basic entomology mg-2012plantclinic.tamu.edu/files/2012/08/tdainspector-training...crustacea&...
TRANSCRIPT
Basic Entomology for Iden4fiers
Carlos E. Bográn, PhD Associate Professor & Extension Specialist [email protected]
TDA Inspector Training, 2012
• Basic Entomology – What is an insect? – Biology and development – Common insect groups – Iden4fica4on, diagnosis
Outline
What type of animal is an insect? • Insects are arthropods in the Class Hexapoda (six-‐legged)
• Invertebrates (lack back-‐bone) with exoskeletons and segmented bodies
• Ventral nerve cord; dorsal diges4ve track
• Common arthropods include arachnids, crustaceans and their rela4ves
Crustacea Malacostraca Decapoda (crabs, shrimp, lobsters)
Isopoda (pillbugs, sowbugs)
Hexapoda Entognatha Collembolla (springtails)
Insecta Thysanura (silverfish)
Odonata (damselflies, dragonflies)
Orthoptera (grasshoppers, crickets)
Hemiptera (bugs, aphids, scales)
Coleoptera (beetles, weevils)
Lepidoptera (moths, buNerflies)
Chelicerata Arachnida Araneae (spiders)
Scorpiones (scorpions)
Acari (4cks, mites, chiggers)
Myriapoda Chilopoda (Cen4pedes) Diplopoda (Milipedes)
Phylum
Arthrop
oda
Myriapoda: Chilopoda
Myriapoda: Diplopoda Crustacea: Isopoda Phylum: Mollusca
Entognatha: Collembola
Arachnida: Scorpiones
Class Arachnida
• Mites, 4cks, spiders and scorpions
• Two body regions: cephalothorax and abdomen
• Four pairs of legs • Most are predators but some are pests
• Approximately 1 million species of insects have been named
• Beetles (Coleoptera), flies (Diptera) and wasps & bees (Hymenoptera) are the most diverse groups
• High insect diversity makes their iden4fica4on/ classifica4on complex
Insect Diversity
Taxonomic Classifica4on • Insects are classified into groups called: Orders
• Orders are subdivided into smaller groups known as Families, genera and species Example: Tea scale Order: Hemiptera Family: Diaspididae Genus: Fiorinia Species: theae
North American Insect Orders 1. Microcoryphia (bristletails) 2. Thysanura (silverfish) 3. Ephemeroptera (mayflies) 4. Odonata (dragonflies) 5. BlaFodea (cockroaches) 6. Isoptera (termites) 7. Mantodea (manKds) 8. GrylloblaFodea (rockcrawlers) 9. Dermaptera (earwigs) 10. Plecoptera (stoneflies) 11. Orthoptera (crickets) 12. Phasmida (sKck insects) 13. Embioptera (webspiners) 14. Zoraptera (angel insects) 15. Psocoptera (barklice)
16. Phthiraptera (barklice) 17. Hemiptera (bugs, scales) 18. Thysanoptera (thrips) 19. Megaloptera (dobsonflies) 20. Rhaphidiopera (snakeflies) 21. Neuroptera (lacewings) 22. Strepsiptera (twisted-‐wings) 23. Coleoptera (beetles) 24. Mecoptera (scorpionflies) 25. Siphonaptera (fleas) 26. Diptera (flies) 27. Trichoptera (caddisflies) 28. Lepidoptera (buFerflies) 29. Hymenoptera (bees)
Insect Anatomy
• Head, thorax & abdomen
• Antennae • Adults may have one or two pairs of wings
• Three pairs of legs aNached to thorax
Insect Physiology
• Insects breath through spiracles; valves on the side of their body
• Open circulatory system
• Flight is accomplished by vibra4ng-‐resona4ng mechanism
• Insects are poikilothermic: temperature changes with ambient
Insect Development
• Metamorphosis
• Stages may show differences in shape, diet and habitat
• Highly developed insects experience complex metamorphosis
Ametamorphosis
Simple, gradual metamorphosis
Complete metamorphosis
Metamorphosis • Anamorphosis (young have less abdominal segments; very rare)
• Ametamorphosis (ametabolous insects; con4nue mol4ng aaer adult stage)
• Simple metamorphosis – Gradual (paurometabolous; young [nymphs] resemble wingless adults; in same habitat)
– Incomplete (hemimetabolous; young [niad] acua4c may not resemble adult)
• Complete metamorphosis (holometabolous; pupal stage; may not be in same habitat)
• Hypermetamorphosis (1st instar triangulin)
Types of Larvae
Eruciform Elateriform
Scarabaeiform
Campodeiform
Vermiform
Grub
Maggot
Caterpillar
Grub
Common Insect Orders
• Orthoptera: grasshoppers, crickets • Hemiptera: true bugs, scales, aphids, whiteflies
• Thysanoptera: thrips • Coleoptera: beetles and weevils • Lepidoptera: moths and buNerflies • Diptera: flies and mosquitoes • Hymenoptera: wasps, bees, ants
Orthoptera: grasshoppers & crickets
• Outer wings leathery (tegmina), inner wings membranous and fan-‐shaped
• All stages have chewing mouthparts
• Undergo simple metamorphosis; wingless nymphs resemble adults
• Enlarged hind legs for jumping
Grasshoppers, Crickets and Katydids
Tree cricket
False katydid
Field cricket
Cave cricket Differential grasshopper Rainbow grasshopper
Hemiptera: Auchenorrhyncha and Stenorryncha; leahoppers, aphids, scales and whiteflies
• Soa bodied insects with sucking mouthparts
• Some adult forms lack wings
• Undergo simple metamorphosis
• Most excrete honeydew
• Can transmit plant diseases
Scales, Aphids, Whiteflies, Mealybugs, Leahoppers and Cicadas
Citrus mealybug
Silverleaf whitefly Green peach aphid
Wax scale
Cicadas
Sharpshooter
Hemiptera: Heteroptera; true bugs • Outer wings thickened or leathery at base and membranous at 4p (hemelytra), inner wings membranous
• Piercing and sucking mouthparts
• Undergo simple metamorphosis
• Triangular plate (scutellum) between thorax and abdomen on the back
The True bugs!!
Water strider
Giant water bug
Leaffooted bug Bigeyed bug
Spined soldier bug Azalea lacebug
Thysanoptera: thrips
• Intermediate metamorphosis • Narrow wings with a fringe of long hairs
• Rasping-‐sucking mouthparts • Less than ¼ inch • Some are predators but most feed on plants
Coleoptera: beetles & weevils
• Hardened outer wings (elytra) and membranous inner wings
• Chewing mouthparts, complete metamorphosis
• Larvae (scarabaeiform, campodeiform, elateriform, grubs) have hardened head capsule and 3 pairs of legs on thorax
• Most diverse group of insects
Beetles & Weevils
Cucumber beetle
Boll weevil
White grubs
Tiger beetle Lady beetle larva
Lady beetle adult
Lepidoptera: moths & buNerflies • Four well developed membranous wings covered with scales
• Larvae have chewing mouthparts, adults have coiled sucking tube
• Undergo complete metamorphosis • Larvae (eruciform, caterpillars) have 3 pairs of true legs on thorax and variable number of prolegs on abdomen
Moths & BuNerflies
Cabbage looper
Bag worm Yellowstriped armyworm Sugarcane borer
Tent caterpillar
Monarch butterfly
Diptera: flies & mosquitoes
• Adults have one pair of wings
• Sponging or piercing (adults), mouth hooks or chewing (larvae) mouthparts
• Undergo complete metamorphosis
• Most larvae (vermiform; maggots) don’t have legs or head capsule
Flies & mosquitoes
Tachinid fly
Horse fly Fungus gnats
Love bugs Med fly
Yellow fever mosquito
Hymenoptera: bees, wasps, ants
• Adults have two pairs of membranous wings
• Most have chewing mouthparts
• Undergo complete metamorphosis
• Social wasps and bees (may s4ng) and solitary wasps (predators and parasitoids)
• Larva (eruciform, grubs) lack legs (except sawflies)
Bees, wasps and ants
Carpenter bee
Paper wasp
Aphelinid wasp
Sawfly larvae
Mud dauber
Red imported fire ant
Causes of Injury to Foliage
• Physical damage (breakage, sunburn)
• Plant diseases (viruses, fungi, bacteria) • Arthropod pests (sow bugs, pill bugs, millipedes, insects, mites)
• Slugs and snails • Vertebrates (rabbits, squirrels, deer, etc.)
Damage Caused by Arthropods
• Direct damage: – Removal of plant nutrients – Induc4on of plant disorders
• Indirect damage: – Honey dew secre4on – Disease transmission – Reduc4on of aesthe4c quality
Proper Iden4fica4on is Key
• Not all insects are pests (only 5% of all) • Informa4on retrieval and communica4on • Save specimens for reference
Insect Iden4fica4on
• Differences in body parts and general anatomy (insect families)
• Type of damage they cause (borers, girdles, leaf miners)
• Feeding mechanisms or mouthparts (chewing, sucking, intermediate)
Insects may be categorized by:
Pest diagnosis based on
feeding damage
• Chewing • Sucking • Intermediate
Chewing Mouth Parts
• Caterpillars • Sawfly larvae • Beetles & grubs • Grasshoppers • (slugs & snails)
Cabbage looper development
Early detec4on: • Minimizes feeding damage
• Facilitates control
Early instar
Late instar
Signs of chewing: Silk and Frass
Genista caterpillar on Texas Mountain Laurel
Fall Webworms and Tent Caterpillars
Physical / mechanical control is best control alterna4ve
Bagworms
• Frequent removal of bags • Timing of applica4on • Use of Bt products like Dipel®
Pest management:
• Life spent in silken ‘bag’
• Females wingless • Eggs emerge mid-‐late May
TwelvespoNed Cucumber Beetle
• Plants tolerate defolia4on
• Damage is only caused during fruit development
• Only large popula4ons require ac4on
Flea Beetles
• Plants can tolerate defolia4on • Aesthe4c damage?
White grubs
Larva
Adult Treatment not required for less than 3-‐ 5 grubs per a2
Identification
Snout Weevils Weevils have chewing mouth parts
Grasshoppers and Crickets
• Behavior depends on density • May feed on many plants • Many species in Texas • May move large distances
Leafcurng Bees
Do not feed on leaves but use them to build nest
Symptoms of Chewing Insects
• Pieces & parts of leaves missing, o_en in characterisKc paFerns
• Silk associated with damage indicates caterpillar presence
• Excrement underneath damage can indicate insect group present
• Brown edges around damage indicates older damage
Sucking Mouth Parts
• True bugs • Aphids & mealybugs • Whitefly & scales
Yucca bug and damage
Lace Bugs and damage
Note frass specks
Leaf footed & Squash bugs
Leaf footed bug
Squash bug
Whiteflies, Scales, Mealybugs & Aphids
• Honeydew or sooty mold indicates presence • May leave cast skins on leaves • Rapid populaKon growth (outbreak) • Can quickly become resistant to insecKcides
Symptoms of Sucking Insects
• Spodng, discoloraKon or death of leaf Kssue can be yellow or reddish to brown
• Honey dew and sooty mold on leaves under infestaKon indicate presence
• Cast skins on underside of leaf indicates developing populaKon
Intermediate: Thrips
• Some feed on pollen inside developing flowers
• Common in Spring, colonize gardens from wild flowers
• Specks of frass are common when feeding on foliage
• Transmit viral diseases; may become resistant
Spider Mites
• SKppling, spodng, “bronzing”, close to the midrib
• Eggs clear & spherical, cast skins on underside of leaves
• Heavily infested plant covered in silk
• Beneficial mites much ‘faster’ than pest
Other types of insect damage • Leaf mines by maggots, beetle larvae or caterpillars
• Teasing apart of plant 4ssue by root maggots
• Galls and deformed plant parts by cynipid wasps, psyllids, some thrips
• Egg-‐laying damage by cicadas, thorn bugs (plant hoppers)
Gall-‐Forming Insects and Mites
Cynipid wasp galls Fly (top) and mite galls
Drees, B.M. & J. A. Jackman. 1998
Evans, A.V. 2007
Wagner, D.L. 2005
Resources (field guides)