pear, peach, cherry and olive trees. Its larvae are wood borers that make deep
tunnels, up to 50 cm, in the main branches and trunk of the tree where the main
damage occurs at phloem and xylem vessels of the tree. Damage causes weakness in
tree and attraction of bark beetles which finally resulted in tree death, especially in
the newly established orchards. In recent years, Z. pyrina has become the most
damaging pest of walnut trees in Iran, as already led to the uprooting of many walnut
groves in some area. The pest has one generation per 2 years, but moths and damages
appear every year. On the other hand, the flight period of the moths lasts about
3 months which a female adult can lays about 1000 eggs during this time, after
hatching, the larvae bore into twigs, branches, and trunks, so its monitoring and
control are extremely difficult (Kutinkova et al. 2006; Gharalari and Kolyai 2014).
Among natural enemies, EPNs have adapted for possible use in such hidden habitat.
Ashtari et al. (2011) started investigations toward development of EPNs against
the leopard moth borer begin with laboratory bioassays to determine EPNs pathogenicity, followed by comparisons of virulence among different microbial isolates or
strains. They used a native isolate of H. bacteriophora and commercial products of
S. carpocapsae and H. bacteriophora against the pest larvae in the laboratory
bioassays at the rate of 2000 IJs per larva in petri dish. In laboratory tests,
S. carpocapsae caused 100% mortality in 2nd, 3rd, and 4th instars larvae at 54, 30
and 36 h after treatment, respectively. Heterorhabditis bacteriophora induced 100%
mortality in 2nd, 3rd, and 4th instar larvae at 44, 40 and 52 h after treatment,
respectively. For field application, Ashtari et al. (2011) applied same strains/isolate
via injection of nematode suspensions, 2000 IJs per active hole, using a 60 cc plastic
syringe into the galleries bored in tree stems or branches. Ten days’ post application,
larvae of Z. pyrina were excerpted from the galleries using a wire, and the number of
alive and dead larva was determined. The result showed that both tested nematodes
at 2000 IJs/larva proved to be effective on the leopard moth borer larvae (Fig. 12.2).
Subsequently, Salari et al. (2014) evaluated the pathogenicity of S. carpocapsae
and H. bacteriophora on Z. pyrina in another study, including the plate and infested
branch assay in laboratory condition. The plate assay showed high virulence of both
EPNs against the larvae. The calculated values of LC 50 indicated that S. carpocapsae
was comparatively more virulent than H. bacteriophora against larvae. For the
branch test, infested branches with active holes were collected from walnut orchards
and transferred to the laboratory. Injection of 160 IJs/cm
2 of S. carpocapsae and
H. bacteriophora to the branch holes induced high mortality (more than 70%) on
pest larvae. Also, S. carpocapsae caused higher mortality in the larger larvae than
H. bacteriophora.
Currently, pheromone traps and occluding the holes created by the pest, through
applying a mixture of glue and fumigating pesticides, are practices that used in IPM
programs in walnut orchards. Hidden habitat like galleries inside the trees is considered as a most favorable environment for EPNs activity, though the EPNs
delivery method is not practical because it is time consuming and difficult; The
female leopard moth lays hundreds eggs which lead to many holes in a tree. On the
other hand, usually the height of branches of the walnut trees is a problem for the
operator. Maybe using hand-held lances for spraying branches is more practical in
494
J. Karimi and M. Hassani-Kakhki
tunnels, up to 50 cm, in the main branches and trunk of the tree where the main
damage occurs at phloem and xylem vessels of the tree. Damage causes weakness in
tree and attraction of bark beetles which finally resulted in tree death, especially in
the newly established orchards. In recent years, Z. pyrina has become the most
damaging pest of walnut trees in Iran, as already led to the uprooting of many walnut
groves in some area. The pest has one generation per 2 years, but moths and damages
appear every year. On the other hand, the flight period of the moths lasts about
3 months which a female adult can lays about 1000 eggs during this time, after
hatching, the larvae bore into twigs, branches, and trunks, so its monitoring and
control are extremely difficult (Kutinkova et al. 2006; Gharalari and Kolyai 2014).
Among natural enemies, EPNs have adapted for possible use in such hidden habitat.
Ashtari et al. (2011) started investigations toward development of EPNs against
the leopard moth borer begin with laboratory bioassays to determine EPNs pathogenicity, followed by comparisons of virulence among different microbial isolates or
strains. They used a native isolate of H. bacteriophora and commercial products of
S. carpocapsae and H. bacteriophora against the pest larvae in the laboratory
bioassays at the rate of 2000 IJs per larva in petri dish. In laboratory tests,
S. carpocapsae caused 100% mortality in 2nd, 3rd, and 4th instars larvae at 54, 30
and 36 h after treatment, respectively. Heterorhabditis bacteriophora induced 100%
mortality in 2nd, 3rd, and 4th instar larvae at 44, 40 and 52 h after treatment,
respectively. For field application, Ashtari et al. (2011) applied same strains/isolate
via injection of nematode suspensions, 2000 IJs per active hole, using a 60 cc plastic
syringe into the galleries bored in tree stems or branches. Ten days’ post application,
larvae of Z. pyrina were excerpted from the galleries using a wire, and the number of
alive and dead larva was determined. The result showed that both tested nematodes
at 2000 IJs/larva proved to be effective on the leopard moth borer larvae (Fig. 12.2).
Subsequently, Salari et al. (2014) evaluated the pathogenicity of S. carpocapsae
and H. bacteriophora on Z. pyrina in another study, including the plate and infested
branch assay in laboratory condition. The plate assay showed high virulence of both
EPNs against the larvae. The calculated values of LC 50 indicated that S. carpocapsae
was comparatively more virulent than H. bacteriophora against larvae. For the
branch test, infested branches with active holes were collected from walnut orchards
and transferred to the laboratory. Injection of 160 IJs/cm
2 of S. carpocapsae and
H. bacteriophora to the branch holes induced high mortality (more than 70%) on
pest larvae. Also, S. carpocapsae caused higher mortality in the larger larvae than
H. bacteriophora.
Currently, pheromone traps and occluding the holes created by the pest, through
applying a mixture of glue and fumigating pesticides, are practices that used in IPM
programs in walnut orchards. Hidden habitat like galleries inside the trees is considered as a most favorable environment for EPNs activity, though the EPNs
delivery method is not practical because it is time consuming and difficult; The
female leopard moth lays hundreds eggs which lead to many holes in a tree. On the
other hand, usually the height of branches of the walnut trees is a problem for the
operator. Maybe using hand-held lances for spraying branches is more practical in
494
J. Karimi and M. Hassani-Kakhki