Updated 01/16/09

Eric H. LaGasa¹, Patrik Hertzog², Denise Bowden², and Bob Fair²

Background

Figure 1. 2000 Archips podana collection sites.

Figure 2. Adult Male Archips podana

Native to Europe and parts of Asia, Archips podana (Scopoli, 1763) was first introduced into North America in British Columbia, Canada sometime earlier this century. Early records of the species in Canada (Freeman 1958) are confused with another similar European species, Archips oporana (Linneaus) (Brown, 2002 USDA Memo), but it was correctly identified (as A podana) in the lower Fraser River Valley of B.C. in 1988 , where it was reported feeding on apple, plum, and blueberry (Belton 1988). (NOTE - Both European and North American technical literature variably list the species as Archips podana and A. podanus, which should be considered synonyms for the same species.)

Specimens of A. podana were first collected in the U.S. in 2000, as non-target captures in a WSDA / USDA CAPS pheromone-trap detection survey for European corn borer, Ostrinia nubilalis (Hbn., 1796) (LaGasa 2000). In that survey, traps at 15 sites in northwestern Whatcom County captured 183 adult male A. podana, delimiting an infested area in the northwest corner of the state (Figure 1.). Confirmation of the these first U.S. collections was received in March, 2002 (Brown, 2002 USDA Memo) which prompted a USDA APHIS New Pest Advisory Group review of the current information and Risk Assessment for the exotic pest species.

In Europe, A. podana (Figure 2.) is considered one of the most abundant and damaging tortricid species occurring on fruit crops (Alford, 1999). The leafrolling-larvae damage the fruit of apple, pear, plum, blueberries, cane-berries and other plants, and feed on the leaves of many forest and ornamental trees, including maple, oak, elm, walnut, birch, hawthorn, and others.

2001 Project Objectives

1. Determine local A. podana host plant preferences.

• Rear leafroller larvae from selected host plants to adult.
• Identify the adults produced and associate host plants.

2. Observe and record A. podana biology and larval parasitism.

• Identify parasitoids and defoliator host species reared.
• Capture digital graphics of EPSB life stages, biology, and feeding damage where possible.

Project Methods and Materials

Fruit trees and ornamental plants known to be A. podana host plants were searched for leaf-roller damage or larvae in selected areas near sites where higher numbers of A. podana adults were collected in 2000. Rolled/damaged leaves and larvae were collected along with additional host leaves and transported to the WSDA Olympia Entomology lab, where all larvae were individually reared on either artificial diet (apple feeding species) or host plant leaves. Larvae were photographed periodically during rearing to produce reference graphics, which were identified to species from adults moths produced. All adult moths and parasitoids produced were identified when possible, photographed as needed, and selectively curated into the WSDA Olympia Entomology Collection.

Host plants which produced larvae included; apple, pear, plum, cherry, blackberry, rose, alder, aspen, amelanchier (serviceberry), hawthorn (native), mountain ash, poplar, and hydrangea.

Digital image files created for this project were captured with a Nikon 990 camera, hand-held or mounted on a Leica MS5 microscope, and macro-photographic images were created using daylight-corrected fiber-optic incandescent lighting and mylar diffuser-filters. Images were also cropped, adjusted, and labeled with Photoshop 5.5.

Project Results and Discussion

In total, 461 individual leaf-damaging larvae were collected and processed in this survey.Of these, 333 specimens were either successfully reared to the adult moth stage or produced parasitoids. A list of leaf roller species reared, which numbered 18 total, the numbers of each reared, and a count of parasitoids or larval mortality is presented in Table 1.

A. podana was reared from 5 host plants, including (in order of abundance) apple, native hawthorn, mountain ash, plum, and amelanchier (serviceberry). Damage from A. podana and other leafroller larvae was not particularly prominent on any of the host plants sampled in the area and timeframes of this project. Where it was found, A. podana occurred in fewer numbers than other leafroller species. A summary of the number of A. podana larvae reared and the percentage of all larvae reared by host plant is listed in Table 2.

Identification of Archips podana larvae collected in this survey proved to be difficult, due to the occurrence of similar larvae of another introduced (long established) exotic species in the survey area; Archips rosanus (L.), known in the region as the European leafroller or filbert leafroller. While microscopic physical characters may exist to differentiate larvae of the two species, a comparison of gross anatomy features failed to distinguish between the species (e.g. comparison of head, thoracic plate, body, leg, and anal plate color). This similarity was also apparent in both the immature (mid-instar) and mature larval forms. Larvae of both species are presented here to show the similarity (Figures 3-8).

Figure 3. Immature Archips podana larva.	Figure 4. Immature Archips rosanus larva.
Figure 5. Mature male Archips podana larva.	Figure 6. Mature male Archips rosanus larva.
Figure 7. Mature female Archips podana larva.	Figure 8. Mature female Archips rosanus larva.

Adult Archips podana moths, in contrast to the larvae, were found to be distinctive, particularly males, and also were found to occur in varying of forms of wing color and pattern. Examples of the more typical color patterns for the sexually-dimorphic adult moths are presented in Figures 9 and 10.

Figure 9. Adult male Archips podana.

Figure10. Adult female Archips podana.

The forewing color and pattern variation noted among adult specimens reared in this study included two basic "schemes", including the more typical (common) configurations shown (Figures 9 and 10) and a darker brown and purple form. Examples of the variant color forms reared are presented in Figures 11 through 16.

Adult A. podana flight was recorded (in part) in light-traps present in the area of this survey for another CAPS detection survey (LaGasa et. Al. 2002). Light-trap collections were recorded between June 27 and Aug 1, with an apparent peak in late July. Collection dates and numbers of adult A. podana are presented in Figure 17., and location of the light-trap survey site (near the U.S./Canadian border at Blaine, WA) is shown on Attachment 1.

A number of parasitoids (all parasitic Hymenoptera spp.) were reared from suspect A. podana larvae in this project. However, due to the difficulty separating (identifying) A. podana and A. rosanus larvae collected in this survey (see page 2), parasitism rates and parasitoid species associated with A. podana are not available at this time. It is possible that on-going collaborations with systematic researchers may provide the ability to identify the species of parasitoid-killed host larval remains (curated with reared parasitoids) through genetic analysis. Reared adult A. podana specimens and larval remains from parasitoid-killed host larvae have been provided to research staff, and results (positive or negative) should be available in early 2003. Once available (and if successful), that data will be reported separately (contact the author for more information).

Figure 11. A. podana male - common form	Figure 12. A. podana male - common form (darker variant)	Figure 13. A. podana male - dark form (purple/brown)
Figure 14. A. podana female - common form	Figure 15. A. podana female - common form (darker variant)	Figure 16. A. podana female - dark form (purple/brown)
Figure 17. 2002 Adult Archips podana Light-trap Collections.

Figure 18. Macrocentrus linearis

Interestingly, one species of parasitic hymenoptera reared from A. podana and/or A. rosanus in this project is a European species considered to be a principle control for A. podana in Europe. That species, Macrocentrus linearis (Nees) (Braconidae: Macrocentrinae), is a gregarious parasitoid that has been cultured and released for biological control of European corn borer and other pest moth species in North America. Previous CAPS defoliator rearing surveys (that didn't include A. podana) recorded the parasitoid only once, from a native leafroller species. More information on M. linearis and previous CAPS defoliator parasitoid surveys are available at: Western Washington Exotic Defoliator Parasitoid Survey

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This project was a cooperative effort of the Washington State Department of Agriculture, Agriculture and Agri-Food Canada, and the USDA Animal and Plant Health Inspection Service (APHIS). Funding for field and lab support staff was provided in part by a Cooperative Agricultural Pest Survey (CAPS) grant from the USDA APHIS Western Region (#01-8553-0249-CA) 1Eric LaGasa, Chief Entomologist, Pest Program / Plant Protection Division, Washington State Department of Agriculture, P.O. Box 42560, Olympia, Washington 98504-2560, (360) 902-2063 PestProgram@agr.wa.gov 2Entomology Aides (Project) - Washington State Dept. of Agriculture, Olympia, Washington 98504-2560 This report is provided as a public resource for the detection and identification of insect pests described. This entire report, as well as individual graphic images, may be freely copied, distributed, and used in electronic and printed format as long as they are not modified for content or used for commercial purposes.