POTENTIAL OF PHEROMONES IN RICE PEST MANAGEMENT

2 Apr


 

K. Krishnaiah1, I. C. Pasalu2 and N. R. G. Varma3

1. Former Project Director, Directorate of Rice Research, Rajendranagar,Hyderabad

2. Former Principal Scientist of Entomology, Directorate of Rice Research, Rajendranagar,Hyderabad

3. Scientist (Entomology), ANGRAU, Rajendranagar,Hyderabad

Rice is the major staple food crop in India with 43.6 million Ha cultivated area and 92.76 million tons (Table 1) of milled rice production (2006-07).Indiaranks next toChinain production. For sustaining self sufficiency in rice, country needs to increase production at a pace to maintain production level of 145 m tons of milled rice in 2020 A.D. With sinking land and other natural resource base, there is a need to seek the help of improved production and protection technologies.

 

Table 1: All-India Area, Production and Yield of Rice

Year

Area

(million hectares)

Production

(million tons)

Productivity (kg/ha)

2001-02

44.90

93.34

2079

2002-03

41.18

71.82

1744

2003-04

42.59

88.53

2077

2004-05

41.91

83.13

1984

2005-06

43.66

91.79

2102

2006-07

43.62

92.76

2127

Source: Directorate of Economics and Statistics

Yield loss associated with pre-harvest insect damage in Indiaare typically estimated at 25-30 per cent in unprotected rice, although losses in excess of 40% have been recorded (Pandya et al., 1989). The major pre-harvest loss inIndia is due to stem borers (Kalode and Krishnaiah, 1991) and on an average stem borer damage in tropical Asia results to an estimated yield loss of 5-10% while inIndia 3-95% losses are reported.

The utilization of pheromones for control of insects was recognized soon after the monumental work of Butenandt and Hecker and in late 19th Century sex pheromones were recognized as potential agents for control of insect pests. Pheromones and related chemicals are potentially sensitive, selective and can be used to monitor insect populations. Due to their high biological activity and low mammalian toxicity, sex pheromones can provide relatively less expensive method of control. They are species specific and have a great potential for use in eco-friendly and sustainable insect pest management. In the recent years semiochemicals have emerged as promising safer alternatives in pest control, which can be integrated in an IPM package.

Insect sex pheromones can be utilized in pest management in many ways such as:

Monitoring (Indirect control)

  • Surveying and monitoring for early warning
  • Timing of control measures(action thresholds/decision support)
  • Knowing the population dynamics
  • Mapping pest distribution
  • Investigating dispersal and migrating behaviour.
  • Quarantine work
  • Risk assessment
  • Knowing the effects of control measures.
  • Enhancing natural enemy effectiveness.
  • Detecting the occurrence of insecticide resistance in insects

Direct control

  • Mass trapping
  • Mating disruption
  • Attract and Kill (lure and kill)

Several parameters that enable efficient pheromone based monitoring for insect pests of rice crop are summarized below in Table 2. Though sex pheromones based monitoring system was optimized for many rice pests major work is done on rice yellow stem borer.

Table 2.  Pheromone based monitoring systems of rice insect pests

Insect

Scirpophaga incertulas

Chilo suppressalis

Sesamia inferens

Cnaphalocrocis medinalis

Components (Z) 11-16:Al

(Z) 9-16:Al(Z) 11-16:Al

(Z) 9-16:Al

(Z) 13-18:Al(Z) 11-16:Ac

(Z) 11-16:OH

(Z) 11-16:Al(Z) 13-18:Ac

(Z) 11-16:AcBest Blend3:110:1:140:10:110:1Dose3 to 5mg0.3 to 0.6mg2mg1mgDispenserRubberRubberRubberPolythene vialReplacement period3-4 weeks4 weeks3-4 weeks4 weeksTrap designSleevePlastic funnelSleeveDelta StickySleeve colourWhiteYellow–Trap elevation0.5-1.0m0.5m1.0mCanopy level

Lepidopteron pests particularly the stem borers (specifically yellow stem borer, Scirpophaga incertulasWalker) due to internal feeding behavior, symptoms of its occurrence are not visible till the damage is done. A minimum of two prophylactic rounds of Insecticides (which form primary method of control) are applied, which often result in the secondary pest resurgence, needing additional pesticide use causing health hazards to human beings and domestic animals through contamination of food and environment as a whole. Further, success of insecticide application depends on the detection of the pest incidence/intensity. Non availability of stem borer resistant cultivars, constraints in successful use of biocontrol agents and partial or ineffective chemical control warranted the need to look for alternative pest management strategies to combat this pest. Among effective alternatives, insect sex pheromones provide promising tool for management S. incertulasWalker and minimize the pesticide load to the rice eco-system.

At Directorate of Rice Research (DRR), Rajendranagar,Hyderabadusing sex pheromones, aspects that will aid in effective management of rice yellow stem borer y have been investigated and the status and potential of pheromone technology in rice pest management is presented here under.

Monitoring of Scirpophaga incertulas through pheromone traps

The trapping of male in the pheromone mediated monitoring devices is influenced by pheromone blend, dispenser quality, pheromone loading and trap design,  For the monitoring of  S. incertulas, rubber dispensers impregnated with 3 or 5 mg slow release formulation of  (Z)-9-hexadecenal and (Z)-11-hexadecenal in the ratio of 1:3 are used in dry funnel or sleeve traps which are installed in the field at the rate of 3 trap per acre at a distance of 60 m in a triangular pattern (Krishnaiah et al., 1998). The rubber dispensers are replaced after 3 and 4 week, respectively. The height of the trap is adjusted in such a way that dispenser is located 0.5 meter above ground level before panicle initiation stage and one meter subsequently or the apical end of the trap remains 30 cm above the plant canopy in any stage of the crop. The study conducted by Ganeswar Rao and Krishnaiah (1995) revealed that polythene dry sleeve trap which captured 81.2 males of S. incertulas /trap/20 days is more efficient than delta sticky trap, water trap and ICRISAT dry funnel trap which caught 50.4, 18.4 and 10.4 males/trap/20 days, respectively. Trials conducted during 1995 to 1998 on monitoring yellow stem borer (YSB) using pheromone traps at several locations across the country revealed positive correlation between trap catch and stem borer damage.

A particularly detailed study on the relationship between pheromone trap catches and larval damage was reported by Varma et al. (2000) working from 1996 kharif season to 1997 rabi season at Medchal, Andhra Pradesh. Three peak periods of moth activity were observed during kharif (July, August, September) and two during rabi (January, March/April). When the information is to be used in a predictive manner, such as assessing the timing of next generation larvae a good understanding of the biology of a pest and the effect of weather and crop stage on development is important. Late planted crops were found to be more affected by S. incertulas than early planted crops. Temporal relationship was noticed between pheromone trap catches and field infestation. Studies were conducted under encaged conditions by placing freshly laid egg masses on the potted plots, which were observed for expression of damage symptoms at vegetative and reproductive stages of plant growth. Dead heart and white ear symptoms appeared after 11 to 15 days and 19 to 25 days respectively. Thus peak dead heart and white ear head infestations occurred two and three weeks after peaks in pheromone trap catches (Table 3).

With long term data on trap catches patterns in population life cycles are being elucidated which has been helpful to define parameters for effective control strategy. A tentative trap catch threshold for a specific area has also been worked out on the basis of trap capture data and relevant pest damage.

The relationship between mean weekly pheromone trap catches and the per cent infestation was expressed as Y = a + bx

10% dead hearts (Y) = 0.596 + 0.315x and x = 29.85 males

Table 3. Relationship between pheromone trap catches and infestation of YSB

Maruteru, Kharif 1995

Medchal, Kharif  1996

Month &week

PT

catch

%

inf. #

Month &week

PT

catch

%

inf. #

Sep 1

13.3

  4.5

Aug 1

25.00

0.86

        2

16.7

  9.3

       2

17.56

1.77

        3

31.0

11.6

       3

   8.44

8.47

        4

25.0

  6.5

       4

10.00

5.49

Oct  1

15.3

20.2

Sep1

10.00

5.44

       2

  8.0

  6.2

       2

21.33

5.11

       3

  5.7

  6.5

       3

62.22

5.03

       4

  3.3

  4.0

       4

35.22

6.46

Nov 1

12.0

  2.7

Oct 1

17.22

2.37

       2

25.0

  1.5

       2

18.11

9.21

       3

35.0

  1.6

       3

15.33

       10.93
       -

-

  -

       4

  4.67

8.00

       -

-

  -

Nov 1
Correlation coefficient

r = 0.79*

Correlation coefficient

r = 0.87*

Ragolu, Rabi 1997

Karjat, Kharif  1997

Month & week

PT

catch

%

inf. #

Month &

week

PT

catch

%

inf. #

Feb  1

45.67

11.20

Jul   1

1.3

0.0

        2

28.00

17.50

        2

3.0

0.0

        3

18.33

15.30

        3

4.0

0.0

        4

10.33

10.20

        4

4.0

0.0

Mar  1

9.67

8.00

Aug  1

3.0

3.8

        2

7.33

4.60

        2

2.3

4.9

        3

5.00

3.80

        3

1.7

5.9

        4

3.67

1.00

        4

40

7.8

Apr   1

12.33

3.60

Sep  1

6.3

9.2

        2

18.00

5.10

        2

11.7

16.6

        3

32.67

6.20

        3

17.0

18.2

        4

14.33

7.40

        4

24.7

21.3

        -

-

-

Oct   1

20.0

19.3

        -

-

-

        2

18.3

12.2

        -

-

-

        3

6.0

7.2

        -

-

-

        4

3.3

4.3

        -

-

-

Nov 1

3.3

4.2

Correlation coefficient

r = 0.94*

Correlation coefficient

r = 0.90*

# Infestation adjusted to 2 weeks after recording of pheromone trap catches

* Significant at 0.05 level of probability.


From regression equations of trap catch and field infestation data, trap catches of 30 and 19 male moths/trap/week resulted in 10% dead heart and 5% white heads, respectively. When catches exceeded 30 male moths/trap/week insecticide application was considered as economic trap capture threshold. Even though the trap catch of 30 is considered ETCT, catches less than this caused economic damage above 10% at Sambalpur during Kharif 1996. This information undermines the importance of developing location specific economic trap capture thresholds for use of insecticides, depending upon the predominant varieties used in a particular location and intensity of stem borer infestation.

Studies on thermal summations of different stages of YSB in the field  indicate that mean degree days accumulated for egg, larvae, pupa and total development were 93.17± 4.88, 313.10 ± 14.67, 103.46 ± 5.00 and 509.68 ± 23.17, respectively. Degree days accumulated for hatching can be used for timing of spray schedules. Further, insecticide applications should be made 95 to 110 degree days after the peak in trap catches in order to synchronize application with egg hatching. The larval development and adult emergence were found to be affected if temperatures fell below 16 or above 35OC.  Maximum temperatures of 29 to 30OC and minimum of 20OC were considered most favorable for development. The development from egg to adult was completed in 430 to 430 degree days. Under adverse weather conditions (below 16 or above 35OC) 630 to 670 degree days were required to complete development (Table 4).

 

Table 4.    Degree days accumulated between two successive peaks of pheromone trap catches of YSB during 1996 to 1997

Peak Periods

(Standard Weeks)

Mean peak moth catch

Total

DD (OC)

Mean max. Temp.(OC)

 

Mean min. Temp.(OC)

 

YEAR 1996

3 to 10 (15 Jan to 11 Mar)

15.72

454.00±38.50

30.42

(27-34.5)

17.05

(14-21)

10 to 16 (11 Mar to 22 Apr)

17.67

511.25±45.90

34.05

(30-40)

20.00

(18-23)

16 to 27 (22 Apr to 8 Jul)

7.33

669.55±53.11

37.36

(30-41.5)

24.36

(21-27)

27 to 34 (8 Jul to 26 Aug)

21.11

501.50±30.57

29.85

 (24-36)

22.45

(15-24)

34 to 40 (26 Aug to 7 Oct)

38.44

429.25±28.60

29.42

(27-32.5)

17.49

(15-21)

YEAR 1997

1 to 11 (7 Jan to 18 Mar)

33.55

532.75±39.58

30.20

(25-36.5)

17.37

(12.5-23)

11 to 17 (18 Mar to 29 Apr)

29.22

481.50±28.00

33.47

(28-36)

20.89

(17-23)

17 to 25 (29 Apr to 24 Jun)

8.22

631.00±0.00

37.74

(34-41)

22.62

 (20-27)

25 to 35 (24 Jun to 2 Sep)

25.33

674.50±0.00

34.49

(26-38)

24.21

(17-25)

35 to 42 (2 Sep to 21 Oct)

25.78

495.50±30.87

28.87

(26-33)

22.77

(20-26)

 

Management of  Scirpophaga incertulas through mating disruption

The sex pheromone of S. incertulas is an ideal tool for disrupting the mating which is essential for progeny production. In this technique very high concentration of pheromone is maintained in the field through out the crop growth period due to which the confused male moths fail to locate the calling virgin female leading to mating failure.

The application of pheromone blend of (Z)-9-hexadecenal and  (Z)-11-hexadecenal in the ratio of 1:10  at the rate of 40 g a.i./ha through 625 point sources have been reported to suppress 98 per cent communication in S. incertulas and provide season long control against this insect (Cork et al., 1998). To maintain the high concentration of pheromone for longer duration controlled release formulation of the pheromone mixture have been developed in polyvinyl chloride (PVC) matrix as base. Similar results have also been obtained with other natural blend containing (Z)-9-hexadecenal, (Z)-11-hexadecenal in ratio of 1:3, (Z)-9-hexadecenal, (Z)-11-hexadecenal and (Z)-9-octodecenal in the ratio of 1:10:0.75 and an unnatural blend containing (Z)-9-hexadecenal, (Z)-11-hexadecenal and (Z)-13-octodecenal in the ratio of 1:10:1(Ganeswar Rao et al., 1994; Cork et al., 1996).

Mating disruption trials conducted in farmers field in Andhra Pradesh and West Bengalproved that season long control of S. incertulas comparable with insecticidal treatment is possible with controlled release formulations of sex pheromone applied in the field at the rate of 40 g a.i./ha through dispensers placed at 625 points at a distance of 4 m (Fig 1). However, very high amount of pheromone required for this purpose and necessity to place the dispensers at 1 m long bamboo sticks at a distance of 4 m in the field makes the technique too costly and cumbersome due to which it may not be adopted by farmers.

Five large scale, on-farm trials conducted in a range of agro-climatic zones confirmed the efficacy of the technique (Table 5).  In each case the results were similar, mating disruption with the natural blend of pheromone components, at 1:3 ratio of (Z)-9-hexadecenal and (Z)-11-hexadecenal impregnated in PVC resin ropes, at an application rate of 40 g a.i. per ha with 625 point sources, provided a level of control that was comparable obtained with conventional insecticides applied by farmers. Mating disruption despite being highly effective was not popularized in the farmers due to prohibitive cost of pheromone material and operational difficulties in its application.

Table 5: Management of rice yellow stem borer through pheromone mediated

               mating disruption (multi-location trials)

Location

Area (acre)

Season

YSB damage

Pheromone

(@40g a.i./ha)

Farmers Practice

Medchal

25

Rabi 1994

5.28

13.04

Warangal

25

Rabi 1994

15.67

20.89

Nellore

25

Rabi 1995

3.76

10.12

Karjat

25

Rabi 1995

4.29

22.70

Mandapaka

12.5

Rabi 1995

5.46

9.63

            Fig 1. Evaluation of controlled release dispensers for pheromone
mediated mating disruption (Mandapaka, Rabi 1998)

Management of  S. incertulas through pheromone mediated mass trapping of male

Several attempts have been made to manage the population of yellow stem borer below economic injury level through pheromone mediated mass trapping of male which was more cost effective (Krishnaiah et al., 2000, Katti et al., 2001).Male annihilation technique is the best inexpensive tool for the management of S. incertulas.

 

Multi-location trials conducted in different part of country clearly indicate that this technique is capable to keep the insect population below economic injury level. For the management of S. incertulas through this technique the pheromone lures containing (Z)-9-hexadecenal and  (Z)-11-hexadecenal in the ratio of 1:3 are used in rubber dispersers loaded with 3, 5 or 10 mg pheromone mixture. The lures containing 3 and 5 mg pheromone are changed after 3 and 4 week, respectively, whereas 10 mg lure work for whole season. For mass trapping of males pheromone traps are installed in field  at the rate of 20 traps/ha in rows maintaining  a distance of 20 and 25 meters between traps and rows, respectively. The trap installation is started leaving 10 m space from the boundary of the field. To adjust the trap height at 0.5 m and 1.0 m in the early vegetative and reproductive stage of crop, respectively  or 30 cm above crop canopy in all the stages of the crop, the traps are tied on 1.25-1.5m long straight bamboo sticks or poles with the help of jute or plastic strings. However, for tall basmati varieties farmers are advised to use 1.75 m long sticks.

The information generated through multi-location trials over several years indicated that YSB could be managed with pheromone mass trapping technique (Table 6,7,8) on par with multiple applications of recommended insecticides.

Table 6.    Management of rice yellow stem borer by pheromone mediated mass trapping (Coordinated trials)

Location Season

Plot size /treatment (acre)

YSB damage

(% WE)

Yield (kg/ha)

PT

FP

PT

FP

Medchal Rabi 1995

25

3.67

19.78

6800

4800

Karjat Rabi 1995

30

4.60

22.46

4700

2900

Nellore Rabi 1995

25

4.09

10.12

-

-

Karjat Kharif 1995

30

6.40

11.50

4547

3480

Pusa Kharif 1995

30

2.20

10.00

3560

2720

Ragolu Kharif 1995

20

8.00

12.70

4432

3938

Kaul Kharif 1995

30

5.60

11.30

-

-

Karjat Kharif 1999

10

6.50

14.30

3106

2320

PT = pheromone traps; FP = farmers practice; %WE = white ears; No. of sub plots/treatment = 10; Observations = 50 hills/ sub plot

Table 7. Management of YSB by pheromone mass trapping on whole village basis

               at Medchal (Rabi, 1997)

Treatment

%DH

%WE

Yield (Kg/ha)

LT catch (males)#

Sex ratio male : female

Cost Benefit Ratio

Pheromone @ 20/ha

0.10

4.75

6380

50.08

0.90:1

1:1.24

Farmers practice

1.24

21.22

4932

164.25

1.14:1

1:1

t-value

3.24*

15.29*

5.19*

3.86*

-

-

DH = dead hearts; WE = white ears; * = significant at P = 0.05; # mean of 10 days.

Table 8. Management of YSB by pheromone mass trapping (Large scale on-farm

               trial) at Mandapaka (Rabi, 1998)

Treatment

%DH

%WE

Yield (Kg/ha)

LT catch

(males)#

Pheromone @ 20/ha

1.39a

4.12a

7140a

11.1a

Farmers practice

7.79b

17.59b

4800b

64.7b

DH = dead hearts; WE = white ears; # mean of 10 days

The residual male and female moth populations were monitored by installing gas lights in the treatment and control area ten days before harvest. This revealed significant reduction (5 times) in the YSB populations in the pheromone treated area compared to farmer’s practice. These results also show the effectiveness of pheromone mass trapping over large areas.

A comparison of cost, efficacy, safety and feasibility of insecticidal and  biological control operations which are most commonly recommended for the control of yellow stem borer of rice reveals  that male annihilation technique is the cheapest and best way for management of this insect. The insecticidal operations generally recommended to control this insect cost around Rs. 2000-5000/ha and even after their use it is not possible to check the infestation of this insect pest beyond a certain level. However, most of  insecticides recommended for borer control have broad spectrum and kill other pest of rice which is not done by pheromone trap. Now a days the egg parasitoids Trichogramma spp. are being recommended most commonly for the control of yellow stem borer. Artificial release of this parasitoid at the recommended rate of 200,000 parasitized eggs/ha for six weeks costs around Rs.3000 at the market rate of Rs.50/trichocard expected to contain 20,000 parasitized eggs. In most of the agro-climatic conditions these trichocards fail to control the pest due to very low emergence of parasitoids, their inability to survive in the field under harsh climatic conditions, poor searching capacity of parasitoid, partial parasitization of the egg mass and heavy mortality due to insecticides applied for the control of other insect pests of rice. Due to these factors farmers fail to get any benefit even after spending Rs.3000/ha in artificial release of parasitoids and due to lack of any verification tools they are cheated by suppliers. On the other hand, the population of yellow stem borer can be brought down below economic injury level comparable to chemical control by adopting mass trapping of male at the cost of approximately Rs. 500-1000/ha.

As the performance of the pheromone traps can be monitored easily by counting the insects trapped in it, the cheating done in supply of spurious product is caught immediately.

In the multi-location/ multi year testing programme of the Directorate of Rice Research, the technique was found to be cost effective, compatible with other management tactics like chemical (Table 10) and biological control involving in-undative release of parasites.

Integration of Pheromones with Bio-control in Rice IPM

        Mass trapping of stem borer through use of pheromone traps @ 20/ha and inundative releases of egg parasite, Trichogramma chilonis at 1,00,000 adults/ha 5 times against leaf folder were evaluated for the control of yellow stem borer (YSB) and leaf folder (LF).   

Stem borer damage reduced significantly in pheromone treatment with only 8.9% white ears compared to 28.0% in farmers practice plots. Similarly T. chilonis  was found effective in reducing leaf folder damage to 8.5% in treated areas compared to 22.0% in FP (Table 9). The grain yield was high in treated plots (4747 kg/ha) compared to control (3421 kg/ha). Therefore, integration of pheromones with bio-control for managing YSB and LF is highly effective strategy that can be employed in areas where these two pests cause economic damage and limit the yields.

 

Table 9. Management of YSB and LF through mass trapping and Bio-control

Treatment

Nellore, Kharif 1995

% WE

% LFDL

Yield (Kg/ha)

Pheromone + Bio-control

  8.9

  8.5

4747

Farmers Practice

28.0

22.0

3421

t-test

*

*

*

WE = White ears; LFDL = Leaf folder damaged leaves; * = significant at P = 0.05

Table 10. Integration of pheromone mass trapping and chemical control

Location Season

Plot size /treatment (acre)

YSB damage

(% WE)

Yield

(kg/ha)

PT PT + I FP PT PT + I FP
Karjat Kharif 1997

30

12.4

9.5

20.5

3176 4208 2320
Kapurthala Kharif 1997

30

2.6

1.6

8.9

4720 5360 4480
Karjat Kharif 1998

35

5.8

4.8

20.8

3302 4149 2393
Pantnagar Kharif 1998

30

35.8

17.7

20.2

3500 3400 4000
Kapurthala Kharif 1998

30

6.3

11.2

31.7

5760 6500 5480
Maruteru Rabi 1998

100

3.4

4.1

10.6

6340 7140 4800
Moncompu Rabi 1998

30

3.3

4.9

15.0

4391 4904 4400

PT = pheromone traps; PT + I = Pheromone + need based insecticide application; FP = farmers practice; %WE = white ears; No. of sub plots/treatment = 10; Observations = 50 hills/ sub plot

Significant decline in infestation both in terms of dead hearts and white ears was noticed in all the pheromone treatments than farmer’s practice at all the centers (Table 11). Even though lowest infestation was recorded when pheromone traps were installed over 5ha area these differences were non significant when compared with 1ha treated area. Similarly, the pheromone treatments irrespective of the size of the field registered significantly higher yield.  These results indicate that pheromone mediated YSB management through mass trapping can be possible in holdings of even 1ha area. Wherever community endeavour is not possible, individual farmers with small land holdings can also use this technology to manage YSB effectively.

Pheromone mass trapping as component of IPM

 

The pheromone mass trapping was integrated with IPM package and tested for its ability to reduce stem borer damage. The results indicated significant reduction in stem borer damage and was identified as ideal component for IPM in stem borer endemic areas. Through multi-location verification of location specific IPM modules with Pheromone mass trapping as one of the components over a number of years, the effectiveness of the technique was confirmed (Table 12). This technology, approved as a commercially viable one by the Indian Council of Agricultural Research, has been popularized through government funded large scale /front line demonstrations all over the country (Fig 2).

Table 11. Optimization of field size for YSB management by mass trapping

Treatment

Mandapaka (Rabi 1998)

Suryaraopalem (Rabi 1999)

%DH

%WE

Yield (Kg/ha)

%WE

Yield (Kg/ha)

1ha

3.53a

3.77a

 5200ab

1.21a

7087a

3ha

2.60a

3.93a

4800b

1.58a

6383a

5ha

2.17a

4.88a

5733a

1.33a

6922a

FP

6.67b

9.69b

4800b

7.83b

6031b

Treatment

Karjat (Kharif 1998)

Karjat (Kharif 1998)

1ha

5.33a

11.68a

4280a

8.25a

4662a

3ha

4.72a

11.12a

4320a

5ha

5.92a

8.96a

4933a

FP

9.02b

21.96b

2427b

    19.87b

2822b

Table 12. On-farm Integrated pest management trials with pheromone mass

                  trapping as an IPM component

Location Season

YSB damage (%WE)

Yield (kg/ha)

Benefit/Re Invested

IPM

FP

IPM

FP

IPM

FP

Warangal Rabi 2002

1.7

7.9

7200

6520

1:2.8

1:2.4

Karjat Kharif 2003

2.7

25.3

5748

3520

1:1.3

1:1

Warangal Kharif 2003

3.6

7.7

8668

7868

1:2.9

1:2.6

Karjat Rabi 2003

5.6

18.3

5520

4240

1:1.2

1:1

                  

Fig 2. Management of rice yellow stem borer by pheromone mediated mass

              trapping (frontline demonstrations)

Improving pheromone lure attractancy through addition of plant extracts and co-attractants

 

In order to further enhance the efficiency of mass trapping technique, both lab studies using electroantennogram and field studies were conducted. Varma et al., 2002 reported significant improvement in the trap catch with addition of Pusa Basmati plant extracts and vitamin E (Table 13).

 

Table 13. Catch of S. incertulas moths in pheromone traps baited with plant extracts, vitamin E in combination with different pheromone blends

Treatments Catch/trap
Medchal DRR Karjat
3:1 + BHT + TN1 plant extract in methanol 55.33abc 14.00bc 21.80bc
3:1 + BHT + Pusa Basmati extract in methanol 133.33a 31.50a 29.80ab
9:1 + BHT + TN1 extract in methanol 60.67abc 0.25d 14.80c
9:1 + BHT + Pusa Basmati extract in methanol 21.33c 1.00d 8.20d
3:1 + BHT (Butylated Hydroxy Toluene) 59.33abc 20.50ab 7.80d
3:1 + vitamin E (Tocopherol) 102.00ab 14.25bc 19.40c
9:1 + BHT (Butylated Hydroxy Toluene) 16.67c 2.75cd 16.60c
9:1 + vitamin E (Tocopherol) 33.67bc 7.50cd 33.20a

DMRT at 5% significance level

MAJOR CONSTRAINTS IN ADOPTION OF PHEROMONE TECHNOLOGY AND MEASURES TO BE ADOPTED

  • Quality of the pheromone lure: Lure quality plays decisive role in the success of male annihilation technique. There is great difference in quality of lures supplied by different companies, which need to be addressed.
  • Trap type: In several trials sleeve trap was found more effective.
  • The quantity of pheromone present in the dispensers: Quantity plays very important role in the trapping of males. The suppliers of pheromone lures generally recommend the use of 3 or 5 mg lure for mass trapping of males which remain effective for 3 and 4 weeks, respectively. Our studies indicate that 10 mg lure which provides season long control may also be used for this purpose. As the efficacy of lures manufactured by different suppliers vary considerably, best quality lures should be used for mass trapping of males.
  • Lack of farmers awareness: There is a need to train the farmers to ensure the quality of the product and use best product in an efficient way.
  • The time of installation is very important. Installation of trap with in 1-2 week of transplanting is essential in the areas where yellow stem borer is a serious pest and is present every year from early stage of the crop. In the regions where the infestation comes late or where it is not a regular pest the traps may be installed after monitoring the pest incidence.
  • Use of straight bamboo pegs of recommended height and trap adjustment: It has been observed that some farmers do not use straight bamboo pegs of required height for fixing the trap and tie the trap in early stage of the crop on small green plant twigs. When such twigs dry after a few days they bend due to which the orientation of the trap also changes to make it unfit for proper trapping. When the plant grows taller, these traps are concealed in the plant canopy due to which spread of the pheromone in the field is seriously affected. Adjustment of trap height in different stages of crop growth, which is also known to affect the trap catches seriously is also not taken care of properly by farmers due to which the traps get concealed in the plant canopy most commonly in the reproductive stage of the crop. This factor seriously affect the trap catches in tall Basmati varieties which cover the trap if not installed on 1.5-1.75 m long bamboo sticks
  • Trap density: The installation of traps in the field at proper distance is also essential for efficient functioning. Normally, the traps should be installed in rows at a distance of 20 and 25 meter between traps and rows. Too close or too sparse installation which is also seen in the farmers field affect the trapping of male as their mode of action changes to work for mating disruption and monitoring, respectively.
  • The polythene supplied with some traps are sealed at the lower end due to which rain water may collect inside it and its weight may damage the sleeve. To prevent such damage the corners of the sleeve may be cut or punctured with pointed pins to make very small holes for water drainage. The lower end of open polythene sleeve are also tied with the stick of the trap to keep it straight and prevent the damage done by air. As the water may also collect inside it if tied tightly, the lower end of such sleeve should be tied loosely to facilitate the drainage.
  • Replacement of damaged sleeves: Sometimes, the polythene sleeve may be damaged by jackals or dogs and non-replacement of such damaged sleeve makes the trap virtually ineffective. Some traps are also dislocated in harsh weather conditions such as heavy rain or very fast blowing wind and relocation of the trap should be done at the earliest.
  • Replacement of lure: Lure replacement is also essential for the success of the technique should also be done at right time as the lures loose their efficacy after a certain period. As most of the above mentioned factors are under control of the farmers, they may enhance the efficacy of male annihilation technique by adopting recommended packages of practices.
  • Storage of pheromone lures: Lures should be preserved in refrigerator till their use. If they are kept in the open the pheromone chemical will be lost, which will effect the lure performance.
  • Use of talc/Insecticide: To prevent escape of trapped moths small quantities of talc or insecticide dust should be used in the sleeve trap.

Extent of adoption of the technology and constraints for country wide adoption of the technology and future strategies for popularization of the technology will be discussed.

Pheromones have been recognized as useful tools in Rice  IPM as reflected by the  recommendations made by some state agricultural universities and states department of agriculture in their package of practices and their follow up action to motivate the farmers; positive image of pheromone as a technique to reduce the pest damage during the interaction with farmers in different states; continued efforts in research, development, sectors of  the public institutions and in  commercialization of the product  by private sector.  While the technology is useful in IPM of Rice in all rice growing areas, its utility will be of greater significance in rain-fed low land rice areas and in the areas where organic rice cultivation of export oriented rice is in practice.

State

Recommendation status

Adoption status

Monitoring

Mass trapping

Monitoring

Mass trapping

Yes No Yes No Wide Sparse Wide Sparse
Karnataka P P
W.B P P
H.P P P P
U.P P P P P
Uttarakhand P P P P
Rajasthan P P
A.P P P
Maharashtra P P P P
Chattisgarh P P
Orissa P
Pondicherry P P P P
Kerala P P

STEPS FOR EFFECTIVE COMMERCIALIZATION OF PHEROMONES

  • Pheromones marketed as blends might contain impurities in trace quantities or may not be appropriate to the geographically isolated pest populations across the country.
  • Use the appropriate pheromone according to the predominant pest/species populations in the given area.
  • Market the appropriate blends of the species prevailing in the area.
  • Evaluate the batches of lures before marketing, for chemical / biological efficacy.
  • In view of lack of information on the availability of pheromones even to the scientific community, pheromone production and marketing companies should have closer association with scientists and extension staff.
  • Promotional activities by the marketing companies should be initiated and strengthened through demonstration, awareness campaigns, electronic media etc.,
  • Extension workers and farmers should be trained on the proper use of pheromones.

Future thrust areas for development of pheromone technology

  • Indigenous development and production of pheromones of the important pests should be stepped up. To cope up with the pest complex and variability of the insect species more chemists and chemical labs should be motivated to take up this work on priority basis.
  • Scope for enhancement of the pheromonal activity by the addition of extracts/additives should be explored and exploited.
  • Emphasis should be placed on the human resource development in pheromone research both in chemistry and Entomology for development of lures.
  • Pheromone lures with season long persistence/attractancy should be developed.

References

Cork A, Souza K D, Krishnaiah K, Kumar D V S S R, Reddy A A, Casagrande E and  De-Souza K. 1996. Control of yellow stem borer, Scirpophaga incertulas (Lepidoptera: Pyralidae) by mating disruption on rice in India: effect of unnatural pheromone blends and application time on efficacy.   Bulletin of Entomological Research. 1996. 86 (5): 515-524

Cork A, Souza K D, Krishnaiah K, Reddy A A and Zainullabuddin S. 1998. Season-long control of yellow stem borer, Scirpophaga incertulas (Lepidoptera: Pyralidae) by mating disruption with the natural ratio of pheromone components. Bulletin of Entomological Research. 1998. 88 (2): 109-116.

Ganeswar Rao A, Krishnaiah K, CorkA and Hall D R. 1994. Disruption of sex pheromone mediate communication in yellow stem borer, Scirpophaga incertulas Walker with a controlled release pheromone formulation. Journal of Entomological Research. 18(3): 287-288.

Ganeswar Rao A and Krishnaiah K. 1995. Factors influencing yellow stem borer, Scirpophaga incertulas (Walker) moth captures in pheromone traps. Pheromone in IPM. In: National Workshop on pheromone in IPM,Hyderabad, 1995. Directorate of Rice Research, Rajendranagar,Hyderabad.  pp. 40-42.

Kalode M B and Krishnaiah K 1991. Integrated pest management in rice. Indian Journal of Plant Protection 19: 117-132.

Katti G, Paslau I C, Varma N R G and Krishnaiah K (2001). Integration of pheromone mass trapping and biological control for management of yellow stem borer and leaf folder in rice. Indian Journal of Entomology. 63:325-328.

Krishnaiah, K.; Zainalabeuddin, S.; Ganeswara Rao, A.; Kumar, D.V.S.S. and Rama Gopalavarma, N. 1998. Pheromone monitoring systems of rice yellow stem borer, Scirpophaga incertulas Walker. Indian Journal of Plant Protection. 26 : 99-106.

Krishnaiah K, Varma N R G, Pasalu I C, Zainulabeudin S and Yadav J S 2000. Development of mass trapping technique for management of yellow stem borer (Scirpophaga incertualsWalker) in rice. Pp 33-40. In: InnovativePest and Disease management in Horticultural and Plantation Crops. (Eds. Narsimhan S, Suresh G and Weisley D) Allied Publishers, Chennai.

Pandya H V, Shah A H and Purohit M S 1989. Assessment of partitional growth stage, and yield loss due to insect pests of rice (Oryza sativa). Indian Journal of Agricultural Sciences 59: 272-273.

Varma N R G, Krishnaiah K, Pasalu I C, Reddy D R R. 2000. Monitoring of rice yellow stem borer, Scirpophaga incertulas Walker using pheromone traps and thermal summations. Indian Journal of Plant Protection 28: 84-93.

Varma N R G, Krishnaiah K, Pasalu I C and Katti G R. 2002. Synergizing rice yellow stem borer pheromone with addition of plant extracts and vitamin E. Indian Journal of Plant Protection 30: 161-163.

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