O. laevigatus (Hem.: Anthocoridae), since it feeds on different prey and also on
pollen, or to a greater extent phytophagous, like Nesidiocoris tenuis (Hem.: Miridae), which also can feed on the plant (Urbaneja et al. 2005). This is an additional
advantage that has contributed to the success achieved with this specie on tomato
crops in all the Mediterranean area, despite that it also may eventually become a
pest of the crop due to their damage (Wheeler 2000; Sánchez and Lacasa 2008).
The early setting up of the population of predators is sometimes also determined by the intraguild competition (IGP) (Brodeur and Boivin 2006). This is the
case of O. laevigatus which can be established on sweet peppers feeding
on predatory mites like A. swirskii Athias-Henriot and Amblyseius (Neoseiulus)
cucumeris (Oudemans) (Acari: Phytoseiidae). Relying on releases of several
species for the pest management is a common practice in greenhouses, both in
Spain and in other areas. Not only different predators but also several parasitoids
are released either at the same time or at different stages of the crop cycle (Cabello
et al. 2011). This can lead to direct and indirect interactions, like apparent competition, resource competition, and intraguild predation (Janssen et al. 1998), with
implications regarding the efficacy of those natural enemies as biological control
agents (Yano 2005; Messelink et al. 2012). In some cases, like the mentioned
O. laevigatus and A. swirskii, the final outcome regarding pest control is commonly favorable (Vila and Cabello 2012), but in others is negative. Intraguild
predation is regarded to be widely present in nature as well as in biological control
systems. As stated and comprehensively reviewed by Janssen et al. (2006), IGP in
biocontrol systems occurs between predators when a natural enemy, the intraguild
predator, engages in trophic interaction with another entomophagous, rendered as
the intraguild prey, while both compete for the same pest, the extraguild prey. The
competition between parasitoid natural enemies and its impact on biological
control programs has also been reviewed by Brodeur and Boivin (2006), but IGP
between predator and parasitoid natural enemies has been reviewed to a lesser
extent (Roshenheim et al. 2005), with the exceptions of the interactions found in
the biological control of aphids (Brodeur and Roshenheim 2000; Traugott et al.
2012) and between predatory mites (Montserrat et al. 2008).
Preventive introductions of natural enemies in the crop can be enhanced
providing direct releases on seedlings, which has become the most extended practice
in the Spanish tomatoes (see below), and also using refuge plants. Both methodologies can reduce the economic cost, and refuge plants have additional advantages
that can mitigate several troubles. On Spanish sweet peppers the two major agents
released, the predatory mite A. swirskii and the flower bug O. laevigatus, offer a good
control of pests, thrips, and whiteflies (Vila and Cabello 2012). But two problems
which are being addressed is that from time to time this crop is subjected to very
high summer temperatures, accompanied by very low humidities which adversely
affects the predatory mites in current use, and the lack offlowers with pollen when the
flower bug is introduced. Refuge plants, as basil, can mitigate this situation,
providing alternative food and enhancing the establishment of O. laevigatus (Cano
106
E. Vila and T. Cabello
pollen, or to a greater extent phytophagous, like Nesidiocoris tenuis (Hem.: Miridae), which also can feed on the plant (Urbaneja et al. 2005). This is an additional
advantage that has contributed to the success achieved with this specie on tomato
crops in all the Mediterranean area, despite that it also may eventually become a
pest of the crop due to their damage (Wheeler 2000; Sánchez and Lacasa 2008).
The early setting up of the population of predators is sometimes also determined by the intraguild competition (IGP) (Brodeur and Boivin 2006). This is the
case of O. laevigatus which can be established on sweet peppers feeding
on predatory mites like A. swirskii Athias-Henriot and Amblyseius (Neoseiulus)
cucumeris (Oudemans) (Acari: Phytoseiidae). Relying on releases of several
species for the pest management is a common practice in greenhouses, both in
Spain and in other areas. Not only different predators but also several parasitoids
are released either at the same time or at different stages of the crop cycle (Cabello
et al. 2011). This can lead to direct and indirect interactions, like apparent competition, resource competition, and intraguild predation (Janssen et al. 1998), with
implications regarding the efficacy of those natural enemies as biological control
agents (Yano 2005; Messelink et al. 2012). In some cases, like the mentioned
O. laevigatus and A. swirskii, the final outcome regarding pest control is commonly favorable (Vila and Cabello 2012), but in others is negative. Intraguild
predation is regarded to be widely present in nature as well as in biological control
systems. As stated and comprehensively reviewed by Janssen et al. (2006), IGP in
biocontrol systems occurs between predators when a natural enemy, the intraguild
predator, engages in trophic interaction with another entomophagous, rendered as
the intraguild prey, while both compete for the same pest, the extraguild prey. The
competition between parasitoid natural enemies and its impact on biological
control programs has also been reviewed by Brodeur and Boivin (2006), but IGP
between predator and parasitoid natural enemies has been reviewed to a lesser
extent (Roshenheim et al. 2005), with the exceptions of the interactions found in
the biological control of aphids (Brodeur and Roshenheim 2000; Traugott et al.
2012) and between predatory mites (Montserrat et al. 2008).
Preventive introductions of natural enemies in the crop can be enhanced
providing direct releases on seedlings, which has become the most extended practice
in the Spanish tomatoes (see below), and also using refuge plants. Both methodologies can reduce the economic cost, and refuge plants have additional advantages
that can mitigate several troubles. On Spanish sweet peppers the two major agents
released, the predatory mite A. swirskii and the flower bug O. laevigatus, offer a good
control of pests, thrips, and whiteflies (Vila and Cabello 2012). But two problems
which are being addressed is that from time to time this crop is subjected to very
high summer temperatures, accompanied by very low humidities which adversely
affects the predatory mites in current use, and the lack offlowers with pollen when the
flower bug is introduced. Refuge plants, as basil, can mitigate this situation,
providing alternative food and enhancing the establishment of O. laevigatus (Cano
106
E. Vila and T. Cabello