylon (13 HU, 31.5 mg/l and 6.9), H. indicus (13.8 HU, 33 mg/l and 7.1), A. vera (16 HU, 33.8 mg/l and 7.4) and C. amboinicus (21 HU, 35 mg/l and 7.5) extracts. The study proved that the extracts of C. dactylon, A. vera, H. indicus and C. amboinicus have both mosquitocidal and water sedimentation properties.

Larvicidal and pupicidal activity of spinosad against the malarial vector Anopheles stephensi

OBJECTIVE@#To investigate the larvicidal and pupicidal activity of spinosad against Anopheles stephensi Listen.@*METHODS@#Spinosad from the actinomycete, Saccharopolyspora spinosa was tested against Anopheles stephensi at different concentrations (0.01, 0.02, 0.04, 0.06 and 0.08 ppm.), and against first to fourth instar larvae and pupae.@*RESULTS@#The larval mortality ranged from 36.1±1.7 in (0.01 ppm) to 79.3±1.8 (0.08 ppm) the first instar larva. The LC(50) and LC(90) values of first, second, third and fourth instar larva were 0.001, 0.031, 0.034, 0.036 and 0.0113, 0.102, 0.111, 0.113, respectively. The pupal mortality ranged from 33.0±2.0 (0.01 ppm) to 80.0±0.9 (0.08 ppm). The LC(50) and LC(90) values were 0.028 and 0.1020, respectively. The reduction percentage of Anopheles larvae was 82.7%, 91.4% and 96.0% after 24, 48, 72 hours, respectively, while more than 80% reduction was observed after 3 weeks.@*CONCLUSIONS@#In the present study spinosad effectively caused mortality of mosquito larvae in both the laboratory and field trial. It is predicted that spinosad is likely to be an effective larvicide for treatment of mosquito breeding sites.