R2103 3.1 – 3.4 Pests

Question 1

Give 3 methods of pest feeding.

Answer 1

Biting mouthparts (aphids, vine weevil, rabbit, deer)

Piercing/sucking mouthparts (whitefly)

Rasping mouthparts (molluscs)

Question 2

Describe the damage done by cabbage white butterfly, and 2 methods to minimise.

Answer 2

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.

Question 3

Outline the lifecycle of the cabbage white butterfly.

Answer 3

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

Question 4

Describe the damage done by black-bean aphid, and 2 methods to minimise.

Answer 4

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.

Question 5

Outline the life cycle of black bean aphid.

Answer 5

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.

Question 6

Describe the damage done by peach-potato aphid. And 2 methods to minimise.

Answer 6

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

Question 7

Describe the damage done by two-spotted spider mite. And 2 methods to minimise.

Answer 7

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.

Question 8

Name the predatory mite used as biological control for red spider mite.

Answer 8

Phytoseiulus persimilis Can’t be used in conjunction with any other chemicals other than organic whilst awaiting delivery.

Question 9

Describe the damage done by glasshouse whitefly. And 2 methods to minimise.

Answer 9

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

Question 10

Name the parasitic wasp used as a control for greenhouse whitefly.

Answer 10

Encarsia formosa

Question 11

Outline the lifecycle of glasshouse whitefly.

Answer 11

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.

Question 12

Describe the damage done by vine weevil. And 2 methods to minimise.

Answer 12

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

Question 13

Outline the life cycle of the vine weevil.

Answer 13

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.

Question 14

Describe the damage done by slugs and 2 methods to minimise.

Answer 14

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

Question 15

Outline the lifecycle of a slug.

Answer 15

Hermaphrodite slugs mate in spring summer and lay clusters of pearl-like eggs in rotting vegetation or under pots.

Question 16

Describe the damage done by potato cyst eelworms and methods to minimise.

Answer 16

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

Question 17

Outline the life cycle of potato cyst eelworm (nematode).

Answer 17

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.

Question 18

Describe how insects breathe.

Answer 18

Insects breathe through holes in their abdomen called spiracles which lead to an internal breathing system of tracheae.

Question 19

Name 3 entry points for insecticides into insects.

Answer 19

Waxy exoskeletons can be penetrated. Spiracles allow fumigant chemicals in or are blocked by sticky pesticides. Digestive systems take in poison to stomach.

Question 20

Which pests have a winter host?

Answer 20

Aphids Black fly /black bean aphid – Euonymus Europaeus Greenfly – peach potato aphid – Prunus

Question 21

Which weed is a host for clubroot?

Answer 21

Capsella bursa pastoris (chickweed)

Question 22

Method of reducing effects of black bean aphid?

Answer 22

Pinching out tops of broad beans Spray with organic pesticide – fatty acids

Question 23

Method of reducing effects of two-spotted spider mite

Answer 23

Increase relative humidity in greenhouse by damping down floors and misting foliage. Biological control with Phytoseiulus persimilis.

Question 24

Method of reducing effects of glasshouse whitefly?

Answer 24

Sticky yellow traps to monitor and control. Biological control with Encarsia formosa.

Question 25

Method of reducing effects of vine weevil?

Answer 25

Inspecting container plants for grubs, staging and outdoor plants for beetles, and removing. A compost drench of a systemic pesticide.

Question 26

Method of reducing effects of slugs and snails?

Answer 26

Beer traps Attracting predator to the garden such as hedgehogs, by providing suitable habitats

Question 27

Method of reducing effects of potato eelworm?

Answer 27

Use early potato crops. Use resistant cultivars.

Question 28

Name i) a glasshouse pest ii) an outdoor pest

Answer 28

(i) 2-spotted spider mite Glasshouse whitefly (ii) Rabbits Cabbage white larvae Black bean and peach potato aphid Vine weevil Slug Eelworm

Question 29

What two named beneficial organisms can be encouraged into a garden to help control peach potato aphid?

Answer 29

 Blue tits can be encouraged with the provision of food e.g. bird seed and fat balls and hedges and bird boxes for nesting  Parasitic wasps e.g. Ahidus praon can be supplied as parasitised aphids which can be placed on plants in the evening. Rove beetles can also be used  Ladybirds and lacewings can be encouraged by providing overwinter shelter in hollow stems, herbaceous material, crevices in walls etc. or by purchasing products which provide a similar habitat and are called ‘insect hotels’.

Question 30

State a named example for each of the following control methods for black bean aphid: Physical Chemical

Answer 30

Physical – squashing/rubbing aphids off between finger and thumb, removal of the bean shoot tips by pinching out by hand before the aphids are able to colonise the plant and using a strong jet of water to wash aphids from an infested plant, without causing damage to the plant. Chemical – The use of fatty acids, pyrethrin or deltamethrin.

Question 31

Describe how slug populations can be controlled using a microscopic biologicalcontrol.

Answer 31

 The nematode Phasmarhabditis hermaphrodita which is available in a spore form is used.  The nematode is applied as a drench to moist soil.  The soil temperature must be above 5°C.  The nematode invades the slug, infecting it with bacteria.  The nematodes feed on the slug body, causing death, and also reproduce in it.  A second application may be required if tender seedlings are grown later in the year.

Question 32

State 2 benefits and 2 limitations of using biological control to minimise the population of pests.

Answer 32

Benefits:  Reduces the use of chemicals  Reduces operator exposure to harmful chemicals  Reduces the incidence of pest resistance  Does not harm beneficial insects  Maintains pest/predator balance  Targets specific pests Limitations:  Requires a knowledge of the pest life cycle  May require a controlled environment  Must accept some pest damage  Must apply when conditions are right  Each pest requires a different control agent  Effects may not be immediate

Question 33

State biological and cultural control method for slugs

Answer 33

Biological: using the nematode Phasmarhabditis hermaphrodita

Cultural: removing any rotting debris where slugs can hide or by surface cultivation to expose slug eggs to predators.

Question 34

State biological and cultural control method for glasshouse whitefly

Answer 34

Biological: by using the parasitic wasp Encarsia formosa or the predatory mite. Cultural: new plants can be placed in quarantine and good hygiene should be practiced by frequently cleaning the greenhouse and glass and removing host weeds that harbour the pest.

Question 35

State biological and cultural control method for black bean aphid

Answer 35

Biological: by using the parasitic wasp or the predatory midge. Cultural: pinching out the tender growing tips of plants before the aphids appear or sowing an autumn crop of beans which are less susceptible to attack as the growing tips will have matured.

Question 36

Describe a suitable method of chemical and physical control for the large cabbage white butterfly.

Answer 36

i) Chemical: e.g. deltamethrin applied as a spray at the larvae stage in the pest’s life cycle. Other suitable chemicals included; Fatty acids, ii) Physical: by covering the crop with fine netting, ‘Enviromesh’ or horticultural fleece before the adult lays eggs. The netting must not touch the crop.It is important to inspect the plants frequently and pick off and squash the eggs or caterpillars to prevent the crop from being damaged.

Question 37

State 2 distinct methods used to minimise the damage caused by the cabbage white butterfly.

Answer 37

 A bacterial spray of Bacillus thuringiensis for the larval (caterpillar) stage.  Crops can be covered by fine netting to prevent the adult butterfly from laying eggs.  Use of the chemicals Deltamethrin or Cyhalothrin can be used to kill the larval stage (caterpillar).

Question 38

State 2 ways of limiting the spread of potato cyst eelworm (other than using a resistant cultivar).

Answer 38

 The use of early crop potatoes so that the eelworm has less chance to develop.  Ensuring good hygiene to avoid transfer of soil on boots, tools etc.  Reduce possible contamination by growing potatoes in pots with fresh, sterilised soil.  Sowing Solanum sisymbriifolium to trigger the eggs to hatch. The eggs cannot develop in the roots, which helps eliminate the soil of live eggs.

Question 39

Give example of biting pest.

Answer 39

Beetles and caterpillars. Consume plants directly.

Question 40

Give example of piercing/sucking pest.

Answer 40

Aphids. Thread their mouth parts through intercellular spaces, tap into the plant’s vascular system, and feed by withdrawing sap from the phloem.

Question 41

Give example of raspers.

Answer 41

Molluscs. Rasping, scraping or slicing the surface of the plant tissue and sucking out the fluids from the ruptured cells.

Question 42

What growth stage does cabbage white (large) do its damage?

Answer 42

Larval (caterpillar). Vast quantities of plant material eaten by the biting mouthparts.

Question 43

Symptoms of black bean aphid damage?

Answer 43

Colonies appear on young shoots. Shoots become distorted and plants weakened.

Question 44

What growth stage does peach potato aphid do its damage?

Answer 44

Nymph and adult. Directly by piercing the leaf with their feeding tubes and sucking the sap, or indirectly by infecting the plant with a virus.

Question 45

Describe the damage caused to plants by the peach potato aphid.

Answer 45

Sap sucking - yellowing, mottled leaves and curled/puckered/distorted young growth. Youngest leaves and shoots, or on the underside of older leaves. Honeydew excreted on the leaf by the aphid which leads to the secondary infection of sooty mould. Reduced psn. The stylets of aphids can also transmit viruses such as severe mosaic virus (on potatoes), and tomato aspermy virus (on chrysanthemums).

Question 46

Describe TWO distinct symptoms of vine weevil damage.

Answer 46

‘Notching’ of the leaf edges carried out by adult weevils on evergreen foliage. Root damage carried out by the larvae which causes wilting, total collapse and often death of the plant, especially in ornamental herbaceous plants.

Question 47

Describe how glasshouse whitefly feed, including the damage they cause.

Answer 47

Piercing-sucking mouthparts Like aphids they feed on the sap and cause a sticky honeydew residue, often leading to a sooty mould which lowers the rate of psn Growth is stunted and crop yields lowered

Question 48

Name ONE pest that causes damage by biting.

Answer 48

vine weevil, deer, rabbit, caterpillars

Question 49

Contact-action synthetic pyrethroid?

Answer 49

Provanto Ultimate Fruit (has deltamethrin)

Westland Resolva Bug Killer (has lambda-cyhalothrin)

Question 50

Plants for whitefly/aphid predators?

Answer 50

calendula, buckwheat (Fagopyrum esculentum), thistles, oregano, fennel, parsley, poached egg plant (Limnanthes douglasii)

Question 51

Cultural control for cabbage white?

Answer 51

Flowers and blooming herbs - nectar for beneficial insects, such as garden wasps, parasitic wasps and insect-eating birds. Check plants regularly, especially for the appearance of holes in the leaves and caterpillar excrement. Remove caterpillars by hand or use a hose daily to knock them off the plants and expose them to ground-dwelling predatory beetles and insectivorous birds. Nasturtiums will attract cabbage butterflies away from the crop.