Stored Grain Insect Pests

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Stored Grain Insect Pests

  1. 1. Insects Attacking Stored Grains, Seeds, and Grain Products Dr. Ayanava Majumdar Extension Entomologist Alabama Cooperative Extension System Gulf Coast Research & Extension Center 8300 State Hwy 104, Fairhope, Alabama 36532 Cell phone: 251-331-8416
  2. 2. front corners of pronotum not pointed rounded or irregular punctures Maize weevil or Sitophilus zeamais oryzae molitor Oryzaephilus
  3. 3. <ul><li>Key pest types: </li></ul><ul><li>Beetles & weevils </li></ul><ul><li>Moths </li></ul><ul><li>Mites (non-insectan) </li></ul>Insect Attacking Stored Grain Insects: hard exoskeleton, three part body (head thorax, abdomen), jointed appendages, legs never >3 pairs Arachnids: two body regions (head+thorax fused, large abdomen), jointed appendages but >3 pair legs normal HEAD PROTHORAX ABDOMEN
  4. 4. How insects respire? <ul><li>Insect blood doesn’t carry O 2 </li></ul><ul><li>Tracheal system : a system of tubes and fine tracheoles that forms respiratory system </li></ul><ul><li>Spiracles : are external openings of tracheal system </li></ul><ul><li>Tracheoles : are fine internal tubes that directly supply oxygen to muscles; this makes oxygen abundant inside but also makes them highly susceptible to fumigants. </li></ul>
  5. 5. BEETLES/WEEVILS IN STORED GRAIN
  6. 6. Granary weevil vs. Rice Weevil <ul><li>Common characters: </li></ul><ul><li>Most destructive grain insects in world </li></ul><ul><li>Thrive in undisturbed grain </li></ul><ul><li>Adult beetles and legless grubs destroy grain </li></ul><ul><li>Mouthparts located at the end of a prominent snout </li></ul><ul><li>Antennae at the base of snout </li></ul><ul><li>Eat out kernel of grain, larvae live inside seeds </li></ul>Granary weevil, Sitophilus granarius S. oryza
  7. 7. Granary weevil vs. Rice Weevil <ul><li>Distinguishing characters: </li></ul><ul><li>Granary weevil: cylindrical, wings with ridges, pits on prothorax are oval, snout very long, does not fly and moves slowly </li></ul><ul><li>Rice weevil: smaller than granary weevil, smoother wings with lighter patches, short snout, pits on prothorax round, good flyer & attracted to light </li></ul>Granary weevil, Sitophilus granarius S. oryza
  8. 8. Feeding injury from weevils <ul><li>Feeding injury : </li></ul><ul><li>Female weevil lays 300-400 eggs one in a cavity </li></ul><ul><li>Larva dev. internally at high growth rate (egg hatch in 3 d at 13% RH, 27C) </li></ul><ul><li>Attack whole grain, on farm storage bins </li></ul><ul><li>Raise grain temp. and moisture to cause germination </li></ul>
  9. 9. Sawtooth vs. Merchant grain beetles <ul><li>Sawtoothed grain beetle: Oryzaephilus surinamensis </li></ul><ul><li>Merchant grain beetle: O. mercator </li></ul><ul><li>Important characters: </li></ul><ul><li>Flattened beetles & larvae (mouthparts directed forward) </li></ul><ul><li>Prothorax with saw-like projections </li></ul><ul><li>Forewings with ridges </li></ul><ul><li>Females can lay 250 eggs on grain </li></ul><ul><li>Pupation in grain by binding damaged seeds </li></ul><ul><li>Saw-T beetle is flightless </li></ul>
  10. 10. <ul><li>Common in grocery stores, storage warehouses, homes </li></ul><ul><li>Adults penetrate packaged products </li></ul><ul><li>Rapid lifecycle of 3 to 4 wk </li></ul><ul><li>Larvae do not enter seed, feed externally as they go (secondary pest?) </li></ul><ul><li>Serious heating of stored grain </li></ul>Damage from grain beetles
  11. 11. Red flour beetle (RFB) Tribolium castaneum <ul><li>Identification: </li></ul><ul><li>Head is visible from above </li></ul><ul><li>Adult beetles very active, strong flyers </li></ul><ul><li>Antennae abruptly enlarged at the terminal segments </li></ul><ul><li>Eyes close to each other </li></ul><ul><li>Side of thorax curved </li></ul><ul><li>Long-lived (3 yr) adult female, ~1000 eggs </li></ul><ul><li>Sticky eggs laid on sacks, in cracks or on food </li></ul><ul><li>3 to 4 months per generation </li></ul>
  12. 12. Confused flour beetle (CFB) Tribolium confusum <ul><li>Identification: </li></ul><ul><li>Flat, shiny beetles with visible head </li></ul><ul><li>Adult beetles slower, poor flyers compared to RFB </li></ul><ul><li>Antennae gradually enlarged at the tip (club-shaped) </li></ul><ul><li>Eyes widely separated from each other </li></ul><ul><li>Side of thorax rounded </li></ul><ul><li>Larvae flattened, creamish, forked terminal </li></ul>
  13. 13. Feeding injury by RFB & CFB <ul><li>First reported as pests in USA in 1893 </li></ul><ul><li>RFB serious in farm storage bins </li></ul><ul><li>CFB in retail grocery stores, serious pest in flour mills, warehouses </li></ul><ul><li>Extended feeding life stages causes more damage </li></ul>
  14. 14. Lesser grain borer (LGB) Rhyzopertha dominica <ul><li>AKA Australian wheat weevil, more southern distribution </li></ul><ul><li>Identification : </li></ul><ul><li>Dark brown cylindrical beetles, head tucked beneath the prothorax </li></ul><ul><li>Larva is thick-bodied, head is retracted, mandibles visible </li></ul><ul><li>Females lay 300 to 500 eggs on or around grain </li></ul><ul><li>Larvae live inside grain and emerge as adult </li></ul>
  15. 15. Lesser grain borer feeding injury <ul><li>Adults and larvae feed on grain </li></ul><ul><li>Extremely active insect with one to two month lifecycle (temp. and food dependent) </li></ul><ul><li>Larva develops within seed, so injury is difficult to assess </li></ul><ul><li>Adults can eat into wood and paper boxes </li></ul><ul><li>Larger grain borer (Prostephanus truncatus) may look similar to the LGB >>>>>>>>>>>>>>>>>>>>>> </li></ul>
  16. 16. Drugstore beetle vs. Cigarette beetle <ul><li>Identification: </li></ul><ul><li>Beetle forewings with ridges or striations, fine body hair </li></ul><ul><li>Feed on a wide variety of retail products, incl. medicines </li></ul><ul><li>Symbiotic yeast in stomach aid in digestion </li></ul><ul><li>Larvae bare and pupate by making a cocoon using food particles </li></ul><ul><li>Identification: </li></ul><ul><li>Cylindrical brown beetles have “hump-backed” appearance </li></ul><ul><li>Velvety appearance of adults </li></ul><ul><li>No ridges on forewings </li></ul><ul><li>Larvae very hairy or fuzzy, darker head (unlike drugstore beetle larvae) </li></ul><ul><li>Larvae pupate in thin cocoons made from food debris </li></ul>Stegobium paniceum Lasioderma serricorne
  17. 17. Feeding injury by drugstore & cigarette beetles <ul><li>Drugstore beetle : major problem in retail stores & dry processed food; can bore through packaging, cardboard and tin cans </li></ul><ul><li>Cigarette beetle : narrow host range - tobacco & spice factories; damage more under warm temp. (70+ degrees) and high humidity </li></ul>Cigarette beetle damage
  18. 18. Cadelle Tenebroides mauritanicus <ul><li>General feeder on stored grain and seed </li></ul><ul><li>Identification : </li></ul><ul><li>One of the largest stored grain insect (0.5 in) </li></ul><ul><li>Adult beetle is black, flattened with mouthparts ahead of the head </li></ul><ul><li>Loose joint between prothorax & abdomen </li></ul><ul><li>Single female may lay >1000 eggs in protected places </li></ul><ul><li>Larvae are fleshy cylindrical grubs, prolonged lifecycle </li></ul><ul><li>Pupation away from food, hidden (e.g., wooden containers)…carry over infestation </li></ul>
  19. 19. Feeding injury from cadelle <ul><li>Wide range of stored grains may be attacked </li></ul><ul><li>Adult and larvae attack grain to feed on the germ or embryo (soft-portions) </li></ul><ul><li>Move rapidly from seed to seed destroying produce </li></ul><ul><li>Adult beetles could be predaceous but prefer seeds </li></ul>
  20. 20. Mealworms <ul><li>Yellow mealworm = Tenebrio molitor </li></ul><ul><li>Dark mealworm = T. obscurus </li></ul><ul><li>Identification : </li></ul><ul><li>Beetles are ½ to 1 inch long, shiny </li></ul><ul><li>Beetles may look like ground beetles (predatory) </li></ul><ul><li>Grubs are cylindrical, sold as fish bait </li></ul><ul><li>Adults and larvae prefer dark, damp places in spoiled grain </li></ul><ul><li>Larvae can remain alive for >600 d in unfavorable conditions </li></ul>Insect is native of Europe. 1 2 3 4 Ground beetle 1 2 3 4 5 5 tarsal segments
  21. 21. Dermestid beetles <ul><li>Scavengers by habit </li></ul><ul><li>Very wide host range/habitat </li></ul><ul><li>Khapra beetle (Trogoderma granarium) – strict quarantine has reduced spread or eliminated local infestations </li></ul><ul><li>Adult beetles are oval, 2 mm, reddish brown </li></ul><ul><li>Larvae are fuzzy, plump shape </li></ul><ul><li>Recent detections in spice warehouses </li></ul>Carpet beetle , Anthrenus sp. Khapra beetle, Trogoderma
  22. 22. MOTHS IN STORED GRAIN
  23. 23. Angoumis grain moth Sitotroga cerealella <ul><li>First site of infestation in USA was North Carolina </li></ul><ul><li>Identification : </li></ul><ul><li>Adult moth is small (2/3 inch), brownish gray with long fringes of hair on wings </li></ul><ul><li>Hindwings extended at the apical angle (arrow) </li></ul><ul><li>Larval and pupal stages remain inside seed </li></ul>
  24. 24. Grain moth damage <ul><li>First reported from France in 1736 </li></ul><ul><li>Most destructive insect of grain in USA, esp. corn </li></ul><ul><li>May also attack developing wheat grain in field </li></ul><ul><li>Adult moths do not feed on grain </li></ul><ul><li>Eggs laid in clusters on grain>>produces larvae that feed in masses </li></ul><ul><li>Larvae feed on starchy portions of seed, adult escapes from a circular exit hole </li></ul><ul><li>There could be 6 generation </li></ul>
  25. 25. Indian meal moth Plodia interpunctella <ul><li>Has European origin </li></ul><ul><li>Moth with a natural parasite (Bracon hebetor) </li></ul><ul><li>Identification (moth): base of forewings gray, half of the wing is reddish brown; black legs; conical head </li></ul><ul><li>Identification (larva): creamish with pinkish tinge and light brown head, make extensive webbing </li></ul><ul><li>Lifecycle: 4 to 6 weeks </li></ul>Meal moth larvae Bracon hebetor
  26. 26. Damage by Indian meal moth <ul><li>Pest with a wide host range </li></ul><ul><li>Rapid lifecycle (4 wk) </li></ul><ul><li>Destroys stored grain by </li></ul><ul><ul><li>Directly feeding on grain </li></ul></ul><ul><ul><li>Producing silken tunnels </li></ul></ul><ul><ul><li>Contaminating grain with excreta </li></ul></ul>
  27. 27. Mediterranean flour moth Ephestia kuhniella <ul><li>First reported from NA in 1889 </li></ul><ul><li>Identification : </li></ul><ul><li>Moth had gray wings with zigzag line that may not be very clear </li></ul><ul><li>Hindwings are white with hairy margin </li></ul><ul><li>Eggs are laid in clusters on food or sacks or cracks </li></ul><ul><li>Larva is damaging: whitish or pinkish with hardened head capsule, spin silken tubes in flour </li></ul><ul><li>Pupate in silken cocoons </li></ul><ul><li>Lifecycle: 9 to 10 weeks </li></ul>
  28. 28. <ul><li>Modern fumigation methods have reduced pest status </li></ul><ul><li>Caterpillars web together flour and live inside </li></ul><ul><li>Flour is favorite but whole grain may be attacked </li></ul><ul><li>Moths may be monitored using pheromone traps </li></ul>Feeding injury by mediterranean flour moth
  29. 29. Storage temp. vs. Insect activity
  30. 30. 0 150 300 450 0 1 2 3 4 No. of Insects Months The number of insects present at the start of storage is critical Treat the storage areas and harvest at the right time to cut postharvest losses!
  31. 31. Back to basics… <ul><li>In USA, stored product losses have been enormous due to rice or maize weevils. </li></ul><ul><li>Reduction of losses: </li></ul><ul><ul><li>By sanitation or hygiene – need of good plant design, stacking, sweeping, vacuum cleaning, and efficient disposal of infested debris </li></ul></ul><ul><ul><li>Use of monitoring devices – light traps (cigarette beetle, med. flour moth), pheromone traps (delta traps for Angoumois grain moth, Indian meal moth), floor traps (sawtooth grain beetle, drugstore beetle, etc.) </li></ul></ul><ul><ul><li>By using fumigants & contact insecticides </li></ul></ul><ul><ul><li>By improved storage/packaging: more research?? </li></ul></ul>Source: Page & Lubatti (1963), Parkin (1956), Fields & White (2002)
  32. 32. Back to basics… <ul><li>Mode of action: fumigants intervene ATP formation, upset enzyme systems, action is rapid </li></ul><ul><li>The rate of uptake of fumigant by insects depends on the rate of fixation in tissues </li></ul><ul><li>Insects that may seem to recover can have sublethal effects </li></ul><ul><li>Success of fumigation depends largely on even distribution of fumigant and on penetration. </li></ul>Source: Page & Lubatti (1963), Parkin (1956), Fields & White (2002)
  33. 33. QUESTIONS?

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