The document summarizes a study on the effects of canopy density and ground cover vegetation on pest and beneficial insects in macadamia orchards. The study compared open canopy orchards with flowering ground cover to closed canopy orchards with no ground cover. Results showed that open canopies harbored more beneficial insects and fewer pests, led to increased nut production, lower levels of fruitspotting bug damage, but did not affect predation of fruitspotting bug eggs.

1. The role of canopy density and ground-cover vegetation on pest and beneficial insects
Prepared by: Alana Danne
October 2014

2. Background

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Canopy management
closed (traditional) vs. open (encouraged)

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Fruitspotting bug damage
Premature nut drop (Sep/Oct-Dec)
Entry point for disease
Overall reduction in yield

5. Methods

6. Study sites
 Two organic
macadamia orchards
in northern NSW
 Common varieties,
similar tree age,
similar tree spacing,
similar ground cover
vegetation
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Both with land aspect that produced
‘light’ and ‘dark’ blocks

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Invertebrates were sampled once a month in ‘light’ and
‘dark’ blocks over summer 2011/2012 at two sites

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• Nut production assessed
from 72 trees in ‘light’ and
‘dark’ blocks at two sites
Fallen nut counted each
month from Nov 2012 -
June 2013

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Sampled fallen nut for fruitspotting bug damage
from 72 trees in ‘light’ and ‘dark’ blocks each
month from Nov 2012 - Jun 2013

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Levels of predation in ‘light’ and ‘dark’ blocks
assessed: sentinel fruitspotting bug eggs
attached to leaves.

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Questions?
How do closed canopy orchards with no ground-cover
vegetation vs. open canopy orchards with
flowering ground-cover vegetation affect:
1. Abundances of pest and beneficial
invertebrates?
2. Nut production?
3. Levels of fruitspotting bug damage?
4. Predation of sentinel fruitspotting bug eggs?

13. Results

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0"
20"
40"
60"
80"
100"
120"
140"
160"
total"
beneficials"
parasitoids" spiders" ants"
0"
1"
2"
3"
4"
5"
6"
total"pests" other"
lepidoptera"
lace"bugs" leafminers"
0"
5"
10"
15"
20"
25"
30"
total"
beneficials"
parasitoids" spiders" brown"
lacewings"
0"
5"
10"
15"
20"
25"
30"
total"pests" lace"bugs" leafminers"
Mean number collected per site (±SE)
canopy mid-row

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Nut yield
Dark
Light
Nov - Feb
48%
52%
Mar - Jun
32%
68%
Nov – Jun
41%
59%

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Fruitspotting bug nut damage
0"
0.1"
0.2"
0.3"
0.4"
0.5"
0.6"
Dark" Light"
0"
0.1"
0.2"
0.3"
0.4"
0.5"
0.6"
Dark" Light"
Nov-Feb Mar-Jun
Mean propor on of nut
damage when damage is
present on a tree (±SE)
a
b
a
b

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Predation of fruitspotting bug eggs
Mean propor on of eggs
predated upon (±SE)
0"
0.02"
0.04"
0.06"
0.08"
0.1"
0.12"
0.14"
0.16"
Dark" Light"
a
a

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Conclusions
Open canopy orchards with flowering mid-row
ground-cover:
• harbour a higher abundance of beneficial invertebrates, and
a lower number of pest invertebrates, than ‘dark’ orchards
• increased nut production
• had lower levels of fruitspotting bug damage
• did not results in higher levels of fruitspotting bug egg
predation (variable)

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Acknowledgements
Supervisors:
Mike Furlong, Margie Mayfield, Nancy Schellhorn,
Ruth Huwer
Funding:
Australian Macadamia Society, Avocados Australia,
Horticulture Australia Ltd.
Farmers at both field sites
Volunteers who helped with field work and
invertebrate identification