MSc

The study on “Oil based biopesticide from Andrographis paniculata (Burm.f.) Nees against sucking pests of cowpea” was conducted at College of Agriculture, Vellayani during 2018 to 2020 with an objective to develop oil based ready to use formulations against sucking pests of cowpea and to evaluate the formulation for its efficacy. In vitro screening of different oil-based formulations of A. paniculate with EOS ratio of 7:2:1 was done using Aphis craccivora as test insect. 1, 2, 3 and 5% concentration of formulations comprising plant extract of A. paniculata +neem oil + Triton -X-100, plant extract of A. paniculata +pongamia oil+ Triton-X-100, plant extract of A. paniculata + Triton -X-100, Neem oil+ Triton -X-100 + Water (2:1:7)(check) and Pongamia+Triton -X-100 + Water (2:1:7) (check) were sprayed directly over aphids and observation for percentage mortality were recorded at 1, 3, 5 and 7 days after spraying.
Results of the laboratory experiment revealed, oil-based formulations of neem at 1% concentration recorded 75.00% mortality of aphidsat1 day after treatment (DAT). Mortality at 3 DAT was 95.00%and 5 and 7 DAT were 100.00%. At 2% concentration of formulations, neem-based formulation exhibited 100% mortality within 24 hours and pongamia based formulation exhibited 100.00% mortality within 5 days after treatment application. At 7 DAT, plant extract of A. paniculata + Triton -X-100 exhibited 100.00% mortality. At 3% concentration of oil-based formulations, neem-based formulation exhibited 100.00% mortality within 24 hours and pongamia based formulation within 72 hours. Plant extract of A. paniculata + Triton -X-100 and pongamia oil + Triton -X-100 exhibited 100.00% mortality at 5 DAT. At 5% concentration of formulations, both neem and pongamia based formulations of A. paniculata exhibited 100.00% mortality within 3 day after treatment and rest of treatments also recorded cent percentage mortality.
A pot culture experiment was carried out in cowpea variety Geethika with two superior treatments to assess the field efficacy against sucking pests. 1, 2, 3, 5 and 6% concentrations of the selected treatments were evaluated with neem oil 2% and thiamethoxam 25% WG as checks. Pre count of pest and natural enemies were documented and a single round of spraying was undertaken at the vegetative phase of crop i.e., 30 DAP. In field evaluation, at 1 DAT, least population of aphids were recorded at 6% concentration of extract of A. paniculata + neem oil + Triton X- 100 and extract of
A. paniculata + pongamia oil + Triton X- 100 sprayed cowpea plants and the results were statistically on par with 5% concentration of extract of A. paniculata + pongamia oil + Triton X-100, 3 and 5% concentration of A. paniculata + neem oil + Triton X-100 and chemical check thiamethoxam 25% WG. Neem oil-based formulation at 3 and 5% concentration recorded least population (0.00 per plant) at 3 DAT. No aphids were observed in plants treated with neem-based formulation (2%) and pongamia based formulation at 3 and 5% on 5th day of treatment. Plants treated with 2% concentration of pongamia based formulation recorded zero population of aphids at 7 DAT while recurrence of aphids was observed in plants treated with neem oil (2%).
Post count of natural enemies viz. syrphids and coccinellid beetles were recorded in all treatments and compared with botanical and chemical check at interval of 1, 3, 5 and 7 DAT. Control plot recorded maximum and chemical check recorded minimum population of natural enemies.
On evaluating the biometric characters, highest pod weight of 49.16 g plant-1 was obtained in 5% concentration of pongamia based formulation. Phytotoxicity studies using treatments like plant extract of A. paniculata + neem oil + Triton X-100, plant extract of A. paniculata + pongamia oil + Triton X-100 and plant extract of A. paniculata + Triton X-100 at 1, 2, 3, 5, 10 and 20 % concentration were carried out and observations for symptoms including yellowing, scorching, necrosis, epinasty and hyponasty were made and graded according to CIBRC (Central Insecticides Board and Registration Committee) protocol. Results revealed that oil-based formulations of A. paniculate does not produce any kind of phytotoxic response on cowpea within a range of 1- 20% concentration.
From the above findings it was concluded that for ecofriendly management of sucking pests of cowpea, efficacy of oil-based formulations comprising Andrographis paniculata + neem oil+ Triton-X-100 (7:2:1) at a concentration of 6% was on par with the chemical treatments when applied at fortnightly intervals.