DICARER WG37.5 as a partner of anti-resistance strategy programme for the control of diamondback moth (Plutella xylostella L.) in Thailand

Jaruek Ribuddhachart1 , Ittidet Chaimongkol1, Patiparn Saitarnthong2 , Somsith Chomenansilpe2 and Amornrut Bhandhufalck2 1R&D Insect Control, Ciba R&D Station, Tak Fah, Nakhon Sawan, Thailand 2Crop Protection Technical, Ciba-Geigy (Thailand) Limited

Abstract DICARER WG37.5 is a mixture of POLOR (diafenthiuron) and INSEGARR (fenoxycarb). POLOR is a representative of a novel chemical class of insecticide, highly active on Plutella xylostella at 50 g ai/hl, whilst INSEGARR (fenoxycarb) is a new juvenile hormone analogue with typical growth regulating features, especially interference with the last larval moult and, or ovicidal activity against many lepidopterous pests, at 10Ð15 g ai/hl. In Thailand, resistance development of P. xylostella and Spodoptera exigua remains a critical factor in shortening the product life cycle of efficacious insecticides, as farmers repeatedly apply effective products. Usually the two pests are observed in a mix population, damaging/destroying cruciferous crops. If an insecticide is only effective on one of these pests,the farmer would mix/cocktail with other insecticide in order to control both pests. Following laboratory test during 1994Ð1995, DICARER 37.5WG, was then evaluated in the farmers’ fields under practical use conditions. Under laboratory test, DICARER (300 ppm POLOR+100 ppm INSEGARR) was very effective against both the egg stage and the last instar larvae of P. xylostella.Whilst under field conditions, DICARER (30 g ai/hl POLOR+7.5 g ai/hl INSEGARR), proved effective against P. xylostella on Chinese kale. In addition, alternate application of DICARER with RAMPAGE (chlorfenapyr) clearly out performed all other treatments, thus proving that DICARER , applied alternately with other effective insecticides, not only provides best control of Plutella xylostella but also can be applied in an IRM programme to further prolong the life cycle of effective products in the market. In conclusion, IRM should continue to be strongly promoted, developed as an effective tool for a better control of P. xylostella and other lepidopterous pests in Thailand and other countries.

Key words: Diamondback moth, DICARE, mixtures, insecticide resistance management

Introduction Field evaluation of these products in 1986 showed Diamondback Moth (DBM), Plutella xylostella (L.) promising results in only the northern area but not in (Lepidoptera : Yponomeutidae) is one of the most the central plains and a loss of the Bt’s efficacy was serious insect pests of cruciferous crops all over the observed if it is applied just before an irrigation world (Hill, 1975). In Southeast Asia, it is a serious (Rushtapakornchai and Vattanatungum, 1986). pest of cabbage, Chinese kale, Chinese cabbage, leaf Ciba-Geigy, as a chemical company, is interested mustard, Chinese radish and cauliflower. In Thailand, to evaluate a new product, DICARE WG37.5 for the diamondback moth is generally prevalent from control of DBM in the Southeast Asian countries. February to April when optimum climatic conditions DICARE WG37.5 is a mixture of POLOR and food plants are more readily available. However, (diafenthiuron) and INSEGAR (fenoxycarb). POLO in many areas of the central plain where crucifers are is a representative of a novel chemical class of planted all year-round, diamondback moth damage can insecticide, which is highly active on P. xylostella at be observed through out the year (Rushtapakornchai 50 g ai/hl (hectoliter) (Streibert and Kaeding, 1994), and Vattanatangum, 1984). Damage from whilst INSEGAR (fenoxycarb) is a new juvenile diamondback moth has been prevented only by hormone analogue with typical growth regulative spraying of chemical insecticide. However, application features, especially interference with the last larval in large quantity and repeat use of the same chemical moult and, or ovicidal activity against many is always threatened by the development of resistance lepidopterous pests, at 10Ð15 g ai/hl (Senn and in a short period of time (Miyata et al., 1986). In Frischnecht, 1994). The evaluation were therefore Thailand, the microbial insecticide, Bacillus carried out to determine the following: thuringiensis (Bt) has been used for diamondback (1) Efficacy of DICARE (POLO/INSEGAR) vs moth control since 1972. Most commercial Bt products P. xylostella under laboratory conditions. available belong to HD-1, var. kurstaki, serotype 3a/3b.

Chemical control 185 (2) Efficacy of DICARE (POLO/INSEGAR) vs Ð Number of newly hatch larvae/plant were P. xylostella under field conditions. recorded (3) Application strategy of DICARE as a partner in Ð Number of larvae/plant at 3 days after anti-resistance programme vs P. xylostella in application were recorded comparison with the farmer’s practices. Ð % mortality was calculated

Materials and Methods 100 Laboratory conditions (Ciba-Geigy R&D Station, Tak Polo+Insegar300+100 ppm 91 Fah) Insegar(WP) 100 ppm 88 ¥ For eggs test: 16 potted cabbage plants (1 month Polo(SC)300 ppm old) were placed in the mating cage in which 100 80 Check pairs of P. xylostella adult moths are released for 66 68 2 days to allow oviposition on the leaves. Remove 61 the cabbage plants from the cage. POLO SC250 60 (300 ppm), INSEGAR WP25 (100 ppm) and a mixture of POLO+INSEGAR (300+100 ppm) were employed in the test. 40 Total no. of treatments: 4, including untreated check 24 Total no. of replicates: 4 (1 potted cabbage plant/ 20 rep) 13 Total cabbage seedlings for this test: 16 1 Ð Number of eggs on the leaf surface were 0 recorded % hatched larvae % mortality at 3 days Ð Chemical solutions, according to the treatment at 1DAA after hatching list were applied individually thoroughly the Figure 1. Effect of POLO, INSEGAR and whole plant with hand spray (10 ml/plant). POLO+INSEGAR on eggs of Plutella xylostella

100 100 100 91 100 96 85 88 80 80 75 80 70 76 65 58 60 60 60 55 44 40 40 40 33

20 20 20 13 15 9 8 13 9 8 4 3 0 0 0 0 0 % mortality of L1 % mortality of % mortality of % mortality of % mortality of % mortality of at 72 h L1 at 120h L3 at 72 h L3at 120h L2 at 72 h L2 at 120h Polo+Insegar300+100 ppm Polo(SC)300 ppm Insegar(WP)100 ppm Check Figure 2. Effect of POLO, INSEGAR and POLO+INSEGAR on Plutella xylostella (L1), (L2) and (L3).

100

80 Check Chlorfenapyr(EC)15 60 Fipronil(SC)+tebufenozide(F)5+30 Abamectin(EC)1.8 40 Dicare(WG)37.5 Polo(SC)50

20

0 Figure 3. Bioefficacy of DICARE on Plutella xylostella on Chinese kale % control (DBM) % leaf damage at Bang Bua Thong with 5 days intervals.

186 Proceedings: The Management of Diamondback Moth and Other Crucifer Pests 100 100 99 95

84 84 80 79 Check Chlorfenapyr(EC)15 67 Fipronil(SC)+tebufenozide(F)5+30 60 DICARE(WG)37.5 55 POLO(SC)50

40

20

0 0 0 % control (DBM) % control (DBM) Figure 4. Bioefficacy of DICARE on Plutella xylostella on Chinese Trial 1 Trial 2 kale at Katumban with 3 days intervals 60

53 50 48 Check 40 Chlorfenapyr(EC)15 Fipronil(SC)+tebufenozide(F)5+30 DICARE(WG)37.5 30 POLO(SC)50

20 20 18 18 18

12 10 5 2 3 0 % leaf damage at 55 DAS % leaf damage at 50 DAS Figure 5. % Leaf damage on Chinese kale at harvesting Trial 1 Trial 2 time under 3 days interval at Katumban

98 100 95 89 89 Farmer's Practice** (as in Figure 7) 81 POLO(50)/chlorf(20)fipro(5)/teb(20) 80 CGStrategy* as in Figure 7) DICARE(WG)37.5 Chlorfenapyr(EC)20 60 58 Abamectin(EC)1.8 53 POLO(SC)50 Check 40

20 Figure 6. DICARE in CG Strategy and as a partner of anti-resistance 0 0 strategy programme against Plutella xylostella on Chinese % control (DBM) cabbage at Bang Bua Thong

¥ For larval test: Potted cabbage plant and chemical Ð 80 L1, 80 L2, 80 L3 (for 4 reps) were preparations were made in the same way as the transferred to the treated leaves, according to egg test. the treatment list :check, POLO (300 ppm), Ð Chemical solutions were applied individually INSEGAR (100 ppm) and POLO+INSEGAR thoroughly the whole plant with hand spray, (300+100 ppm), respectively. according to the treatment list (10 ml/plant) Ð Number of dead larvae at 3 and 5 days after Ð The treated leaves were cut and put in the application were recorded plastic box, accordingly. Ð % mortality was calculated Ð Total no. of treatments: 4, including untreated ¥ Field trials: A suspension concentrate formulation check of POLO (diafenthiuron), 250SC, INSEGAR Ð Total no. of replicates : 4, 1 leaf/rep (fenoxycarb) 25WP and a ready mixed formulation

Chemical control 187 100 96 96 88 Farmer's Practice** 86 POLO(50)/chlorf(20)fipro(5)/teb(20) 80 CGStrategy* 73 DICARE(WG)37.5 Chlorfenapyr(EC)20 Abamectin(EC)1.8 60 57 POLO(SC)50 49 Check 40 *CG-Strategy = DICARE (37.5) / chlorfenapyr (20) g ai/hl : Application No. 1, 2 & 5 = DICARE 37.5 g ai/hl Application No. 3 & 4 = chlorfenapyr 20 g ai/hl 20 **Farmer's Practice : Application No. 1Ð5 = chlorfenapyr+fipronil (20+5 g ai/hl) Figure 7. DICARE in CG Strategy and as a partner of anti-resistance 0 0 strategy programme against Plutella xylostella on Chinese kale % control (DBM) at Bang Bua Thong 100 90 Farmer's Practice** (as in Figure 7) POLO(50)/chlorf(20)fipro(5)/teb(20) 80 CGStrategy* (as in Figure 7) 67 DICARE(WG)37.5 Chlorfenapyr(EC)20 60 53 Abamectin(EC)1.8 POLO(SC)50 Check 40 37 30

20

5 8 5 0 Figure 8. Percent leaf damage occurring in DICARE alternation strategy % leaf damage was comparable to a good standard, chlorfenapyr

4 4 4 Farmer's Practice** (as in Figure 7) POLO(50)/chlorf(20)fipro(5)/teb(20) CGStrategy* (as in Figure 7) 3 DICARE(WG)37.5 3 Chlorfenapyr(EC)20 Abamectin(EC)1.8 POLO(SC)50 Check 2 2 2 2 1.8 1.7 1.5 1.5 1.5 ***Crop grading: 0 = Very poor 1 = Poor 3 = Good 4 = Very good 1 1 1 0.8

Figure 9. Yield & Grading*** of Chinese kale treated with DICARE (alternation 0 0 0 strategy) in comparison to the farmer's Yield (kg/m2) Grading practice.

of POLO & INSEGAR (DICARE 37.5WG) were per replicate, and/or a final leaf damage rating at evaluated in the field.A randomized complete just before harvest. Marketable yield was also block design was employed with 4 replicates (37.5 recorded. g.ai). The plot sizes varied from 10Ð20 m2. Foliar application of POLO (50 g.ai/hl), and Results & Discussion POLO+INSEGAR, 30+7.5 or DICARE 37.5 g ai/ ¥ Under laboratory condition ha with a spray volume of 1000 L/ha were made Egg test: POLO+INSEGAR, 300+100 ppm with local standard treatments and untreated check. showed superior ovicidal effect to either POLO or The applications were timed on eggs, and young INSEGAR.Very high % mortality of the newly P. xylostella larvae (L1, L2 & L3). The first hatched larvae at 3 days (72 h) after application application was made when eggs was observed on was also recorded in a POLO+INSEGAR the leaves or 2Ð3 weeks after sowing. treatment (Figure 1). The assessments were made by counting the Larval test: POLO+INSEGAR, 300+100 ppm number of living larvae and pupae on 10Ð20 plants showed superior larvicidal effect than either POLO

188 Proceedings: The Management of Diamondback Moth and Other Crucifer Pests 5

Farmer's Practice** (as in Figure 7) 4.3 4.3 4.2 POLO(50)/chlorf(20)fipro(5)/teb(20) 4 4 CGStrategy* (as in Figure 7)

3.5 DICARE(WG)37.5 3.3 Chlorfenapyr(EC)20 3 3 3 Abamectin(EC)1.8 2.8 2.7 POLO(SC)50 Check 2.2 2 2 ***Crop grading: 0 = Very poor 1 = Poor 3 = Good 4 = Very good

1 1

0 0 0 0 Yield (kg/m2) Grading Figure 10. Yield & Grading* of C. cabbage treated with DICARE (alternation strategy) in comparison to the farmer's practice

or INSEGAR.Very high % mortality of the L3 recommendations for use of DICARE on cruciferous larvae at 5 days (120 h) after application was also crops are as follows: recorded in a POLO+INSEGAR treatment 1) Do not apply DICARE repeatedly. (Figure 2). 2) Alternate DICARE with other P. xylostella ¥ Field trials effective products At Bang Bua Thong (BBT) and Krathumban 3) DICARE should be applied right at the beginning (KBT), DICARER 37.5 g ai/hl at 5 days intervals of P. xylostella infestation (oviposition period). with a spray volume of 1000 L/ha was effective 4) Apply only 2 applications of DICARE/crop. against P. xylostella and superior to abamectin, 1.8 g ai/hl and fipronil+tebufenozide, 5+30 g ai/hl. References However DICARE was inferior to chlorfenapyr, Hill, P.S. (1975). Agricultural Insect Pests of the Tropic and 15 g ai/hl. (Figure 3). their control. Cambridge University Press, London. When DICARE, 37.5 g ai/hl was applied at 500 p. 3 days intervals, the bioefficacy on P. xylostella Miyata, T., T. Saito and V. Noppun (1986). Studies on the mechanism of diamondback moth resistance to increased and comparable to chlorfenapyr, 15 insecticides, p. 347Ð357. In: T.G., Griggs and N.S. g ai/hl. (Figures 4 and 5). B. DICARE as a partner Talekar (eds). Diamondback Moth Management. in an anti-resistance strategy programme against AVRDC, Taiwan. P. xylostella. Rushtapakornchai, W. and A. Vattanatungum (1984). Trials were conducted at Bang Bua Thong, Comparison study on the efficacy of certain insecticides in comparison with farmer’s practices.The results for control lepidopterous larvae on Chinese cabbage. showed that DICARE (37.5 g ai/hl) applied right Annual Research Report for 1984. Entomology and at the beginning and in alternation with Zoology Division, Department of Agriculture, chlorfenapyr 20 g ai/hl gave good control of Bangkok, Thailand. Rushtapakornchai, W. and A. Vattanatungum (1986). Present P. xylostella. Percent P. xylostella control and the status of insecticide control of diamondback moth in marketable yield were taken into account (Figures Thailand, p 307Ð312. In: T.G., Griggs and N.S. Talekar 6, 7, 8, 9 and 10). (eds.). Diamondback Moth Management. AVRDC, Taiwan. Conclusions & Recommendations Streibert, H.P., and D. Kaeding (1994). Use of PegasusR DICARER (POLO+INSEGAR) at 300 ppm+100 ppm (diafenthiuron) against diamondback moth (Plutella under laboratory condition, and at 37.5 g ai/hl under xylostella) and other lepidopterous pests in cruciferous field condition showed enhancement of activity in the crop. Crop Protection Division, Ciba-Geigy AG, CH- control of P. xylostella. Besides, DICARE can be 4002 Basle, Switzerland, 6 p. Senn R., and M.L. Frischnecht (1994). Use of fenoxycarb to considered as an ideal partner in an anti-resistance control the citrus leaf miner (Phyllocnistis citrella) strategy programme for the control of P. xylostella (Stnt).Crop Protection Division, Ciba-Geigy AG, CH- and/or Spodoptera exigua in cruciferous crops. In order 4002 Basle, Switzerland, 4 p. to maintain the effective life of an insecticide, the

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