379
10‰), Alphacypermethrin (SC 6% at 20‰), Deltamethrin mixture (EC 10% at
10‰) plus Methyl Ethyl Azinphos (SC 36% at 6‰), and Azadirachtin (EC1% at
5‰), an organic farming insecticide extracted from neem seeds (Azadirachta
indica). They obtained near-total control with Alphacypermethrin and the mixture
of Deltamethrin and Methyl Ethyl Azinphos (Tapia 2012). These results are consistent with those obtained under nursery conditions by Eskiviski et al. (2010).
However, the World Health Organization restricted the use of organophosphorus
compounds Methyl Ethyl Azinphos (highly dangerous, Class Ib according to
WHO). In contrast, Alphacypermethrin (as well as Deltamethrin) is a low toxicity
pyrethroid (WHO Class II), making it the recommended choice (Tapia 2012).
It is important to understand the insect population dynamics in order to decide
the appropriate moments of action. Likewise, knowing its natural enemies could be
relevant, since this will allow the exploration of research lines based on biological
controllers, as part of a pest integrated management. In this regard, Baca et al.
(2013) were able to isolate from soil samples a strain of Beauveria sp., an entomopathogenic fungus capable of parasitizing the insect. It presents a good rate of sporulation, being possible its multiplication at large scale on solid substrate. This
fungus could be used as a biological control strategy against H. grandella. Similarly,
a microhymenoptera of the Chalcididae family was found parasitizing the pupae of
H. grandella. The emergence of this parasitoid was observed in pupae collected in
the field in the north of the Province of Salta, which is the first report of its presence
on H. grandella in Argentina. It was identified as Brachymeria subconica (Aquino
et al. 2015). This opens the door to further research on its potential and effectiveness
as a biological controller.
An alternative to reduce the effect of H. grandella attacks would be to explore
plants genetic resistance. The effect of provenance was proved to be highly significant in C. odorata and Swietenia macrophylla for the susceptibility to H. grandella.
The mean number of attacks per tree ranged from 0.8 to 2.4 and from 0.6 to 1.3
depending on the provenances, in both species, respectively (Newton et al. 1999),
that is, some provenances had triple the attacks than others. Likewise, a different
susceptibility was observed among cedar species in a field trial carried out in Yuto
Experimental Station of INTA, where 100% of C. fissilis saplings were affected
while only 38% and 28% of C. saltensis and C. odorata saplings, respectively, were
attacked by H. grandella (Del Castillo and Tapia 2005).
So far, chemical treatments with Alphacypermethrin and Deltamethrin are the
most effective and with less toxicity. They must be conducted during the first 3 years
of planting, and involve 15% of the total costs of cultivating Cedrela spp. (Tapia
2012). Applications should be made from the first year of planting to obtain a trunk
length free of deformation of 3.5–4 m. The appropriate moment to start this treatment is defined by the insect population dynamics, and according to the abovementioned studies, it is commonly recommended from the second half of December
until February.
14 Breeding Strategy for the Cedrela Genus in Argentina
10‰), Alphacypermethrin (SC 6% at 20‰), Deltamethrin mixture (EC 10% at
10‰) plus Methyl Ethyl Azinphos (SC 36% at 6‰), and Azadirachtin (EC1% at
5‰), an organic farming insecticide extracted from neem seeds (Azadirachta
indica). They obtained near-total control with Alphacypermethrin and the mixture
of Deltamethrin and Methyl Ethyl Azinphos (Tapia 2012). These results are consistent with those obtained under nursery conditions by Eskiviski et al. (2010).
However, the World Health Organization restricted the use of organophosphorus
compounds Methyl Ethyl Azinphos (highly dangerous, Class Ib according to
WHO). In contrast, Alphacypermethrin (as well as Deltamethrin) is a low toxicity
pyrethroid (WHO Class II), making it the recommended choice (Tapia 2012).
It is important to understand the insect population dynamics in order to decide
the appropriate moments of action. Likewise, knowing its natural enemies could be
relevant, since this will allow the exploration of research lines based on biological
controllers, as part of a pest integrated management. In this regard, Baca et al.
(2013) were able to isolate from soil samples a strain of Beauveria sp., an entomopathogenic fungus capable of parasitizing the insect. It presents a good rate of sporulation, being possible its multiplication at large scale on solid substrate. This
fungus could be used as a biological control strategy against H. grandella. Similarly,
a microhymenoptera of the Chalcididae family was found parasitizing the pupae of
H. grandella. The emergence of this parasitoid was observed in pupae collected in
the field in the north of the Province of Salta, which is the first report of its presence
on H. grandella in Argentina. It was identified as Brachymeria subconica (Aquino
et al. 2015). This opens the door to further research on its potential and effectiveness
as a biological controller.
An alternative to reduce the effect of H. grandella attacks would be to explore
plants genetic resistance. The effect of provenance was proved to be highly significant in C. odorata and Swietenia macrophylla for the susceptibility to H. grandella.
The mean number of attacks per tree ranged from 0.8 to 2.4 and from 0.6 to 1.3
depending on the provenances, in both species, respectively (Newton et al. 1999),
that is, some provenances had triple the attacks than others. Likewise, a different
susceptibility was observed among cedar species in a field trial carried out in Yuto
Experimental Station of INTA, where 100% of C. fissilis saplings were affected
while only 38% and 28% of C. saltensis and C. odorata saplings, respectively, were
attacked by H. grandella (Del Castillo and Tapia 2005).
So far, chemical treatments with Alphacypermethrin and Deltamethrin are the
most effective and with less toxicity. They must be conducted during the first 3 years
of planting, and involve 15% of the total costs of cultivating Cedrela spp. (Tapia
2012). Applications should be made from the first year of planting to obtain a trunk
length free of deformation of 3.5–4 m. The appropriate moment to start this treatment is defined by the insect population dynamics, and according to the abovementioned studies, it is commonly recommended from the second half of December
until February.
14 Breeding Strategy for the Cedrela Genus in Argentina