Biology and Management
of Avocado Thrips
Mark S. Hoddle,
Dept. of Entomology,
University of California, Riverside
Avocado Thrips, Scirtothrips perseae
Nakahara (Thysanoptera: Thripidae)
• First discovered in CA in
1996 near Port Hueneme in
Ventura Co.
• Similar to specimens found
on smuggled avocados from
Oaxaca at the Port of San
Diego in 1971
• Undescribed species when
first discovered. Officially
named in 1997
• Appears to be monophagous
in CA and native to Mexico
& Guatemala
Avocado Thrips Feeding Damage
Leaf scarring
“Alligator Skin”
on small fruit
Elongate scarring
on maturing fruit
Distribution of Avocado Thrips
(Scirtothrips perseae) in Central
America
Not found in
Caribbean
Atlixco
Uruapan
Guatemala City
Coatepec-Harinas
Oaxaca
S. perseae replaced by new Scirtothrips sp. in Costa Rica
Mean No. Avocado Thrips Larvae Emerging
in Each Fruit Size Category
1060 Fruit Examined
45
11,998 Thrips Larvae Counted
35
30
25
20
15
10
5
Fruit Size Category (inches)
>3.13
2.96-3.12
2.79-2.95
2.59-2.76
2.40-2.56
2.20-2.36
2.00-2.17
1.81-1.97
1.57-1.77
1.22-1.42
1.02-1.18
0.82-0.98
0.62-0.79
0.43-0.59
0
0.20-0.40
Mean No. Larvae
40
Mulches for Avocado Thrips
Control
• Composted
organic yard waste
– Root rot control
– Water retention
– Improved soil
fertility
– Weed suppression
– Improved plant
growth
– Thrips control????
Egg
Adult
1st Instar
Larva
GENERALIZED
THRIPS
LIFECYCLE
2nd Instar
Larva
Pupa and Propupa beneath leaf litter and soil
Pupa
Propupa
Mulched Plot
Unmulched Plot
Non Mulch Plots
Sampling Date
Mulch Plots
11/22/2000
10/22/2000
9/22/2000
8/22/2000
7/22/2000
6/22/2000
5/22/2000
4/22/2000
3/22/2000
Mean No. Emerged Adults
Adult Avocado Thrips Trapped on Bottom
of Traps
80
70
60
50
40
30
20
10
0
Thrips Days Comparisons
Mean Cumulative Thrips Days
1200
A
1000
t = 2.19, df = 12, P = 0.049
800
B
600
400
200
0
Non-Mulch
Mulch
Treatment
Overview of Franklinothrips
Biology
•
•
Franklinothrips orizabensis are
predatory thrips native to CA and
their home range stretches to
Orizaba in MX
They are generalist predators
–
–
–
–
–
•
•
•
Thrips
Whiteflies
Moth eggs
Mites & mite eggs
Avocado pollen & juice
Two larval instars, & the two
pupal stages occur within silk
cocoons
Adult stage are ant mimics and
sex ratio varies depending on
food quality
Appear to be the most important
natural enemy associated with
outbreaks of avocado thrips
2nd instar
larva
Silk pupal
cocoon
Adult
female
Franklinothrips Field Trials
• Ventura
– Trial started June 2001
– Small trees 6-8 ft
– Starting larval
densities ~ 1.5 per leaf
– Franklinothrips been
released weekly
– Targeted release rate
50 adults per tree
– Predators being
supplied by Buena
Biosystems and
American Insectaries
Sample Date
Non-Release (Control)
5/17/2002
3/17/2002
1/17/2002
11/17/2001
9/17/2001
7/17/2001
Log Mean No. Larvae/Leaf
San Marcos Field Site
100
10
1
0.1
0.01
0.001
Release
Non-Relase (Control)
Sampling Date
Release
6/27/02
5/23/02
4/11/02
2/28/02
1/24/02
12/22/01
11/15/01
10/11/01
9/6/01
8/2/01
6/26/01
Log Mean No. Larvae/Leaf
Ventura Field Site
10
1
0.1
0.01
0.001
Determining the Longevity of
Franklinothrips Adults in the Field
• Adult Franklinothrips males
& females caged with
varying amounts of food
– Lots of food = 200 irradiated
Ephestia eggs
– Moderate (100 eggs – 50% of
1)
– Low (50 eggs – 25% of 1)
– Minimal (10 eggs – 5% of 1)
– Leaf only
– Nothing
• Longevity recorded daily
• Temperature recorded daily
Field Survivorship
of Males
Take
Home Message
Proportion Surviving
At an average
field temperature of 22oC (72oF) male
1
0.9
Franklinothrips
will live on average for:
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
No Food:
4 days
Leaf:
0
4.5 days
5% Food:
5 days
25% Food:
5.5 days
1
2
3
50% Food:
Nothing
100%
25% Food
4
5
6
7
8
9
6 days
Days Alive
Leaf
Food:
50% Food7
5% Food
days 100% Food
10
Take Home Message
Field Survivorship of Females
Field Survivorship of Males
average field temperature of 22oC (72oF)
0.9
0.8
0.8
0.7
0.6
0.6
0.5
0.4
0.4
0.3
0.2
0.2
0.1
0
0
Proportion Surviving
Proportional Alive
At an1
female1 Franklinothrips will live on average for:
0
0
No Food:
4 days
Leaf:
5 days
5% Food:
6 days
25% Food:
9 days
2
4
150%
2
6
8
10 12 14
3
4
5 10
6 days
7
8
Food:
Days Alive
Days Alive
100%
Nothing
25% Food
Food:
Leaf
16 18
9
10
12 days
5% Food
50% Food
100% Food
Lacewings For Control of Avocado
Thrips
• Lacewing larvae
voracious predators
• Consume a wide
variety of soft bodied
arthropods – mites,
aphids, thrips,
whiteflies
• Commercially available
– eggs or larvae
• Typically adults are not
predatory
Lacewing Field Trials
• Field trials were run by PCA’s who regularly
use lacewing eggs and get good control of
avocado thrips
• Site One
– San Marcos – lacewing eggs on paper stapled to
leaves every other week over critical time period
• Site Two
– Irvine – lacewing eggs held until 75% egg hatch
then sprayed onto trees
• Trees sampled bi-weekly for thrips and
predators, egg hatch rates and egg
adherence to trees recorded
• Lacewing predation towards Franklinothrips
studied
Thrips Population Trends at Site One
Control
Staple
Blower
6
5
Arrows indicate time of lacewing releases
4
3
2
1
Sampling Date
7/9/03
6/26/03
5/28/03
5/16/03
4/29/03
4/17/03
4/3/03
0
3/18/03
Mean No. S. perseae per Leaf
7
Thrips Population Trends at Site Two
1.6
1.4
1.2
Staple
Blower
1
Control
0.8
0.6
0.4
0.2
Sampling Date
7/17/03
7/2/03
6/20/03
6/3/03
5/20/03
5/8/03
4/25/03
4/8/03
0
3/24/03
Mean No. S. perseae per Leaf
1.8
Take Home Message
• Stapled eggs deployed at 4000
eggs per acre
• Blower method about 50,000 eggs
per acre
• Staple method – 72% eggs hatched
• Blower method - 68% eggs hatched
• 35-96% eggs/larvae blown onto
trees falls to the ground
Lacewing Longevity in the Field
Different amounts or types of food affects lacewing
larvae survivorship times
Food
Longevity in Days
No food
1.5 days
Avocado leaf
1.5 days
Avocado pollen
2 days
15 Ephestia eggs
6 days
150 Ephestia eggs
14 days
300 Ephestia eggs
15 days
Lacewing & Franklinothrips Predation
Lacewing larvae show no
preference for 1st or 2nd
instar avocado thrips
larvae
All three lacewing instars
attack 1st instar
Franklinothrips larvae
2nd & 3rd instar lacewing
larvae attack 2nd instar
Franklinothrips
Franklinothrips females
are not attacked
Franklinothrips does not
attack lacewings