Managing the interactions of insects with other pests in ......Managing the interactions of insects...

Managing the interactions of insects with other pests in agricultural fields

Zsofia Szendrei

MSU, Department of Entomology

Interactions in agricultural fields

arthropods pathogens

weedspositive

negative

Interactions between two pests

Interactions among three pests

Interactions in the agroecosystemPathogen transmission by vector

Pathogen transmission by vector

Plant virus transmission

Aphids transmit the majority (~55%) of plant viruses - partly due to the shape of their mouth!

http://vimeo.com/64269766

How do aphids feed?

Vector - pathogen interactionsPathogen transmission by vector

By P. Sforza:http://www.ppws.vt.edu/~sforza/tmv/bydv_aph.html

What kind of virus transmission is this?

Hogenhout et al. 2008 Ann. Rev Phytopath.

Vector - pathogen interactions

How should IPM tactics differ for non/semipersistent vs. persistent viruses?


Hogenhout et al. 2008 Ann. Rev Phytopath.


Needs immediate management action! MONITORING!!!

Needs to stop subsequent generations to emergeand spread to new areas.


Non-persistent

Persistent

VECTOR IPM

1.

prevent pathogen acquisition and transmission by vectora. prevent vector from landing on host plant (repellents, mulches) b. prevent landing vector from probing/feeding (feeding deterrents, oils)

2.reduce the population density of vectora.insecticides b.natural enemies


Midwest Vegetable Production Guide for Commercial Growers 2009 (ID‐56)

Aphid transmission of viruses on cucurbits


potato

a border crop that does not harbor the virus

contrast between brown and green attracts aphids to land

DiFonzo et al., 1996

Aphid management with border crops

Fewer aphids landed on the outer edge of the potato when it had a crop border.

potato

DiFonzo et al., 1996

Aphids “clean” virus off on border crop.

Cucumber beetle and bacterial wilt

bacterial wilt

cucumber beetle bacterial wilt symptoms


cucumber or muskmelon

Cucumber beetle and bacterial wilt

•squash with imidacloprid drench•planted 2 weeks prior to main crop

BORDER:

Trap crops, the basics: http://www.youtube.com/watch?v=ELP1ylYJxco


TRAP CROP: Buttercup squash

MAIN CROP: Muskmelon

http://www.ifvga.org/documents/filelibrary/ifvga_2013_powerpoint_presentations/Mark_Gleason__ifvga_veg_diseases_B0320B0D0DD74.pdf


IMMEDIATEpathogen changes

vector behavior

DELAYEDpathogen changes host plant suitability

for the vector

The effect of potato leafroll virus on Myzuspersicaeadult longevity on potato. Srinivasan et al. 2008 Env. Entomol.

adul

t lon

gevi

ty(d

ays)


virus

Blue &Perring 1992 Env. Entomol.

Zucchini yellow mosaic virus

(1 h

r dur

atio

n)

non-persistent

persistent

phloem feeding

probing

Non-vector pathogen interactions

Most insect herbivores are not vectors of plant pathogens!

53 bean arthropod pests

94% non-vector

54 tomato arthropod pests

83% non-vector

Hatcher & Paul, 2001

Non-vector herbivoresExamples: physical wounding allows pathogen entry, honeydew provides nutrients for pathogen growth

Feeding on plant causes changesExamples:1.induced susceptibility:above ground insects cause increase in crown rot severity

2.induced resistance: induced immunization of plants against pathogens, hypersensitive response, lignification

Hatcher, Biol. Rev. 1995

Non-vector pathogen interactions

non-vector pathogen interactions

Dillard & Cobb, Crop Protection 1995

Sclerotinia sclerotiorum on cabbage

These types of interactions are likely to be variable!

QuestionYou are the owner of an asparagus farm. You notice that the occurrence of the asparagus miner is associated with asparagus stem & crown rot. It seems likely that this positive correlation is due to the fact that the mines provide ideal infection sites for the fungus.

What integrated pest management methods would you use?

non-vector pest interactions

non-vector pest interactions

•removal of plant debris •pre-plant soil fumigation•insecticides/fungicides

QuestionYou are the owner of an asparagus farm. You notice that the occurrence of the asparagus miner is associated with asparagus stem & crown rot. It seems likely that this positive correlation is due to the fact that the mines provide ideal infection sites for the fungus.

What integrated pest management methods would you use?

Interactions among three organisms

Interactions in the agroecosystemWeed arthropod interaction

Interactions among three organisms

Interactions in the agroecosystemWeed pathogen interaction

Impact of weeds on pests

Weeds can serve as alternate hosts for pests when the crop is absent or when it is not in a suitable phenological stage for the pest.

weed

Weed-pest interaction

Impact of weeds on pests

weed

Weeds can alter within field microclimate which in turn may favorpest survival/abundance when the crop canopy is suboptimal.


Weeds can serve as cues or provide resources for pests, thus recruiting pests to the cash crop.

Impact of weeds on arthropodsWeed-pest interaction

Increased herbivore pressure on crop reduces its competitive ability, which in turn leads to increased weed growth.

Indirect impact of weeds on crop through herbivoresWeed-pest interaction

Pests move to feeding on weeds…

Indirect impact of weeds on crop through herbivoresWeed-pest interaction

0

10

20

30

40

50

60

weeds present weeds absent

Ave

rage

±SE

M c

abba

ge

aphi

ds p

er p

lot

B

A

Impact of weeds on crop pest abundance

http://www.picturesof.net/pages/090408-152733-731048.html

cabbage

pigweed

Interaction based on provision of oviposition substrate

Greenberg et al. 2002 Env. Entomol.


Beet armyworm, Spodoptera exigua

Pigweed, Amaranthus sp.

75% grasses38% broad leaves 39% mix of grasses and broad leaves

grassy weeds increase aster leafhopper abundance

broadleaf - weeds decrease aster leafhopper abundance


Temporal considerations of weed management

March May July Sept

leve

l of w

eedi

ness

tillage

herbicide/cultivation

pests can overwinter on weeds

Interactions between weeds and arthropods

weed IPM

Managing weeds outside the field

Interactions among four organisms

Interactions in the agroecosystemarthropod – pathogen –weed interaction

potato leafroll virus management

persistent

symptoms on potato

symptoms on tomato

Effect of an alternate weed host on the biology of the two important potato leafroll virus (Luteoviridae: Polerovirus) vectors

Myzus persicaepeach aphid

Macrosiphum euphorbiapotato aphid

hairy nightshade Solanum sarrachoides

potato Solanum tuberosum

arthropod – pathogen –weed interaction

Srinivasan et al. 2008 Env. Entomol.

virus infected healthy virus infected healthy

nightshade

potato

days

Srinivasan et al. 2008 Env. Entomol.


Effect of an alternate weed host on the biology of the two important potato leafroll virus (Luteoviridae: Polerovirus) vectors

Longevity of aphids

Midwest Vegetable Production Guide for Commercial Growers 2009 (ID‐56)

Recommendation from the Midwest Vegetable Production Guidefor management of aphids that transmit viruses on peppers


Emphasis on preventive measures:• Intensive monitoring• Sanitation: weed control, removal of plant debris• Quarantine measures• Virus transmission by arthropod agents

Crop:• plant resistant varieties • proper fertilization, irrigation, pruning, drainage, plant spacing

Pathogen: • virus free seeds, cuttings and other propagation materials

Vector: • insecticides• preserve beneficial organisms• cultural control: i.e. trap crops• physical/mechanical controls, i.e.: removal of debris

IPM to minimize pest interactions

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