MSc

The study entitled “Oil based formulation of Andrographis paniculata (Burm.f.) Nees against sucking pests of chilli” was conducted during 2017-2019, in the Department of Agricultural Entomology, College of Agriculture, Vellayani with objectives to develop oil based ready to use formulation of A. paniculata, to study the shelf life and to fix optimum dose for the management of the sucking pest complex of thrips (Scirtothrips dorsalis Hood), aphids (Aphis gossypii Glover) and mites (Polyphagotarsonemus latus Banks) in chilli.
Different combinations of extract of A. paniculata, oils and surfactants were tested in the laboratory for finding the suitable surfactant and their effective combination. Extract oil surfactant combination (EOSC) in the ratio of 7:2:1 was found to be the suitable combination with good miscibility and Triton X-100 as most suitable surfactant. Laboratory evaluation of various concentrations (5, 10 and 20%) of the different oil based combinations with EOSC ratio 7:2:1 was done using aphids, thrips and mites as test insects.
Results of the laboratory experiment revealed that extract of A. paniculata + neem oil + Triton X-100 and extract of A. paniculata + pongamia oil + Triton X-100 at 5% concentration was sufficient for 100 per cent mortality of aphids at 24 hours after treatment (HAT) and it was statistically on par with 5% concentration of extract of A. paniculata + castor oil + Triton X-100. The above mentioned treatments gave 100 per cent mortality against thrips and mites also. Lower concentrations (1, 2, 3 and 4%) of the above mentioned three treatments were selected for further evaluation against aphids. It was found that pongamia oil based combination at 4% gave 100 per cent mortality at 24 HAT.
A pot culture experiment was carried out in chilli variety Vellayani Athulya with the selected three effective treatments to assess the field efficacy against sucking pest complex. Different concentrations (1, 2, 3, 4, 5, 7, 10, 15 and 20%) of the above selected treatments were evaluated with thiamethoxam 25% WG and spiromesifen 22.9% SC as chemical check. Two rounds of spraying viz., 30 and 60 days after planting (DAP) of the crop were undertaken.
In pot culture experiment lowest population of chilli aphids, thrips and mites were recorded at 5% concentration of extract of A. paniculata + pongamia oil + Triton X- 100 sprayed chilli plants and the effects were on par with chemical check thiamethoxam 25% WG and spiromesifen 22.9% SC.
The per cent reduction in the thrips population was 98.97, 97.94 and 97.94 over control at 5% concentration of pongamia, neem and castor based formulation respectively at 3 days after treatment (DAT) in vegetative stage of chilli. The population of aphids was found to be least in the treatments with 5% concentration of pongamia based formulation at 3 and 5 DAT which did not vary significantly with neem and castor based formulation at 5% concentration and these treatments were also on par with chemical check thiamethoxam 25% WG and spiromesifen 22.9% SC. It was observed that there was significant reduction in the mites population in pongamia based formulation at 5% concentration which recorded 90.16 per cent over control at 3 DAT.
At second spraying, 5% concentration of castor, neem and pongamia based formulation were found to be superior in managing chilli thrips and as effective as chemical check thiamethoxam 25% WG and spiromesifen 22.9% SC in the reproductive phase of the crop. At 3 DAS, castor, neem and pongamia based formulation had low population of 0.44. 0.33 and 0.44 thrips leaf-1 at 5% concentration which were on par with chemical check. The aphid population were controlled effectively by 5% concentration of pongamia based formulation upto seven DAT. Pongamia formulation at 5% concentration gave good control upto seven DAT with 0.33 aphids leaf-1 as against 45.00 aphids leaf-1 in control. Neem and castor based formulation at 5% concentration were found to be the next effective treatments against chilli aphids. At 3 DAT, pongamia and neem based formulation showed 90.34 and 88.93 per cent reduction in the mite population respectively over control at 5% concentration and were found to statistically on par with chemical check.
Significant difference in leaf curl index was recorded 100 days after planting in treatments compared to control. Pongamia oil based combination at 5% concentration recorded lowest leaf curl index value (2.00) as against 3.20 in control.
Higher number of natural enemies including coccinellid beetles and spiders; pollinators and neutrals were recorded in all treatments compared to thiamethoxam 25% WG and spiromesifen 22.9% SC.
Shelf life studies of pongamia based formulation revealed that the bio pesticide formulation is effective upto 60 days after preparation.
From the study it can be concluded that Triton X-100 is the best surfactant for the development of oil based formulation of A. paniculata. The treatment with extract of A. paniculata + pongamia oil + Triton X-100 at 5% concentration found to be effective against sucking pest complex with lowest leaf curl index. Shelf life studies were revealed that 5% concentration of pongamia oil based formulation was highly effective upto 60 days after preparation. It can be recommended as an eco-friendly bio pesticide formulation for the management of sucking pest complex in chilli.