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FINAL REPORT:

Title: Identification of chemical attractants from apple foliage and fruit for codling moth.

PI: Peter J. Landolt, USDA-ARS, Wapato, WA

Objectives:

2001 Objectives

Test chemicals for responses of codling moth females

Test chemicals for responses of codling moth larvae

Study moth responses to host odor

Repeat GC-EAD work with walnut

Significant Findings:

1). Codling moth larvae are more strongly attracted to apple fruit that is infested and are notattracted

in laboratory assays to the odors of apple fruit that are undamaged.

2). Codling moth larvae are attracted to three different apple kairomones, but in all cases,

amounts of the chemicals required for attraction are dramatically higher than that released by

apple fruit.

3). Codling moth adults are more strongly attracted to apple fruit that is infested compared to

un-infested fruit.

4). Trapping of male and female codling moth with kairomones was significantly improved in

a preliminary trapping test using 2 and 3 component blends of compounds found in induced

apple fruit, compared to compounds tested individually.

5). Codling moth adults are attracted to the odor of un-infested Bartlett pear fruit and

similarly to the odor from cut Bartlett pear.

Methods:

Codling moth female responses to fruit, fruit odor, and fruit chemistry were evaluated both in

a flight tunnel and in the field. Flight tunnel assays included responses to fruit, fruit odors piped into

the tunnel, and to solvent washes of fruit. Larval responses to fruit odors and fruit chemistry were

evaluated in Y-tube and parallel tube olfactometers.

Volatile collections were made to characterize the odorants released from uninfested and

infested immature apple and pear fruit at 2-week intervals through the season. Most of these odorants

were characterized, using GC-MS. GC-EAD was used to determine which of the numerous

compounds found in apple and pear odor are detected by codling moth females.

One of the chemicals tested is not commercially available and was isolated from an essential

oil of a different plant and was purified using both preparatory column and HPLC methods.

Results and Discussion:

Results of flight tunnel assays of female codling moth responses to fruit, fruit odors, fruit

washes, and fruit kairomones yielded interesting biological results but no clear identification of the

kairomonal attractant from infested immature apples. Codling moth adults were attracted to immature

apples, but more so to apples that were infested by codling moth larvae. Moths were similarly

attracted to odors of apples piped into the flight tunnel, indicating that the attraction is a response to

volatile chemicals from the fruit. Female codling moths were also attracted to the odor of Bartlett

pear fruit in the flight tunnel and similarly to the odor of damaged Bartlett pear fruit.

Results of trapping experiments that tested apple fruit kairomones were mixed, but did yield a

blend of compounds that attracted more male and female codling moth than any of the single

chemical treatments, which included the pear ester. As reported by others for the pear ester, there

appeared to be more varied performance of kairomonal lures in the second generation in apple which

obscured results when attempts were made to replicate tests through the season (that is, attraction

results seen early in the season were sometimes not repeatable later in the season).

Field tests of synergism of codlemone and apple fruit kairomones did not yield any evidence

of the enhancement of trap catch over that of codlemone alone. These tests were conducted during

both codling moth flights, with similar results. However, this experiment was done with a limited set

of apple fruit kairomones and will be pursued further with additional chemicals and over ranges of

release rates. Some fruit kairomones significantly reduced male response (trap catch) to sex

pheromone.

Laboratory olfactometer tests of neonate larval responses yielded a series of positive findings.

In the first series of tests, it was determined that larvae were not significantly attracted to the odor of

fresh-picked apple fruit, unless the apple fruit was infested. Larvae were attracted to the odor,

however, of cold-stored thinning apples. Studies to isolate and identify the active ingredients in apple

odor are still incomplete but indicate strong activity in two different liquid chromatography solvent

fractions (one polar and one non-polar) obtained from volatile collections from infested, fresh-picked

apples.

Testing of several chemicals known to be present or increased in the odors produced by

infested apples yielded positive responses. E,E-alpha farnesene was identified in New Zealand

(Sutherland and Hutchins 1972, Nature 239: 170) as an apple-produced attractant for codling moth

larvae. We demonstrated upwind attraction of larvae to this compound at relatively high release rates.

Such release rates occur from stored fruit but not immature fresh fruit. This compound may be part of

a blend of compounds from apple that are attractive to larvae. Similar results were obtained with a

second chemical identified in Europe as likely to be a codling moth attractant in apple. This chemical

is not commercially available and was purified for use in assays from an essential oil. Again,

attraction of larvae to this chemical was demonstrated, but at release rates that are high compared to

our measurements of the compound from attractive apple fruit. Neonate codling moth larvae also

responded to the pear ester, ethyl (E,Z)-2,4-decadienoate, at higher release rates. In addition, this

response appeared to be limited to a turning response (Y-tube assay) and was not seen in a parallel

tube olfactometer test designed to look at upwind forward movement. Experiments are underway to

test for evidence of synergism among these chemicals as attractants for codling moth larvae.

Chemical analyses of volatile collections from apple and pear fruit clearly indicate a strong

effect of codling moth larval infestation on the odor profile of these fruit. The number of chemicals

produced and emitted is increased in response to codling moth damage and the total amount of

volatiles emitted is increased greatly. This provides not only more odorants for the codling moth to

detect and respond to, but provides a stronger signal that the insect may be able to more readily detect

at some distance.

References:

Landolt, P. J., R. W. Hofstetter, and P. S. Chapman. 1998. Neonate codling moth larvae

(Lepidoptera: Torticidae) orient anemotactically to odor of immature apple fruit. Pan-Pacific

Entomol. 74: 140-149.

Landolt, P. J., J. A. Brumley, C. L. Smithhisler, L. L. Biddick, and R. W. Hofstetter. 2000. Apple

fruit infested with codling moth are more attractive to neonate codling moth larvae and possess

increased amounts of E,E-alpha farnesene. J. Chem. Ecol. 26: 1685-1699.

Reed, H. C. and P. J. Landolt. Attraction of mated female codling moths, Cydia pomonella L.

(Lepidoptera: Tortricidae), to apples and apple odor in a flight tunnel. Florida Entomol. (In press).

Budget:

Identification of chemical attractants from apple foliage and fruit for codling moth.

Peter J. Landolt

Project Duration: 1999-2001

Current Year: 2002

Year Year 1 (1999) Year 2 (2000) Year 3 (2001)

Salary 21,200 34,000

Benefits 6,700

Supplies 6,000 5,0002

Travel 500

Total 29,000 34,400 39,000

This work complemented funding from and efforts made under IFAFS and RAMP grants in 2001.

Total Project funding: $102,400

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