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

2. 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

3. 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

4. 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

5. 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)

6. Early Records of Stored-Product Insects
Egyptian pyramids, 1345 B.C.
Red flour beetle
Israel, B.C.
Granary weevil
Iron Age or Roman Period, 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

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

8. 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?

9. Insects Go Through Various Stages

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

11. 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
72.6
aSurvival of eggs is based on 288 eggs.

12. Frequency distribution of head capsule with
measurements by instar

13. 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
Second 23
0.26 ± 0.002c
Third 34
0.40 ± 0.002b
Fourth 40
0.64 ± 0.002a
aMeans followed by different letters are significantly different (P < 0.05,
by Fisher’s protected lsd test)

14. 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)

15. Internal Feeders
Weevils

16. Internal Feeders
Moth
Borer

17. 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 days days days days days
Source: Edmond L. Bonjour, Oklahoma State University, Stillwater, OK

18. 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

19. External Feeders - Scavengers
Dermestids

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

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

22. 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

23. 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)

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

26. 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

27. 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

28. 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

29. 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

30. Classification of Stored-Product Insects
Mode of feeding
Food preference

31. 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

32. 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

33. 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

34. 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)

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

39. 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

40. 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?