Insect dynamics in hedgerowsRachael Long, Farm Advisor, Yolo Co., CA
Hedgerow research sites, Yolo County, 1992-2011
Crops:Processing tomatoesAlfalfaWheatSeed crops (sunflower)Almonds
Control
Control
Control
Control
Mature Hedgerow
Mature Hedgerow
Mature Hedgerow
Mature Hedgerow
CollaboratorsUC DavisUC BerkeleyYolo RCDHedgerow farms
Hedgerows: Rows of trees, shrubs, grasses, forbs that surround farm fields. In existence for thousands of years. Relic of cleared lands, natural dispersal, or direct plantings.
Enhance biodiversityWeed suppressionFilter traps (air and water quality protection)Erosion controlWindbreaksBeneficial insect and pollinator habitat
Hedgerow Benefits
Insectary Hedgerow
Green lacewingsAdults larva
Many beneficial insects need nectar and pollen to survive and reproduce.
Wasps: longevityWater: 2 daysNectar: 9 days
Syrphid flies: Water 50 eggs; Pollen: 500 eggs
0
10
20
30
40
50
Lacewings Wasps Lady beetles
% Rubidium marked beneficial insects in crops adjacent to hedgerows.%
labe
led
in c
rop
Lacewings 20-450 ft; parasitic wasps, lady beetles 250 ft.
Long RF et al. 1998. Journal of California Agriculture.
Percent Rubidium marked beneficial insects in trees 100 ft from insectary cover crop
0
10
20
30
40
50
60
70
Wasps Lacewings Syrphid flies
% labe
led
Grape leafhopper Grape leafhopper egg parasitized by Anagrus
Anagrus parasitoidAnagrus overwinters outside vineyards
Up to 34% of Anagrus in grape vineyards came from prune hedgerows in rubidium marking studies.
Native California shrubs and grasses
Coffeeberry
Toyon
CoyotebrushBuckwheat
Elderberry Ceanothus
Purple needlegrassCreeping wildrye
Beneficial InsectsPest Insects
0
1
2
3
4
5
6
Native Perennial Grasses Weeds
Beneficial insects Pests*
Beneficial and pest insects per 10 sweeps in weeds vs. native perennial grasses, Yolo Co., CA 1999-2000.
# pe
sts
and
bene
ficia
l ins
ects
/10
swee
ps
*
Pests Predators Parasitoids Beneficial Ratio
Mea
n nu
mbe
r of i
nsec
ts +
SE
0
50
100
150
200
250
300
Hedgerow Control
*
*
Average number of pest and beneficial insects per sample site
(Weedy field edges)
Morandin L, RF Long, CG Pease, et al. In press. Journal California Agriculture.
Overwintering DataVery few pests overwintering in hedgerows (~1% of samples had stinkbugs). Lady beetle aggregations in deergrass.
Impact of hedgerows on pest management: 20% higher parasitism in fields that have hedgerows compared to fields with weedy edges.
Distance from edge
0 50 100 150 200 250
Mea
n pr
opor
tion
of p
aras
itism
(+/-S
E)
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Mature HedgerowWeedy Edges
Mean proportion of stinkbug egg parasitism between distances from the field edge by treatment, Yolo County, CA 2009.
Currently working on models to show economic benefits of hedgerows and ecosystem services they provide in terms of both pollination and pest control.
In 74% of cases studied, landscapes with high proportions of non-crop habitat had enhanced natural enemy populations in crop fields .
Establishing hedgerows on farm in California, ANR 8390, 2010.
High abundance of vinca (periwinkle) in riparian areas correlated with high Pierce’s incidence. Himalayan blackberry is also an important host for Pierce’s disease that’s vectored by sharpshooters.