R2103 3.1 – 3.4 Pests COPY Flashcards
Give 3 methods of pest feeding.
Biting mouthparts (aphids, vine weevil, rabbit, deer)
Piercing/sucking mouthparts (whitefly)
Rasping mouthparts (molluscs)
Describe the damage done by cabbage white butterfly, and 2 methods to minimise.
Leaves of brassicas, nasturtiums etc are gradually eaten away. Skeleton leaves may result. Larvae and excrement on leaves. Cover crops with fine netting. Pick off larvae. Encourage blue tits by building nest boxes. Spray with insecticide containing pyrethrum.
Outline the lifecycle of the cabbage white butterfly.
April/May: butterfly emerges from pupa April/May and July/Aug: females lay < 50 yellow/skittle-shaped eggs on underside of brassica leaves + 4–14 days: eggs hatch into caterpillar larvae which feed on the leaves and go through 4 moults (instars) for a month + 2 weeks (June): larvae form a pupa + 10 days (July/August): adult emerges winter: pupa over-winters
Describe the damage done by black-bean aphid, and 2 methods to minimise.
Most commonly damaged are broad beans. Dense swarms of aphids on soft new growth and flowers. Shoots weakened by the aphids sucking phloem out of shoots. Aphids secret sugary liquid (honeydew) that can get infected by sooty mould. Growth is affected and seed production dramatically reduced. Control biologically by encouraging ladybirds, lacewings, hoverflies. Physical hand squishing. Spray with insecticide containing Pyrethrum, or natural fatty acids.
Outline the life cycle of black bean aphid.
Eggs overwinter on woody host e.g. Euonymous europaeus or Vibernum opulus. Spring: female nymphs emerge, feed on winter host. At maturity they grow wings and fly to summer host such as beans. Females give birth to many live young. In autumn these live young include males and along with females they fly back to winter host to mate and lay eggs.
Describe the damage done by peach-potato aphid. And 2 methods to minimise.
Greenfly Glasshouse and hot outdoors Sucking stylet - inject a digestive juice - distorts tissues Secrete honeydew - blocks stomata - attracts sooty mould - slows photosynthesis/growth Transfers viruses such as leaf roll virus, mosaic virus Control by ladybirds, lacewings, hoverflies Insecticide containing Pyrethrum, or fatty acids
Describe the damage done by two-spotted spider mite. And 2 methods to minimise.
Piercing and sucking mouth parts inject poison into leaf cells, causing localised death Yellowish mottling of the leaf. Lose green colour, dry up and drop off. Severe infestations – fine silk webbing. Chemical – spray insecticides containing fatty acids. Biological – introduce predatory mite. Cultural – check all new plants. In winter clean and disinfect.
Name the predatory mite used as biological control for red spider mite.
Phytoseiulus persimilis Can’t be used in conjunction with any other chemicals other than organic whilst awaiting delivery.
Describe the damage done by glasshouse whitefly. And 2 methods to minimise.
Attacks Solanum persicum and other greenhouse plants. When plant disturbed clouds of small white winged insects fly up. Flat oval, scale-like nymphs on underside of leaves. Honeydew on foliage which attracts black sooty mould Biological – Encarsia formosa parasitic wasp Sticky yellow sheets hung above plants to trap whitefly. Quarantine new plants. Chemical – Pyrethrin and fatty acids
Name the parasitic wasp used as a control for greenhouse whitefly.
Encarsia formosa
Outline the lifecycle of glasshouse whitefly.
Adult lays eggs Eggs – 200 minute white rugby-ball shaped in circular pattern on under side of the leaf. Eggs turn black Hatch into nymphs (crawlers) which then turn into scales 3rd instar Pupa Adult Lays eggs again 3 days later.
Describe the damage done by vine weevil. And 2 methods to minimise.
Damage grape vines, and tubers such as cyclamen and begonias Irregular-shaped notches on leaf margins in summer Plants wilt and die during autumn – winter due to white grubs eating roots. Cultural – encourage natural predators such as birds, shrews, frogs etc. Picking/shaking off adult weevils at night in summer. Biological – nematodes Chemical – Bug Clear Ultra vine weevil killer
Outline the life cycle of the vine weevil.
Adults feed on leaves and then lay eggs in august in soil or compost next to roots of Cyclamen or Begonia. Larvae emerge white and legless with brown head usually lying in C-shape. Pupate in soil in December and adult emerges.
Describe the damage done by slugs and 2 methods to minimise.
Feeds with radula and can scoop out cavities. In moist warm weather damage is done to leaves of hostas etc. Completely eat young seedlings Irregular holes in plants Slime trails Biological - Nemaslug nematodes watered in in spring Place traps such as scooped out citrus halves, jars filled with beer Hand pick with torch. Encourage frogs and birds Copper tape around pots
Outline the lifecycle of a slug.
Hermaphrodite slugs mate in spring summer and lay clusters of pearl-like eggs in rotting vegetation or under pots.
Describe the damage done by potato cyst eelworms and methods to minimise.
Stunted potato plant, yellow leaves turn brown and hang down Cysts on the roots. (Dead body of females containing up to 600 eggs) Use of resistant cultivars such as Maris Piper and certified seed. Four-year crop rotation or more
Outline the life cycle of potato cyst eelworm (nematode).
Eggs hatch in spring and larvae invade roots and suck up cell contents. Once larvae are fully developed they wriggle to outside of root. Female leaves head buried in root and swells. Males leave root and fertilise females. Females change colour and form cyst which then drops from the root into the soil where it can survive many years with eggs inside.
Describe how insects breathe.
Insects breathe through holes in their abdomen called spiracles which lead to an internal breathing system of tracheae.
Name 3 entry points for insecticides into insects.
Waxy exoskeletons can be penetrated. Spiracles allow fumigant chemicals in or are blocked by sticky pesticides. Digestive systems take in poison to stomach.
Which pests have a winter host?
Aphids Black fly /black bean aphid – Euonymus Europaeus Greenfly – peach potato aphid – Prunus