developed by biomanufacturers is not possible to discuss the latest improvements,
but at least two major advances have been uptake and further developed by the
major companies. First, the production of bugs on greenhouses has been replaced
by rearing in cages on climatic controlled rooms, without whole plants, where the
different cohorts can be separated so that the age of the populations can be
carefully controlled. This allows a perfect control of the climate throughout all the
year, avoiding any temperature threshold problem and fluctuations due to changes
with the number of hours with light. Then, not only reducing production costs, but
also favoring a homogeneous product all year round. The populations can be
packaged at the optimal age for laying eggs when released, for instance, with
young mated adults after the pre-oviposition period, which will fasten the establishment of the first generation in the crop. This means that the crop is protected
against pest from early stages and growers feel ‘more confident’ with biological
control. This is an important subject since most growers and technical advisers
over the world, who have been working for many years with chemical control, get
anxious at the beginning of the crop when they see the first pest individuals, and
very often they apply erroneously the so called preventive chemical treatments,
which delays even more the growth of the predatory populations and compromise
the biological control success.
A second major improvement by biomanufacturers that also guarantees the early
establishment of the predatory populations is the release of the natural enemies in
the seedlings before transplant into the greenhouse. This was already evaluated
many years ago with M. pygmaeus and has recently been developed for introduction
of N. tenuis in protected tomato crops (Vila et al. 2012). Major companies have
participated not only with research trials but also with a strong extension effort,
offering the first years many hectares per free to the main tomato cooperatives in
Almeria, which have contributed to the fast adoption of the system to almost all the
growers in only 2 years. Using this release system all the plants have eggs of the
predator when transplanted so all the crop is protected from the beginning. Since N.
tenuis is a zoophytophagous predator that can damage the plant when too high
populations are built up and few prey is available (Wheeler 2000; Sánchez and
Lacasa 2008) carefully adjustments have to be made of the ratio of introduction,
according not only to the season but also to the cultivar (Cabello et al. 2012a, b).
The use of not only artificial living but also plant-free oviposition substrates and
substitutive artificial food to eliminate the need of Ephestia eggs has been evaluated
by several academic researchers. As it has already been stated in the field by the
researchers and technicians of the private companies, Vandekerkhove et al. (2011)
also did not find any lose of quality between populations of M. pygmaeus when
reared for over 30 generations using artificial living and oviposition substrates
compared with those of conventionally plant reared, both regarding biological
parameters or predation capacity. Similar artificial living substrates were described
for O. laevigatus (Bonte and De Clercq 2010). But the results when combining
artificial food, as well as other alternatives to Ephestia eggs, plus the plant-free
substrates, are not so clear and have not yet being adopted by commercial productions. Vandekerkhove et al. (2011) stated a similar predation rates when feeding
120
E. Vila and T. Cabello
but at least two major advances have been uptake and further developed by the
major companies. First, the production of bugs on greenhouses has been replaced
by rearing in cages on climatic controlled rooms, without whole plants, where the
different cohorts can be separated so that the age of the populations can be
carefully controlled. This allows a perfect control of the climate throughout all the
year, avoiding any temperature threshold problem and fluctuations due to changes
with the number of hours with light. Then, not only reducing production costs, but
also favoring a homogeneous product all year round. The populations can be
packaged at the optimal age for laying eggs when released, for instance, with
young mated adults after the pre-oviposition period, which will fasten the establishment of the first generation in the crop. This means that the crop is protected
against pest from early stages and growers feel ‘more confident’ with biological
control. This is an important subject since most growers and technical advisers
over the world, who have been working for many years with chemical control, get
anxious at the beginning of the crop when they see the first pest individuals, and
very often they apply erroneously the so called preventive chemical treatments,
which delays even more the growth of the predatory populations and compromise
the biological control success.
A second major improvement by biomanufacturers that also guarantees the early
establishment of the predatory populations is the release of the natural enemies in
the seedlings before transplant into the greenhouse. This was already evaluated
many years ago with M. pygmaeus and has recently been developed for introduction
of N. tenuis in protected tomato crops (Vila et al. 2012). Major companies have
participated not only with research trials but also with a strong extension effort,
offering the first years many hectares per free to the main tomato cooperatives in
Almeria, which have contributed to the fast adoption of the system to almost all the
growers in only 2 years. Using this release system all the plants have eggs of the
predator when transplanted so all the crop is protected from the beginning. Since N.
tenuis is a zoophytophagous predator that can damage the plant when too high
populations are built up and few prey is available (Wheeler 2000; Sánchez and
Lacasa 2008) carefully adjustments have to be made of the ratio of introduction,
according not only to the season but also to the cultivar (Cabello et al. 2012a, b).
The use of not only artificial living but also plant-free oviposition substrates and
substitutive artificial food to eliminate the need of Ephestia eggs has been evaluated
by several academic researchers. As it has already been stated in the field by the
researchers and technicians of the private companies, Vandekerkhove et al. (2011)
also did not find any lose of quality between populations of M. pygmaeus when
reared for over 30 generations using artificial living and oviposition substrates
compared with those of conventionally plant reared, both regarding biological
parameters or predation capacity. Similar artificial living substrates were described
for O. laevigatus (Bonte and De Clercq 2010). But the results when combining
artificial food, as well as other alternatives to Ephestia eggs, plus the plant-free
substrates, are not so clear and have not yet being adopted by commercial productions. Vandekerkhove et al. (2011) stated a similar predation rates when feeding
120
E. Vila and T. Cabello