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Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa armigera Hubner in India



T. Ramasubramanian
 
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ABSTRACT

The magnitude of pyrethroid resistance was very high throughout India irrespective of the Helicoverpa armigera strains. The mechanism of pyrethroid resistance in H. armigera varies across the different regions of India, but PBO suppressible resistance (MFO mediated) appeared to be the major mechanism and the role played by carboxyl esterase was only marginal. Nerve insensitivity mechanism was observed in strains from areas where, the selection pressure from pyrethroids was intense over the past one decade. Since the pyrethroid resistance is more aggressive in India, several resistant management strategies were discussed in this review.

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T. Ramasubramanian , 2004. Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa armigera Hubner in India. Journal of Entomology, 1: 6-11.

DOI: 10.3923/je.2004.6.11

URL: https://scialert.net/abstract/?doi=je.2004.6.11

INTRODUCTION

The cotton bollworm, Helicoverpa armigera Hubner (Lepidoptera: Noctuidae), which was never traced as a major bollworm of cotton in any part of the country before 1986 has become number one agricultural pest in India. The crop loss due to this pest was estimated at 47-90%[1], the monetary value of damage was more than $450 million[2]. To combat the unprecedented pressure from H. armigera, farmers in South India had applied over 30 sprays as against the recommended 6-10 sprays[1]. More than 75% of insecticides sprayed over the cotton crop are being targeted towards H. armigera[3] of which, synthetic pyrethroids constituted 50-70%[4]. Frequent outbreaks of this national pest on cotton crop led to severe social disturbances, with several reports of suicide by farmers[5]. The failure to control the H. armigera was traced to the development of resistance to insecticides[6]. This pest has developed resistance to all the major group of insecticides (synthetic pyrethroids, organophosphates and organochlorines) used against it[7]. The pyrethroid resistance was peak[7] and ubiquitous across the Indian Sub-continent[8]. The magnitude of resistance, the mechanism involved in pyrethroid resistance and the insecticide resistant management (IRM) strategies recommended to overcome the threat posed by H. armigera have been discussed in this review.

Magnitude of pyrethroid resistance in H. armigera in India: The compilation of pyrethroid resistance data reported for different strains in India is a complicated task. The methodology followed and subsequent discussion of results obtained on pyrethroid resistance varies widely among the insecticide toxicologists. Some entomologists reported the resistance frequency on the basis of discriminating dose assay and the remainder expressed the resistance ratio on the basis of log-dose-probit-mortality (LDPM) assay. In LDPM assay, the stage of the pest used for bioassay and the susceptibility of the standard strain employed to calculate the resistance ratio vary widely among the reports available in India. So, the compilation and comparison among the strains is not possible for the whole country with the existing data. In this review the median lethal dose (LD50 to third instar) reported for different strains were compiled and the resistance ratio was calculated using the susceptible Reading strain as standard (maintained at the University of Reading, UK, for atleast 15 years[9] so as to compare the strains from different regions of India without any ambiguity.

Log dose probit mortality assay: The data compiled in this review clearly indicates that the pyrethroid resistance is ubiquitous throughout India. The Raichur strain exhibited very high level of resistance to cypermethrin (2489 fold) followed by Guntur strain (1213 fold) (Table 1). Raichur, the cotton city of India, is known historically for its high intensity use of insecticides in Asia. The number of sprays recorded was 20-25 in Raichur as against 10-12 in Madurai[1]. This intense selection pressure could be the reason for the development of multifold resistance in Raichur strain.

Table 1: Magnitude of cypermethrin resistance in H. armigera strains from different regions of India (LDPM assay)
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India
a: Strains assayed in 1997
RR= LD50 of Field Strain / LD50 of reading susceptible strain

Table 2: Magnitude of pyrethroid resistance in H. armigera strains from different regions of Tamil Nadu (LDPM assay)
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India
a: Strains assayed in 2002; b: Strains assayed in 2001
RR= LD50 of Field Strain / LD50 of Reading Susceptible Strain

The Madurai strain showed comparatively lower level of resistance (16 fold) to cypermethrin in the compiled data.

Among the four synthetic pyrethroids, the extent of resistance was comparatively higher to deltamethrin. The resistance level varied from 1900 to 4300 fold in different strains of Tamil Nadu state (Table 2).

Discriminating dose assay: The pyrethroid resistance was at peak irrespective of the locations in India (Table 3). The resistance frequency was more than 85% to cypermethrin, fenvalerate, deltamethrin and lambdacyhalothrin in all the locations of Tamil Nadu state, India (Table 4). The very high level of resistance to all the synthetic pyrethroids irrespective of the locations indicated the possibility of cross resistance. The laboratory studies conducted at Tamil Nadu Agricultural University, Coimbatore confirmed the positive cross resistance among the pyrethroids. The populations selected for resistance to one pyrethroid exhibited positive cross resistance to all other pyrethroids tested[10,11].

Mechanism of pyrethroid resistance in H. armigera in India: Physiological and biochemical mechanisms of pyrethroid resistance can be categorised into three types; delayed penetration, enhanced metabolism and nerve insensitivity[12]. The penetration resistance has generally been considered to be of minor importance[13]. Moreover, the work on this aspect of penetration resistance is almost nil in India.

Enhanced metabolism
Enhanced enzyme activity:
The metabolic resistance (oxidases and esterases) was observed to be an important mechanism mediating pyrethroid resistance in H. armigera populations in India[14]. The simplest explanation for the greater response of the oxidative over the nerve insensitivity resistance mechanism could be due to differential genetic dominance. The oxidative pyrethroid resistance mechanism in H. armigera had shown to be semi dominant, while the nerve insensitive gene is recessive[15-17]. The monitoring survey carried out by Kranthi et al.[9] during the 1995-1999 cropping season in seven states of India (Andhra Pradesh, Tamil Nadu, Karnataka, Maharashtra, Punjab, Haryana and Uttar Pradesh-which together account for approximately 80% of the total cotton growing area and 70% of the total insecticide use on cotton in the country) revealed that the activities of mixed function oxidases (MFO) and esterase were significantly higher in approximately 50 and 75% of the strains respectively. Very high level of MFO activity (>300 p mol mg protein-1 of the tissue supernatant) was observed in the strains from Karimnagar, Warangal, Rengareddy, Bangalore and Coimbatore districts of South India. The enhanced activity of MFO in Coimbatore strain of H. armigera had also been reported by other workers[10,18]. The MFO titre was found to be comparatively higher in almost all the strains assayed when compared to the susceptible Reading strain with the exception of Nagpur and Guntur strains, which were on par with the Reading susceptible strain.

Table 3: Magnitude of cypermethrin and fenvalerate resistance in H. armigera strains from different regions of India (Discriminating dose assay)
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India

Table 4: Magnitude of pyrethroid resistance in H. armigera strains from different regions of Tamil Nadu (Discriminating dose assay)
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India

Table 5: Synergistic suppression of pyrethroid resistance in H. armigera strains of Tamil Nadu State, India
Image for - Magnitude, Mechanism and Management of Pyrethroid Resistance in Helicoverpa 
  armigera Hubner in India

However, the Nagpur strain exhibited the highest activity of carboxyl esterases (5.30 m mol min-1 mg protein-1), indicating the predominance of esterase mediated metabolic resistance.

Synergistic suppression: One of the easiest and fastest ways to gain preliminary information about possible mechanism of resistance is by the use of synergists. Hence, they are frequently utilised as indicators of the possible metabolic pathways and biochemical mechanism involved in resistance[19]. Synergists act by inhibiting specific detoxication enzymes. The synergistic suppression studies with MFO inhibitors (piperonylbutoxide and pungam oil) and carboxyl esterase inhibitor (profenofos) over a decade clearly demonstrated the predominance of MFO mechanism (Table 5) in imparting resistance to H. armigera strains from Tamil Nadu state, India[17,18,20-22]. Armes[23] also concluded that the mechanism of pyrethroid resistance in H. armigera varies across the different regions of India, but PBO suppressible resistance (MFO mediated) appeared to be the major mechanism and the role played by carboxyl esterase was only marginal.

Enzyme induction: Brattsten[24] pointed out that the maintenance of high levels of microsomal oxidases is an energy expensive task for the insects and argued that induction provides energy economies for activating the detoxication system only when it is needed. This argument had been proved from the studies with H. armigera strains of Tamil Nadu State, India. All the five synthetic pyrethroids were found to induce the MFO activity when they were applied topically to the third instar larvae of H. armigera. The induction of MFO was found to be higher in cypermethrin selected population and lower in betacyfluthrin selected population[10.18].

Scott and Georghiou[25] had shown that the MFO-mediated mechanism is specific to pyrethroids having phenoxy-benzyl group. Since, all the five synthetic pyrethroids (fenvalerate, cypermethrin, deltamethrin, lambdacyhalothrin and betacyfluthrin) generally used in the Indian subcontinent against H. armigera are ester bonded phenoxzy-benzyl alcohols, it is not surprise that MFO-mediated mechanism is the dominant one which dictates the resistance in H. armigera. The positive cross resistance observed among all the five synthetic pyrethroids in the laboratory also seems to support the involvement of common MFO-mediated mechanism[10].

Nerve insensitivity mechanism: The MFO and Carboxyl esterase activities of Guntur strain were observed to be low (MFO-183 and 187 p mol mg protein-1; CE-1.24 and 1.33 μ mol min-1 mg protein-1) and on par with the susceptible strain of Reading University (MFO 172-212 p mol mg protein-1; CE 1.39-1.67 μ mol min-1 mg protein-1); whereas, nerve insensitivity to cypermethrin was the highest in a strain from Guntur[9]. Brattsten[26] suggested that the metabolic resistance is usually selected first as it involves changes in a system that is already designed for defense against toxic chemicals, whereas, target site resistance is more difficult to acquire because it involves changes in a crucially important process that is optimized through evolution. Thus altered target site resistance, such as nerve insensitivity, should evolve later and probably only after prolonged and intense selection pressure[27]. This suggestion had been strengthened by the H. armigera strain from Guntur where the selection pressure from pyrethroids was intense over the past one decade.

Management of pyrethroid resistance in H. armigera in India: Since the pyrethroid resistance is more aggressive in India, the insecticide resistant management strategies suggested here under are mostly focussing on the pyrethroid resistant management.

1. Regular monitoring should be carried out to detect the extent of resistance to different insecticides used against H. armigera.
2. Since, the pyrethroid resistance in H. armigera is ubiquitous[28] across the Indian subcontinent, frequent application of synthetic pyrethroids may be discouraged to reduce the selection pressure.
3. Since, the over dependence of synthetic pyrethroids which constituted 50-70% of the insecticides sprayed over the cotton crop[4] for the past one decade resulted in peak level of resistance in H. armigera[7], the rotation of insecticides with different modes of action may be preferable than over dependence of a particular chemistry. The reversion of resistance observed due to withdrawal of selection pressure from a particular insecticide group[10,41] also discourages the constant pressure with a single group of insecticides.
4. The new insecticide indoxacarb (the only representative of oxadiazines) may be considered as one of the components in insecticide rotation strategy to manage the resistant cotton bollworm, H. armigera. The enhanced level of carboxyl esterases in pyrethroid resistant populations was reported to activate the indoxacarb into its more toxic metabolite DCJW (decarbo methoxyllated JW-64)[29]. This might be the reason for the increased susceptibility of H. armigera populations resistant to synthetic pyrethroids. The negative cross resistance noticed in the pyrethroid selected populations of H. armigera also seems to support this recommendation. Indoxacarb (100 g a.i ha-1) was found to be effective in managing the pyrethroid resistant field populations of H. armigera in Tamil Nadu[10].
5. The pyrethroid resistant population of India was reported to be highly susceptible to spinosad at its discriminating dose of 10 μg larva-1[7]. Hence, careful rotation of spinosad in the IRM strategies of H. armigera may be advisable to manage the resistant bollworms. The unique mode of action of spinosad[30], which is different from the modes of action of other available insecticides, may also delay the possibility of cross resistance[10]. The use of new chemistries spinosad and indoxacarb had been proposed as a component of H. armigera IRM strategy in Pakistan[31].
6. Since, the MFO activity is directly proportional to the age of the larvae[32], targeting pyrethroids to egg hatch will avoid the detoxification of pyrethroids by MFO.
7. Insecticides possessing both ovicidal and larvicidal actions may be included in the IRM programme.
8. Hand picking and destruction of grownup larvae may be suggested as one of the components in IRM of H. armigera in India, where the human resource is abundant.
9. The use of predators and parasitoids may give better management in perennial crop ecosystem and also if the land holdings are large like in developed countries whereas, in developing countries like India wherein more than 75% of the farmers are small or marginal farmers having less than two hectares of land that too not in a continuous stretch, the recommendation of entomophages may not be viable due to dispersal behaviour. Hence, it is essential to go for community approach, but achieving cooperation among the farmers is very difficult since their choice of crop, socio-economic condition and subsequent management aspects vary largely among the Indian farmers. This might be the reason why; the extension functionaries could not convince the Indian farmers even after a prolonged effort hence, it is suggested that instead of going for augmentative release of entomophages, maintaining the natural enemy population by spraying with safer insecticides is preferable.
10. To conserve the natural enemy complex in the cotton eco system, the foliar spray may be replaced with seed treatment chemicals to manage the early season sucking pests. This may avoid the direct contact of natural enemies with insecticides
11. One of the insecticide resistant mechanisms is the absorption of insecticides by the fat bodies because of their lipophilic nature

So that the toxic amount of insecticides cannot reach the target site. It is a known fact that nuclear polyhidrosis viruses multiply mostly in fat bodies. The resistant populations have more fat bodies; this will help in quick and fast multiplication of the virus. Hence, application of NPV at 500 larval equivalents ha-1 with jaggery and teepal® as spray adjuvant[33] may be encouraged to manage the pyrethroid resistant populations of H. armigera.

REFERENCES

1:  Fakrudin, B., B.V. Patil, P.R. Badari Prasad and S.H. Prakash, 2003. Insecticide usage patterns in South Indian cotton ecosystems to control cotton bollworm Helicoverpa armigera. Resist. Pest Mang. Newslett., 12: 35-38.

2:  Regupathy, A., D.S. Rajavel, S. Rajkumar and D. Russell, 1999. Present status of insecticide resistance in Helicoverpa armigera and its management in Tamil Nadu, India. Proceedings of the ICAC-CCRI Regional Consultation Insecticide Resistance Management in Cotton, Jun. 28-Jul. 1, CCRI, Multan, Pakistan, pp: 48-55

3:  Banerjee, S.K., K.S. Turkar and R.R. Wanjari, 2000. Evaluation of newer insecticides for the control of bollworms in cotton. Pestology, 24: 14-16.

4:  Jayaswal, A.P., 1989. Management of american bollworm on cotton in andhra pradesh. Indian Farm., 17: 6-7.

5:  Patil, B.V., S. Lingappa, A.G. Srinivasa and M. Bheemanna, 1996. Integrated pest management strategies for cotton. Proceedings of the 20th International Congress of Entomology, Aug. 25-31, Firenze, Italy, pp: 32-33

6:  Kranthi, K.R., N.J. Armes, G.V. Nagarjun, R.S. Rao and V.T. Sundaramurthy, 1997. Seasonal dynamics of metabolic mechanisms mediating pyrethroid resistance in Helicoverpa armigera (Hub.) in central India. Pestic. Sci., 50: 91-98.
CrossRef  |  

7:  Ramasubramanian, T. and A. Regupathy, 2004. Magnitude and mechanism of insecticide resistance in Helicoverpa armigera Hub. population of Tamil Nadu, India. Asian J. Plant Sci., 3: 94-100.
CrossRef  |  Direct Link  |  

8:  Armes, N.J., D.R. Jadhav and K.R. DeSouza, 1996. A survey of insecticide resistance in Helicoverpa armigera in the Indian sub-continent. Bull. Entomol. Res., 86: 499-514.
CrossRef  |  

9:  Keshav Raj, K., J. Deepak, W. Ravindra, K. Sandhya and R. Derek, 2001. Pyrethroid resistance and mechanisms of resistance in field strains of Helicoverpa armigera (Lepidoptera: Noctuidae). J. Econ. Entomol., 94: 253-263.
CrossRef  |  PubMed  |  Direct Link  |  

10:  Ramasubramanian, T., 2003. Pattern of cross resistance in pyrethroid selected populations of Helicoverpa armigerahubner. Ph.D. Thesis, Tamil Nadu Agricultural University, Coimbatore, India.

11:  Ramasubramanian, T. and A. Regupathy, 2004. Pattern of cross resistance in lambdacyhalothrin and betacyfluthrin selected populations of Helicoverpa armigera Hub. J. Entomol., 1: 17-20.
CrossRef  |  Direct Link  |  

12:  West, A.J. and A.R. McCaffery, 1992. Evidence for nerve insensitivity to cypermethrin from Indian Strains of Helicoverpa armigera. Proceedings of the Brighton Crop Protection Conference Pests and Diseases, (BPCCPD'92), The British Crop Protection Council, Farnham, UK., pp: 233-238

13:  Matsumura, F., 1983. Penetration, Binding and Target Insensitivity as Causes of Resistance to Chlorinated Hydrocarbon Insecticides. In: Pest Resistance to Pesticides, Georghiou, G.P. and T. Saito (Eds.). Plenum Press, New York, pp: 367-386

14:  Gunning, R.V. and C.S. Easton, 1987. Inheritance of resistance to fenvalerate in Heliothis armigera (Hubner) (Lepidoptera: Noctuidae). J. Aust. Entomol. Soc., 26: 249-250.
CrossRef  |  

15:  Daly, J.C., 1988. Insecticide resistance in Heliothis armigera in Australia. Pestic. Sci., 23: 165-176.
CrossRef  |  

16:  Daly, J.C. and J.H. Fisk, 1992. Inheritance of metabolic resistance to the synthetic pyrethroids in Australian Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae). Bull. Entomol. Res., 82: 5-12.

17:  Tamilselvi, S., 2001. Studies on detoxification mechanism of pyrethroid resistance in Helicoverpa armigera (Hubner) populations of Tamil Nadu. M.Sc. Thesis, Tamil Nadu Agricultural University, Coimbatore, India.

18:  Ahmad, M. and A.R. McCaffery, 1991. Elucidation of detoxication mechanisms involved in resistance to insecticides in the third instar larvae of a field-selected strain of Helicoverpa armigera with the use of synergists. Pestic. Biochem. Physiol., 41: 41-52.
Direct Link  |  

19:  Regupathy, A., T. Manoharan, G. Ashokan, R. Nalini and N.J. Armes, 1995. Detoxification mechanisms involved in fenvalerate resistance in field population of Helicoverpa armigera Hub. in Tamil Nadu. In: Proceedings of the National Symposim IPM: An Entomological Approach to Sustainable Agriculture, pp: 22-24.

20:  Regupathy, A., N.J. Armes, G. Asokan, D.R. Jadhav, R.P. Soundararajan and D.A. Russell, 1997. Best-bet method for insecticide resistance management of Helicoverpa armigera. Proceedings of the International Conference on Integrated Approaching to Combating Resistance, Apr. 14-16, Harpenden, Herts, UK., pp: 116-116

21:  Gavigowda, G., 1996. Studies on Synergism with reference to the Insecticide Resistance Management (IRM) of Helicoverpa armigera (Hubner). Ph.D. Thesis, Tamil Nadu Agricultural University, Coimbatore, India.

22:  Armes, N.J., 1994. Helicoverpa armigera insecticide resistance management in India. Adoptive Res. Initiative. 1993/94 Technical Report, pp: 153.

23:  Brattsten, L.B., 1979. Biochemical Defense Mechanisms in Herbivores Against Plant Allelochemicals. In: Herbivores, In: Rosenthal, G.A. and D.H. Janzen (Eds.). Academic Press, New York, pp: 200-262

24:  Scott, J.G. and G.P. Georghiou, 1986. Mechanisms responsible for high levels of permethrin resistance in the housefly. Pestic. Sci., 17: 195-206.
Direct Link  |  

25:  Brattsten, L.P., 1990. Resistance Mechanisms to Carbamate and Organophosphate Insecticides. In: Managing Resistance to Agrochemicals: From Fundamental Research to Practical Strategies, Green, M.B., H.M. LeBaron and W.K. Moberg (Eds.). American Chemical Society, Washington, DC., pp: 420-460

26:  Forrester, N.W., M. Cahill, L.J. Bird and J.K. Layland, 1993. Management of pyrethroid and endosulfan resistance in Helicoverpa armigera (Lepidoptera: Noctuidae) in Australia. Bull. Entomol. Res., 1: 1-132.
Direct Link  |  

27:  Gunning, R.V. and A.L. Devonshire, 2002. Negative cross resistance between indoxacarb and pyrethroids in Australian Helicoverpa armigera: A tool for resistance management. Resist. Pest Manage. Newslett., 11: 52-52.

28:  Watson, G.B., 2001. Actions of insecticidal spinosyns on γ-aminobutyric acid responses from small-diameter cockroach neurons. Pestic. Biochem. Physiol., 71: 20-28.
Direct Link  |  

29:  Ahmad, M., M.I. Arif and Z. Ahmad, 1999. Insecticide resistance in Helicoverpa armigera and Bemisia tabaci, its mechanisms and management in Pakistan. Proceedings of the Regional Consultation on Insecticide Resistance Management in Cotton, June 28-July 1, 1999, Multan, Pakistan, pp: 143-150

30:  Wilkinson, C.F., 1983. Role of Mixed Function Oxidases in Insecticide Resistance. In: Pest Resistance to Pesticides, Georghiou, G.P. and T. Saito (Eds.). Plenum Press, New York, pp: 175-205

31:  Regupathy, A., 1994. Problems and prospects of management of insecticide resistance in Helicoverpa armigera (Hubner) in India. Proceedings of the World Cotton Research Conference, Feb. 14-17, Brisbane, Australia, pp: 556-562

32:  McCaffery, A.R., A.B.S. King, A.J. Walker and H. EL-Nayir, 1989. Resistance to synthetic pyrethroids in the bollworm, Heliothis armigera from Andhra Pradesh, India. Pestic. Sci., 27: 65-76.
CrossRef  |  Direct Link  |  

33:  Fakrudin, B., P.R.B. Prasad, K.B. Krishnareddy, S.H. Prakash, V.B.V. Patil and M.S. Kuruvinashetti, 2003. Insecticide resistance in cotton bollworm, Helicoverpa armigera in South Indian cotton ecosystems. Resist. Pest Manage. Newslett., 12: 13-16.

34:  Tripathy, M.K. and H.N. Singh, 1999. Circumstantial evidence for migration of resistant moths of Helicoverpa armigera at Varanasi, Uttar Pradesh. Ind. J. Entomol., 61: 384-395.

35:  Tikar, S.N., N.G.V. Rao, D.R. Arya and M.P. Moharil, 2001. Pyrethroid resistance monitoring and mechanism in Helicoverpa armigera in central India. Crop Res., 22: 474-478.
Direct Link  |  

36:  Niranjankumar, B.V., 2002. Management of insecticide resistance in Helicoverpa armigera: laboratory measured resistance level and field control. Ph.D. Thesis, Tamil Nadu Agricultural University, Coimbatore, India.

37:  Clement, G.P., 1999. Development of insecticide resistance in Helicoverpa armigera (Hubner). Ph.D. Thesis, Tamil Nadu Agricultural University, Coimbatore, India.

38:  Rao, N.V., P. Rajasekhar and M. Venkataiah, 1996. Helicoverpa armigera insecticide resistant management research in India. Podborer Management Newslett., pp: 7.

39:  Lingappa, S. and K. Basavanagoud, 1996. Helicoverpa armigera insecticide resistant management research in India. Podborer Management Newslett., pp: 7.

40:  Armes, N.J. and D.R. Jadhav, 1996. Helicoverpa armigera insecticide resistant management research in India. Podborer Manage. Newslett., pp: 7.

41:  Kranthi, K.R., K.M. Kherde and S. Gaikwad, 1996. Helicoverpa armigera insecticide resistant management research in India. Podborer Manage. Newslett., pp: 7.

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