Plant pests: Animals

1. Plant pests: Animals • Nematodes • Insects • Animal pests in horticulture • Other invertebrates • Birds • Mammals

2. Plant pests: Animals • Small, round worm-like animals found in soil • Those parasitic to plants feed on roots • Nematodes • Can be controlled by crop rotation; plant species not hosts to nematodes (10-years is necessary) • Chemical control also possible • Sanitary practices reduce spread of nematodes

3. Plant pests: Animals • 50% of insect species feed on plants; potential pests • But many species beneficial to horticulture: • Insects • Pollination of crops • Production of silk and honey • Serve as biological control agents

4. Plant pests: Animals • Insects have 3 body regions and 3 pairs of legs • May undergo incomplete or complete metamorphosis • Insects • Incomplete = eggs hatch into nymphs that grow into adults • Complete = eggs hatch into larvae that become pupae before emerging as adults • Most insect damage to plants results from feeding

5. Plant pests: Animals • Mouthparts of insects cause different types of damage • Chewing mouthparts: • Insects • Holes in plants or missing organs (such as leaves and flowers) • Order Lepidoptera (butterfly and moth larvae), Orthoptera (grasshoppers), Coleoptera (beetles)

6. Plant pests: Animals • Mouthparts of insects cause different types of damage • Piercing-sucking mouthparts: • Insects • Puncture plant tissue and suck out ‘sap’ • Order Hemiptera (true bugs), Homoptera (leafhoppers, aphids, scale) • Presence of piercing-sucking insects apparent from sticky, shiny ‘honeydew’ • Ants and mold may be attracted to honeydew

7. Plant pests: Animals • Mouthparts of insects cause different types of damage • Rasping-sucking mouthparts: • Insects • Abrade plant tissue and suck ‘sap’ • Order Thysanoptera (thrips) • Elongated scrapings on leaves

8. Plant pests: Animals • Root damage • White grubs (larvae of June bugs, Japanese beetles) cause damage to roots of lawn grasses • Insect damage to plants • Cutworms (larvae of moth) chew roots and stems at soil line

9. Plant pests: Animals • Stem damage • Damage includes wilting, witches’ brooms, holes, death of stem or entire plant • Insect damage to plants • Borers feed and tunnel within stems of plants; cause sudden wilting and create wound in which infectious diseases enter

10. Plant pests: Animals • Leaf damage • Leaves with chew holes or tunnels • Insect damage to plants • Cabbage worms (larvae of white butterflies) feed on crucifers; signs include green feces • Leaf miners tunnel within leaves; reduce aesthetic appeal • Colorado potato beetles chew on potato and tomato leaves

11. Plant pests: Animals • Flower and fruit damage • Loss of flowers by feeding insects such as Japanese beetles • Insect damage to plants • Fruit damaged by feeding or egg laying • Codling moth larvae feed within fruits such as apples • Corn earworms feed on kernels of corn (near top)

12. Plant pests: Animals • Cultural techniques • Crop rotation, selecting resistant cultivars • Insect pest management • Reproductive controls • Use of sterile males, pheromones to lure insects into traps • Biological control • Use of parasitoids, predators and bacteria (BT)

13. Plant pests: Animals • Chemical control • Stomach insecticides: enter digestive system (effective on insects with chewing mouthparts; e.g.boric acid) • Insect pest management • Contact insecticides: sprayed directly onto pests (e.g. insecticidal soaps, pyrethrins ) • Systemic insecticides: absorbed by plants and then ingested by sucking insects in ‘sap’ (e.g. Disyston granules ) • Many insecticides act in multiple ways (e.g both as contact and stomach poison)

14. Plant pests: Animals • Mites • 8-legged, tiny arthropods • Other invertebrates • Spider mites cause yellow stippling and produce web-like material on underside of leaves • Can be controlled with predatory mites and insecticides • Slugs and snails • Soft-bodies mollusks detected by shiny trails • Controlled by eliminating hiding places, molluscicides, dehydration barriers, shallow dishes filled with beer

15. Plant pests: Animals • birds • Can damage fruit crops such as cherries • Vertebrate pests • Crops protected with netting • mammals • Tree guards, fencing and repellents can reduce damage by rabbits, voles, deer