Ahmadpour et al. (2013) obtained four adults of both species of O. telenomicida and
O. fecundus emerged from an egg. In contrast O. pityocampae is rather a solitary and
telytokous species. Male progeny is very rare and just one male was recorded among
152 adult wasps. Also seldom more than one wasp can emerge from a single egg of
Eurygaster integriceps. The adults of the recent wasp are larger and it may be the
reason of solitary development of immature stages. Development in larger hosts has
not been examined. Majority of Ooencyrtus species are not host-specific and can
attack large number of moths’ and true bugs’ eggs. However, their host range is not
studied enough. Hyperparasitism on Trissolcus species also was reported (Safavi
1970). This is considered an undesirable property that may restrict application of
Ooencyrtus spp. against the cereal bugs. Furthermore Ooencyrtus species are poorer
parasitoids in comparison to platygastrid egg parasitoids of cereal bugs (see Chap. 8
for comparative biostatistics of both groups). This is due to lower fecundity, slower
development and polyphagy, which reduce overall impact of these wasps on target
hosts particularly E. integriceps. Often natural parasitism of these species does not
exceed 5% (Iranipour et al. 2011), although egg traps may be attacked by a higher
rate late season (Shafaei et al. 2011; Nozad-Bonab and Iranipour 2011). An explanation may be role of the other hosts during massive oviposition of the target host. In
other words, Ooencyrtus species may have other hosts that prefer them to target host
and just switch to target host late season when the other hosts are going to become
rare. In fact, except in West Azarbaijan province (Shafaei et al. 2011), no place else
Ooencyrtus species was observed early season and their early season activity in West
Azarbaijan province was very limited and ceased for a month. On the other hand,
cereal bugs also are going to terminate their oviposition late season. Hence, only few
eggs are available for parasitism.
Rafat et al. (2013a, b), Iranipour et al. (2013a, b) and Ahmadpour et al. (2013)
studied effects of superparasitism and gregarious development on life history,
functional response and aggregation of O. telenomicida and O. fecundus respectively. Life history studies on O. telenomicida revealed that two progenies within a
single host develop by the same rate that one progeny develops in similar unit. They
also have similar fecundity and no difference is present between twins and singletons
(Rafat et al. 2013a). Ahmadpour et al. (2013) extended this arguement to higher
superparasitism rates by O. fecundus i. e. triplets and quadruplets. Except development time and generation time, other statistics were affected by number of progenies
that shared a host egg. However, no difference was observed between twins and
singletons again.
Functional response studies revealed that parasitism rate was inversely density
dependent in O. telenomicida (Rafat et al. 2013b). On the other hand, superparasitism rate decreases by increasing host density. Taking into account that four progenies can develop in a single host egg, one can expect to achieve this extreme in lower
host/parasitoid rates. However, such a capacity never realizes. Safavi (1970) stated
that the reason is host feeding behavior of this parasitoids that pierce egg shells for
feeding and those eggs with several holes on egg shell became useless. In
O. fecundus, Iranipour et al. (2013a) showed that parasitism rate was 100% as
long as host density remained eight or less and only slightly decreased at density
220
S. Iranipour and N. Vaez
O. fecundus emerged from an egg. In contrast O. pityocampae is rather a solitary and
telytokous species. Male progeny is very rare and just one male was recorded among
152 adult wasps. Also seldom more than one wasp can emerge from a single egg of
Eurygaster integriceps. The adults of the recent wasp are larger and it may be the
reason of solitary development of immature stages. Development in larger hosts has
not been examined. Majority of Ooencyrtus species are not host-specific and can
attack large number of moths’ and true bugs’ eggs. However, their host range is not
studied enough. Hyperparasitism on Trissolcus species also was reported (Safavi
1970). This is considered an undesirable property that may restrict application of
Ooencyrtus spp. against the cereal bugs. Furthermore Ooencyrtus species are poorer
parasitoids in comparison to platygastrid egg parasitoids of cereal bugs (see Chap. 8
for comparative biostatistics of both groups). This is due to lower fecundity, slower
development and polyphagy, which reduce overall impact of these wasps on target
hosts particularly E. integriceps. Often natural parasitism of these species does not
exceed 5% (Iranipour et al. 2011), although egg traps may be attacked by a higher
rate late season (Shafaei et al. 2011; Nozad-Bonab and Iranipour 2011). An explanation may be role of the other hosts during massive oviposition of the target host. In
other words, Ooencyrtus species may have other hosts that prefer them to target host
and just switch to target host late season when the other hosts are going to become
rare. In fact, except in West Azarbaijan province (Shafaei et al. 2011), no place else
Ooencyrtus species was observed early season and their early season activity in West
Azarbaijan province was very limited and ceased for a month. On the other hand,
cereal bugs also are going to terminate their oviposition late season. Hence, only few
eggs are available for parasitism.
Rafat et al. (2013a, b), Iranipour et al. (2013a, b) and Ahmadpour et al. (2013)
studied effects of superparasitism and gregarious development on life history,
functional response and aggregation of O. telenomicida and O. fecundus respectively. Life history studies on O. telenomicida revealed that two progenies within a
single host develop by the same rate that one progeny develops in similar unit. They
also have similar fecundity and no difference is present between twins and singletons
(Rafat et al. 2013a). Ahmadpour et al. (2013) extended this arguement to higher
superparasitism rates by O. fecundus i. e. triplets and quadruplets. Except development time and generation time, other statistics were affected by number of progenies
that shared a host egg. However, no difference was observed between twins and
singletons again.
Functional response studies revealed that parasitism rate was inversely density
dependent in O. telenomicida (Rafat et al. 2013b). On the other hand, superparasitism rate decreases by increasing host density. Taking into account that four progenies can develop in a single host egg, one can expect to achieve this extreme in lower
host/parasitoid rates. However, such a capacity never realizes. Safavi (1970) stated
that the reason is host feeding behavior of this parasitoids that pierce egg shells for
feeding and those eggs with several holes on egg shell became useless. In
O. fecundus, Iranipour et al. (2013a) showed that parasitism rate was 100% as
long as host density remained eight or less and only slightly decreased at density
220
S. Iranipour and N. Vaez