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Bioefficacy of Spiromesifen (Oberon®) 240 SC against Coconut Eriophyid Mite Aceria guerreronis Keifer and Determination of Residues



A. Suganthi, K. Ramaraju , S. Kuttalam and S.Chandrasekaran
 
ABSTRACT

Bio efficacy of spiromesifen (Oberon®) 240 SC was tested against coconut eriophyid mite, Aceria guerreronis Keifer in comparison with recommended insecticide, triazophos 40 EC. Spiromesifen was applied as spot application (crown spraying) at 1, 2, 3, 4 mL L-1 and triazophos at 5 mL L-1 per tree. Observations recorded at 7, 15 and 30 days after spraying showed that spiromesifen at the rate of 4 mL L-1 was significantly superior than triazophos and control, while spiromesifen at the rate of 3 mL L-1 and triazophos at the rate of 5 mL L-1 were equally effective in reducing the mite population. The residue levels in coconut water and kernel samples collected on 0, 1, 3, 5, 10, 15, 30, 45 and 60 days after third spray were found to be below detectable level.

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  How to cite this article:

A. Suganthi, K. Ramaraju , S. Kuttalam and S.Chandrasekaran , 2006. Bioefficacy of Spiromesifen (Oberon®) 240 SC against Coconut Eriophyid Mite Aceria guerreronis Keifer and Determination of Residues. Journal of Entomology, 3: 325-330.

DOI: 10.3923/je.2006.325.330

URL: https://scialert.net/abstract/?doi=je.2006.325.330

Introduction

In Tamil Nadu, India, severe outbreak of a nut infesting eriophyid mite Aceria guerreronis Keifer (Eriophyidae: Acari) feeding on tender nuts of coconut (Cocos nucifera) resulted in heavy damage and loss in yield and quality of nuts (Ramaraju et al., 1999). At present, the infestation is widespread in India and reported from Karnataka, Andhra Pradesh, West Bengal, Gujarat, Andaman and Nicobar Islands and Lakshadweep Islands (Haq, 1999). Commonly used insecticides have lost their efficacy because of continuous and discriminate use. Hence, there is a need to go for newer molecules to avoid the risk of resurgence and pest resistance. Spiromesifen is the latest insecticidal innovation from Bayer crop Science. The product belongs to a new chemical class named spirocyclic phenyl substituted tetronic acids and offers unique mode of action classified as lipid biosynthesis inhibitors. It is a new insecticide/miticide for foliar application against white fly, mite and psyllids. Spiromesifen (Oberon®) showed excellent efficacy against Bemisia tabaci and Trialeurodes vaporariorum in laboratory and greenhouse trials (Nauen et al., 2002). In the present study, the efficacy of spiromesifen (Oberon®) 240 SC was tested against coconut eriophyid mite A. guerreronis by crown application.

Materials and Methods

Field Experiment
A field experiment was conducted in farmer’s holdings at Coimbatore, T.Nadu, during March, 2003, with 8-10 year old coconut trees. Six treatments were included to evaluate the efficacy of the new chemical, spiromesifen 240 SC. The treatments consisted of spiromesifen at 1, 2, 3, 4 mL L-1, triazophos at 5 mL L-1 and an untreated check. The variety used was west coast tall and eight trees constituted one replication. Spot application (spraying) of treatments was done by using a rocker sprayer. Pre treatment and post treatment counts on mite population were made from three month old buttons (single button/tree) at 7, 15 and 30 Days After Spraying (DAS). The mite population was assessed in an area of 4 sq mm on the innermost three bracts and nut surface covered by the perianth (Ramaraju et al., 2000) using a binocular stereo zoom microscope. Three rounds of treatments were given at 45 days interval.

Determination of Residues
Sampling
Samples of 75% matured coconut were collected on 0, 1, 3, 5, 10, 15, 30, 45 and 60 days after third spray. A representative sample of 100 mL coconut water and 50 g coconut kernel were placed in a wide mouthed sampling container containing 100 mL acetone. The bottles were sealed with Teflon lined cap and stored in deep freezer until extraction of residues.

Extraction
Fifty gram coconut kernel sample and 100 mL of coconut water sample was extracted with 100 mL acetone. The kernel sample was blended in a warring blender for 3 min and filtered through Buchner funnel with mild suction and condensed.

Liquid-liquid Clean up
The extract was taken in a 250 mL separating funnel. Then 25 mL ethyl acetate/cyclohexane (1:1, v/v) and 25 mL saturated sodium chloride was added to kernel and water sample homogenates and the samples were shaken vigorously for 1 min. The phases were allowed to separate for 30 to 60 min. The partitioning process was repeated twice with additional 25 mL portions of ethyl acetate. The organic phase layer was filtered through Whatman No. 1 filter paper overlaid with anhydrous sodium sulphate (10 g). The filtrate so obtained was concentrated to watery residue (near dryness) using a rotary flash vacuum evaporator at 40°C. Ethyl acetate 1.5 mL was added and residues were dissolved completely. Approximately 1.5 g of mixture of sodium sulphate/sodium chloride (1/1 W/W) were added and flask was swirled. Then, cyclohexane (1.5 mL) was added to obtain a total volume of 3 mL and flask was swirled vigorously.

Column Clean up
Glass chromatographic column with 50 cm length and 1.5 cm diameter was used in the column clean up. The drip tip of the glass column was plugged with cotton wool and packed air tight using a mixture of Silica gel: Celite: Florisil: Charcoal 4:4:1:1 v/v/v/v. Layers of sodium sulphate were packed at top and bottom. The column was pre washed with 25 mL of hexane initially and eluted with ethyl acetate/cyclohexane (1:1 v/v). The collected elutant was condensed to near dryness and reconstituted by acetone for final determination.

Final Determination
The residues of spiromesifen 240 SC were estimated by using a Chemito model 2685 HT gas liquid chromatography fitted with a Ni63 electron capture detector with the following operating parameters.

Column : 5% SE 30 on Anakrom Q
Temperature (°C) : Column
220
Injector
240
Detector
300
Flow rate (mL min-1) : 60 Retention time : 3.50 min

The final quantification was made using the formula

Where:

HS - Height of the sample Hstd - Height of the standard
Wstd - Weight of the standard in ng Ws - Weight of the sample in g
Vs - Volume of the sample in mL (final extract) Asj - Aliquot of the sample injected in μL

Recovery Studies
The mean recovery of spiromesifen spiked at 1 and 2 μg g-1 in kernel was 88% and at 0.5 and 1 μg g-1 in coconut water was 80.93% . The sensitivity of the instrument was 0.1 ng and the determinability was 0.004 μg g-1 for kernel and 0.002 μg g-1 for water considering the final volume of the extract as 2 mL.

Results and Discussion

The pre treatment mite population ranged from 75.75 to 84.75 number per 4 sq. mm (Table 1). The spot application of spiromesifen 240 SC at the rate of 4, 3, 2 and 1 mL L-1 and triazophos 40 EC at the rate of 5 mL L-1 recorded 17.89 to 33.36% reduction of mite population when sampled on 7 days after first round of treatment. Spiromesifen at the rate of 3 mL L-1 and triazophos at the rate of 5 mL L-1 were on par in their effect after 15 (39.71 and 39.65%) and 30 days after spraying (DAS) (43.47 and 42.39%). After the second spray, mite population reduction was much better than the first round and per cent reduction over control ranged from 13.53 to 39.10, 22.87 to 72.35 and 42.58 to 76.54 after 7, 15 and 30 days of treatment, respectively (Table 2). Spiromesifen applied at the rate of 4 and 3 mL L-1 recorded 72.35 and 56.44% reduction in mite population after 15 DAS, respectively and were on par with the standard check which gave 57.82% reduction. At 30 DAS, spiromesifen at the highest dose resulted in significantly higher percent reduction compared to all other treatments. After third spray, spiromesifen applied at lower doses i.e., 1 and 2 mL L-1 showed 67.51 and 68.94% reduction of mite population at 15 DAS, respectively, whereas the higher doses, i.e., 3 and 4 mL L-1 recorded significantly higher population reduction of 79.26 and 87.96%, respectively (Table 3).

Table 1: Efficacy of spiromesifen 240 SC against coconut mite, A. guerreronis - I spray
No. Number of mite per 4 sq. mm; DAS- Days after spraying, Figures in parenthesis are */arc sin **transformed values, In a column, means followed by a common letter are not significantly different by DMRT (p = 0.05)

Table 2: Efficacy of spiromesifen 240 SC against coconut mite, A. guerreronis - II spray
No. Number of mite per 4 sq. mm; DAS- Days after Spraying, Figures in parenthesis are */arc sin **transformed values, In a column, means followed by a common letter are not significantly different by DMRT (p = 0.05)

Table 3: Efficacy of spiromesifen 240 SC against coconut mite, A. guerreronis - III spray
No. Number of mite per 4 sq. mm; DAS- Days After Spraying, Figures in parenthesis are */arc sin **transformed values, In a column, means followed by a common letter are not significantly different by DMRT (p = 0.05)

At 30 DAS, spiromesifen at the rate of 3 mL L-1 and triazophos at the rate of 5 mL L-1 treatment were on par with each other in their effect. The mean per cent reduction in mite population after third spray was 86.75, 78.96, 66.65, 61.88 and 79.01 respectively, when applied with spiromesifen at the rate of 4, 3, 2 and 1 and triazophos at the rate of 5 mL L-1. The relative efficacy was in the order of spiromesifen 240 at 4 > 3 mL L-1 ≤ triazophos 40 EC 5 mL L-1 > spiromesifen 2 ≤ 1 mL L-1.

It was observed that reduction in mite population was more significant up to 15 DAS and increased thereafter in few treatments during first and third round of spraying. But a gradual reduction in mite population was recorded up to 30 DAS after second spray. This may be due to overlapping generation of mites, egg hatchability and delivery of chemicals which either directly or indirectly contributes favourably for the multiplication of mites inside the perianth. Once the residual effect of sprayed chemical ceases, the mite population tend to increase with the multiplication of unaffected mites inside the perianth (Ramaraju et al., 2000).

Spiromesifen was also found highly active against tetranychid mite eggs, all juvenile and quiescent stages and female adults by contact (Nauen et al., 2005). Kavitha et al. (2006) reported higher efficacy of spiromesifen 240 SC at the rate of 120 g a.i. ha-1 against chilli mite, Polyphagotarsonemus latus.

Table 4: Dissipation pattern of spiromesifen 240 SC in coconut
BDL- Below Detectable Level

A good efficacy of spiromesifen was reported against nymphal stages of B-type B. tabaci feeding on melons and collard (Liu, 2004). Earlier workers have also reported that spot application of triazophos satisfactorily controlled the mite population. Spot application of triazophos 5 mL L-1 was found effective in reducing the mite population up to 70%, 30 days after two rounds of spraying (Karuppuchamy et al., 2001). Spraying of 4 mL of triazophos 40 EC once in 30 days as topical application was suggested for mite control (Ramaraju et al., 1999). In contrast, a low cumulative mite population reduction of 49.1% after five rounds of triazophos (0.2%) treatment was reported by Prakash (2002).

The residues of spiromesifen in coconut kernel and water were determined from the samples collected from treated field and the results revealed that residues of spiromesifen applied at 1, 2, 3 and 4 mL L-1 were at Below Detectable Level (BDL) in both the matrices, up to 60 days (Table 4). Similarly, the residues of spiromesifen applied at 96 g a.i. ha-1 on chilli fruits reached BDL on 7 DAS and the half life was 2.29-3.84 days (Kuttalam et al., 2004). Also, Kuttalam et al. (2000) reported that no detectable amount of residues were found in coconut water and kernel when sprayed with monocrotophos (1.5 and 3 mL L-1), triazophos (5 and 10 mL L-1), dicofol (2.5 and 5 mL L-1) and methyl demeton (4 and 8 mL L-1), up to 60 days after application. No detectable amount of residues was found in coconut water and kernel when triazaphos was administered through root at 10, 15, 20 and 40 mL per palm (Narasimha Rao, 2000).

The results of the present study clearly revealed that spiromesifen is an excellent chemical in controlling eriophyid mite without any adverse effect on the consumption utility of coconut water and kernel because of its quicker dissipation and short lived residues and will be an excellent tool in resistance management programmes.

Acknowledgment

The authors are grateful to M/S Bayer Crop Science Limited. India for the help rendered during the study.

REFERENCES
Haq, M.A., 1999. Amazing trends in distribution of the coconut mite in Peninsular India and adjacent Island. Entomonology, 24: 371-379.

Karuppuchamy, P., R.J. Rabindra and R.S. Phillip, 2001. Evaluation of Spot Application of Insecticides for the Management of Coconut Eriophyid, Aceria guerreronis Keifer. In: IPM in Horticultural Crops: Emerging Trends in the New Millennium, Verghese, A. and P.R. Parvatha (Eds.). IIHR, Bangalore, pp: 111-112.

Kavitha, J., S. Kuttalam and S. Chandrasekaran, 2006. Evaluation of spiromesifen 240 SC against chilli mite, Polyphagotarsonemus latus (Banks). Ann. Plant Prot. Sci., 14: 52-55.

Kuttalam, S., J. Kavitha and S. Chandrasekaran, 2004. Dissipation of Spiromesifen (Oberon) in/on Chilli Fruits. In: Myths, Realities and Remedies and Pesticide Expo-2004, Gajbhiye, V.T., P. Dureja and B.S. Parmar (Eds.). Indian Agricultural Research Institute, New Delhi.

Liu, T.X., 2004. Toxicity and efficacy of spiromesifen, a tetronic acid insecticide, against sweetpotato whitefly (Homoptera: Aleyrodidae) on melons and collards. Crop Prot., 23: 505-513.

Nauen, R., H.J. Schnorbach and A. Elbert, 2005. The biological profile of spiromesifen (Oberon7)-A new tetronic acid insecticide/acaricide. Pflanzenschutz-Nachrichten Bayer, 58: 417-440.

Nauen, R., T. Bretschneider, E. Brueck, A. Elbert, U. Reckmann, U. Wachendorff and R. Tiemann, 2002. BSN 2060-A novel compound for whitefly and spider mite control. Proc. Brighton Crop Prot. Conf. Pests Dis., 1: 39-44.

Prakash, S., 2002. Bio-ecology and management of nut infesting eriophyid mite, Aceria guerreronis. Keifer (Eriophyidae: Acari) on coconut. M.Sc. Thesis, Tamil Nadu Agric. Univ., Coimbatore, India, pp: 4-128.

Ramaraju, K., K. Natarajan, P.C.B. Sundara and G.T.R. Murali, 1999. Management of coconut eriophyid mite Aceria guerreronis Keifer in Tamil Nadu. J. Acarol., 14: 82-83.

Ramaraju, K., K. Natarajan, P.C.B. Sundara, S. Palaniswamy and R.J. Rabindra, 2000. Studies on coconut eriophyid mite, Aceria guerreronis keifer in Tamil Nadu, India. Proceedings of the International Workshop on Coconut Mite (Aceria guerreronis), 2000, Coconut Research Institute, Srilanka, pp: 13-31.

Rao, B.N., 2000. Residues of triazophos in coconut water and kernel when administered through root. Pestology, 24: 2-4.

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