Monitoring and control of pest mirid species in the UK using sex pheromones
Michelle Fountain & Jerry Cross East Malling Research, UK David R Hall & Dudley Farman Natural Resources Institute, UK Damage to UK horticultural crops
Lygus rugulipennis European tarnished plant bug (strawberry, raspberry, cucumber) Lygocoris pabulinus Common green capsid (apple, pear, blackcurrant, raspberry) Mirids are common and polyphagous
Sporadic and unpredictable Damage at low densities Natural enemies (e.g. Peristenus) do not maintain populations at low levels, no biocontrols Sampling methods unsuitable for growers Controlled with broad-spectrum insecticides - not IPM compatible (e.g. WFT in strawberry!) Serious damage in organic crops Pheromones of Lygus species
hexyl butyrate (HB)
(E)-2-hexenyl butyrate (E2HB)
(E)-4-oxo-2-hexenal (KA)
Produced in metathoracic glands Used both for “defence” and as pheromones Ketoaldehyde difficult to stabilise and dispense Research goes back > 30 years (Gueldner and Parrott, 1978) No satisfactory attraction in field Males attracted to females at dawn
70
50 trapped 40
30 L. rugulipennis 20 Total
10
0 dawn-noon noon-evening evening-dawn Air entrainment
Collected pheromone from single, undisturbed virgin females and males at different times of day Time of release of pheromone components coincides with attractiveness of virgin females
250
Lygus rugulipennis All All live 200 Live excl zeros
150
100 Mean HB ± SE (ng/h)
50
0 0800-1600 1600-2400 2400-0800 Very different ratio – E2HB and KA much lower! Attraction to synthetic lure Relative amounts of components species-specific
30 Lygus rugulipennis Lygocoris pabulinus Lygus pratensis Liocoris pustulatus
20
10 Ratio (HB = 100) ± SE Ratio (HB = 100) ±
0 E2HB/HB KA/HB Pipette tip dispensers provide sustained release of all three components at appropriate rate
1.5
1.0
HB E2HB 0.5 KA Mean release rate (ug/h)
0.0 0 10203040506070 Time (d) Pipette tip dispensers provide sustained attraction in field > attractiveness of female Trap design
100
80
60
40 L. rugulipennis
20
0 number of male ofnumber male vane vane vane vane white x- white x- green x- yellow x- premould premould premould clear delta clear green delta green sticky stake
Funnelled bucket traps Trap design Different trap designs for different species
Lygus rugulipennis Lygocoris pabulinus Blends not so specific in field trapping
40
L. pratensis L. pabulinus 30 L. rugulipennis
20 Total Catch
10
40 L. tripustulatus L. pratensis 0 L. pabulinus L. rugulipennis L. pabulinus L. pratensis L. tripustulatus Unbaited 30 L. rugulipennis Treatment
20 Total Catch
10
0 L. rugulipennis L. pabulinus L. pratensis L. tripustulatus Unbaited Treatment Pheromone traps provide sensitive early warning of infestation
80
Pheromone trap males Tap sample nymphs 60 Tap sample males Tap sample females
40
Numbers of capsids 20
0
08-Jul 22-Jul 29-Apr 13-May 27-May 10-Jun 24-Jun 05-Aug 19-Aug 02-Sep 16-Sep 30-Sep 14-Oct Sampling Date Traps now commercially available Conclusions
Lygus species use 3 components in female sex pheromones Females produce species-specific blends, but males respond to wider range of blends Species-specificity ensured by other, non-chemical factors – e.g. time of pheromone production Pipette tip dispensers - effective dispensing system for pheromone components in field, including (E)-4-oxo-2- hexenal Trap design critical: conventional designs not suitable We are grateful to the following for funding this work:
UK Department for Environment, Food and Rural Affairs (Defra) Horticultural Development Company (HDC) Commercial grower organisations as part of Defra LINK projects