Insect Orders of Agricultural Importance

1. Coleoptera – beetles (weevils, white grub).
2. Lepidoptera – moths and butterflies (borers, armyworms).
3. Hemiptera – bugs, hoppers, aphids, whiteflies.
4. Orthoptera – grasshoppers, locusts, crickets.
5. Diptera – flies, mosquitoes, maggots.
6. Hymenoptera – bees, wasps, ants.
7. Isoptera – termites.
8. Thysanoptera – thrips.
9. Odonata – dragonflies and damselflies (predators).
10. Blattodea – cockroaches.

Pest Management & Control

1. Cultural control – crop rotation, deep ploughing, sanitation.
2. Mechanical control – hand picking, traps, barriers.
3. Physical control – heat, cold, light traps.
4. Chemical control – insecticides, fumigants, repellents.
5. Biological control – use of natural enemies (predators, parasitoids, pathogens).
6. Predator example – Ladybird beetle (Coccinella spp.) vs. aphids.
7. Parasitoid example – Trichogramma spp. (egg parasitoid).
8. Microbial control – Bacillus thuringiensis (Bt), NPV, fungi.
9. Regulatory control – quarantine laws, import restrictions.
10. Host plant resistance – using resistant crop varieties.
11. Pheromone traps – attract males for monitoring and mass trapping.
12. Light traps – attract night-flying insects.
13. Neem-based pesticides – Azadirachtin (antifeedant, repellent).
14. Bt cotton – contains gene from Bacillus thuringiensis for pest resistance.
15. IPM pyramid – prevention → monitoring → thresholds → control.

Insecticides & Toxicology

1. First synthetic insecticide – DDT (Paul Müller, 1939).
2. Organophosphates – inhibit acetylcholinesterase (malathion, chlorpyrifos).
3. Carbamates – carbaryl, carbofuran.
4. Pyrethroids – cypermethrin, deltamethrin.
5. Neonicotinoids – imidacloprid, thiamethoxam.
6. Chlorinated hydrocarbons – DDT, BHC, aldrin, dieldrin.
7. Insect growth regulators (IGRs) – methoprene, diflubenzuron.
8. Fumigants – phosphine, methyl bromide.
9. Botanical insecticides – pyrethrum, nicotine, neem.
10. Mode of entry – contact, stomach, fumigant, systemic.
11. LD₅₀ – lethal dose to kill 50% test population.
12. Pesticide formulations – EC, WP, DP, GR, SC, WG.
13. Phytotoxicity – plant injury due to pesticide.
14. Resistance management – pesticide rotation and mixture.
15. Compatibility – ability of pesticides to mix without losing effectiveness.

Beneficial Insects

1. Pollinators – honeybee, bumblebee.
2. Honeybee species:
   • Apis dorsata – rock bee (max honey).
   • Apis indica – Indian bee (domesticated).
   • Apis mellifera – European bee (high yield).
   • Apis florea – little bee.
3. Queen bee – lays eggs only.
4. Drone – male, mates with queen.
5. Worker bee – sterile female, does all work.
6. Bees communicate via – waggle dance (von Frisch).
7. Silkworm (Bombyx mori) – reared on mulberry leaves.
8. Lac insect (Kerria lacca) – secretes resinous lac.
9. Cochineal insect (Dactylopius coccus) – produces carmine dye.
10. Pollination – transfer of pollen by insects, essential for seed set.

Insect Morphology

1. Insect body segmentation – 3 main regions: head (6), thorax (3), abdomen (11).
2. Antennae arise from frontal region of head capsule.
3. Antenna parts: scape, pedicel, flagellum.
4. Types of antennae – filiform, moniliform, clavate, serrate, plumose, pectinate, aristate.
   1. Filiform antenna – grasshopper.
   2. Plumose antenna – male mosquito.
   3. Aristate antenna – housefly.
5. Compound eyes – made up of ommatidia.
6. Ommatidia number determines visual resolution.
7. Types of vision – apposition (day) and superposition (night).
8. Insect mouth opening – ventral, hypognathous in grasshopper.
9. Prognathous mouth – beetles (forward directed).
10. Opisthognathous mouth – bugs (backward directed).
11. Leg parts – coxa, trochanter, femur, tibia, tarsus.
12. Tarsus often has 5 segments.
13. Cursorial leg – running type (cockroach).
14. Saltatorial leg – jumping type (grasshopper).
15. Raptorial leg – grasping type (praying mantis).
16. Fossorial leg – digging type (mole cricket).
17. Natatorial leg – swimming type (water beetle).
18. Wings arise from meso- and metathorax.
19. Forewings = elytra (beetles), tegmina (grasshopper).
20. Hindwings – membranous, used for flight.
21. Wing coupling devices – frenulum, hamuli.
22. Abdomen has 11 segments, last few modified for reproduction.
23. Cerci – paired appendages at abdomen tip (cockroach).
24. Ovipositor – egg-laying organ (grasshopper, wasp).
25. Spiracles – openings for respiration (10 pairs).
26. Genitalia – differ in male and female; useful in taxonomy.