3.Pests Flashcards
1
Q
Give 4 methods of pest feeding.
A
- Biting mouthparts (vine weevil, rabbit, deer)
- Piercing mouthparts (whitefly)
- Rasping mouthparts (molluscs)
- Sucking through tubular stylet (black bean aphid)
2
Q
Describe the damage done by Large cabbage white butterfly,
And methods to minimise.
A
- Caterpillars do the damage
- Leaves of brassicas, nasturtiums are gradually eaten away
- Eventually completely defoliated
- Physical = Cover crops with fine netting to prevent adult butterfly laying eggs
- Cultural = Manually wash of off eggs
- Provide alternate host
- Encourage blue tits by building nests
- Biological = Nematode sprayed on to caterpillar infested leaves
3
Q
Outline the lifecycle of the cabbage white butterfly.
A
- Spring - butterfly emerges from pupa
- Females lay 20-100 yellow/skittle-shaped eggs on underside of brassica leaves
- 2 Weeks: eggs hatch into caterpillar larvae which feed on the leaves and
- June larvae form a pupa (attach to woody stem with silk threads)
- Autumn adult emerges - 2nd Gen
- 2nd gen pupa over-winters
4
Q
Describe the damage done by black-bean aphid
And methods to minimise.
A
- Most commonly damaged are broad beans
- Shoots weakened by the aphids sucking phloem
- Aphids secret sugary liquid (honeydew) that can get infected by sooty mould (Blocks out light, preventing photosynthesis)
- Growth is affected and seed production dramatically reduced
- Biological = by encouraging predators ladybirds, lacewings, hoverflies
- Chemical = Spray with insecticide containing Pyrethrum, or natural fatty acids (Breaks down outer waxy cuticle)
- Cultural = Removal of host plants
5
Q
Outline the life cycle of black bean aphid
A
- Eggs overwinter on woody host e.g. Euonymous europaeus
- 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 (5 per day)
- In autumn these live young include males and along with females they fly back to winter host to mate and lay eggs
6
Q
Describe the damage done by glasshouse whitefly.
And methods to minimise.
A
- Attacks a wide range of food and flower crops
- Rapid reproduction - introduced from tropics
- Stylets - Honeydew on foliage which attracts black sooty mold and prevents photosynthesis
- Biological – Encarsia formosa parasitic wasp
- Sticky yellow sheets hung above plants to trap whitefly
- Quarantine new plants/ check leaves
- Chemical – Pyrethrin and fatty acids
7
Q
Outline the lifecycle of glasshouse whitefly.
A
- 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
- Which then turn into flat scales
- 3rd instar Pupa and flying adult emerge
- Adult Lays eggs again 3 days later
8
Q
Describe the damage done by vine weevil
And methods to minimise
A
- Larvae live in soil and attack roots and tubers
- Adults emerge at night and eat irregular wholes in leaves
- Damage grape vines, and tubers such as cyclamen and begonias
- Plants have slow growth wilt and die
- Cultural – encourage natural predators such as birds, shrews, frogs etc.
- Picking/shaking off adult weevils at night in summer
- Biological – nematodes can be used on larvae
- Chemical – Bug Clear Ultra vine weevil killer (ornamental plants in containers)
9
Q
Outline the life cycle of the vine weevil.
A
- Autumn Adults feed on leaves and then lay eggs in soil or compost next to roots
- Larvae emerge white and legless with brown head
- Dec - Pupate in soil and adult emerges
10
Q
Describe the damage done by potato cyst eelworms (nemotodae)
And methods to minimise.
A
- Stunted potato/ tomato plant
- Yellow leaves turn brown and hang down
- Cysts on the roots
- Damage is patchy and increases year on year
- Use of resistant cultivars such as Maris Piper and use certified seed
- Remove host weeds (nightshade family)
- Five-year crop rotation
- Use young mustard crop as manure
11
Q
Outline the life cycle of potato cyst eelworm (nematode)
A
- Spring - Eggs hatch in and larvae invade roots and suck up cell contents
- Once larvae are fully developed they wriggle to outside of root and mate
- Female leaves head buried in root and swells
- Females change colour and form cyst which then drops from the root into the soil where it can survive many years with eggs inside
12
Q
Describe the damage done by peach-potato aphid
And methods to minimise
A
- Affect a wide variety of plants - prefer tender plants
- Sucking stylet - inject a digestive juice - distorts tissues
- Secrete honeydew - blocks stomata - attracts sooty mold - slows photosynthesis/growth
- Transfers viruses such as mosaic virus
- Physical = cover crop with fleece
- Biological = ladybirds, lacewings, hoverflies
- Small parasitic wasps
- Chemical = Insecticide containing Pyrethrum, or fatty acids
13
Q
Describe the damage done by two-spotted spider mite
And methods to minimise
A
- Affects a wide range of plants - few plants are completely immune
- Piercing and sucking mouth parts inject poison into leaf cells, causing localised death
- Yellowish mottling of the leaf
- Leaves lose green colour, dry up and drop off
- Spider mites and eggs can be visibly seen on underside of leaf
- Biological – introduce predatory mite
- Cultural – check all new plants
- In winter clean and disinfect glass house
- Chemical – spray insecticides containing fatty acids
14
Q
Describe the damage done by slugs
And methods to minimise.
A
- Feeds with radula and can scoop out cavities.
- Completely eat young seedlings
- Irregular holes in plants, leaves, roots, tubers, bulbs
- Leave a slime trail from undulating foot
Grey field slug, large black slug, garden slug
- Biological - Parasitic nematodes watered in spring, penetrate the slug and release bacteria (best for underground infestations)
- Physical - Place traps such as scooped out citrus halves, jars filled with beer
- Hand pick with torch
- Copper tape around pots
- Cultural - Encourage predators, hedgehogs, frogs and thrushes
- Chemical - Slug pellets, using metaldyhide (adult) or aluminium sulphate (young slugs)
15
Q
Outline the lifecycle of a slug
A
- Hermaphrodite (both sexual organs)
- Spring/summer - mate and lay clusters of up to 50 pearl-like eggs in rotting vegetation or under pots
