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

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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

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Wasps Lacewings Syrphid flies

% labe

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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

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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

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bene

ficia

l ins

ects

/10

swee

ps

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Pests Predators Parasitoids Beneficial Ratio

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mbe

r of i

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SE

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Hedgerow Control

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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

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itism

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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.