B. bassianaare produced annually in China for treatment
of 0.8 –1.3 million hectares of forest and agricultural
land. Several other medium- to large-scale field trials
or field releases have been conducted with selected
species/strains of Metarhizium. Unfortunately, many
of the reports of successful biocontrol in these field
programs are anecdotal; the experimental data are not
published, nor supported by statistical analysis.
One of the most comprehensive, field-scale, insect-
biocontrol programs to date was termed LUBILOSA
- a French acronym, Lutte Biologique contre les
Locustes et Sauteriaux (biological control of locusts and
grasshoppers). This program was funded by international
development agencies, with the aim of developing a
biocontrol agent that could be used in Central African
countries to control grasshoppers and locusts (see
On-line resouces). The strain used was characterized
as M. anisopliaevar acridum, based on ribosomal DNA
sequence analysis, and it was developed as an oil-
based formulation that could be dried to less than
5% moisture content and sealed hermetically for long-
term storage below 20°C.
The results of field trials with this strain are
reported to have been successful, but – at least for the
LUBILOSA strain – the only economical production
method seems to be large-scale solid-state fermentation,
which requires the expertise of commercial production
companies rather than medium-technology facilities that
could operate locally. The LUBILOSA product has now
been transferred to private sector companies under
trade names that include “Green Muscle.”
Several interesting features emerged from the field
trials of the LUBILOSA program:
1 The initial small-scale field trials proved to be
unsatisfactory because too many treated insects
left the trial area, and untreated insects moved in.
But when large-scale field plots of 800 hectares were
used there was clear evidence of grasshopper mort-
ality within 10 days of spraying, and grasshoppers
continued to die until the end of the season.
2 A comparison between plots treated with Metar-
hiziumand a commercial insecticide, fenitrothion,
showed that the insecticide killed the grasshoppers
rapidly but the insects soon recolonized the plots.
By contrast, grasshoppers did not recolonizethe
Metarhizium-treated plots. The consequence of this
was that, 10 days after spraying, the grasshopper
populations in the two types of plot were roughly
the same, and from that time onwards the Metarhizium
treatment provided better control than did the
insecticide.
3 Grasshoppers and locusts can raise their body tem-
perature in response to fungal infection – a “fever”
response that can help the insect to overcome the
infection. Locusts do this naturally, but grasshoppers
need to expose themselves to sun in order to raise
their body temperature. This knowledge could be
incorporated into a geographical information system
(GIS) that could predict the best conditions for
using Metarhiziumin field situations.The development of Lecanicillium lecaniias a
commercial biocontrol agent
Lecanicillium lecanii is one of the most successful com-
mercial biocontrol agents of insects. It was developed
in the late 1970s and is used primarily in glasshouses
for the control of aphids on potted chrysanthemums
and (using a different strain) for control of whitefly on
cucumbers and other indoor-grown crops. For these
purposes the fungus is produced as fermenter-grown
conidia because it is one of the relatively few fungi that
produce conidia readily in submerged liquid culture.
L. lecaniioccurs naturally as a parasite of aphids
and scale insects in the subtropics, but requires relat-
ively warm conditions (>15°C) for infection. Like all
the entomopathogenic fungi, it needs a high relative
humidity during the germination and penetration
phases, but then the humidity can be reduced without
affecting its parasitism. All these factors make this
fungus an ideal control agent for use on potted chry-
santhemums – one of the most important year-round
horticultural crops – because chrysanthemums have
to be “blacked-out” with polythene sheeting for part
of each day to produce the short daylengths that are
necessary to initiate flowering. The blackout sheeting
raises the humidity for infection by L. lecanii, so that
a single spray of conidia just before blacking-out can
be sufficient to give season-long control of the import-
ant aphid pest, Myzus persicae. However, experimental
trials showed that treatment with L. lecanii(under
blackout conditions) was less effective for two minor
aphid pests of chrysanthemum, Macrosiphoniella sanborni
and Brachycaudus helichrysi. Hall & Burges (1979)
showed that this was not related to inherent differences
in susceptibility of the three aphid species. Instead, it
is explained by their behavioral differences.M. persicae
tends to feed on the undersides of leaves where the
humidity is higher, and it is more mobile than the other
aphids on chrysanthemum, feeding for short times
and then moving on, because chrysanthemum is not
its preferred host plant. L. lecaniioften sporulates on
the body while an aphid is still alive, so the infected
individuals of M. persicaecan spread the infection to
other individuals of this species feeding in the same
locations on the crop.
L. lecaniiis currently marketed as two products,
Mycotal®and Vertalec®, by the Dutch-based com-
pany, Koppert BV. The product Mycotal is used primarily
to control whitefly and thrips in protected crops
such as cucumbers, tomatoes, sweet peppers, beans,