Post on 16-Dec-2015
National Plant Diagnostic NetworkNational Plant Diagnostic Network
Diagnosing Plant Problems:Insects and Other Arthropods
Hodges and Ellis. December 2006.Hodges and Ellis. December 2006.Update, August 2008.Update, August 2008.NPDN Publication No. 0008NPDN Publication No. 0008
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Insect Diagnosis
Focuses on classic, morphology based taxonomy.
Often requires an expert taxonomist for species-level identification.
Limited resources for diagnosticians.
Quality of sample submitted is important!
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
How is an Insect Identified to Species?
First Detectors (County Extension Agents, Crop Consultants)
Extension Diagnostic Specialists (at Land
Grant Universities)
Taxonomic Specialists (usually federal, state, or university employees)
Species Identification Confirmed
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and Symptoms of Damage
• Over-development of tissues• Necrosis of tissue• Types of arthropod feeding damage
- Stippling- Chlorosis- Sooty Mold- Leafmining- Leaf Defoliaters- Spider Mites- Borers- Root Damage
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Photo 1: Paul Weston, Cornell University, www.forestryimages.orgPhoto 2: Jim Occi, BugPics, www.forestryimages.org Photo 3: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, www.forestryimages.orgPhoto 4: Jerald E. Dewey, USDA Forest Service, www.forestryimages.org
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and Symptoms
Over-development of tissues
• Some insect and mite species can induce gall formation on a variety of host plant structures.
• Gall-makers are generally host plant specific.
A mite gall, Aculops laevigata on willow
Photo: William M. Ciesla, Forest Health Management International, www.forestryimages.org
Photo: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, www.forestryimages.org
Gall Mite Damage
Eyespot Gall
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsOver-development of
tissues• How do you know if an
insect has caused this damage?
• Closely examine plant deformation.
• Cut open gall.• Exit holes, frass, empty
larval chambers, etc.• Rear insects to adult
stage.
Photo: Ronald F. Billings, Texas Forest Service, www.forestryimages.org
cynipid gall wasps
Photo: Jerry A. Payne, USDA Agricultural Research Service, www.forestryimages.org
oriental chestnut gall wasp
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsOver-development
of tissues• Can insect or mite galls
cause serious damage to host plants?
Yes, heavy infestations can negatively effect overall plant health and reduce the aesthetic value of ornamentalcrops.
ash flower gall mite damage Photo: A. Steven Munson, USDA Forest Service, www.forestryimages.org
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsOver-development
of tissues Non-insect bacterial and fungal galls may resemble insect galls.
Crown gall bacterium causes galls on roots, crowns and stems.
Fungi can also form large galls that superficially resemble the crown gall bacterium.
Photo: USDA Forest Service - Ogden Archives, USDA Forest Service, www.forestryimages.org
bacterial gall on douglas-fir
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsNecrosis of tissue
Dieback-insect damage• Feeding damage from
several types of insects can lead to limb dieback.
• Death of the host may result.
Loblolly pine killed by southern pine beetle
larch casebearer damage
Top Photo: Petr Kapitola, Forestry and Game Management Research Institute - Czechia, www.forestryimages.org
Bottom Photo: Ronald Billings. Texas Forest Service. http://www.forestryimages.org/.
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and Symptoms
Types of Insect Feeding Damage Insects with piercing- sucking mouthparts cause stippling and/or chlorosis on the host.
Example groups: aphids, true bugs, hoppers, scale insects, whiteflies, etc.
Azalea lace bug damage
Top Photo: Clemson University - USDA Cooperative Extension Slide Series, www.forestryimages.org
Bottom Photo: John A. Weidhass, Virginia Polytechnic Institute and State University, www.forestryimages.org
wax scale
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsTypes of Insect Feeding
Damage• Presence of sooty mold
may suggest an infestation of honeydew producing insects such as scales, mealybugs, whiteflies, or aphids.
• Presence of ants may also be an indicator of these insects!
Photo: Scott Tunnock, USDA Forest Service, www.forestryimages.org
sooty mold on grand fir
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and Symptoms
Types of Insect Feeding Damage
Leafmining• Insects that produce
characteristic “mines” in leaves by feeding.
• Formed by various insects including flies, wasps, moths, and beetles.
Aspen blotchminer
Bottom Photo: Minnesota Department of Natural Resources Archives, Minnesota Department of Natural Resources. http://www.forestryimages.org/
columbine leafminer
Top Photo: Lisa Ames, UGA, www.forestryimages.org
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsTypes of Insect Feeding
Damage
Leaf Defoliaters• Damage caused to a
plant by insect feeding.
• “Skeletonizing” results when the veins or the “skeleton” of the leaf is left behind.
Bottom Photo: E. Bradford Walker, Vermont Department of Forests, Parks and Recreation, www.forestryimages.org
maple trumpet skeletonizer
oak skeletonizer
Top Photo: James Solomon, USDA Forest Service, www.forestryimages.org
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsTypes of Arthropod
Feeding Damage
Spider Mites
• Leaf damage includes flecking, bronzing, and/or scorching of leaves.
• Several natural enemies. Most problematic in heavy insecticide use areas.
gorse spider mite damage
Photo: Eric Coombs, Oregon Department of Agriculture, www.forestryimages.org
twospotted spider mite
Photo: Mississippi State University Archives, Mississippi State University, www.forestryimages.org
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsTypes of Insect
Feeding DamageBorers• Insects that bore into a
host trunk, stem, or twig as part of their life cycle.
• Damage often results in weakening or killing the host.
A Lepidopteran stalk borer, Papaipema nebris, in silver maple Photo: James Solomon. USDA Forest Service.
http://www.forestryimages.org/
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Signs and SymptomsTypes of Insect
Feeding Damage
Roots• Don’t forget to look
for potential insect damage on roots!
Aspen root girdler
Bottom Photo: Robert L. Anderson, USDA Forest Service, www.forestryimages.org
Scarab beetle larval feeding damage on root system of pine
Top Photo: Ostry, Mike. USDA Forest Service. http://www.forestryimages.org/
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Insect IdentificationKnow Common Pest Arthropod Groups!• Numerous lepidopteran caterpillars (ex.
armyworms, cutworms)• Beetles (Order Coleoptera): numerous leaf-
feeding and wood-boring pests• Sawflies (Order Hymenoptera)• Various flies (Order Diptera)• Various insects with piercing-sucking
mouthparts including scales, mealybugs, whiteflies, aphids, psyllids, hoppers, various other members of the Order Hemiptera.
• Spider Mites
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
Insect Identification• Know the difference
between pests and beneficials!
• There are several predatory or parasitic beneficial insects!
Pest - southern green stink bug
Top Photo: David Cappaert, www.forestryimages.org
Beneficial-a predatory stink bug
Bottom Photo: Lawrence Abrahamson, State University of New York, www.forestryimages.org
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
• Amanda C. Hodges, Ph.D., achodges@ufl.edu
SPDN Assistant Director, University of Florida
• Amanda M. Ellis, ellisam@ufl.edu,
University of Florida, SPDN
Authors
MODULE 4 – Diagnosing Plant Problems: Insects & Arthropods
• This publication can be used for non-profit, educational use only purposes. Photographers retain copyright to photographs or other images contained in this publication as cited. This material was developed as a core training module for NPDN First Detector Training. Authors and the website should be properly cited. Images or photographs should also be properly cited and credited to the original source.
• Publication Number: 0008• Publication Date: December 2006
Publication Details