Ecology and Sustainable Management of Major Bactrocera Fruit Flies in Goa, India

V. R. Satarkar, S. V. Krishnamurthy, J.R. Faleiro, A. Verghese, R. Ramesh and J. Ashok Kumar

Email: vved20@yahoo.co.injrfaleiro@yahoo.co.in

INTRODUCTION

• Fruit flies are an important group of insects that occuracross India.

• This Tephritidae family consists of over 4500 species ofthe fruit flies in the world of which 200 species are ofeconomic importance.

• They are among the most important world widebecause of their direct economic impact and strictquarantine implications.

Technical details

Series of field and laboratories experiments were conducted from April 2006 to  March 2008.

For trapping, three villages were selected in the coastal , midland and upland regions of Goa.

Trapping was done by using methyl eugenol and cu‐lure traps

Trials on Management of B. cucurbitae (BAT) and B. dorsalis (HWT) were taken up.

Study sites

Old Goa‐ Coastal zone ‐ 10km from Arabian sea/15m above MSL

Keri‐Midland zone‐ 25km from Arabian sea/70m above MSL

Molem‐ Upland zone‐ 50km from Arabian sea/100m above MSL

The midland and upland form a part of Western Ghats (mountainous region ) –biodiversity hot spot

Fabrication of Bottle Trap

1. Fabricated using disposable plasticwater bottles (capacity: 1L).

2. Each trap had four windows of 1square inch, cut open just belowthe shoulder of the bottle.

3. For facilitating the recording of datawith respect to flies captured, thebottom of the bottle trap was cutand reversed into the open lowerend of the bottle.

4. The trap was loaded separatelywith Methyl Eugenol (ME) blockand Cue Lure (CL) block. MEblocks were prepared usingplywood pieces of 5 X 5 X 1.2 cmwhich were soaked overnight in amixture of ethanol solvent, ME and0.1 % malathion 50 EC in a ratio of6:4:1 by volume, while the CLblocks were procured from acommercial dealer

Suspension thread

Opening for entry of fly

Wooden block dipped in attractant

Small holes for water draining

Cue‐lure trap Methyl eugenol trap

Each trap was set 1 km apart from the other in the above selected three ecologicalzones.

At each study site, 16 traps (8 traps each with ME and CL) were set.

Each trap was fastened with the help of small nylon ropes to the twigs of the trees at2m height.

Number of flies trapped in each trap was recorded at weekly intervals.

The lures were replaced at bimonthly intervals in order to sustain the trappingefficiency.

The captured flies were brought to the laboratory, dried, separated species wise andwere preserved.

Ecology

Incidence and abundance of Orchard and Melon flies

Orchard flies (ME)

• Bactrocera dorsalis (Hendel)• Bactrocera caryeae (Kapoor)• Bactrocera zonata (Saunders)• Bactrocera affinis (Hardy)• Bactrocera correcta (Bezzi)

Melon flies (CL)

• Bactrocera cucurbitae (Coquillett)• Bactrocera tau (Walker)• Bactrocera gavisa (Munro)• Bactrocera caudata (Fabricius)• Bactrocera nigrotibialis (Perkins)

SpeciesPercent incidence ANOVA

Upland Midland Coastal F p

Orchard  flies

B. caryeae 95.25 98.11 81.13 8.235 0.001*

B. dorsalis 100 98.12 100 11.248 0.001*

B. zonata 59.43 39.62 48.11 2.911 0.056

B. correcta 41.50 40.56 51.88 2.179 0.115

B. affinis 10.37 2.80 3.77 2.040 0.132

Melon

flies

B. cucurbitae 98.11 100 100 23.507 0.0001*

B. tau 53.78 76.41 59.43 6.643 0.001*

B. gavisa 19.81 17.92 29.24 4.203 0.016*

B. caudata 0.04 3.77 19.81 13.256 0.0001*

B. nigrotibialis 16.03 14.15 2.83 5.565 0.004*

Incidence (%) of fruit flies at three geographical zones of Goa

* Significant at 0.05 level.

Spatio-temporal occurrence and abundance of orchard flies

0

2

4

6

8

10

12

14

16

18

B. caryeae B. dorsalis B. affinis B. zonata B. correcta

Mean de

nsity

 (No/trap/m

onth)

Species

Mean density (Number/trap/month) of orchard flies in Goa

Mean density (Number/trap/month) of melon flies in Goa. 

Spatio-temporal occurrence and abundance of melon flies

Rank Abundance of orchard and melon flies

0

0.1

0.2

0.3

0.4

1 2 3 4 5 6 7 8 9 10Pi

Rank

B. gavisa

B. caryeae

B. dorsalis

B. cucurbitaeB. zonata

B. tauB. correcta

B. nigrotibialisB. affinis

B. caudata

0

0.1

0.2

0.3

0.4

0.5

1 2 3 4 5 6 7 8 9 10

Pi

Species

B. caryeae

B. dorsalis

B. tauB. cucurbitae

B. correctaB. zonata

B. nigrotibialisB. caudata

B. affinis

B. gavisa

0

0.1

0.2

0.3

0.4

1 2 3 4 5 6 7 8 9 10

Pi

Species

B. cucurbitaeB. dorsalis

B. caryeaeB. tau

B. correcta

B. zonata

B. gavisa

B. caudataB. affinis

UPLAND

MIDLAND

COASTAL

B. nigrotibialis

Rank

Rank

Melon flies are indicated in red and orchard flies are in black letters

Spatial Distribution pattern of Orchard flies

Parameters/Index Upland Midland Coastal

Variance to Mean ratio      184.13 194.49 1257.33

Cole’s Index

Maximum regularity (1/n) 0.0094 0.0094 0.0094

Randomness (1/n + (n‐1)/n X 1/X) 0.0094 0.0094 0.0095

Index value (I) 0.023 0.018 0.055

David Moore`s Index 183.13 193.49 1256.33

Dispersion Parameter (K) 0.693 1.098 0.0205

Common ‘K’ 0.684 1.089 0.196

Llyod`s Index (X*) 310.08 406.03 1514.38

Morisita`s Index 2.43 1.90 5.82

Dispersion indices for orchard flies at three geographical zones

Parameters/Index Upland Midland Coastal

Variance to Mean ratio 60.52 213.34 391.38

Coles Index

Maximum regularity (1/n) 0.0094 0.0094 0.0094

Randomness (1/n + (n‐1)/n X 1/X) 0.0094 0.0095 0.0096

Index value (I) 0.017 0.022 0.027

David Moore`s Index 59.523 212.343 390.382

Dispersion Parameter ‘K’ 1.227 0.748 0.547

Common ‘K’ 1.217 0.739 0.537

Llyod`s Index (X*) 132.551 371.277 603.768

Morisita`s Index 1.807 2.324 2.812

Dispersion indices for melon flies at three geographical zones

Spatial Distribution pattern of melon flies

Seasonality

0

200

400

600

800

1000

1200

1400

1600

Pre monsoon Monsoon Post monsoon

Abu

ndan

ce

Season

Orchard flies Melon flies

Abundance of orchard and melon flies recorded during pre monsoon, monsoon and post monsoon seasons.

0

200

400

600

800

1000

1200

B. dorsalis B. caryeae B. zonata B. affinis B. correcta B. cucurbitae B. tau B. gavisa B. caudata B nigrotibialis

Mea

n M

ontly

abu

ndan

ce (N

os/tr

ap)

Species

Pre monsoon Monsoon Post monsoon

Mean density of orchard and melon flies (Numbers/trap/season ± SE) recorded during different seasons

Orchard flies Melon flies

Phylogenetic Relationship

Dendrogramme showing phylogenetic relationship of major fruit flies in 3 different ecological zones

Management of B. cucurbitae and B. dorsalis

A view of the hill cucurbit agro-ecosystem in Goa

Different cucurbits cultivated in the Western Ghats region of Goa

Cucumber

Ridge gourd Red Pumpkin

Bitter gourd Snake gourd

Traditionally preserved cucurbit seeds by tribal farmers of Goa, India

Crop production to marketing

Melon fly, Bactrocera cucurbitae is a major pest, causing more than 20 % loss in the yield.

B. cucurbitae infested cucumber vines

Bactrocera cucurbitae infested cucumbers

Farmers sometimes use insecticides to control B. cucurbitae ‐ A potential hazard to children of the tribal farmers in the agro‐ecosystems

Cage used for Single Killing Point study

A

A

A

B

B

B

Attraction of B. cucurbitae to different baits in single killing point Studies

Sl No. Treatment Mean SD t 

1 Standard PH as spray 5.17 0.753 0.542Standard PH as spray 4.83

2 Standard PH as spray 5.50 0.775 1.581Standard banana as spray 4.50

3 Standard PH as spray 5.67 1.722 0.948Standard jaggery spray 4.33

4 Standard PH as spray 4.83 0.606 0.674Standard banana spray double dose 5.17

5 Standard PH as spray 4.25 1.369 ‐1.342Standard jaggery spray double dose 5.75

6 Standard PH as spray 5.92 1.563 1.437St. jaggery spray + st.banana spray 4.08

7 Standard PH as spray 4.58 0.917 ‐1.112St. jaggery spray + st.banana spray + tuna spray 5.42

8 Standard jaggery spray 5.08 1.021 0.200Standard jaggery trap 4.92

9 Standard banana as spray 5.33 0.983 0.830Standard banana trap 4.67

10 Standard PH as spray 5.50 0.894 1.369Standard PH as trap 4.50

11 Standard PH as trap 5.50 0.707 1.732Standard banana trap 4.50

12 Standard PH as trap 4.83 0.258 ‐1.581Standard jaggery trap 5.17

13 St. jaggery spray + st.banana spray 5.17 0.753 0.542St. jaggery spray+ st.banana spray + tuna spray 4.83

Treatments  tested in cucumber field

1. Commercial PH (obtained from Anand Agricultural University,Gujarat) made up as a solution with 1L water containing 30ml of PH (3% volume: volume)

2.Banana (velchi) made as 10g banana mashed up and liquidized in 1L of water (10% weight: volume)

3. Jaggery + bananamixture, made up as 5g of jaggery and  5g of banana in 1L of water (5% jaggery and 5%banana weight: volume)

4. Insecticide sprays (0.1% malathion 50EC)

5. Untreated control (no bait / insecticide application)

(1-4: In farmers field, 5: Institute farm)

Squirting of the Baits

8L/ha @200 splashes/ha (each splash 40ml)  Applied in a 7m square gridWeekly application 30days after planting up to end of commercial fruit production

On farm Bait Application Technique (BAT) to control B. cucurbitae

Sl. No TreatmentsPercent damage

Pooled meanTrial‐I Trial ‐II Trial‐III

1 Protein Hydrolysate 17.38 (10.74) b 11.15 (3.80)bc 14.38 (6.28)b 15.02 (6.94) bc

2 Banana 13.31 (05.38) bc 13.16 (5.41)b 16.61 (8.23)b 14.51 (6.33)bc

3 Banana +Jaggery 13.26 (13.26) bc 09.19 (2.60)c 11.41 (4.05)c 11.55 (4.28)cd

4 Insecticide 06.54 (01.32) c 10.09 (3.08)bc 10.48 (3.37)c 09.25 (2.59) d

5 Control 26.50 (21.00) a 26.58 (20.24)a 25.70 (18.86)a 26.47 (20.04) a

CD (p =0.05) 7.43 3.53 2.96 3.26

Values in parenthesis denote original value

Average yield of hill cucumber in Goa 30t/ha

Cumulative damage due to B. cucurbitae in control plot 20.04 %

Cumulative damage due to B. cucurbitae in treated plot 4.28 %

Loss in yield that was saved due to treatment 15.76 % (4.7 t/ha )

Estimated gain due to treatment Rs 30,550 (@ Rs. 6500/t )

Cost of treatment (10 applications) Rs 2000 / ha

Cost –Benefit ratio 1: 15.3

Cost‐benefit ratio of BAT in hill cucurbits of Goa to manage B. cucurbitae

Hot water Treatment

Mass rearing of fruit fly

Freshly harvested mangoes  Fruits exposed overnight to fruit flies

Hot Water Treatment

Hot water treated mangoes (48c for 1 hr/48c for 1.5 hr/untreated control)

Sensitivity tests (Colour, aroma sweetness)

63.33 65.74

58.15

32.7828.70 27.41

3.89 5.56

14.44

0

10

20

30

40

50

60

70

48oC at 1hr 48oC at 1.5hr Control

Hot water treatments of mangoes (Colour)

Resp

onde

nts

(%)

Good Very Good Poor

62.7858.33

64.63

28.8924.81

18.15

8.7016.85 17.22

0

10

20

30

40

50

60

70

48oC at 1hr 48oC at 1.5hr Control

Hot water treatment of mangoes (Aroma)

Res

pond

ents

(%)

Good Very Good Poor

48.15 48.3352.04

46.3042.78

31.67

5.938.89

16.30

0

10

20

30

40

50

60

48oC at 1hr 48oC at 1.5hr Control

Hot water treatments of mangoes (Sweetness)

Res

pond

ents

(%)

Good Very Good Poor

Sensitivity tests (colour, sweetness, aroma)