1. Lecture

Visual inspection

Beating samples

Bait and interception traps

Degree-days

Field cages

Aspects on counting arthropods directly on plants and plant parts:

Sample size: plant parts / organs: number of samples needed depends on the economic threshold levels of a pest species

->low level requires high number of sample

Mature and immature developmental stages: depends on pest species / damaging developmental stage

Counting beneficials (Nützlinge)

Examples:

Rosy apple aphid Dysaphis plantaginea: Economic threshold level 1% infested bunches of blossoms

European fruit tree red spider mite Panonychus ulmi: winter eggs on a branch

Drop cloth is held underneath plant foliage

Foliage is struck hard a standard number of times using a short stick

Arthropods falling into the tray are counted immediately

Example apple blossom weevil (Anthonomus pomorum): economic threshold 10 – 40 adults / 100 beats at green bud stage

Bait traps: rely on insect olfaction and / or vision:

Kairomone traps (food lures): example fruit juice and vinegar in plastic bottles for trapping wasps and spotted wing drosophila

Pheromone traps: example sex pheromones in traps for monitoring the codling moth

Colour traps: example white traps for monitoring the apple sawfly

Interception traps:

Water-pan traps

Sticky traps

->Most trapping devices are combinations between bait and interception traps.

Each species requires a defined number of degree-days to complete its development.

Development can be estimated by accumulating degree-days between the upper and the lower temperature thresholds

The biofix date is the date to begin accumulating degree-days

Family Tetranychidae – spider mites

Tetranychus urticae

Polyphagous on all fruit crops

Females overwinter sheltered on the soil

All stages live and feed on the underside of the leaves

several overlapping generations / year

Damage:

Generally, mites pierce plant cells and suck out the sap:

Pale spots on leaves

Severe infestations cause distinct speckling, silvering or bronzing of the foliage

Foliage of heavily infested host plants with silken webbing

Plant (tree) in the field or plant part (branch) in a meshed cage:

Developmental stages of the pest released in the caged is controlled regularly

Method for monitoring services

Disadvantage microclimate in cage

Example: Field cage for codling moth monitoring

Family Tetranychidae – spider mites

Panonychus ulmi

Polyphagous on all fruit crops

Eggs overwinter on the bark

All stages live and feed on the underside of the leaves

several overlapping generations / year

Damage:

Light speckling on foliage

Leaves become dull green, brownish, silvery bronze

Yield may be affected

Family Eriophyidae - gall mites, rust mites

Cecidophyopsis ribis

All life stages have only 2 pairs of legs

Overwintering occurs in the pre-adult or adult stage in the “big buds”

In spring mites feed on leaves and flowers

In June they invade young buds, eggs are laid and rapid develoment takes place

Damage:

Attacked black currant buds begin to swell during the summer

In the following spring, they swell further: “big buds”

Although opening buds do not produce leaves or flowers

Leaves on infested shoots are deformed

Vectors of the plant virus causing reversion disease

Family Eriophyidae - gall mites, rust mites - Aculus fockeui

On plum, also attacks apricot, cherry, peach and various other kinds of Prunus.

Description

Two adult female forms: protogyne (summer female); deutogyne (winter female): slightly smaller

Deutogynes overwinter under bud scales and deposit eggs only after a period of winter cold.

Protogynes and males are the primary (summer) forms; they breed normally.

Protogynes and males are free-living on the underside of leaves

several generations per year

Damage:

Mites feed on the leaves -> leaves become inwardly rolled and brittle

Lower leaf surface turns brown, upper surface develops a silvery coloration

Terminal buds may be killed by heavy infestations, and shoot growth may become distorted and stunted

Family Eriophyidae - gall mites, rust mites - Aculus schlechtendali (Nalepa)

Protogyne; deutogynae: smaller.

Deutogynes overwinter under bud scales and deposit eggs only after a period of winter cold.

Protogynes and males are the primary (summer) forms; they breed normally.

Protogynes and males are free-living on the underside of leaves

several generations per year

Damage:

The underside of heavily infested leaves becomes brown.

Mite infestations may cause fruit russeting

Family Tarsonemidae - tarsonemid mites

Phytonemus pallidus fragariae

Sexual dimorphism: hind legs of females are reduced; those of males are robust, often clasper-like

Adult females overwinter; in spring mites live and feed on the upper surface of young foliage

Mainly parthenogenetic reproduction throughout the season

Several generations per year, population peaks in late summer

Damage:

Mites inject toxic saliva into the plant cells

Leaves become roughened, wrinkled, discoloured and brittle

Fruits developing on infested plants are undersized, dull coloured and leathery

Family Pentatomidae - shield bugs

Dolycoris baccarum

Adults occur from August onwards and after hibernation, in spring.

Adults and nymphs feed on foliage and young fruits.

Damage:

On raspberry and strawberry the bugs can impart an obnoxious odour to the fruits.

Direct feeding on developing fruits can cause malformation

Family Pentatomidae - shield bugs

Halyomorpha halys

Recently introduced; highly polyphagous pest of fruits.

Stink glands

Adults generally feed on fruits, whereas the nymphs feed on leaves, stems and fruit.

200-450 eggs/female; nymphs with 5 instars.

1 -2 generations / year in Europe.

Damage:

Leaf feeding: small lesions, may become necrotic and coalesce

Fruits have small necrotic spots or blotches, grooves and brownish discolorations

Family Miridae - Plant bugs, Capsid bugs

Lygocoris pabulinus -

Polyphagous: trees, herbaceous plants, vegetables, fruits, ornamentals

Overwinters as egg in the bark on shoots of apple, currant and other woody hosts

Nymphs and adults attack the foliage and fruits of their host plants

Damage:

Adults and nymphs cause feeding damage to buds, flowers, fruits, leaves and shoots.

Symptoms vary from host to host, attacked tissue becoming discoloured, distorted, ragged, tattered or peppered with holes

Family Scarabaeidae - scarab beetles

Melolontha melolontha

Adults appear in May, pre-feeding flight towards deciduous trees;

Oviposition on soft soil

Chafer grubs develop over 3 years

Damage:

Polyphagous: adults feed on forest and fruit tree leaves, the larvae attack the roots of various crops: cereals, vegetables, meadow grasses, fruit or forest trees.

Larvae destroy all underground parts of the plants

Family Curculionidae - weevils

Anthonomus pomorum

In April beetles start feeding on unopened buds and females deposit eggs singly inside a flower bud

Larvae develop inside the flower buds

1 generation / year

Damage:

Larvae feed on the reproductive parts in the unopened buds

Buds do not open, “clove-like” appearance

Family Curculionidae - weevils

Anthonomus rubi

In April beetles start feeding on unopened buds and females deposit eggs singly inside a flower bud

Larvae develop inside the flower buds

Eggs are laid in unopened strawberry flower buds

Larvae feed on wilted and shrivelled flower organs

Also on blackberry and raspberry

1 generation / year

Damage:

damaged buds do not develop and either fall to the ground or remain dangling from the severed stalks

Females girdle the flower stalks with several punctures

Family Curculionidae - weevils

Anthonomus piri

In April beetles start feeding on unopened buds and females deposit eggs singly inside a flower bud

Larvae develop inside the flower buds

1 generation / year

In autumn eggs are laid inside the buds, hatch at the end of the winter and at the beginning of spring.

Larvae feed on the future floral structure inside the bud

Family Curculionidae - weevils

Anthonomus bituberculatus

In April beetles start feeding on unopened buds and females deposit eggs singly inside a flower bud

Larvae develop inside the flower buds

1 generation / year

On apricot, plum; and other host plants

Oviposition in autumn

Larvae feed inside flower buds in spring

Family Curculionidae - weevils

Otiorhynchus sulcatus

Polyphagous: vine, strawberry, ornamentals etc.

Females feed on buds and leaves, typical feeding marks

Adult females are nocturnal

During summer and autumn females lay eggs on the ground

Larvae live in the ground and feed on plant roots

1 generation / year, parthenogenetic reproduction

Damage:

Larval attacks on roots cause the decline and death of plants.

Adults damage leaves of various ornamentals and fruits.

Family Byturida - Byturus tomentosus

A generally common and important pest of blackberry and raspberry.

Adult beetles migrate in spring to raspberry and begin to feed on flowers and unopened flower buds

Eggs are laid in blossoms that have set fruit

Larvae invade the fruit plugs at the pink-fruit stage, when the receptacles have softened

Pupation on the ground

Damage:

Adult feeding may destroy buds

Main damage caused by larval feeding on drupelets

Fruits do not develop and are generally damaged