Field Efficacy of Biopesticides Against Plusia signata (Fabricius) on Gloriosa superba

Field experiments were carried out in the Department of Medicinal and Aromatic Crops, Tamil Nadu Agricultural University, Coimbatore and in the farmer’s holdings at Vellipalayam from August, 2011 to December, 2011 to study the field efficacy of bio-pesticides against Plusia signata (Fabricius) on Gloriosa superba . The results of the experiments revealed that flavanoids recorded superiority in the management of P. signata starting from 3 rd day after treatment and it was statistically on par with quinalphos. Pungam oil 3 ml/litre was next in the order of efficacy, followed by azadirachtin 1% and NSKE 5%. Efficacy of Bacillus thuringiensis ( Bt ) (2 ml/lit) was realized only at seven days after treatment and persisted even after 14 days of second spray. At 14 days after treatment, Bt was second in the order of efficacy next to chemical pesticides and flavanoids. From the findings of both the field trials, flavanoids (Max Ranger-D2 ® ) from Maxgrow Biotech (P) Ltd, Ludhiana was adjudged and recommended as the best alternative to chemical pesticides in gloriosa eco-system and are recommended as one of the components in organic pest management.

Glory lily, Gloriosa superba (Linnaeus) (Family : Liliaceae) is an important medicinal crop that originated from tropical Asia and Africa. It is the state flower of Tamil Nadu.It is a medicinal plant of immense value in the traditional systems of medicine in India. The seeds are of economic value and possess many medicinal and curative properties.The seeds contain alkaloid called colchicine and thiocolchicocide (Chaudari and Thakur, 1998). In Ayurveda and Unani systems of medicine, the tuber of the plant was well known due to its pungent, bitter, acrid, heating, antihelminthic, laxative, alexiteric and abortifacient nature. It was widely used in the treatment of gout, ulcers, leprosy, piles, inflammations, abdominal pains, intestinal worms, thirst, bruises, infertility and skin problem (THDC, 2002). According to Lyla et al. (1992), severe incidence of Polytela gloriosae was noticed on G. superba in the garden at the College of Horticulture, Vellanikara, Kerala during October-November, 1989. Rathikannu (2005 recorded lily caterpillar, Polytela gloriosae (Fabricius), semilooper, Plusia signata (Fabricius) and tobacco cutworm, Spodoptera litura (Fabricius) in G. superba apart from the natural enemies viz., spiders, Oxyopus sp and ladybird beetle, Chilomenes sexmaculatus (Fabricius).
Neem is a rich source of insecticide in the tropics and its potential for the management of several insect pests. The unique properties of the toxic principles from the seeds of Meliaceae are repellent, antifeedant and insect growth regulation combined with low cost, local availability, safety to the environment and compatibility with the agroecosystem which emphasize their potential in insect pest management. The efficacy of all neem products was observed by Karmarkar and Bhole (2000) and several field studies on the efficacy of neem based insecticides have been conducted by many workers (Sarode et al., 1995;Bhatnagar and Sharma, 1995;Rao et al., 1993;Gowri et al., 2002;Rathikannu, 2005). Shankar et al. (1993) reported that Bt formulation was found to be superior over the conventional insecticides and pyrethroids for the management of H. armigera. Hence, the present study was undertaken to test the field efficacy of bio-pesticides and flavanoids against P. signata infesting G. superba.

Materials and Methods
Field trials were carried out in the Department of Medicinal and Aromatic Crops, Tamil Nadu Agricultural University (TNAU), Coimbatore and in the farmer's holdings at Vellipalayam, Coimbatore during August, 2011 to December, 2011 to assess the efficacy of selected bio-pesticides and flavanoids against P. signata on G. superba. The experiments were conducted in randomized block design (RBD) with seven treatments and three replications (Table  1). G. superba was sown at a spacing of 60×45 cm. Recommended packages of practices were followed to raise good crop. Two rounds of sprays were given at 15 days interval. Pre-treatment count on pest population was taken before spraying. Post-treatment counts were taken at 1, 3, 5, 7 and 14 days after spraying. Fourteenth day count was taken as pre-treatment count for the second spray. Ten plants were selected at random from each plot and the larval count was recorded and expressed as number per plant. (* Flavanoids -Distilled purified flavanoids (6 %), Adjuvant spreader (42 %), Surfactant (22 %), Aqua (30 %)) The data from field trials were analyzed following the procedure described by Panse and Sukatme (1969).

Results and Discussion
Results of the field experiment conducted in the farmer's holdings at Vellipalayam revealed that the pre-treatment count on larval population ranged from 2.4 to 2.6 larvae per plant. At one day after spraying there was no significant difference among the treatments in the larval population except flavanoids and standard check quinalphos, which registered 2.10 and 2.07 larvae per plant, respectively. Similar trend was observed on 3 rd day after treatment (DAT) also. At 5 DAT, significant population reduction was observed in all the treatments except Bt. Significant reduction in larval population was observed in flavanoids and quinalphos treated plots which recorded 0.27 and 0.20 larvae per plant, respectively at 5 DAT. At 7 DAT, cent per cent reduction in larval population was observed in flavanoids and quinalphos treatments followed by pungam oil, azadirachtin and neem seed kernel extract with a larval population of about 0.67, 0.87 and 0.97 larvae per plant respectively. Results of earlier studies 369 suggest that spraying with NSKE 5% reduced the damage by P. signata to an extent of 35.92 to 45.83 per cent (Rathikannu, 2005). At 14 DAT, significant reduction in larval population was observed in Bt treated plots with a larval population of about 0.87 larvae per plant (Table 1).
Pre-treatment population count during second spraying ranged from 0.0 to 1.3 larvae per plant. There was no larval population in flavanoids and quinalphos treated plots during pre-treatment count of the second spray. There was no significant difference in the larval population of other treatments at one day after spraying. Similar trend was observed at third day after second spray also. At 5 DAT, significant reduction in larval population was observed in all the plots. Significant population reduction was observed in pungam oil (0.80 larvae per plant), azadirachtin (0.83 larvae per plant) and neem seed kernel extract (0.90 larvae per plant). At 7 DAT, significant reduction in larval population was observed in Bt treated plot (0.43 larvae per plant) followed by pungam oil (0.60 larvae per plant), azadirachtin (0.63 larvae per plant) and neem seed kernel extract (0.67 larvae per plant). At 14 days after second spraying, significant reduction in larval population was observed in Bt treated plots with a larval population of about 0.27 larvae per plant. Reduction in the larval population of P. signata in flavanoids treated plot was found to be on par with the standard chemical check quinalphos (Table 1). Experimental results of the field trial conducted in the Department of Medicinal and Aromatic Crops, TNAU, Coimbatore revealed that the pre-treatment larval count ranged from 4.20 to 4.73 larvae per plant (Table 2). There was no significant reduction in larval population at one day after spraying. At 3 DAT, significant larval reduction was observed in flavanoids and quinalphos treated plots, with the larval population of 0.67 and 0.57 larvae per plant, respectively. At 7 DAT, flavanoids and quinalphos treated plots recorded cent per cent larval population reduction, followed by pungam oil (1.67 larvae per plant), azadirachtin (1.80 larvae per plant) and neem seed kernel extract (2.23 larvae per plant). At 14 DAT, Bt treated plots recorded significantly less number of P. signata (1.27 larvae per plant), as against 6.03 larvae per plant in untreated control plots. Flavanoids and quinalphos treated plots were completely free from the population of P. signata (Table 2).
Pre-treatment count on larval population before second spraying ranged from 0.0 to 6.03 larvae per plant. At 1, 3 and 5 DAT, flavanoids and the chemical check, quinalphos recorded their superiority by  Table 2). The results were in accordance with the findings of Ramprasad et al. (1998), who reported that NSKE 5% was found to be effective as fenvalerate (0.01%) against S. litura. Rathikannu (2005) reported that spraying of NSKE 5% was better in reducing the damage by semilooper, P. signata to an extent of 35.92 to 45.83 per cent followed by NEEMAZAL T/S 1% 900 ml ha -Hence, it is concluded that flavanoids are highly comparable with chemical pesticides in the management of semilooper infesting G. superba. Thus, flavanoids are adjudged as the best alternative to the chemical pesticides in gloriosa eco-system and are recommended as one of the components in organic pest management for P.signata.