Biological Control of Pest Mole Crickets in Florida – to

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Biological Control of Pest Mole Crickets in
Florida – to Benefit Ranchers
J.H. Frank, for the University of Florida/IFAS
Mole Cricket Research Program
The largest cattle ranch in the USA is in
Florida.
Florida has about 7.6 million acres in
cattle range.
In 2006, Florida ranked 12th nationally in
beef cattle with approximately 926,000
head. In 2005, 880,000 calves were born
in the state.
The worst insect pests of pasture grasses
are (were) invasive mole crickets of the
genus Scapteriscus.
Scapteriscus borellii, S.
vicinus, S. abbreviatus
most widespread
the major pest
all arrived from
southern/ eastern
South America in
1899-1924 in ship
ballast.
flightless, so a minor pest
They destroy vegetable
plantings, golf courses,
lawns, playing fields,
and pastures
throughout Florida (and
other southern states).
After the cheap, effective, persistent chemical
chlordane was banned in the 1970s...
The Florida Cattlemen’s association (FCA)
asked the Florida Legislature for help…
The Legislature instructed the Agricultural
Experiment Station to begin a research
program on mole crickets…
which fell upon the Entomology &
Nematology Department to perform
…
Larra bicolor attacking a mole cricket. This
crabronid wasp is widely distributed in South
America and is now spreading in northern
Florida.
from Bolivia
in 1988-1989
Its larvae are koinobiont ectoparasitoids.
Bolivian stock,
released in 1988, its
known distribution
by end of 2008
Larra bicolor
Brazilian stock,
introduced from
Puerto Rico in 1981,
its known distribution
by end of 2008
Adult L. bicolor need
nectar sources. The
best source detected is
Spermacoce verticillata
(Rubiaceae) from the
West Indies. Wasp
populations may be
enhanced by planting
this ‘weed’/ ‘wildflower’
A preliminary estimate is of almost 70%
generational mortality inflicted on pest
mole crickets where this wasp is wellestablished. Effects are now being
calculated/modelled more precisely.
It may be able to achieve >70% mortality
where its population is managed by
provision of nectar sources (like butterfly
gardening).
Adult wasps can be monitored visually at
nectar source patches.
Juvenile Steinernema scapterisci
nematodes emerging from a dead mole
cricket. This species was imported from
Uruguay in 1985 as a classical
biocontrol agent.
But it is achieving more use as a
biopesticide because the concept of a
pesticide is familiar to users.
Steinernema scapterisci
confirmed establishment
by application of < 2
billion in 1989-1990
by release of a few
millions in 1989-1990
Applications were made in more
counties in 1999-2002 by the “Mole
Cricket Task Force” and by sales –
results are yet unevaluated.
Eight years after application of S. scapterisci
in pastures in three counties, few mole
crickets were trapped during 8 months of
1997, but infection levels were still high.
County
Flagler
Number of mole
crickets trapped
60
% infection
37
Osceola
18
50
Pasco
42
40
Observed % infection underestimates generational
mortality because of the brief development time of the
nematode vs the single annual mole cricket generation.
Twelve years after application of S. scapterisci
on golf courses, few mole crickets could be
trapped in October 2001, but infection levels
were still moderate
Golf course
Ironwood GC
Gainesville G&CC
Number of mole
crickets trapped
59
91
% infection
17
14
Observed % infection underestimates generational
mortality because of the brief development time of the
nematode vs the single annual mole cricket generation.
Steinernema scapterisci serves as a successful
classical biocontrol agent, not just a biopesticide.
Nocturnal, phonotactic, larviparous fly
Ormia depleta (Tachinidae), female
from
23oS in
Brazil
in 1988
its larvae are koinobiont endoparasitoids
copyright R. Noonan
30oN
Ormia depleta
from releases in 1988-1992
29oN
counties
occupied all year
28oN
counties occupied
mainly in the autumn
of each year
Presence of O. depleta in all counties
indicated yellow or orange-brown has
been affirmed by trapping specimens.
Ormia depleta adults, just like Larra
bicolor, may need nectar sources. An
analysis of gut contents of wild-trapped
flies showed they use melezitose, from
insect honeydew, as a source.
But insect honeydew is not their only
nectar source. Research has not
progressed to the point where we know
what works best, much less how to
manipulate it.
Funding for such research has been hard to
obtain – is “too basic” for many agencies, is
‘too applied” for another.
a sound-synthesizer producing male song here is the bait
to trap mole crickets
phonotactic flies are trapped here
timer
S. vicinus mole crickets are
trapped in this bucket of sand
S. borellii mole
crickets are
trapped here
200
baseline
period
S. vicinus
Gainesville
02-03
01-02
00-01
99-00
98-99
97-98
96-97
biocontrol
period
There is no trend, upward
or downward, for those
years. The question was –
what will happen when
biocontrol agents arrive at
the trap sites?
150
baseline=
100
100
89-90
88-89
87-88
86-87
85-86
84-85
82-83
81-82
S. vicinus
Gainesville
80-81
250
79-80
0
83-84
50
95-96
100
94-95
baseline=
100
93-94
150
Tens of thousands of
molebiocontrol
crickets were
period
trapped annually in
1979-1988. For
simplicity, data were
converted to a baseline
figure of 100 (the
average annual catch
for those years).
92-93
baseline
period
91-92
S. borellii
S.
borellii
Gainesville
Gainesville
90-91
200
50
02-03
01-02
00-01
99-00
98-99
97-98
96-97
95-96
94-95
93-94
92-93
91-92
90-91
89-90
88-89
87-88
86-87
85-86
84-85
83-84
82-83
81-82
80-81
79-80
0
02-03
01-02
00-01
99-00
98-99
97-98
96-97
95-96
baseline=
94-95
150
93-94
baseline
period
92-93
02-03
01-02
00-01
99-00
98-99
97-98
96-97
95-96
94-95
93-94
92-93
150
91-92
90-91
89-90
88-89
87-88
86-87
baseline
period
91-92
90-91
89-90
88-89
87-88
86-87
S. vicinus
Gainesville
85-86
84-85
83-84
82-83
81-82
S. borellii
S.
borellii
Gainesville
Gainesville
85-86
84-85
83-84
100
82-83
S. vicinus
Gainesville
80-81
100
81-82
200
80-81
250
79-80
0
79-80
200
biocontrol
period
baseline=
100
4% of baseline
50
biocontrol
period
<0.5% of baseline
100
50
0
So by 2000, winged mole crickets no longer
swarmed around neon and sodium lights (at gas
stations and parking lots) in the early spring, at
least in Alachua County and neighboring areas.
A large lawn care company reported for
Gainesville that its accounts had dropped from
about 60 to 3 or 4 (those lawns that it treated
with chemicals to control mole crickets).
The state funds that had been “earmarked for
mole cricket research” in 1979 “lost that
earmarking” in 1991  , by which time,
however, 3 biocontrol agents had been
introduced and established.
But the nematode Steinernema scapterisci was
became unavailable commercially in 1996.
Norm Leppla (Florida IPM co-ordinator) worked
with the UF Office of Technology Licensing to
negotiate a license agreement in 2000 with an
experienced company. The nematode was
again brought to market as Nematac S.
So everything was fine and the biocontrol
agents were spreading? And there was a
website on mole crickets plus online extension
publications about the biocontrol agents
But the research committee of FCA again listed
mole cricket research as a major objective.
The disconnect seemed to be because:
● no training sessions for Livestock Extension
Agents had been held – so they were not
promoting use of biocontrol.
● machines for applying the nematode
seemed unavailable for rent.
So we consulted our longest-standing Livestock
Extension Agent and the FCA, and they
supported the concept. We applied to SRIPM.
We were funded for calendar year 2010. And
then additional Livestock Extension Agents
became enthused and carried a lot of the load!
I asked Livestock Extension Agents
everywhere to identify sites with lots of mole
crickets, and I visited those sites. Somewhat
to my surprise, all with promising sites
proved to be in northeastern Florida.
We are immensely grateful to the Southern
IPM Center for most of the funding that made
this project possible.
An assurance
The native, non-pest mole cricket Neocurtilla
hexadactyla is only distantly related (belongs
to another tribe or subfamily). Natural enemies
of Scapteriscus mole crickets, imported from
South America, do not affect N. hexadactyla.
There are no “non-target effects.”
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