Bio-Efficacy of Agro Clean, A Bioproduct Against Sucking Insect Pests of Bt Cotton

An experiment was conducted during two consecutive kharif seasons of 201314 and 2014-15 in order to evaluate the bio-efficacy of agro clean, a bioproduct @ 1, 2, 3 and 4% along with NSKS @ 5% and imidacloprid 17.8 SL @ 0.008% as standard check against sucking insect pests of Bt cotton. The results of the field efficacy experiment showed that the standard check, a synthetic insecticide imidacloprid 17.8 SL @ 0.008% was found highly effective in reducing the population of aphid, leaf hopper, thrips and whitefly in cotton followed by biopesticides, agro clean @ 3 and 4%. The seed cotton yield was also recorded significantly the highest in imidacloprid 17.8 SL @ 0.008 (31.05 q/ha) followed by agro clean @ 4% (28.32 q/ha) and agro clean @ 3% (26.90 q/ha). Considering the results of bio-efficacy and yield, agro clean, a bioproduct of M/s Shukla Ashar Impex Private Limited, Rajkot @ 3 and 4% was found effective against major sucking pests in Bt cotton.


INTRODUCTION
Cotton is an important commercial crop, designated as 'king of fibre crops' and is prone to insect pests attack at various stages of crop growth. World total cotton production was 120.97 million bales from the 34.35 million hectares of total cultivated area and 767 kg/hectare productivity in 2012-13 (Anon., 2013. Among the variety of reasons of low yield, the magnitude of insect-pests, which damage (average 5-10 percent) the cotton crop from sowing to maturity, plays an important role. The severe attack of insect pests causes heavy qualitative and quantitative yield losses varying from 40-50 per cent (Naqvi, 1976). India is the third largest consumer of pesticides in the world and highest among the South Asian countries. Insecticides account for 60% of total pesticides consumed in India, out of which natural pesticides (including botanicals) consumption is a meagre 2% (Agnihotri, 2000). Botanicals are now emerging as a viable component of integrated pest management (IPM) strategies for all crops due to their efficacy to managing pests, environmental and public health safety, eco-friendly nature and cost effectiveness. Botanical pest control is a distinct possibility in subtropical countries which are endowed with the biodiversity of such plants. Introduction of synthetic pyrethroids resulted in resurgence of sucking pests in cotton especially the whitefly, Bemisia tabaci Gennadius (Ajri et al., 1986 andPatil et al., 1986). Introduction of Bt cotton, resulted in the suppression of major bollworms like Helicoverpa. However, year after year, the infestation of sucking pests is in increasing trend. A wide range of insecticides have proved as effective weapons in reducing the pest population. However, negligence of the principles in the crop protection, indiscriminate and extensive use of synthetic pesticides led to problems like insecticidal resistance, pest resurgence and destruction of natural enemies. Therefore, to overcome the above problems, discovery of new bioproduct is essential which are effective and have least exposure in the environment. Some plant products have pesticide properties against sucking pests (Parmar, 1995;Schmutterer and Singh, 1995;Haris, 2001). Chemical pest control agents are extensively used in all countries of the world but they are regarded as ecologically unacceptable. Therefore, there is an increased social pressure to replace them gradually with biopesticides which are safe to humans and non-target organisms. The harmful environmental implications of the synthetic chemicals have compelled to search for some alternative methods. This leads to increased development of compounds based on the models of naturally occurring toxins of biological origin, having various biological activities. Biopesticides include a broad array of microbial pesticides, biochemical derived from micro-organisms and other natural sources and processes involving the genetic modification of plants to express genes encoding insecticidal toxins. In view of this, an attempt was made to determine the bio-efficacy of agro clean, a bioproduct at various doses against sucking insect pests of Bt cotton.
Agro Clean, a product of M/s. Shukla Ashar Impex Private Limited, Rajkot is fundamentally an augmented bio-remediation technology derived from a relatively new field of advanced materials science known as organic colloidal chemistry. Using proprietary manufacturing process, renewable, sustainable plant and vegetable oils are blended to create a truly eco-friendly particle that is too small and able to penetrate and emulsify complex organic molecules quickly and easily. Agro Clean makes impacts on the pest by disrupting the molecular structure of chitin and other protein substances those protect insect. This action triggers the rapid deterioration of the insect spiracles and tracheal system resulting in suffocation. Agro clean has a favourable mammalian toxicity coupled with a low toxicity to beneficial insects and predatory mites. As such, it is considered an important addition in pest management programmes in various agricultural systems for controlling the diversity of sucking pests.

MATERIALS AND METHODS
Field experiment was conducted at Agronomy farm, B. A. College of Agriculture, AAU, Anand during two consecutive kharif seasons of 2013-14 and 2014-15 in Randomized Block Design with seven treatments and three replications to determine the bio-efficacy of agro clean, a bioproduct at various doses against sucking insect pests infesting Bt cotton (RCH-2 BG-II). The treatments are agro clean (agro clean @ 1, 2, 3 and 4%) and two standard checks viz., Neem Seed Kernel Suspension (NSKS) @ 5% and imidacloprid 17.8 SL @ 0.008%. The respective chemical treatments were sprayed on cotton as and when sucking insect pest population reached to ETL using knapsack sprayer with high volume fitted hollow cone nozzle. Altogether, four applications were made at 15 days intervals during both the seasons. The observations on population of sucking pests (Aphis gossypii Glover, Amrasca biguttula biguttula Ishida, B. tabaci and Thrips tabaci Lindeman) were recorded on five plants selected randomly in each plot. On each plant, three leaves were selected randomly from top, middle and bottom canopy and population counts were made before the first spray as well as on 5, 10 and 15 days after each spray. Seed cotton yield was also recorded plotwise and converted in to q/ha. The data on populations of the sucking pests were subjected to square root transformation before statistical analysis following Gomez and Gomez (1984) to test the significance of treatment effects.

RESULTS AND DISCUSSION Effect on aphid, A. gossypii
The pooled mean data on aphid population during 2013-14 and 2014-15 was uniform in all the treatments before first spray as treatment difference was non-significant ranging from 12.24 to 12.53/ leaf (Table 1). Among the treatments, imidacloprid 17.8 SL @ 0.008% significantly reduced the aphid population and recorded 3.91 per leaf at five days after spray (DAS). Next best treatment was agro clean @ 4% (6.31 aphids/ leaf) and was at par with agro clean @ 3% (7.12 aphids/ leaf) and found equally effective in reducing aphid population followed by NSKS @ 5% (9.36 aphids/ leaf). Among the treatments, the highest aphid population was recorded in agro clean @ 1% (11.40 aphids/ leaf) at 5 th day after spray. More or less same trend of effectiveness was noticed after 10 DAS as observed after 5 DAS. After 10 days of spray, the aphid population slightly increased in all the treatments during both the years. The pooled data revealed that all the insecticidal treatments were significantly superior to untreated control. Imidacloprid 17.8 SL @ 0.008% was found most effective in reducing aphid population (3.66/ leaf) was at par with Agro clean at 4% (5.90/ leaf). The highest (11.33/ leaf) aphid population was noticed in treatment with Agro clean at 1% followed by Agro clean at 2% and proved inferior treatments.

Effect on leaf hopper, A. biguttula biguttula
The pooled data (2013-14 and 2014-15) showed that the population of leaf hopper before initiation of spray was uniform with the range of 13.34 to 13.49 per leaf (Table 2). After the 5 th , 10th and 15 th day of spray, imidacloprid 17.8 SL @ 0.008% was found significantly more effective in controlling the leaf hoppers. Agro clean @ 4% recorded 6.21 leaf hoppers per leaf at five days after application and 4.70 leaf hoppers per leaf at 10 days after application. After 15 days of spray, the leaf hopper population slightly increased in all treatments during both years. Agro clean @ 3% and NSKS @ 5% were the next effective treatments against A. biguttula biguttula. Among the evaluated treatments, the highest leaf hopper population was recorded in the plots treated with Agro clean @ 1% (11.96 leaf hoppers/ leaf) and followed by Agro clean @ 2% ( Table 2). The pooled data revealed that all the insecticidal treatments were significantly superior to control (Table 2). In all, leaf hopper population was effectively managed with the application of imidacloprid 17.8 SL @ 0.008% followed by Agro clean @ 4%, Agro clean @ 3% and NSKS @ 5%. Agro clean @ 1% and Agro clean @ 2% treated plots registered higher population of leaf hopper and were less effective treatments.

Effect on whitefly, B. tabaci
The whitefly population was uniform in all the treatments before first spray as treatment difference was non-significant and the population ranged between 10.86 to 11.13 / leaf (Table 3). After one day, imidacloprid 17.8 SL @ 0.008% was found significantly more effective (3.54 whiteflies/ leaf). Agro clean @ 4% recorded lower population of whitefly i.e. 6.26 per leaf after 5 th day and 4.47 per leaf after 10 th day of spray. In case of agro clean @ 3%, it recorded 7.01 per leaf after 3 rd day of spray and 5.16 per leaf after 10 th day of spray. After 15 days of spray, the aphid population slightly increased in all treatments during both years. The highest pest population was observed in plots treated with agro clean @ 1% during both the years. The pooled data over years (Table 3) showed that all the insecticidal treatments were significantly superior to control. Imidacloprid 17.8 SL at 0.008% (3.34 whiteflies/ leaf) and agro clean @ 4% (5.80 whiteflies/ leaf) were found more effective than the rest of the treatments followed by agro clean @ 4%. The lower dose, agro clean @ 4% was found least effective by recording higher whitefly population and proved inferior treatment.

Effect on thrips, T. tabaci
The pooled data clearly indicated that the population of thrips before initiation of spray was uniform with a range of 9.23 to 9.42 per leaf (Table 4). After five days of spray, imidacloprid 17.8 SL @ 0.008% found significantly more effective in controlling thrips (3.26 thrips/ leaf). Agro clean @ 4% recorded 5.65 thrips per leaf at 5 th day after application; 4.08 thrips per leaf at 10 th day after application. Agro clean @ 3% and NSKS @ 5% were found equally effective in reducing thrips population in cotton. Lower doses of agro clean i.e. 2% and 1% were less effective as these treatments registered higher (10.00 and 10.46/ leaf, respectively) number of thrips after 10 th days of spray (Table 4). The pooled data revealed that all the treatments were significantly superior to control (Table 4). Thrips population (3.15 /leaf) was effectively managed with the application of imidacloprid 17.8 SL @ 0.008%. Agro clean at 4% recorded lower (5.40/leaf) thrips population which was at par with succeeding dose i.e. 3% (5.95 thrips/ leaf) and NSKS at 5% (7.06 thrips/ leaf). Agro clean @ 1% and Agro clean @ 2% treated plots registered higher population of thrips and were proved less effective.
The results of present investigation are in close conformity with the findings of Kranthi et al., (2004) reported that the imidacloprid was more effective on the sucking pests of cotton as compared to conventional insecticides. Preetha et al., (2012) who mentioned that imidacloprid 17.8 SL at the recommended dose of 25 g a.i./ ha was quite promising in reducing the population of aphids. Yazdani et al., (2000) who reported the higher efficacy of imidacloprid against leaf hoppers in cotton. Mustafa (2000) reported that imidacloprid exert almost 72.60% mortality of whitefly. Asi et al., (2008) proved that imidacloprid showed better results against cotton thrips with the mortality of 96.12% at 72 hrs after spray. The scanty of information is available as far as the bioefficacy of agro clean against sucking pests of cotton is concerned. Biopesticides are plant substances to control insect pests (Nzanza and Mashela, 2012) and these naturally occurring substances control pests by nontoxic mechanisms (Bardin et al., 2008) while toxic effects of synthetic pesticides cannot be tolerated hence safer insect pest control may be possible by biopesticides application (Adalbert et al. 2013). The biopesticides have been used for almost all field crops and vegetables against bollworms, fruit borers, aphids, jassids, thrips, whitefly, diamond back moth etc. by acting act as repellant, anti-feedant and its seeds contain certain chemicals, which inhibits the population of insect pests (Ursani et al., 2014). Some plant products have pesticide properties against sucking pests (Sharma, 2007;Anon., 2014). Ghelani (2014) reported that biopesticides were effective in reducing the thrips population in cotton. Singh et al. (2011) reported that biopesticides treated plots are superior to control treatment in thrips reduction in onion. Biopesticides coupled with insecticides were effective for the management of thrips in tomato (Bharani et al., 2015). Vekaria and Patel (2000) reported significant results with biopesticides for the control of aphids in mustard. The biopesticides are effective in suppressing the larval population of jassids in cabbage (Prasad and Devappa, 2006) and many other insect pests infesting vegetables (Jeyarani and Kennedy, 2004).

Effect on seed cotton yield
Data on seed cotton yield over years (2013-14 and 2014-15) revealed that there was significant impact of biopesticidal treatments on seed cotton yield (Table 5). Imidacloprid 17.8 SL at 0.008%, synthetic insecticide produced significantly the highest (31.05 q/ha) seed cotton yield and it was at par with Agro clean at 4% (28.32 q/ha) followed by Agro clean at 3% (26.90 q/ha). Mandal et al. (2008) reported 16.91% to 27.07% increase in yield of cotton over control due to the use of biopesticides.
In nutshell, Agro clean at 3 and 4% was found effective apart from imidacloprid 17.8 SL @ 0.008% for the management of sucking pests infesting Bt cotton and also realized the higher yield of seed cotton. The spraying of the biopesticides for sucking pest of cotton can reduce the population of soft bodied insect as well as save the natural enemies in cotton ecosystem. This schedule will also benefit in reducing the egg and early instar larval damage of bollworm in proceeding days.
Mandal, S. Patel, A. M. and Patel, C. C. Efficacy of certain commercially available biopesticides against boll worm of cotton. Indian J. Applied Entomol. 2008; 22 (2): 128-130. those outside are transformed values; Treatment mean with letter(s) in common are not significant at 5 % level of significance within a column; DAS = Days after spray. those outside are transformed values; Treatment mean with letter(s) in common are not significant at 5 % level of significance within a column; DAS = Daya after spray. those outside are transformed values; Treatment mean with letter(s) in common are not significant at 5 % level of significance within a column; DAS = Days after spray. those outside are transformed values; Treatment mean with letter(s) in common are not significant at 5 % level of significance within a column; DAS = Days after spray.