focused on enhancemant of early-season parasitism. In this regards selection or
breeding parasitoids with the lower thermal threshold for reproduction and development may be useful. Iranipour et al. (2010, 2015) compared two populations of
T. grandis and T. vassilievi respectively in terms of their thermal phenotypes. The
more detectable difference was observed in T. grandis. Reciprocal crosses between
two populations of the latter species revealed that thermal phenotypes are inheritable
and a maternal effect was observed. This may show that we can find, select or breed
parasitoids with superior traits among different populations and enhance early
season parasitism.
8.4 Augmentation Efforts
Applied biological control against sunn pest started in Varamin in 1941. An Iranian
entomologist (Kowsari) harvested parasitized eggs from an infested field in Garmsar
and then released them in an uninfested field in Varamin. The first augmentative
effort was carried out at 1947 in Varamin. However, due to inappropriate conditions
in Varamin (drought and absence of wide spread orchards and/or shade trees), the
control measurements was ceased and re-established in Isfahan. Reports showed
successful control in Isfahan in a time interval as long as nine years (1951–1959).
During this interval, pest density declined from 8 to 0.25/m
2 by releasing %779 million T. semistriatus (Safavi 1960). No artificial diet introduced for mass culture of
Trissolcus spp. Therefore, natural rearing method has been an obvious choice
(Alexandrov 1948b; Vaezi 1950). However, there was not a straightforward method
for the rearing of the host. Initial efforts were concentrated on rearing on grown
wheat plants. Sunn pest adults were collecting from their resting sites in altitudes
(2300 m ASL, Qara-aghach Mountains, Tehran province, 30 km distant to Varamin
wheat fields) which flew to find their resting sites during June in Varamin. Formerly
it was believed that such a flight is necessary for maturation of ovarioles. Hence,
scientists waited for migration toward mountains and then arranged a trip for
collecting aestivating adults in autumn. The collected individuals were kept in
boxes among debris to spend the remaining of their diapause. Finally, they were
reared on grown wheat and the obtained eggs were offered to parasitoids. Parasitized
eggs, as well as, adult wasps themselves were released in wheat fields at a rate of
10,000 wasps/4–5 adult bugs per m
2 . Furthermore, close field cages were used for
rearing both the host and parasitoids in wheat fields and then parasitoids were
released via small windows with fine mesh to permit wasps only to leave the cage.
Approximately 500,000 parasitoids per a cage (2 Â 1.2 Â 0.3 m) can be reared and
this quantity adequate pest control in 50–100 ha. Next efforts showed that flight is
not a necessity in terminating reproductive diapause and starting oogenesis.
Collecting from resting sites was difficult and this small modification accounted as
a large success (Safavi 1960). Adult bugs are collected in larger number and by
lower labour in wheat fields prior to emigration. Another improvement was rearing
on kernels instead grown plants. Higher reproductive output, lower costs and
312
S. Iranipour
breeding parasitoids with the lower thermal threshold for reproduction and development may be useful. Iranipour et al. (2010, 2015) compared two populations of
T. grandis and T. vassilievi respectively in terms of their thermal phenotypes. The
more detectable difference was observed in T. grandis. Reciprocal crosses between
two populations of the latter species revealed that thermal phenotypes are inheritable
and a maternal effect was observed. This may show that we can find, select or breed
parasitoids with superior traits among different populations and enhance early
season parasitism.
8.4 Augmentation Efforts
Applied biological control against sunn pest started in Varamin in 1941. An Iranian
entomologist (Kowsari) harvested parasitized eggs from an infested field in Garmsar
and then released them in an uninfested field in Varamin. The first augmentative
effort was carried out at 1947 in Varamin. However, due to inappropriate conditions
in Varamin (drought and absence of wide spread orchards and/or shade trees), the
control measurements was ceased and re-established in Isfahan. Reports showed
successful control in Isfahan in a time interval as long as nine years (1951–1959).
During this interval, pest density declined from 8 to 0.25/m
2 by releasing %779 million T. semistriatus (Safavi 1960). No artificial diet introduced for mass culture of
Trissolcus spp. Therefore, natural rearing method has been an obvious choice
(Alexandrov 1948b; Vaezi 1950). However, there was not a straightforward method
for the rearing of the host. Initial efforts were concentrated on rearing on grown
wheat plants. Sunn pest adults were collecting from their resting sites in altitudes
(2300 m ASL, Qara-aghach Mountains, Tehran province, 30 km distant to Varamin
wheat fields) which flew to find their resting sites during June in Varamin. Formerly
it was believed that such a flight is necessary for maturation of ovarioles. Hence,
scientists waited for migration toward mountains and then arranged a trip for
collecting aestivating adults in autumn. The collected individuals were kept in
boxes among debris to spend the remaining of their diapause. Finally, they were
reared on grown wheat and the obtained eggs were offered to parasitoids. Parasitized
eggs, as well as, adult wasps themselves were released in wheat fields at a rate of
10,000 wasps/4–5 adult bugs per m
2 . Furthermore, close field cages were used for
rearing both the host and parasitoids in wheat fields and then parasitoids were
released via small windows with fine mesh to permit wasps only to leave the cage.
Approximately 500,000 parasitoids per a cage (2 Â 1.2 Â 0.3 m) can be reared and
this quantity adequate pest control in 50–100 ha. Next efforts showed that flight is
not a necessity in terminating reproductive diapause and starting oogenesis.
Collecting from resting sites was difficult and this small modification accounted as
a large success (Safavi 1960). Adult bugs are collected in larger number and by
lower labour in wheat fields prior to emigration. Another improvement was rearing
on kernels instead grown plants. Higher reproductive output, lower costs and
312
S. Iranipour