Mode of Action of Insecticide

MOA of Most Insecticides

General Anatomy of Insect A- Head B- Thorax C- Abdomen 1. Antenna 2. ocelli (lower) 3. ocelli (upper) 4. compound eye 5. brain (cerebral ganglia) 6. Prothorax 7. dorsal blood vessel 8. tracheal tubes (trunk with spiracle) 9. Mesothorax 10. metathorax 11. Forewing 12. hindwing 13. mid-gut (stomach) 14. dorsal tube (Heart) 15. Ovary 16. hind-gut (intestine, rectum & anus) 17. Anus 18. oviduct 19. nerve chord (abdominal ganglia) 20. Malpighian tubes 21. tarsal pads 22. claws 23. Tarsus 24. tibia 25. Femur 26. trochanter 27. fore-gut (crop, gizzard) 28. thoracic ganglion 29. coxa 30. salivary gland 31. subesophageal ganglion 32. Mouthparts

Insect Anatomy Exoskeleton – Epicuticle, a thin and waxy water resistant outer layer and contains no chitin – Procuticle. The procuticle is chitinous and much thicker than the epicuticle and has two layers: an outer layer known as the exocuticle and an inner layer known as the endocuticle. The tough and flexible endocuticle is built from numerous layers of fibrous chitin and proteins, criss- crossing each others in a sandwich pattern, while the exocuticle is rigid and hardened.

Insect Digestion System Foregut : Foregut is lined with a cuticular lining made of chitin and proteins as protection from tough food. Midgut: also known as the mesenteron, where the majority of digestion takes place Hindgut: Undigested food particles are joined by uric acid to form fecal pellets. The rectum absorbs 90% of the water in these fecal pellets, and the dry pellet is then eliminated through the anus. The uric acid is formed using hemolymph waste products diffused from the Malpighian tubules

Insect Mouth

Insect Nervous System

Neurons in Insect Mono-polar: Common Dipolar/Multipolar: Less common but more Toxicologically relevant

Synaptic gap

Synapse Neuron A (transmitting) to neuron B (receiving) 1. Mitochondria 2. synaptic vesicle with neurotransmitters 3. Autoreceptor 4. Synapse with neurotransmitter released (serotonin) 5. Postsynaptic receptors activated by neurotransmitter (induction of a postsynaptic potential) 6. Calcium channel 7. Exocytosis of a vesicle 8. Recaptured neurotransmitter

Class of Chemical Synapse

Cholinergic Synapse

GABAergic Synapse

Keys of Insect Nervous System Acetylcholine receptor

Respiration in Insects Insect respiration is accomplished without lungs. The insect respiratory system uses a system of internal tubes and sacs through which gases either diffuse or are actively pumped, Delivering oxygen directly to tissues that need it via their trachea Since oxygen is delivered directly, the circulatory system is not used to carry oxygen, and is therefore greatly reduced. Toward the thorax, the dorsal tube, divides into chambers and acts like the insect's heart. The opposite end of the dorsal tube is like the aorta of the insect circulating the hemolymph, arthropods' fluid analog of blood, inside the body cavity. Air is taken in through openings on the sides of the abdomen called spiracles.

Repreduction in Insects

Flying!

Classification of Insect Kingdom -- Animal Phylum -- Arthropoda Class -- Hexapoda (= insects) Order -- Lepidoptera (= butterflies and moths) Family -- Noctuidae (= noctuids) Genus -- Helicoverpa Species -- Helicoverpa armigera (= Am erican bollworm)

More details Order Thysanura Bristletails Order Diplura Diplurans (Two-pronged Bristletails) Order Protura Proturans Order Collembola Springtails Apterygota

Exopterygota Order Isoptera *Termites Order Embioptera Web-spinners Order Plecoptera Stoneflies Order Zoraptera Zorapterans Order Psocoptera Psocopterans (Psocids, Booklice) Order Mallophaga Chewing lice (Biting lice) Order Anoplura (= Siphunculata) Sucking lice Order Thysanoptera *ThysanopteraThrips Order Hemiptera suborder Heteroptera *Heteroptera Bugs suborder Homoptera *Homoptera Cicadas, Hoppers, Psyllids, Whiteflies, Aphids, and Scale in sects

Order Neuroptera Alderflies, Dobsonflies, Fishflies, Snakeflies, Lacewings, Antlion s, and Owlflies Order Coleoptera *ColeopteraBeetles Order Strepsiptera Twisted-winged parasites (Stylopids) Order Mecoptera Scorpionflies Order Trichoptera Caddisflies Order Lepidoptera *LepidopteraButterflies and Moths Order Diptera *DipteraTrue Flies Order Siphonaptera Fleas Order Hymenoptera * Sawflies, Ichneumons, Chalcids, Ants, Wasps, and Bee Endopterygota