Stored Grain Insect Pests
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Stored Grain Insect Pests






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Stored Grain Insect Pests Stored Grain Insect Pests Presentation Transcript

  • 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
  • front corners of pronotum not pointed rounded or irregular punctures Maize weevil or Sitophilus zeamais oryzae molitor Oryzaephilus
    • Key pest types:
    • Beetles & weevils
    • Moths
    • Mites (non-insectan)
    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
  • How insects respire?
    • Insect blood doesn’t carry O 2
    • Tracheal system : a system of tubes and fine tracheoles that forms respiratory system
    • Spiracles : are external openings of tracheal system
    • Tracheoles : are fine internal tubes that directly supply oxygen to muscles; this makes oxygen abundant inside but also makes them highly susceptible to fumigants.
  • Granary weevil vs. Rice Weevil
    • Common characters:
    • Most destructive grain insects in world
    • Thrive in undisturbed grain
    • Adult beetles and legless grubs destroy grain
    • Mouthparts located at the end of a prominent snout
    • Antennae at the base of snout
    • Eat out kernel of grain, larvae live inside seeds
    Granary weevil, Sitophilus granarius S. oryza
  • Granary weevil vs. Rice Weevil
    • Distinguishing characters:
    • Granary weevil: cylindrical, wings with ridges, pits on prothorax are oval, snout very long, does not fly and moves slowly
    • Rice weevil: smaller than granary weevil, smoother wings with lighter patches, short snout, pits on prothorax round, good flyer & attracted to light
    Granary weevil, Sitophilus granarius S. oryza
  • Feeding injury from weevils
    • Feeding injury :
    • Female weevil lays 300-400 eggs one in a cavity
    • Larva dev. internally at high growth rate (egg hatch in 3 d at 13% RH, 27C)
    • Attack whole grain, on farm storage bins
    • Raise grain temp. and moisture to cause germination
  • Sawtooth vs. Merchant grain beetles
    • Sawtoothed grain beetle: Oryzaephilus surinamensis
    • Merchant grain beetle: O. mercator
    • Important characters:
    • Flattened beetles & larvae (mouthparts directed forward)
    • Prothorax with saw-like projections
    • Forewings with ridges
    • Females can lay 250 eggs on grain
    • Pupation in grain by binding damaged seeds
    • Saw-T beetle is flightless
    • Common in grocery stores, storage warehouses, homes
    • Adults penetrate packaged products
    • Rapid lifecycle of 3 to 4 wk
    • Larvae do not enter seed, feed externally as they go (secondary pest?)
    • Serious heating of stored grain
    Damage from grain beetles
  • Red flour beetle (RFB) Tribolium castaneum
    • Identification:
    • Head is visible from above
    • Adult beetles very active, strong flyers
    • Antennae abruptly enlarged at the terminal segments
    • Eyes close to each other
    • Side of thorax curved
    • Long-lived (3 yr) adult female, ~1000 eggs
    • Sticky eggs laid on sacks, in cracks or on food
    • 3 to 4 months per generation
  • Confused flour beetle (CFB) Tribolium confusum
    • Identification:
    • Flat, shiny beetles with visible head
    • Adult beetles slower, poor flyers compared to RFB
    • Antennae gradually enlarged at the tip (club-shaped)
    • Eyes widely separated from each other
    • Side of thorax rounded
    • Larvae flattened, creamish, forked terminal
  • Feeding injury by RFB & CFB
    • First reported as pests in USA in 1893
    • RFB serious in farm storage bins
    • CFB in retail grocery stores, serious pest in flour mills, warehouses
    • Extended feeding life stages causes more damage
  • Lesser grain borer (LGB) Rhyzopertha dominica
    • AKA Australian wheat weevil, more southern distribution
    • Identification :
    • Dark brown cylindrical beetles, head tucked beneath the prothorax
    • Larva is thick-bodied, head is retracted, mandibles visible
    • Females lay 300 to 500 eggs on or around grain
    • Larvae live inside grain and emerge as adult
  • Lesser grain borer feeding injury
    • Adults and larvae feed on grain
    • Extremely active insect with one to two month lifecycle (temp. and food dependent)
    • Larva develops within seed, so injury is difficult to assess
    • Adults can eat into wood and paper boxes
    • Larger grain borer (Prostephanus truncatus) may look similar to the LGB >>>>>>>>>>>>>>>>>>>>>>
  • Drugstore beetle vs. Cigarette beetle
    • Identification:
    • Beetle forewings with ridges or striations, fine body hair
    • Feed on a wide variety of retail products, incl. medicines
    • Symbiotic yeast in stomach aid in digestion
    • Larvae bare and pupate by making a cocoon using food particles
    • Identification:
    • Cylindrical brown beetles have “hump-backed” appearance
    • Velvety appearance of adults
    • No ridges on forewings
    • Larvae very hairy or fuzzy, darker head (unlike drugstore beetle larvae)
    • Larvae pupate in thin cocoons made from food debris
    Stegobium paniceum Lasioderma serricorne
  • Feeding injury by drugstore & cigarette beetles
    • Drugstore beetle : major problem in retail stores & dry processed food; can bore through packaging, cardboard and tin cans
    • Cigarette beetle : narrow host range - tobacco & spice factories; damage more under warm temp. (70+ degrees) and high humidity
    Cigarette beetle damage
  • Cadelle Tenebroides mauritanicus
    • General feeder on stored grain and seed
    • Identification :
    • One of the largest stored grain insect (0.5 in)
    • Adult beetle is black, flattened with mouthparts ahead of the head
    • Loose joint between prothorax & abdomen
    • Single female may lay >1000 eggs in protected places
    • Larvae are fleshy cylindrical grubs, prolonged lifecycle
    • Pupation away from food, hidden (e.g., wooden containers)…carry over infestation
  • Feeding injury from cadelle
    • Wide range of stored grains may be attacked
    • Adult and larvae attack grain to feed on the germ or embryo (soft-portions)
    • Move rapidly from seed to seed destroying produce
    • Adult beetles could be predaceous but prefer seeds
  • Mealworms
    • Yellow mealworm = Tenebrio molitor
    • Dark mealworm = T. obscurus
    • Identification :
    • Beetles are ½ to 1 inch long, shiny
    • Beetles may look like ground beetles (predatory)
    • Grubs are cylindrical, sold as fish bait
    • Adults and larvae prefer dark, damp places in spoiled grain
    • Larvae can remain alive for >600 d in unfavorable conditions
    Insect is native of Europe. 1 2 3 4 Ground beetle 1 2 3 4 5 5 tarsal segments
  • Dermestid beetles
    • Scavengers by habit
    • Very wide host range/habitat
    • Khapra beetle (Trogoderma granarium) – strict quarantine has reduced spread or eliminated local infestations
    • Adult beetles are oval, 2 mm, reddish brown
    • Larvae are fuzzy, plump shape
    • Recent detections in spice warehouses
    Carpet beetle , Anthrenus sp. Khapra beetle, Trogoderma
  • Angoumis grain moth Sitotroga cerealella
    • First site of infestation in USA was North Carolina
    • Identification :
    • Adult moth is small (2/3 inch), brownish gray with long fringes of hair on wings
    • Hindwings extended at the apical angle (arrow)
    • Larval and pupal stages remain inside seed
  • Grain moth damage
    • First reported from France in 1736
    • Most destructive insect of grain in USA, esp. corn
    • May also attack developing wheat grain in field
    • Adult moths do not feed on grain
    • Eggs laid in clusters on grain>>produces larvae that feed in masses
    • Larvae feed on starchy portions of seed, adult escapes from a circular exit hole
    • There could be 6 generation
  • Indian meal moth Plodia interpunctella
    • Has European origin
    • Moth with a natural parasite (Bracon hebetor)
    • Identification (moth): base of forewings gray, half of the wing is reddish brown; black legs; conical head
    • Identification (larva): creamish with pinkish tinge and light brown head, make extensive webbing
    • Lifecycle: 4 to 6 weeks
    Meal moth larvae Bracon hebetor
  • Damage by Indian meal moth
    • Pest with a wide host range
    • Rapid lifecycle (4 wk)
    • Destroys stored grain by
      • Directly feeding on grain
      • Producing silken tunnels
      • Contaminating grain with excreta
  • Mediterranean flour moth Ephestia kuhniella
    • First reported from NA in 1889
    • Identification :
    • Moth had gray wings with zigzag line that may not be very clear
    • Hindwings are white with hairy margin
    • Eggs are laid in clusters on food or sacks or cracks
    • Larva is damaging: whitish or pinkish with hardened head capsule, spin silken tubes in flour
    • Pupate in silken cocoons
    • Lifecycle: 9 to 10 weeks
    • Modern fumigation methods have reduced pest status
    • Caterpillars web together flour and live inside
    • Flour is favorite but whole grain may be attacked
    • Moths may be monitored using pheromone traps
    Feeding injury by mediterranean flour moth
  • Storage temp. vs. Insect activity
  • 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!
  • Back to basics…
    • In USA, stored product losses have been enormous due to rice or maize weevils.
    • Reduction of losses:
      • By sanitation or hygiene – need of good plant design, stacking, sweeping, vacuum cleaning, and efficient disposal of infested debris
      • 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.)
      • By using fumigants & contact insecticides
      • By improved storage/packaging: more research??
    Source: Page & Lubatti (1963), Parkin (1956), Fields & White (2002)
  • Back to basics…
    • Mode of action: fumigants intervene ATP formation, upset enzyme systems, action is rapid
    • The rate of uptake of fumigant by insects depends on the rate of fixation in tissues
    • Insects that may seem to recover can have sublethal effects
    • Success of fumigation depends largely on even distribution of fumigant and on penetration.
    Source: Page & Lubatti (1963), Parkin (1956), Fields & White (2002)