4.4.1 An Inert Diet
Frequently, the introduction of a new suitable predator is thwarted by the fact that
when presented with a strange factitious host it refuses to predate. Two factors
seem to be operating; first the astigmatid prey is often very active, using fast jerky
movements as a defence against predators. Second, the Astigmata are known to
possess an alarm pheromone defence system used to ward off attackers (Kuwara
1991). Under such circumstances it is impossible to produce a viable commercial
product.
The R&D department of the SME’s company Agrobio S.L. have recently
overcome this problem by employing a new diet, which is based on the application
of the well-developed fast frozen technologies for human consumption to rear
predatory mites, then using dead Astigmatid preys (EP 2380436 B1). To date, in
house trials, still on-going, have shown that by using this new system it is most
likely possible to rear difficult predator candidates so that the high intrinsic rates of
development needed to produce a viable sales product is attainable.
4.4.2 The Sachet á La Carte
The packaging method and releasing system is another issue improved by biomanufacturers that contribute significantly to the final outcome of the biocontrol
programs. An initial problem was that the only practical way of applying the
Phytoseiidae to the crop was to sprinkle loose material onto the plant leaves.
Where the prey, which is susceptible to low humidities, below 70 % RH soon died
or ran out of food. So that predators, in the absence or shortage of the pest species
and pollen, failed to establish. An additional problem is the frequent application of
fungicides that can prevent the development of the populations on the plants. This
is the case in the protected cucumbers in Almeria, where weekly treatments of
fungicides are made during autumn, since high incidence of phytopathogenic fungi
occur during this period, partially due to unsatisfactory structures of the greenhouses with poor ventilation. Some active ingredients have been stated to kill more
than 50 % of the populations, while others less aggressive may have a washing
effect. The problem was partially solved by the amelioration of the sachet system
used to distribute the predators in the crop, already developed many years ago,
based on packaging quantities of the predator plus prey in a mixture of prey food
and a filler substrate, often bran, in sachets made of a breathable chapter. A small
hole pierced toward the top of the sachet permits the predator to exit, and the
sachet can be attached to an individual plant thanks to a small hook (Sampson
1998). Recently, the enhanced system has been called Controlled/Quick Release
System. The rate of emergence of the predator can be controlled by altering the
initial balance of predator to prey and some other conditions of the packaged
material. Basically, too little prey gives a quick release whereas a higher quantity
118
E. Vila and T. Cabello
Frequently, the introduction of a new suitable predator is thwarted by the fact that
when presented with a strange factitious host it refuses to predate. Two factors
seem to be operating; first the astigmatid prey is often very active, using fast jerky
movements as a defence against predators. Second, the Astigmata are known to
possess an alarm pheromone defence system used to ward off attackers (Kuwara
1991). Under such circumstances it is impossible to produce a viable commercial
product.
The R&D department of the SME’s company Agrobio S.L. have recently
overcome this problem by employing a new diet, which is based on the application
of the well-developed fast frozen technologies for human consumption to rear
predatory mites, then using dead Astigmatid preys (EP 2380436 B1). To date, in
house trials, still on-going, have shown that by using this new system it is most
likely possible to rear difficult predator candidates so that the high intrinsic rates of
development needed to produce a viable sales product is attainable.
4.4.2 The Sachet á La Carte
The packaging method and releasing system is another issue improved by biomanufacturers that contribute significantly to the final outcome of the biocontrol
programs. An initial problem was that the only practical way of applying the
Phytoseiidae to the crop was to sprinkle loose material onto the plant leaves.
Where the prey, which is susceptible to low humidities, below 70 % RH soon died
or ran out of food. So that predators, in the absence or shortage of the pest species
and pollen, failed to establish. An additional problem is the frequent application of
fungicides that can prevent the development of the populations on the plants. This
is the case in the protected cucumbers in Almeria, where weekly treatments of
fungicides are made during autumn, since high incidence of phytopathogenic fungi
occur during this period, partially due to unsatisfactory structures of the greenhouses with poor ventilation. Some active ingredients have been stated to kill more
than 50 % of the populations, while others less aggressive may have a washing
effect. The problem was partially solved by the amelioration of the sachet system
used to distribute the predators in the crop, already developed many years ago,
based on packaging quantities of the predator plus prey in a mixture of prey food
and a filler substrate, often bran, in sachets made of a breathable chapter. A small
hole pierced toward the top of the sachet permits the predator to exit, and the
sachet can be attached to an individual plant thanks to a small hook (Sampson
1998). Recently, the enhanced system has been called Controlled/Quick Release
System. The rate of emergence of the predator can be controlled by altering the
initial balance of predator to prey and some other conditions of the packaged
material. Basically, too little prey gives a quick release whereas a higher quantity
118
E. Vila and T. Cabello