T. vassilievi and T. grandis on E. integriceps (Sheikhmoss 2009),
T. megallocephalus on Nezara viridula (Awadalla 1996), Telenomus isis (Polaszek)
on Sesamia calamistis Hampson (Chabi-Olaye et al. 2001).
Host Storage Cold-stored host eggs also may decrease parasitoid efficiency in a
similar manner. In a similar study 0, 1, 2, 4, 6 and 8 week stored eggs were offered to
T. vassilievi females (BenaMolaei et al. 2015b). Many statistics remained unchanged
up to two weeks, but storing for longer times caused undesirable effects. Parasitism
decreased somewhat linearly at a rate of one less host egg parasitized per 8.5 days
storing at 4
C. Such trend predicts ceasing parasitism after 4 months. This prediction was true in Kivan and Kiliç’s (2005) studies on T. semistriatus. Cold-storage
had a stronger effect than fetal development on the development time of the
parasitoid. It caused four days (32%) delay in emergence following eight weeks
storing at the cold condition. Effect on emergence rate was more moderate (maximum 12% lower emergence). This trend also is true in T. semistriatus (Kivan and
Kiliç 2005), T. grandis and Telenomus chloropus (Asgari 1995). Sex ratio was high
(80–90%) prior to the first month of storage but beyond a month, it declined to
50–60%. Higher allocation of low-quality hosts to male progeny is a known
phenomenon among parasitoids (Wage 1986), particularly in T. grandis and
T. semistriatus (Gusev and Shmettser 1975). Anastatus bifasciatus Forcroy lay
only male eggs within E. integriceps eggs (Iranipour et al. 1998b). This is due to
the small size of these eggs. Total fecundity of T. vassilievi reached to 2/3 of control
(182 vs. 118) in eggs stored for 1.5 months at refrigerator. The detectible difference
was observed in the second week of storage. A continuous reduction in age-specific
oviposition was observed in fresh eggs and one week stored ones, whereas in
remaining treatments oviposition reached to a maximum at the end of the first
week (BenaMolaei et al. 2015b). Such pattern resembles those of the developed
host eggs (BenaMolaei et al. 2015a). The wasp size reduced -steeper in females- as
the duration of storage increased. The results of this research showed that host eggs
can store and used for two months with undesirable effects on parasitoids. The
higher rate of release (up to twice as many as parasitoids developed on fresh eggs)
may overcome the problem in inundation programs, but in research programs, it is
recommended to avoid more than two week stored eggs. Two week stored eggs may
cause biases <10%. Gusev and Shmettser (1975) obtained similar results with
T. grandis and T. semistriatus in response to cold-stored eggs. After 1.5 months,
sex ratio was affected and after 2 months emergence rate declined suddenly. In
addition, egg stored at 6 and À 20
C were suitable for two and four months
respectively (Kivan and Kiliç 2005). Previous works on telenomin wasps showed
that cold storage of wasps themselves had poor results (Asgari 1995; Foerster et al.
2004; Kodan and Gürkan 2004; Foerster and Doetzer 2006).
Competition
The behaviour of the parasitoid in a single-patch experiment cannot show all
behavioural components of a host-parasitoid system. A better understanding
achieves when experiments are conducted in conditions nearer to the real world.
Natural enemies often are foraging in a multi-patch environment while other
320
S. Iranipour
T. megallocephalus on Nezara viridula (Awadalla 1996), Telenomus isis (Polaszek)
on Sesamia calamistis Hampson (Chabi-Olaye et al. 2001).
Host Storage Cold-stored host eggs also may decrease parasitoid efficiency in a
similar manner. In a similar study 0, 1, 2, 4, 6 and 8 week stored eggs were offered to
T. vassilievi females (BenaMolaei et al. 2015b). Many statistics remained unchanged
up to two weeks, but storing for longer times caused undesirable effects. Parasitism
decreased somewhat linearly at a rate of one less host egg parasitized per 8.5 days
storing at 4
C. Such trend predicts ceasing parasitism after 4 months. This prediction was true in Kivan and Kiliç’s (2005) studies on T. semistriatus. Cold-storage
had a stronger effect than fetal development on the development time of the
parasitoid. It caused four days (32%) delay in emergence following eight weeks
storing at the cold condition. Effect on emergence rate was more moderate (maximum 12% lower emergence). This trend also is true in T. semistriatus (Kivan and
Kiliç 2005), T. grandis and Telenomus chloropus (Asgari 1995). Sex ratio was high
(80–90%) prior to the first month of storage but beyond a month, it declined to
50–60%. Higher allocation of low-quality hosts to male progeny is a known
phenomenon among parasitoids (Wage 1986), particularly in T. grandis and
T. semistriatus (Gusev and Shmettser 1975). Anastatus bifasciatus Forcroy lay
only male eggs within E. integriceps eggs (Iranipour et al. 1998b). This is due to
the small size of these eggs. Total fecundity of T. vassilievi reached to 2/3 of control
(182 vs. 118) in eggs stored for 1.5 months at refrigerator. The detectible difference
was observed in the second week of storage. A continuous reduction in age-specific
oviposition was observed in fresh eggs and one week stored ones, whereas in
remaining treatments oviposition reached to a maximum at the end of the first
week (BenaMolaei et al. 2015b). Such pattern resembles those of the developed
host eggs (BenaMolaei et al. 2015a). The wasp size reduced -steeper in females- as
the duration of storage increased. The results of this research showed that host eggs
can store and used for two months with undesirable effects on parasitoids. The
higher rate of release (up to twice as many as parasitoids developed on fresh eggs)
may overcome the problem in inundation programs, but in research programs, it is
recommended to avoid more than two week stored eggs. Two week stored eggs may
cause biases <10%. Gusev and Shmettser (1975) obtained similar results with
T. grandis and T. semistriatus in response to cold-stored eggs. After 1.5 months,
sex ratio was affected and after 2 months emergence rate declined suddenly. In
addition, egg stored at 6 and À 20
C were suitable for two and four months
respectively (Kivan and Kiliç 2005). Previous works on telenomin wasps showed
that cold storage of wasps themselves had poor results (Asgari 1995; Foerster et al.
2004; Kodan and Gürkan 2004; Foerster and Doetzer 2006).
Competition
The behaviour of the parasitoid in a single-patch experiment cannot show all
behavioural components of a host-parasitoid system. A better understanding
achieves when experiments are conducted in conditions nearer to the real world.
Natural enemies often are foraging in a multi-patch environment while other
320
S. Iranipour