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OBJECTIVES OF INSECT DEFOLIATORS At the end of this section students should be able to:

OBJECTIVES OF INSECT DEFOLIATORS At the end of this section students should be able to: 1) Know the difference among polyphagous, oligophagous and monophagous defoliators. 2) Know the principles of detection, evaluation and management of defoliators.

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OBJECTIVES OF INSECT DEFOLIATORS At the end of this section students should be able to:

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  1. OBJECTIVES OF INSECT DEFOLIATORS • At the end of this section students should be able to: • 1) Know the difference among polyphagous, oligophagous and monophagous defoliators. • 2) Know the principles of detection, evaluation and management of defoliators. • Know the life history, economic importance and ecological impact of the following defoliating insects: • (A) spruce budworm • (B) gypsy moth • (C) Douglas-fir tussock moth • (D) Defoliators of the Southeastern U.S.

  2. Defoliation damage by insects can • easily be recognized from symptoms: • Foliage thin or absent • Frass “raining” from trees • Sometimes webs are apparent • Larva crawling up/down tree

  3. Fall Webworm – Hyphantria cunea

  4. Symptoms Leaf chewers – eat entire leaf and include the Pine sawflies, Gypsy moths, Spruce bud worm

  5. Symptoms Leaf skeletonizers – eat soft parts or the epidermal layers – not the veins.

  6. Symptoms Leaf miners – bore inside leaves, between The upper and lower epidermis. Includes, the Pine needle miners and the Aspen leaf miner

  7. Blotch mines

  8. Damage by defoliators • Primary Damage – • Trees are killed by defoliation • or growth is reduced. • Conifers – 1 severe defoliation • can kill tree • Deciduous trees – better able • to stand defoliation

  9. Damage by defoliators Secondary damage occurs when defoliated trees are weakened and subject to attack by secondary pests such as wood borers, bark beetles, or soil fungi – Armillaria spp

  10. Defoliators – Taxonomic Groups Lepidoptera: Many insect species Includes Pine Butterfly, spruce budworm Gypsy moth, catalpa worms

  11. Defoliators Hymenoptera- Sawflies Red Headed Pine Sawfly Loblolly pine Sawfly Oak slug sawfly

  12. Defoliators – Coleoptera: Cottonwood Leaf beetle, June beetles, Elm leaf beetle, & the Locust leaf miner.

  13. Generalized Host Range of defoliators Polyphagous - Many hosts, e.g. Gypsy Moth Oligophagous – Few Hosts, e.g. Spruce budworm Monophagous – one hosts, e.g. Larch casebearer

  14. Population Dynamics: Sporadic - Periodic -

  15. Spruce Budworm - Choristoneura fumiferana

  16. Life Cycle

  17. Spruce Budworm Larva

  18. Adult Moth

  19. Spruce Budworm egg mass on needle

  20. Spruce budworm 3rd Instar in bud

  21. Instars 4-6 feed on new foliage first and move to older foliage if necessary.

  22. Populations are cyclic with peaks roughly every 8-10 yr. Major outbreaks every 60 years or so that corresponds with maturation of Balsam fir stand.

  23. Management Considerations: Stand Composition- Chemicals- Biologicals-

  24. Budworm Treated area to left of road

  25. End of Spruce Budworm Section

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