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MOHANKUMAR AND D.N. KAMBREKAR*
Department of Agricultural Entomology, University of Agricultural Sciences, Dharwad-580 005, Karnataka
Studies on the field efficacy of different new insecticide molecules and botanicals against safflower leaf eating caterpillar Perigea capensis Guenée under field condition was conducted during 2014. All the treatments rendered significant suppression of leaf eating caterpillar compared to untreated control. Among the chemical treatments, least larval population was recorded in chlorantraniliprole 18.5 SC which was significantly superior in recording the lowest population and was on par with emamectin benzoate 5 SG, flubendiamide 480 SC and spinosad 45 SC. Among botanicals significantly lowest larval population was re-corded in the treatment with garlic chilli kerosene extract @ 2 per cent which was significantly superior in recording the lowest population and was on par with NSKE @ 5 per cent and chilli garlic aqueous extract @ 3 per cent. Among chemical treatments highest grain yield and BC ratio was realised in chlorantraniliprole 18.5 SC and emamectin benzoate 5 SG followed by flubendiamide 480 SC and spinosad 45 SC.
Safflower, Perigea capensis, New molecules and Botanicals
Safflower (Carthamus tinctorius Linn.) is one of the important rabi oilseed crops cultivated in India. In India, safflower is mainly grown in the drought prone areas of Maharashtra, Karnataka and Andhra Pradesh either as a strip crop, mixed crop, border crop or as a sole crop. In India, Maharashtra is the leading producer (63%) of safflower from the largest growing area of 67 per cent followed by Karnataka (32% in production and 27% in area) (Jadhav et al., 2012).
Among the several factors that are responsible for safflower yield loss, insect pests contribute a major share. A total of 101 insect pests have been recorded on safflower throughout the world (Vijay Singh et al., 1996). In Karnataka, 20 insect pests have been recorded on safflower along with nine species of natural enemies (Mallapur et al., 1997).
Safflower aphid, Uroleucon compositae Theobold, capsule borer, Helicoverpa armigera (Hub.) and leaf eating caterpillar, Perigea capensis Guenée are considered as major pests which cause severe damage to safflower causing high to very high levels of infestation. During the recent years, the incidence of safflower leaf eating caterpillar is increasing in Karnataka (Balikai,
2000). Since, not much work has been carried out on the incidence and management of Perigea capensis , the research for evaluation of newer insecticides was the need of the hour in effective management of the pest.
The experiment was conducted at Regional Agricultural Research Station (RARS), Vijayapur during rabi 2014-15. The experiment was laid out in randomized block design in three replications with sixteen treatments. The size of each plot was 17.64 m2 (4.2 m × 4.2 m). The crop was raised using A-1 variety of safflower with a spacing of 60 cm × 30 cm by adopting recommended agronomical practices. Totally there were 16 treatments including control. Treatments were imposed twice at an interval of 20 days when leaf eating caterpillar population exceeded economic threshold level.
Observations were recorded on number of safflower leaf eating caterpillars from five randomly selected plants from each treatment a day before and three, seven, nine and fifteen days after each spray. The larval population count was recorded and later data was transformed to
0.5 before analysis. Per cent larval reduction was subjected to arc sine transformation before analysis. Grain yield from each plot with respect to the treatments was
recorded after harvest and was expressed as q ha-1. Later data was analyzed using ANOVA technique and subjected to DMRT (Duncan’s Multiple Range Test).
A day before spray, there was no statistical significant difference among the treatments with respect to mean number of larvae per plant. The larval population in different treatment was uniform and ranged from 3.47 to 4.20 per plant (Table 1).
In first spray, at three day after spray, there was a significance difference among the treatments where the population of leaf eating caterpillar ranged between 1.20 to 4.37 larvae per plant. The plots sprayed with chlorantraniliprole 18.5 SC @ 0.15 ml/l recorded least number of larvae per plant (1.20 larvae/plant) which was on par with emamectin benzoate 5SG @ 0.2gm/l (1.30 larvae /plant), flubendiamide 480 SC @ 0.1ml/l (1.47 larvae/plant), spinosad 45 SC @ 0.15ml/l (1.60 larvae/ plant) and indoxacarb 15 EC @ 0.3ml/l (1.73 larvae/ plant). Among the botanicals, garlic chilli kerosene extract@ 2 per cent recorded less number of larvae per plant
(2.47 larvae/plant) which was statistically on par with NSKE @ 5 per cent (2.60 larvae /plant), chilli garlic aqueous extract 3 per cent (2.73 larvae/plant) and nimbecidine 1500ppm @ 5 ml/l (3.03 larvae/plant). The highest number of larvae (4.37 larvae/plant) were observed in control followed by treatments with neem oil 10 ml/l (3.23 larvae/plant) and Vinca rosea @ 2 per cent (3.17 larvae/plant) which were statistically inferior to other treatments. With respect to the per cent larval reduction, the highest reduction of larval population (72.22%) was observed in the plots treated with chlorantraniliprole 18.5 SC @ 0.15 ml/l followed by emamectin benzoate 5SG @ 0.2gm/l (58.82%), flubendiamide 480 SC @ 0.1ml/l (61.11%) and spinosad 45 SC @ 0.15ml/l (50.00%). The least reduction (8.57 %) of population was in neem oil @ 10ml/l and Vinca rosea @ 2 per cent (15.79%) (Table 1).
At seven day after spray, the larval population ranged between 0.07 to 4.93 larvae per plant. The least number of larvae per plant (0.07) were recorded in chlorantraniliprole 18.5 SC, which was on par with emamectin benzoate 5SG (0.13), flubendiamide 480 SC (0.27), spinosad 45 SC (0.30 larvae /plant) and indoxacarb 15 EC (0.87 larvae/plant each). Similarly, the highest larval reduction (97.22%) was recorded in the plots sprayed with chlorantraniliprole 18.5 SC, followed by
emamectin benzoate 5SG (94.44%), flubendiamide 480 SC (94.12%), spinosad 45 SC (70.04%) and indoxacarb 15 EC (83.33%). The least per cent reduction (28.57%) of population was recorded in neem oil @ 10ml/l and Vinca rosea 2% (35.47 %) (Table 1).
In second spray, at three day after spray, the treatments with chlorantraniliprole 18.5 SC recorded least number of larvae per plant (0.40 larvae/plant) which was on par with emamectin benzoate 5SG (0.47 larvae/plant), flubendiamide 480 SC (0.57 larvae/plant), spinosad 45 SC (0.60 larvae/plant) and indoxacarb 15 EC (1.00 larvae/ plant). The data on per cent reduction revealed that, chlorantraniliprole 18.5 SC recorded highest per cent reduction (68.19%) of larvae followed by emamectin benzoate 5SG (65.16%), flubendiamide 480 SC (55.70%) and spinosad 45 SC (55.08%) (Table 2).
The mean population of Perigea capensis was between 0.07 to 5.57 larvae/plant at seven days after spray. Among the treatments, least number of larvae per plant (0.07) were recorded in chlorantraniliprole 18.5 SC, which was on par with emamectin benzoate 5SG (0.10), flubendiamide 480 SC (0.13), spinosad 45 SC (0.13 larvae/plant) and indoxacarb 15 EC (0.37 larvae/plant). The highest larval reduction (93.45%) was also recorded in the plot sprayed with chlorantraniliprole 18.5 SC, followed by emamectin benzoate 5SG (92.62%), flubendiamide 480 SC (90.01%), spinosad 45 SC (79.82%) and indoxacarb 15 EC (65.18%) (Table 2). Similar trend was noticed at nine and fifteen days after both first and second spray.
In general, chlorantraniliprole 18.5 SC, emamectin benzoate 5 SG, flubendiamide 480 SC and spinosad 45 SC shown more efficacy only up to nine days after spraying. Later, the larval population was increased due to reduced efficacy of insecticides.
Chlorantraniliprole belongs to a new class of selective insecticides (anthranilic diamides) featuring a novel mode of action. By activating the insect ryanodine receptors (RyRs) it stimulates the release and depletion of intracellular calcium ions from the sarcoplasmic reticulum of muscle cells, causing impaired muscle regulation, paralysis and ultimately death of sensitive species. It has very low toxicity for mammals (both acute and chronic), high intrinsic activity on target pests, strong ovi-larvicidal and larvicidal properties, long lasting crop protection and no cross-resistance to any existing insecticide.
Emamectin benzoate is a novel semi-synthetic derivative of the natural product in the avermectin family of 16-membered macrocylic lactones derived from the fermentation of the soil actinomycete Streptomyces avermitilis. The mode of action is similar to abamectin (GABA and glutamate-gated chloride channel agonist) (Jansson et al., 1996). Flubendiamide a novel class of insecticide having a unique chemical structure used against broad spectrum of lepidopterous insect pests including resistance strains. It has a unique mode of action i.e. acts on ryanodine receptor modulator (Tohnishi et al., 2005). Spinosad is the active ingredient proposed for a new class of insect control products like naturalytes. Spinosad is derived from the metabolites of the naturally occurring actinomycetes, Saccharopolyspora spinosa. It is neuro toxin and acts on nicotinic acetylcholine receptors.
The present results clearly indicated the superiority of these four newer insecticides in controlling safflower leaf eating caterpillar. There is no published literature to compare present findings as the present investigation is first of its kind to evaluate newer insecticides and botanicals against P. capensis in safflower crop ecosystem. The efficacy of new insecticides molecules against lepodopteran insect pests is well documented in various crops. Spinosad 45 SC and indoxacarb14.5 SC were found more effective against greengram leaf eating caterpillar, Agrius convolvuli (Jayaram, 2006). Similarly, emamectin benzoate 5 SG was found most effective against Spodoptera litura in soybean (Harish et al., 2009), Helicoverpa armigera in groundnut (Gadhiya et al., 2014) and chickpea (Kambrekar et al., 2012). These findings confirm the efficacy of new molecules used in the present investigation.
The moderate efficacy of GCK (Garlic Chilli Kerosene extract) and NSKE in the present study is inconformity with the results of Hegde and Nandihalli (2009), who found that GCKE recorded least number of eggs of bhendi fruit borer (1.40 eggs/plant) followed by NSKE (5%).
The data pertaining to seed yield and cost economics of different treatments is presented in Table 3. The seed yield obtained from different insecticides and botanicals was significantly higher compared to untreated control. Among the different treatments, chlorantraniliprole 18.5 SC @ 0.15 ml/lit registered higher seed yield (12.34 q/ ha) followed by emamectin benzoate 5 SG @ 0.2 g/lit (11.39 q/ha), flubendiamide 480 SC @ 0.10ml/lit (11.04 q/ha) and spinosad 45 SC @ 0.15 ml/lit (10.77 q/ha).
Whereas, GCK extract @ 2 per cent recorded seed yield to the extent of 8.45 q/ha followed by NSKE @ 5 per cent (8.20 q/ha) and chilli garlic aqueous extract @ 1 per cent (7.73 q/ha). The lowest seed yield was recorded in neem oil @ 10 ml/lit (5.06 q/ha) followed by Vinca rosea @ 2 per cent (5.97 q/ha).
The cost economics of different treatment revealed that, among different chemicals highest net return was realized in the treatment with chlorantraniliprole 18.5 SC
@ 0.15 ml/lit (` 27776 ha-1) followed by emamectin benzoate 5 SG @ 0.2 g/lit (` 25524 ha-1), flubendiamide 480 SC @ 0.10 ml/lit (` 24232 ha-1) and spinosad 45 SC
@ 0.15 ml/lit (` 23454 ha-1). Whereas, among the botanicals, the higher net returns (` 15312) per hectare was realized in NSKE @ 5 per cent followed by GCK extract @ 2 per cent (` 14228 ha-1) and nembecidine 1500 ppm @ 5 ml/lit (` 12302 ha-1). The results on the benefit cost ratio revealed that, among the chemical treatments, highest benefit cost ratio was obtained in chlorantraniliprole 18.5 SC @ 0.15 ml/lit and emamectin benzoate 5 SG @ 0.2 g/lit (2.65) followed by flubendiamide 480 SC @ 0.10 ml/lit (2.56) and spinosad 45 SC @ 0.15 ml/lit (2.53) (Table 3).
In the present investigation, all the chemical treatments recorded significantly superior seed yield and benefit cost ratio over botanicals. The new insecticide molecules used in the present study have shown greater efficacy against safflower leaf eating caterpillar because they have already been found most effective against different lepidopteran pests in various crops. Since, these are having unique mode action and highly toxic to the lepidopteran insect’s pests, they have successfully controlled the pest and that has reflected on higher yield and benefit cost ratio. Gadhiya et al. (2014) reported that, highest benefit cost ratio 3.3 was observed in chlorantraniliprole (0.006%) treatment in groundnut for the management of both H. armigera and S. litura. Sreekanth et al. (2014) also reported highest benefit cost ratio of 4.64 in chlorantraniliprole 18.5 SC (0.43) treatment in pigeonpea for the management of gram pod borer H. armigera. These studies strongly support the results of the present investigation.