R2103 3 PESTS Flashcards
Plant pest definition
A mammal, bird, insect, mollusc or nematode that is damaging to plants
Describe the damage: rabbit
BITES
Grazing, ring barking. Commonly eats lettuces, carrots, annual bedding plants.
Describe the damage: Cabbage white butterfly larvae
BITES
Usually eats plants in brassicaceae family. Defoliates the plants, may result in skeletonised leaves with just the main veins showing
Describe the damage: Black bean aphid
PIERCING
Stunts growth. Curled and distorted foliage. Can cause sooty mould and carry viruses as secondary damage
Describe the damage: Peach potato aphid
PIERCING
Sap sucking, Yellowing, mottled leaves, distorted young growth. Can cause sooty mould and carry viruses as secondary damage
Describe the damage: Two spotted spider mite
PIERCING
Webbing on leaves, leaf mottling, foliage and flower detoriation, loss of plant vigour
Describe the damage: Glasshouse whitefly
PIERCING
Weakened growth, reduced flowering and fruiting potential. Sticky honeydew on the leaves, can cause sooty mould
Describe the damage: Vine weevil
BITES
Notched leave margings
Larvae eat roots
Describe the damage: Slugs
RASPING
Eat mostly leafy and young growth. Make irregular holes in plant tissue. Can completely decimate young seedlings
Describe the damage: Potato cyst eelworm
PIERCING
Damaged root system of patotoes and tomatoes cause lack of vigour and poor yield. Also causes cyst on roots
Life cycle: Cabbage white butterfly
- April- May adults emerge from overwintering pupa, mate and lay eggs on the underside of the leaves.
- Withing fortnight larvae emerge. Usually around 2.5cm in lengh yellow and green in colour with black markings
- June pupa stage occours in crevices of woody stems
- July second generation or adults emerge and lay eggs. In fortnight, the larvae appear which is usually more damaging than the first generation.
- The second generation pupa overwinters
Life cycle: Black bean aphid
- Overwinters in an eggs state usually on Euonymus europaeus
- March/April female nymphs emerge and at maturity fly to summer host plants such as beans and beets
- Females lay as many as 5 females per day which are themselves then ready to produce more young aphids within 14 days
- In Autumn nymps start producing winged males and females which fly to lay eggs on winter host plants where they overwinter
Life cycle: Slugs
- Slugs are hermaphrodites
- Spring/Summer - mating season. Lay clusters of up to 50 eggs in rotting vegetation.
- Take around a year to mature
- Overwinters as young slugs or eggs
- More active in moist conditions
Life cycle: Potato cyst eelworm
- Spring: the eggs hatch which are stimulated by chemicals present in neightbouring potatotes
- The larvae invade the potato roots, disturbing vascular systems
- Summer: adult females start to swell, the body develops into a cyst and protrudes outside the root. Male fertilises the cyst and dies
- Autumn/winter fertilised cyst detaches from the plant root, back into the soil when plant is harvested.
- Cyst can persist in the soil for 10 years until the viable host is detected
Methods of breathing used by insect pests
Insects breathe through spiracles. Fatty acid chemicals block the spiracles
How can chemicals enter the insects
- Through spiracles
- Waxy exoskeleton
- Digestive system
How the pests can be controlled x2: Rabbit
Physical - plastic guards
Chemical - Aluminum ammonium sulphate sprayed aroung the plants
How the pests can be controlled x2: Cabbage white butterfly larvae
Physical - very fine netting to prevent adults laying eggs
Biological - encouraging birds such as blue tits who eat them
How the pests can be controlled x2: Black bean aphid
Biological - attached by ladybirds, lacewings, hoverfly larvae
Physical - hosing them off, squashing them by hand
How the pests can be controlled x2: Peach potato aphid
Biological - lady birds, lacewings, hoverfly larvae etc
Chemical - fatty acids
How the pests can be controlled x2: Two-spotted spider mite
Chemical - fatty acids
Physical - removing badly infected plants
How the pests can be controlled x2: Glasshouse whitefly
Chemical - fatty acids
Cultural - removing alternative hosts
How the pests can be controlled x2: Vine weevil
Physical - hand picking when active at night
Biological - nematodes
How the pests can be controlled x2: Slugs
Physical - hand picking them off at night
Chemical - Ferric phosphate
How the pests can be controlled x2: Potato cyst eelworm
No chemical control available
Cultural - growing early potatoes which allow harvesting before the cyst forms
long crop rotation
growing resistant varieties
Life cycle: Glasshouse whitely
- Fertilised female lays about 200 eggs in a circular pattern on the undersurface of the leaf
- The eggs produce nymphs which develop into scales (pupa) from which the male and female adults emerge
- Females are ready to lay legs within 3 days
- The whole cycle can take 23-32 days depending the season. The warmer the weather, the faster
- Active all year due to being mainly houseplant and glasshouse pest
Life cycle: Vine weevil
- The adult is 9mm long, black in colour. Incapable of flight. No males known
- The female lays eggs (mainly in august and september) in soil or compost next to roots of preferred speciels. Over of period of 2 years she may lay 1000 eggs as she visits many plants
- The larvae are white and legless with chestnut brown head
- They pupate in December in soil
