Lecture 15 Stored-Product Insect Pests Associated with Grain and Food Plants (1)

Student Learning Outcomes Know the differences between beetles and moths as well as internal and external feeding modes of stored-product insects Understand why stored-product insects are successful as pests Understand damage caused by stored-product insects to commodities Assessment by instructor: Ability answer questions in the final lecture exam

What are Stored-Grain/Product Insects Insects associated with cereal grains or commodities that are harvested and stored are called “stored-grain insects” These insects are also called “stored-product insects” because they are capable of infesting stored non-cereal commodities and processed cereal or non-cereal products These insects have spread throughout the world through grain trade

Insects can infest grain and grain products from the farm Transport Storage Insects can infest grain and grain products from the farm to the consumer Farm Processing plant Consumer Retail store

Stored-Product Insects in the Marketing System Type of study No. samples No. species Reference Imports into CA 902 37 Olsen (1981) Imports in CA 3,381 63 Zimmerman (1990) Imports into UK 3,632 81 Howe & Freeman (1981) Empty cargo containers 3,001 22 Stanaway et al. (2001) Food-handling areas of ships 1,428 16 Evans & Porter (1965) Bakeries in CT 290 11 Hankin & Welch (1991) Packaged food warehouses 20 24 Highland (1978) Import warehouses in CA 18 26 Source: Hagstrum and Subramanyam (2006)

Early Records of Stored-Product Insects Egyptian pyramids, 1345 B.C. Red flour beetle Israel, 700-900 B.C. Granary weevil Iron Age or Roman Period, 0-400 A.D. Drug store beetle, cadelle, rusty grain beetle, sawtoothed grain beetle, hairy fungus beetle, yellow and dark meal worms Mid 1700s Mentioned in literature

Important Orders Coleoptera or beetles Lepidoptera or moths Psocoptera or book/bark lice

stored-product insects Egg Larva Pupa Adult Development cycle of stored-product insects Egg Larva Pupa Adult What are the active stages? What are the inactive stages?

Insects Go Through Various Stages

Cigarette beetle, Lasioderma serricorne Coleoptera: Anobiidae Adult, dorsal view Adult, lateral view Larvae Photos, courtesy: Dr. Bh. Subramanyam

Development and survival of cigarette beetle life stages on ground, pelleted feed No. Duration (days) Survivala stage insects Mean ± SE Range (%) Egg 265 8.1 ± 0.05 5 – 11 92.0 First instar 262 4.7 ± 0.04 3 – 7 98.9 Second instar 260 4.5 ± 0.04 3 – 6 99.2 Third instar 259 3 – 8 99.6 Fourth instar 219 11.8 ± 0.2 7 – 20 84.6 Pupa 210 4.6 ± 0.05 3 - 7 95.9 Egg-to-adult 209 38.3 ± 0.24 24 - 59 72.6 aSurvival of eggs is based on 288 eggs.

Frequency distribution of head capsule with measurements by instar

Width of head capsule (mm)a Head capsule with of cigarette beetle instars Instar Number of insects Width of head capsule (mm)a Range (mm) Mean ± SE First 26 0.14 ± 0.002d 0.13 - 0.16 Second 23 0.26 ± 0.002c 0.25 - 0.29 Third 34 0.40 ± 0.002b 0.38 - 0.41 Fourth 40 0.64 ± 0.002a 0.63 - 0.66 aMeans followed by different letters are significantly different (P < 0.05, by Fisher’s protected lsd test)

Stored-Product Insects Beetles (50 or more species) Moths (3 species in U.S.) Indian meal moth Almond moth Angoumois grain moth Psocoptera (several species)

Internal Feeders Weevils

Internal Feeders Moth Borer

100 adults left in grain for 7 days and then removed Stages of Lesser Grain Borer Infestation 100 adults left in grain for 7 days and then removed 86o F (30oC) 0 days 28 days 56 days 76 days 106 days 128 days Source: Edmond L. Bonjour, Oklahoma State University, Stillwater, OK

External Feeders Cigarette beetle Rusty grain beetle Spider beetle Larger black flour beetle larvae Sawtoothed grain beetle Cigarette beetle Rusty grain beetle Spider beetle Develop on broken kernels, grain dust

External Feeders - Scavengers Dermestids

External Feeders - Moths Almond moth Moth larvae Indianmeal moth Moth scales

Mold Feeders Foreign grain beetle Psocids or booklice Hairy fungus beetle Flourish under humid conditions Mold/cheese mite

Proposed Origins Mostly tropical or subtropical in origin Some species were seed feeders; others fed on molds under the tree bark or on rotting animal and plant matter Some species still inhabit these areas Majority infest habitats provided by humans

Exclusive Seed Feeders Wild grass seeds Wild ancestors to currently cultivated crops (Angoumois grain moth) Seeds stored by rodents Timber (Lesser grain borer) Acorns (Rice weevil)

Scavengers Feed on molds Decaying plant material Dried plant or animal materials Bird feathers (dermestids)

Sources Created by Humans Food-processing facilities Spilled grain in fields or on farms Grain/flour residues Combines Trucks Wagon beds Bins Under perforated floors Equipment

Features of Stored-Product Insects Small Highly mobile Live in cracks and crevices Feed on a wide variety of food products High reproductive rates Occur in natural or anthropogenic habitats

General Biology: Beetles Adults can live between 2 months and a year Short-lived and long-lived beetles Mate multiple times Both adults and larvae cause damage Females lay eggs throughout their adult life

General Biology: Moths Adults live 6-8 days Only larvae cause damage Eggs by females are laid within 6 days May mate 1-3 times

Classification of Stored-Product Insects Mode of feeding Food preference

Mode of Feeding Internal feeders - remove energy from foods Rice, Maize, and Granary weevils Lesser grain borer Larger grain borer Angoumois grain moth External feeders - contaminate food products All other species, except those listed above

Food Preference Whole grain feeders Broken kernel feeders Germ feeders Weevils and borers Broken kernel feeders Sawtoothed grain beetle, Red flour beetle, Rusty grain beetle, Indian meal moth larvae Germ feeders Indianmeal moth larvae, Rusty and Flat grain beetles, Sawtoothed grain beetles Flour feeders Red and Confused flour beetles Mold feeders Hairy fungus beetle, Foreign grain beetle

Damage Caused by Insects Weight loss Heating (110oF [43.3oC] or higher) Increase in moisture Increase in protein content Increase in fatty acid content Increase in uric acid content Structural damage (Cadelle larvae) Contamination of raw and processed foods Excreta, cast skins, eggs, body parts

Damage Caused by Insects (continued) Decrease in seed germination Distribution of molds from infected to healthy kernels Penalties or rejection at time of sale Rejection by customers of infested foods Indianmeal moth larvae in pop corn Allergic reactions in sensitive people Dermestid hairs (hastisetae)

Reproductive Potential Moths mate once or twice during their life time Beetles mate more than twice A female, on average, lays 200-400 eggs in her lifetime

Why Are Stored-Product Insects Successful as Pests? Abundant food of high quality Insects are protected from extreme climatic changes Behavioral adaptations (refuge-seeking behavior) Physiological/biochemical adaptations Presence of other organisms (molds), broken kernels and grain dust promotes insect survival, growth, and reproduction

Questions Why is it important to know the biology of insects as it relates to their management? What are the differences in biology of beetles and moth pests of stored products? Why are stored-product insects successful as pests? List types of losses caused by stored-product insects?