allplantprotection.blogspot.com

Behavioral evidence for the exploitation of a host plant on the basis of vision in the

melon fly, Bactrocera cucurbitae, (Diptera: Tephritidae)

Jaime C. Piñero1, Steven Souder2, and Roger I. Vargas2

1Lincoln University, Cooperative Research and Extension, Jefferson City, Missouri 2USDA-ARS, Pacific Basin Agricultural Research Center, Hilo, Hawaii

Native to southeast Asia Polyphagous feeding habits:

> 125 host plant species Preferred host: cucumber

Introduced into the Hawaiian Islands, it became established

by 1897

Introduced to Hawaii in the 1800s

Native to tropical America

Main producers: India, Brazil, Indonesia, Nigeria, and Mexico

Melon fly infests papaya fruit

High carrying capacity of papaya fruits: up to 400 larvae/fruit

Is papaya odor attractive to melon fly females?

What is the relative contribution of olfactory and visual cues in host

location?

0

10

20

30

40

50

60

70

80

Papaya Papaya Papaya Papaya

1-wk oldfemales

2-wk oldfemales

3-wk oldfemales

4-wk oldfemales

Mea

n nu

mbe

r (±

SEM

) res

pond

ing

in 2

0 m

in

0

10

20

30

40

50

60

70

80

Tomato Tomato Tomato Tomato

1-wk oldfemales

2-wk oldfemales

3-wk oldfemales

4-wk oldfemales

0

10

20

30

40

50

60

70

80

Bittermelon Bittermelon Bittermelon Bittermelon1-wk oldfemales

2-wk oldfemales

3-wk oldfemales

4-wk oldfemales

0

10

20

30

40

50

60

70

80

Cucumber Cucumber Cucumber Cucumber

1-wk oldfemales

2-wk oldfemales

3-wk oldfemales

4-wk oldfemales

Olfactory response to six host fruit species

Non-choice tests in 1 m3 cages using sliced fruit covered with black, perforated tray

Ten color-marked females (1, 2, 3, and 4 weeks old) released per cage

Number of responding females recorded continuously for 20 min

Replicated 15 times

Mature green: 0 responded (out of 160 released (80: 3-wk; 80: 4-wk old)

Quarter ripe: 0 responded (out of 160 released (80: 3-wk; 80: 4-wk old)

Half-ripe: 0 responded (out of 160 released (80: 3-wk; 80: 4-wk old)

Ripe: 0 responded (out of 160 released (80: 3-wk; 80: 4-wk old)

Olfactory response to papaya (various ripening stages)

Choice and non-choice tests in cages, either, covered with black, perforated tray, or uncovered (8 replicates)

NON-CHOICE TEST RESULTS WITH COVERED FRUITS

Example of choice tests using uncovered fruits

0

50

100

150

200

250

covered uncovered covered uncovered0

50

100

150

200

250

covered uncovered covered uncovered

Mea

n nu

mbe

r (±

SEM

) egg

s la

id in

24

hour

s

cucumber papaya cucumber papaya

Ability of female melon flies to locate host fruits

CHOICE TEST NON-CHOICE TEST

20 females (4 weeks old) Cucumber or

papaya Fruits dissected

after 24 hours

A

BB

C0

2

4

6

8

10

12

Present Absent

Num

ber (

mea

n ±

SE)

of fe

mal

es c

aptu

red

host odor

Yellow

Clear

Interaction Vision and Olfaction

Piñero et al. (2006), Ent. Exp. Appl.

Host (cucumber) odor

A

BB

C0

2

4

6

8

10

12

Present Absent

Num

ber (

mea

n ±

SE)

of fe

mal

es c

aptu

red

host odor

Yellow

Clear

0

1

2

3

4

5

20 min 2 hours 24 hours

Mea

n nu

mbe

r (±

SEM

) res

pond

ing

Papaya mimic (visual) Papaya mimic + sliced papaya (visual + olfactory)

a a

a

a

a a

Does papaya odor contribute to the visual response? Non-choice tests in 1 m3 cages using papaya mimics

coated with Tangletrap with and without papaya odor (sliced papaya underneath)

Ten 4-week old females released per cage (8 replicates)

Responses recorded for 20 min, then after 2h and 24 h

Conclusions

Under a variety of conditions, female melon flies showed not to be attracted to volatiles emitted by papaya fruit

Rather, vision seems to be the main mechanism underlying the response to papaya fruit

No contribution of papaya odor to the visual response

Applications for pest management: e.g., importance of field sanitation, use of visually-attractive bait stations

Thanks! (to Russell Ishima)

Questions?