Entomology For Master Gardeners

Jeff Schalau (Adapted from Dr. Mike Wagner,Regents Professor-Emeritus,NAU School of Forestry)Agent, Ag. & Nat. Res.University of Arizona Cooperative Extension,Yavapai County

Outline of Topics Covered• Extent and Economic Importance• Insect Growth and Development• Insect Feeding/Mouthparts• Classification and Taxonomy • Movement and Spread• Population Dynamics/Concept of Pest• Diagnosing Insect Problems• Pest Management Approaches

Extent and Economic Importance• Major component of current fauna• Attack all stages of all plant species• Damage equals harvest• Beneficial aspects

Beneficial Aspects• Pollination (honey/bumble/mason bees) • Predators/Parasites• Human food• Biological control agents• Nutrient recycling• Insect products: honey, wax, shellac, dye• Conservation biology • Art and literature• Ecotourism- butterfly farms/exhibits

Orchard Mason Bee• Hymenoptera: Megachilidae

-thick jaw • Osmia lignaria

Mason Bees• Solitary/Gregarious bee• Blue/black color• Non-aggressive; rarely stings • Native to U.S; east/west species • Better pollinator than honey bees

-scopa vs pollen basket • Commercial use

-almonds, walnuts, alfalfa, fruit trees

Mason Bee Life Cycle - 1• Overwinters as adult in tunnel/ tube • Male emerges first

-when high temp is above 55F for 4 days• Female emerges 3-15 days later • Mating begins as soon as female emerges• Female lays 6 nest holes; 6 cells each• Female dies immediately after 6th cell

Mason Bee Life Cycle - 2• Eggs hatch in 3-4 days • Larvae feed for 28-29 days• Larvae spins cocoon (pupae) • Rest for 30 days • Pupal stage lasts 21 days • Egg to adult is about 3 months

Mason Bee Propagation • Nest boxes: holes in wood/nest tubes• Wooden block 6” deep

-holes 5/16” diameter-spaced ¾” apart

• Place facing east under eave• Harvest tubes in fall; keep in fridge at 38F

Mason Bee Taj Mahal

Mason Bee Management • Short period of pollination in spring • Remove overwintering bees in fall • Use staggered removal from cold for longer

pollination period • Protect from woodpeckers, ants, diseases,

parasites, and predators • Use liners to allow winter storage

Butterfly Exhibits(Sertoma Butterfly House, Sioux Falls, SD)

Characteristics of Insects • Arthropods: exoskeleton, jointed

appendages• Adult Insects:

• Head, thorax, abdomen• 1 pair antennae• 3 pair legs• 2 pair of wings• Bilateral symmetry

ArthropodsPhylum Arthropoda: includes trilobites, horseshoe crabs, spiders, mites, sowbugs, crustaceans, millipedes, and centipedes.

Prolegs

Thoracic legs

Thoracic legs

Insects are all in the Class HexopodaInsects are all in the Class Hexopoda1. The head is a sensory organ with paired

appendages (antennae and eyes) and mouthparts

2. The thorax is mainly involved in motility (walking and flying)

3. The abdomen has reproductive and digestive functions

Insect Growth and Development• Metamorphosis • Shed exoskeleton (molting)• Stages

• Egg• Larva/nymph• Pupa• Adult

• Instars

Metamorphosis: Simple

Wing pads

Wings

Squash bugs

Metamorphosis: Complete

Metamorphosis

Insect Growth and Development• Gradual (aka Simple):

• Egg-nymph-adult• Nymph similar to adult• Ex. Aphids, scales, grasshoppers

• Complete (aka Complex):• Egg-larva-pupa-adult• Larva does damage• Stages occur in different habitats• Ex. Beetles, butterflies, flies

Insect Feeding/Mouthparts• Chewing

• Hard mandibles• Holes, tunnels, partially eaten leaves

• Sucking• Straw (stylet), probosis• Curling, stunting, mottling, galls• Phytotoxic necrosis

Four Types of Mouth Parts

Piercing/sucking

Straw

Chewing Mandibles

Piercing/sopping

Insect Classification

Kingdom

Phylum

Class

Order

Family

Genus

Species

Animal

Arthropods

Insecta

Coleoptera

Scolytidae

Dendroctonus

brevicomis

keen

pretty

clothes

out

fill

guys

some

Taxonomic Classification• Common levels: Order and Family• Basis for classification

• Mouthparts• Type of wings• Type of metamorphosis• Genetics has also taken a role in

classification

Common Insect Orders• Coleoptera: beetles, weevils• Dermaptera: earwigs• Diptera: flies, mosquitoes, gnats, midges• Hemiptera: true bugs• Homoptera: aphids, scales, leafhoppers,

cicadas, whiteflies, mealy bugs• Hymenoptera: bees, wasps, ants,

sawflies• Isoptera: termites

Common Insect Orders (cont.)• Lepidoptera: moths, butterflies• Neuroptera: lacewings, antlions• Odonata: dragonflies, damselflies• Orthoptera: grasshoppers, crickets,

mantids, cockroaches • Siphonaptera: fleas• Thysanoptera: thrips• Thysanura: siverfish, firebrats

Coleoptera: beetles, weevils

Attributes: 400,000 species, hard front wings, beneficial and pest species, adults and larvae may feed on same host

Complete metamorphosis

Chewing

Dermaptera: earwigs

Attributes: front wings thickened, pest or beneficial (aphid predator), nocturnal, hide during the day

Gradual metamorphosis

Chewing

Diptera: flies, mosquitoes

Attributes: larvae legless, adults soft bodied, compound eye, one pair of wings, haltere, vector of human diseases (Zika, Malaria, Yellow Fever) , pest and beneficial

Complete metamorphosis

Larvae: chewing/hooksAdult: sponging, piercing

Hemiptera: true bugs

Attributes: nymphs resemble adults, many plant feeding pests, triangle on back, some predators, some disease vectors (Chagas disease)

Gradual metamorphosis

Piercing, sucking

Homoptera: aphids, leaf hoppers, white flies, scales

Attributes: small soft bodied insects, unwinged forms, attack many vegetables, multiple generations, parthenogenesis, some disease vectors (CTV), greenhouse pests

Gradual metamorphosis

Sucking

Hymenoptera: bees, wasps, ants, sawflies

Attributes: legless larvae, adult stinger, two pair of membranous wings, ants with narrow waist, many species, pollinators, parasites, predators, sawflies are important defoliators, many species have social behavior

Complete metamorphosis

Chewing

Isoptera: termites

Attributes: soft bodied insects, winged or wingless, colonies occur in ground or in wood, drywood and subterranean termites, caste system, social

Gradual metamorphosis

Chewing

Lepidoptera: moths, butterflies

Attributes: caterpillars, adults have two pairs of scaled wings, many defoliators, adults feed on nectar, adults pollinate, basis for ecotourism

Complete metamorphosis

Larvae: chewing Adults: sucking

Monarch Life Stages

Monarch Life• Butterflies (and moths) undergo

complete metamorphosis• The four distinct stages: egg, larva

(caterpillar), pupa, and adult• The development from egg to adult is

completed in about 30 days

Stage 1: egg• Monarchs lay 100-300 eggs • Often on the bottom of a milkweed

leaf for protection• The eggs hatch about four days after

they are laid

Stage 2: larva (caterpillar)• Eggs hatch into larvae (0-14 days)• They first eat their eggshell, then start

munching away on plants for energy to grow

• Caterpillars sequester cardiac glycosides from milkweed for defense against predation

• When the larva outgrows its skin, it sheds it and grows a new skin

Stage 3: pupa (chrysalis)• Transformation from larva to an adult

butterfly• Camouflaged to protect against

predators• Has no eyes, antennae or legs • Mouthparts change from chewing in

the caterpillar to straw-like tongue that the adult butterfly will need to sip nectar and it grows wings. All in just about two weeks!

Stage 4: Adult Monarch• Summer generations live from 2-5 weeks• Late summer and early fall generations

migrate to their central Mexico (Easterns) or California (Westerns)

• They return to the north when the colder weather ends to reproduce. These adults can live up to eight or nine months

Neuroptera: lacewings, antlions

Attributes: adults have 2 pairs of membranous wings, wings held roof-like, many species are predators

Complete metamorphosis

Chewing

Orthoptera: grasshoppers, crickets, mantids, cockroaches

Attributes: hard bodied adult, two pair of wings, front wings are hard, adults and nymphs cause damage, moderate pests

Gradual metamorphosis

Chewing

Siphonaptera: fleas

Attributes: wingless insects, live as ectoparasites on birds and mammals, body is laterally flattened, often jumping, important vector of human disease (Plague, Hantavirus, and typhus)

Complete metamorphosis

Sucking

Thysanoptera: thrips

Attributes: adults are minute soft bodied, two pairs of long wings, many feed on plants and especially flowers, cause cosmetic damage to fruit, some disease transmission

Gradual metamorphosis

Sucking

Movement and Spread• Adults have wings & legs• Adults can migrate• Larvae have legs• Larvae can walk• Larvae can move with wind

Population Dynamics• Insects have high reproductive

potential• Can migrate; move with plants• Population limited by:

• Environmental resistance• Host plant resistance

• “If you build it, they will come”• Exotic (non-native) insects

Concept of a Pest• Interfere with objectives• Insects play vital ecological roles• 1% of insects are pests• Learn to live with damage- economic

threshold

Diagnosing Insect Pest Problems• Recognize limitations• Most “sick” plants are abiotic• Identify the plant• Note the symptoms• Look for broad patterns

• Within plant (leaf vs. fruit)• Across plant (spot vs. all plants)

• Collect specimens• Take notes• Formulate hypothesis• Important? Seek professional advice

Pest Management• Integrated Pest Management• Legislative Control• Physical/Mechanical Control• Cultural Control• Genetic Resistance • Biological Control• Chemical Control

Integrated Pest Management (IPM)• Integrate all approaches to manage

pest• Pest ID• Detection, monitoring models• Know insect biology• Ecologically sound

Legislative Management• Quarantine• State regulation- noxious weeds• Public education critical

Physical Management• Insect removal/habitat destruction• Sanitation/salvage• Firewood in direct sun• Physical barriers- cutworms• Mass trapping• Trap trees

Cultural Management• Crop rotation• Green manure fallow• Farmscaping• Genetic resistance

• Conventional resistant varieties• GMO’s

Row Cover: Excludes pest/ moderates temperature

Row Cover: Excludes pest/ moderates temperature

Physical barriers for cutworms

Farmscaping• Whole farm approach to improve

natural control of agricultural pests• Includes:

-Inter-planting vs companion planting-Support population of beneficial insects, biological control, habitat for natural enemies, nectar for pollinators

Genetic Resistance• Pest impact increasing: climate change

complications/ globalization/ exotic pests • Genetic manipulation very powerful• Work with conventional genetic methods• Possible to eliminate major human disease

(Zika, Malaria)• Cost effective/time efficient • Deployment of technology is key

Pest impact increasing: climate change complications/ globalization/ exotic pests Genetic manipulation very powerfulWork with conventional genetic methodsPossible to eliminate major human disease (Zika, Malaria)Cost effective/ time efficient Deployment of technology is key

GMO Risks• Genetic contamination of natural/ non-

target populations• Evolution of super weeds • Non-target effects (Bacillus thuringiensis in

pollen) • All options have consequences

Biological Control/Management• Ecologically best strategy• Life history knowledge critical• Bio control agents

• Vertebrate predators• Invertebrate predators• Invertebrate parasites• Pathogenic microorganisms

• Ex. Virus, bacteria (Bt), fungi, protozoa, nematodes

Chemical Management• Limitations: ecological, cost, hazard• Follow label-legal document• Pay attention to pre-harvest interval• Federal regulation of residual

tolerance• Pesticide applicator certification

Summary• Insects are part of natural system

-Provide lots of useful functions• Learn to tolerate plant damage• Apply the least effort to reduce

economic threshold• Try to target pest management efforts• Share the planet!