Insecticidal and Genotoxic effects of some indigenous plant extracts in Culex quinquefasciatus Say Mosquitoes.

Five different weed plants viz. Convulvulus arvensis, Chenopodium murale, Tribulus terrestris, Trianthema portulacastrum, and Achyranthes aspera were investigated for their entomocidal and genotoxic effects against Culex quinquefasciatus mosquitoes. High mortality was observed at 72 hours in a dose dependent manner. Among all the tested plants, A. aspera was found highly significant which showed 100% mortality at 250 ppm after 72 hours with LC50 of 87.46, 39.08 and 9.22 ppm at 24, 48, respectively. In combination with Bacillus thuringiensis israelensis (Bti); A. aspera also caused 100% mortality at 250 ppm concentration after 72 hours (LC50 8.29 ppm). Phytochemical analysis of all the tested weed plants showed the presence of flavonoids, saponins, tannins, steroids, cardiac glycosides, alkaloids, anthrequinones and terpenoids. Random Amplification of Polymorphic DNA-Polymerase chain reaction (RAPD-PCR) and comet assay were performed to assess the genotoxic effect of A. aspera but no change in DNA profile was observed. Furthermore, FTIR showed the presence of phenolic compounds in A. aspera extract. It is suggested that certain phenolic compounds such as flavonoids modulate the enzymatic activity and, hence, cause the death of larvae of Cx. quinquefasciatus. Altogether, current study would serve as an initial step towards replacement of synthetic insecticides to plant-microbe based biopesticide against Culex mosquitoes in future.

Insecticidal, biological and biochemical response of Musca domestica (Diptera: Muscidae) to some indigenous weed plant extracts.

In the current study; insecticidal, growth regulation, oviposition deterrence and repellency of petroleum ether extracts of Azadirachta indica, Penganum harmala, Datura stramonium, Tribulus terrestris and Chenopodium murale against 2nd instar larvae of housefly was investigated. Five different concentrations (5%, 10%, 15%, 20% and 25%) were used through larval feeding and the mortality data was recorded after 24, 48 and 72 hrs. Highest mortality was induced by P. harmala (63.87%) followed by D. stramonium (62.78%), A. indica (53.84%), T. terrestris (41.86%) and C. murale (4.09%) after 72 h at 25% concentration, respectively. Increased mortality was observed with increased time duration and concentration. Longest larval duration (9.33 ±â€¯0.33 days) and pupal duration (7.33 ±â€¯0.33 days) days) was recorded in larvae treated with 25% concentration of P. harmala which also caused a decrease in the activity of AChE, ACP, AKP, α-Carboxyl, and ß-Carboxyl enzymes. However, at 25% concentration, C. murale showed highest oviposition deterrence activity (81.88%) followed by D. stramonium (79.58%). In comet assay test, at highest concentration (25%) the mean comet tail lengths represented by Penganum harmala, Datura stramonium and Azadirachta indica (Reference plant) were 10.20 ±â€¯0.49, 9.20 ±â€¯0.37 and 7.80 ±â€¯0.49 µm while percent DNA damage was 10.56 ±â€¯0.77, 10.67 ±â€¯1.62 and 8.11 ±â€¯0.85% respectively compared to controls cells. Phytochemical analysis indicated the presence of flavonoids, steroids, saponins, cardiac glycosides, tannins, alkaloids, terpenoids and anthraquinones. Fourier Transform Infrared spectroscopy (FTIR) analysis revealed the presence of phenolic flavonoids, saponins, tannins as major functional groups. Further studies are needed to explore and thus, to incorporate weed plant extracts for the management of house flies.